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PubMed2005

Neural stem cell migration toward gliomas in vitro.

Various in vivo studies demonstrated a migration tendency of neural stem cells (NSCs) toward gliomas, making these cells a potential carrier for delivery of therapeutic genes to disseminated glioma cells. We analyzed which factors determine NSC migration and invasion in vitro. Conditioned media prepared from 10 different human glioma cell lines, as well as 13 different tumor-associated growth factors, were analyzed for their chemotactic effects on murine C17.2 NSCs. The growth factor receptor status was analyzed by reverse transcriptase-polymerase chain reaction. Invasion of NSCs into multicellular tumor spheroids generated from 10 glioma cell lines was quantified. NSCs displayed a heterogeneous migration pattern toward glioma spheroids as well as toward glioma-cell-conditioned medium. Chemotactic migration was stimulated up to fivefold by conditioned medium as compared to controls. In coculture assays, NSC invasion varied from single cell invasion into glioma spheroids to complete dissemination of NSCs into glioma spheroids of different cell lines. Among 13 different growth factors, scatter factor/hepatocyte growth factor (SF/HGF) was the most powerful chemoattractant for NSCs, inducing a 2.5-fold migration stimulation. An antibody against SF/HGF inhibited migratory stimulation induced by conditioned media. NSC migration can be stimulated by various growth factors, similar to glioma cell migration. The extent to which NSCs infiltrate three-dimensional glioma cell aggregates appears to depend on additional factors, which are likely to include cell-to-cell contacts and interaction with extracellular matrix proteins.

Animals↗
PubMed1997

Patterns of geographic mobility of persons with AIDS in Canada from time of AIDS index diagnosis to death.

OBJECTIVE: To characterize migration patterns of persons with AIDS in Canada during the period from AIDS diagnosis to death. DESIGN: Descriptive, population-based study. SETTING: Canada. PATIENTS: Canada's AIDS Case Reporting Surveillance System (ACRSS) was linked to deaths in the Canadian Mortality Data Base (CMDB). Probabilistic linkage was based on initials, date of birth, date of death, birthplace, and location at diagnosis and at death. Analysis was restricted to AIDS cases reported from Jan. 1, 1982, to Sept. 30, 1994, and to deaths reported from Jan. 1, 1982, to Dec. 31, 1992. MAIN OUTCOME MEASURES: Change in usual place of residence; migration rates by region and community size. RESULTS: A total of 5755 AIDS cases recorded in the ACRSS were linked to deaths in the CMDB. Of these linked cases, 5366 (93%) included information on province or territory of usual residence or community size. A total of 160 (3.0%) persons with AIDS changed their province or territory of residence between the time of their AIDS diagnosis and death. Multivariate analysis indicated that those who changed residences between AIDS index diagnosis and death were more likely than other persons with AIDS to live in provinces other than British Columbia, Ontario and Quebec (p < 0.001), to be diagnosed earlier (p = 0.004), to be younger (p < 0.001) and to be gay or bisexual (p = 0.042). CONCLUSIONS: Our analysis revealed that only a small proportion of persons changed their residence between AIDS diagnosis and death. Geographic mobility was the greatest among persons with AIDS residing outside of the regions where the overwhelming majority of persons with AIDS in this country reside.

Acquired Immunodeficiency Syndrome↗
PubMed1998

Community mobility and public school enrollments.

"This paper has two related purposes. The first is to present an argument for the systematic use of public school enrollments data to study family mobility at the community level. The second is to demonstrate the utility of these data for mobility research. This is accomplished with case studies, chosen for distinctive patterns of movement which have produced observed changes in enrollments data, and which correspond to migration patterns of interest to research. The case studies are illustrative of the potential for the use of these data to illuminate patterns of movement that might otherwise go largely undetected."

Americas↗
PubMed1990

Timing and patterns of astrocyte migration from xenogeneic transplants of the cortex and corpus callosum.

The timing, pattern, and pathway of astrocyte migration were investigated in vivo by transplantation of CD-1 mouse cerebral cortex (E13-14) or corpus callosum (P2-3) into neonatal rat cortex. A monoclonal antibody specific for a mouse astrocyte surface antigen (M2) was used to identify the location of the grafts and the migrated donor astrocytes. Within the host cortex, astrocytes from cortical grafts began migration at post-transplantation day (PTD) 7. Over the next 4 days, the most distant displaced donor cells were found progressively further away from the grafts, migrating at a rate of about 220 microns/day. After PTD 11, the migration rate for the farthest displaced donor cells slowed to 25 microns/day, and the cells appeared to stop at about PTD 16 at a distance of 1,100 microns from the edge of the graft. Astrocytes had a faster migration speed in the white matter and covered a longer distance (5 mm) than those in the gray matter, extending on occasion into the contralateral hemisphere. The patterns of astrocyte migration differed depending on local cues around the transplant. Donor astrocytes that had been implanted into the host cortex migrated toward the host cortical surface, sometimes in several radial lines. Astrocytes from grafts, especially callosal grafts, placed in the subcortical white matter migrated along the host fiber tracts. Many astrocytes transplanted into the hippocampus formed laminar patterns close to the hippocampal neuronal layers. These results suggest that the direction, pattern, and speed of astrocyte migration are influenced by local substrates in the host brain.

Animals↗
PubMed1990

Elderly Hispanic migration in the United States.

The specific aim of this study was to extend the analysis of migration patterns to Hispanics (Mexican, Cuban, Puerto Rican, and Other Hispanic) over the age of 60. The 1980 Census public use sample provided the data for this study, which was structured by four research expectations derived from features of the Hispanic population and from migration concepts. First, because of population growth, migration from abroad was expected to be heavy, and about half came from abroad. Second, because of the pattern of Hispanic population concentration and the different settlement patterns of the four subgroups, a relatively small migration system with distinct subsystems for the four nationality groups was expected and found. Florida is the major ethnomagnet. Third, traditional family values, as reflected in dependent living arrangements, were expected to be more prevalent among migrants from abroad, and they were. Finally, returning to one's state of birth was highest among Mexican interstate migrants, as expected.

Aged↗
PubMed1995

Immigration impacts on internal migration of the poor: 1990 census evidence for U.S. states.

"This article presents newly-available migration data from the 1990 U.S. census to assess immigration and internal migration components as they affect state poverty populations. New immigrant waves are heavily focused on only a few 'port-of-entry' states. It is suggested that these immigrants have begun to impact upon internal migration into and out of these 'high immigration states', and have also altered the national system of internal migration patterns. This article addresses three questions: How do the magnitudes of poverty population out-migration from high immigration states compare with those of other states? Is this out-migration selective on particular social and demographic groups? Is immigration a significant determinant of internal migration of the poor population? The results of this analysis are consistent with the view that recent, focused immigration is associated with out-migration among a state's poor longer-term residents."

Americas↗
PubMed1994

Diel Migrations of Microorganisms within a Benthic, Hypersaline Mat Community.

We studied the diel migrations of several species of microorganisms in a hypersaline, layered microbial mat. The migrations were quantified by repeated coring of the mat with glass capillary tubes. The resulting minicores were microscopically analyzed by using bright-field and epifluorescence (visible and infrared) microscopy to determine depths of coherent layers and were later dissected to determine direct microscopic counts of microorganisms. Microelectrode measurements of oxygen concentration, fiber optic microprobe measurements of light penetration within the mat, and incident irradiance measurements accompanied the minicore sampling. In addition, pigment content, photosynthesis and irradiance responses, the capacity for anoxygenic photosynthesis, and gliding speeds were determined for the migrating cyanobacteria. Heavily pigmented Oscillatoria sp. and Spirulina cf. subsalsa migrated downward into the mat during the early morning and remained deep until dusk, when upward migration occurred. The mean depth of the migration (not more than 0.4 to 0.5 mm) was directly correlated with the incident irradiance over the mat surface. We estimated that light intensity at the upper boundary of the migrating cyanobacteria was attenuated to such an extent that photoinhibition was effectively avoided but that intensities which saturated photosynthesis were maintained through most of the daylight hours. Light was a cue of paramount importance in triggering and modulating the migration of the cyanobacteria, even though the migrating phenomenon could not be explained solely in terms of a light response. We failed to detect diel migration patterns for other cyanobacterial species and filamentous anoxyphotobacteria. The sulfide-oxidizing bacterium Beggiatoa sp. migrated as a band that followed low oxygen concentrations within the mat during daylight hours. During the nighttime, part of this population migrated toward the mat surface, but a significant proportion remained deep.

Journal Article↗
PubMed1986

[The new migratory deal in Southern Europe].

The author examines migration patterns in Southern Europe during the 1970s and early 1980s, noting particularly the reduction in migration northward from this region. It is noted that "departure potential remains sizable in certain areas of Portugal, Spain, Southern Italy, and most particularly, of Turkey and Yugoslavia. Transoceanic migrations have by no means ceased, as new flows of skilled labor have, since 1974, gone towards Arab states endowed with petrol (oil) revenues. And yet, the paramount fact is most surely the emergence and the proliferation in Greece, Spain, and (especially) in Italy, of basically clandestine (illegal) immigration. This movement is due to the convergence of several factors: economic and demographic disparities between northern and southern shores of the Mediterranean Sea, the sealing-off of borders in Northwestern Europe and the 'carry-over' effect upon nations of 'transit', the extent of the flow of refugees, and--most particularly--the appeal provided by the development, in these new employer countries, of an underground economy accompanied by the extension into industry of the practice of 'undeclared' work. And notwithstanding the series of rules lastly drawn up in Spain and in Greece, such forms of clandestine (unauthorized) migration appear highly likely--to say the least--to persist." (SUMMARY IN ENG AND SPA)

Africa↗
PubMed1991

Patterns of epithelial migration in the unaffected ear in patients with a history of unilateral cholesteatoma.

Epithelial migration in a centrifugal manner is an established phenomenon in the normal human tympanic membrane. This pattern of migration is symmetrical in both ears of any one individual. We present a prospective study on the pattern of tympanic ink dot migration on the normal drum, in patients with a history of cholesteatoma in one ear. It was demonstrated that patients who develop cholesteatoma have a normal migratory pattern and rate in the unaffected ear. The conclusion from this study is that defective migration is not the initiating factor in the development of acquired cholesteatoma.

Cell Movement↗
PubMedDate not supplied

Selective role of vagal and nonvagal innervation in initiation and coordination of gastric and small bowel patterns of interdigestive and postprandial motility.

Our previous studies suggested that extrinsic innervation modulates upper gut motility but is not requisite for cyclic interdigestive and postprandial motility of the stomach. However, the specific role of vagal and nonvagal extrinsic innervation in the initiation, coordination, and pattern of gastric motility in dogs after denervation of the entire upper gastrointestinal tract remains unclear. The aim of this study was to determine the role of vagal and nonvagal extrinsic innervation in control of gastric motility patterns. Mongrel dogs were subjected first to extrinsic denervation (in situ neural isolation) of the stomach, small bowel, proximal colon, liver, and pancreas but specifically maintaining vagal innervation to the stomach alone. After fasting and fed motility patterns were measured with indwelling gastric and small bowel manometry catheters, the dogs underwent transthoracic truncal vagotomy (completion of total extrinsic denervation of stomach), and motility studies were repeated. Vagal integrity to the stomach and pancreas was confirmed by means of a modified Hollander test and serum pancreatic polypeptide concentrations after the injection of exogenous insulin, respectively. We found that a cyclic motility pattern (migrating motor complex) persisted during fasting in both the stomach and the small bowel and that the patterns of the stomach and the duodenum remained temporally coordinated before and after vagotomy. However, although a cyclic phase III activity persisted in the stomach after vagotomy, the number of contractions and the motility index during phase III were decreased, and the duration between groupings of contractions was increased. No differences were noted in the duration of postprandial inhibition after feeding meals before and after vagotomy. These observations support our hypothesis that the vagal nerves are not necessary for the initiation or temporal coordination of global fasting or postprandial gastroduodenal motility patterns but are involved in modulating the pattern of contractions during gastric phase III.

Animals↗
PubMed1994

The turnaround in Australia: some first observations from the 1991 census.

"The aim of this paper is to utilise recently released census results to examine patterns of population change in non-metropolitan Australia during the 1986-91 period, focusing particularly upon the net migration component of that change. The paper presents an overview of recent trends in population change in non-metropolitan areas and then moves to an analysis of net migration patterns in non-metropolitan local government areas during the late 1980s using a Life Table Survival Ratio technique to estimate net migration. It appears that the trends observed in the early 1980s have continued into the late 1980s and early 1990s, and that overall the 'turnaround' is slowing down and becoming more diversified, more complex, and much less predictable in the 1990s."

Australia↗
PubMed1985

Migration during early married life.

"A one percent sample drawn from the 1971 Census (the OPCS Longitudinal Study) [of England and Wales] was used to study the migration patterns of women in the early years of first marriage. Information from the retrospective fertility and migration history contained in the 1971 Census record was analyzed and the results show migration at, or soon after, marriage to be almost universal." The focus is on internal migration. Factors considered include marriage duration, age, husband's occupation, and timing of births. The value of the OPCS Longitudinal Study as a source of migration data is noted. (summary in FRE)

Age Factors↗
PubMed1980

Leukocyte migration enhancement as an indicator of immunologic enhancement. II. Malignancy.

Leukocyte migration studies were performed on 19 cancer patients and 24 control subjects. Amniotic fluid (AF) as well as autologous plasma (PL) were investigated. No difference in the migration pattern between patients and control subjects was observed with AF, but cancer patients showed significant leukocyte migration enhancement (LME) with PL when compared to control subjects (p less than 0.04). Among 18 cancer patients with persistent disease only three did not show significant LME. All three represented specifically immunodepressed states. None of the untreated group of cancer patients failed to show LME with autologous PL. It is concluded that, as in pregnancy, an immunologic active factor is present in PL of cancer patients which induces a specific subpopulation of leukocytes and thereby LME. The possible mechanism of activation is briefly discussed. Through the detection of LME leukocyte migration may become of importance for the early detection of malignancy and monitoring of treatment success.

Adenocarcinoma↗
PubMed2002

Histone H1 is phosphorylated in non-replicating and infective forms of Trypanosoma cruzi.

The nuclear structure changes during the differentiation from growing to infective stages of Trypanosoma cruzi. As histone modifications have been correlated with structural and functional changes of chromatin, we investigated whether histones in T. cruzi are modified during the life cycle of this protozoan parasite. We found that histone H1 isolated from proliferating forms (epimastigotes) and from differentiated/infective forms (trypomastigotes) have a distinct migrating pattern in Triton-acetic acid-urea gel electrophoresis. While epimastigotes contain predominantly a fast migrating form, a slow migrating band is prominent in trypomastigotes. By metabolically labeling the cells with radioactive phosphate, we demonstrated that the slow migrating histone H1 band is phosphorylated, and that after alkaline phosphatase treatment, it migrates as the fast form. Parasites arrested at the onset of the S phase of the cell cycle with hydroxyurea (HU) also predominantly have the phosphorylated form of histone H1, suggesting that phosphorylation occurs in non-replicating stages of T. cruzi. We also found that the phosphorylated histone H1 is more weakly associated with the chromatin, being preferentially released at 150 mM NaCl. Therefore, histone H1 phosphorylation varies during the life cycle of T. cruzi, and might be related to changes in the chromatin structure.

Alkaline Phosphatase↗
PubMed1987

Migration age profiles for local authority areas in England, 1971-1981.

"This paper is a report on continuing research on the application of age profiles in migration analysis. In particular, it is an update of previous work published in this journal with an analysis of 1981 Census data for local authority areas in England. The changes in migration patterns over the intercensal period from 1971 to 1981 are described." The focus is on internal migration

Age Factors↗
PubMed1985

Homozygosity, effective number of alleles, and interdeme differentiation in subdivided populations.

The amount and pattern of genetic variability in a geographically structured population at equilibrium under the joint action of migration, mutation, and random genetic drift is studied. The monoecious, diploid population is subdivided into panmictic colonies that exchange migrants. Self-fertilization does not occur; generations are discrete and nonoverlapping; the analysis is restricted to a single locus in the absence of selection; every allele mutates to new alleles at the same rate. It is shown that if the number of demes is finite and migration does not alter the deme sizes, then population subdivision produces interdeme differentiation and the mean homozygosity and the effective number of alleles exceed their panmictic values. A simple relation between the mean probability of identity and the mean homozygosity is established. The results apply to a dioecious population if the migration pattern and mutation rate are sex independent.

Alleles↗
PubMed1983

Proliferation and migration of rat incisor mesenchymal cells.

Sixty female Wistar rats were injected with tritiated thymidine and killed at intervals between 1 hr and 72 hr after injection. Autoradiographs of paraffin and Vestopal W embedded sagittal sections of the maxillary incisors were prepared. The distribution of labeled cells after 1 hr revealed the basal pulp cells and the preodontoblasts as proliferative cells. The growth rate of the incisor and the migration of the basal pulp cells were established from the position of labeled cells at 72 hr observation time. The number and localization of labeled and unlabeled mitoses were registered in order to determine the duration of the generation cycle of the proliferative cells. The identical cell generation time of preodontoblasts and basal pulp cells and the migration pattern of the latter indicate that the preodontoblasts are renewed by preodontoblast multiplication and not by migration of basal pulp cells.

Animals↗
PubMed1998

Migration and race in the southern United States.

"Using data from the 1985-1990 [U.S.] County-to-County Migration Flow Files..., which facilitate a disaggregated analysis of the effects of migration patterns on the extent of black concentration in the South, this paper analyzes and assesses how migration to and from the South has affected the distribution of blacks and whites in both metropolitan and nonmetropolitan areas."

Black or African American↗