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PubMed2002

Discriminating the loosening behaviour of cemented hip prostheses using measurements of migration and inducible displacement.

In vitro pre-clinical tests of hip prostheses have not yet been developed to the extent that inferior prostheses can be 'screened-out' prior to animal or clinical trials. This paper reports the experimental part of a project to develop a pre-clinical testing platform for cemented femoral hip implants. It is based on the clinical observation (Kärrholm et al. JBJS, 76B (1994) 912-916) that higher subsidence (distal migration) correlates with early revision of hip prostheses. A protocol to measure the relative movement between implant and bone was designed to test whether or not such a measurement, if made in a laboratory, could discriminate between hip prostheses. The protocol was applied to the Lubinus SPII prosthesis (W. Link, Germany) and a Müller Curved Stem (JRI Ltd., UK)-these prostheses were chosen because they are known to have different loosening rates in vivo. Five prostheses of each design were tested. The migration, the rate-of-migration, and the inducible displacement of each prosthesis was recorded over two million cycles of loading. For each implant, rapid initial migration was found, followed by a period of steady-state migration. In the majority of cases, the prostheses migrated medially, distally and posteriorly. On average, the Lubinus migrated less than the Müller in all directions. The average Lubinus migration was less than half that of the Müller, and this difference was significant at a level of p=0.05. Inducible displacement was greater for the Müller compared to the Lubinus. Furthermore, the inducible displacement decreased over time for the majority of Lubinus prostheses whereas it increased over time for the majority of the Müller prostheses leading to the conclusion that a rapid pre-clinical test based on measurement of inducible displacement may be possible.

Bone Cements↗
PubMed2004

Magnification and toxicity of PCBs, PCDDs, and PCDFs in upriver-migrating Pacific salmon.

The depletion of lipids associated with pre-spawning migration of Pacific salmon has the potential to magnify concentrations of hydrophobic organic contaminants (HOCs), which elevates risk of toxic effects. We present data from a field study of sockeye salmon (Oncorhynchus nerka) migrating to spawn in Great Central Lake, BC, which demonstrate that pre-spawning migration causes a magnification of PCB, PCDD, and PCDF concentrations in female gonads (1.9-2.5-fold), female soma (3.4-5.6-fold), and male soma (5.6-9.7-fold). We further develop a model of prespawning migration chemical magnification for sockeye salmon stocks as a function of migration distance. This model is shown to be consistent with available empirical data on pre-spawning magnification and predicts magnification factors ranging between 1.4 and 7.9 in gonad and between 1.6 and 10.4 in soma in seven Pacific salmon stocks in British Columbia. Post-migration (prespawning) toxic equivalent dioxin concentrations in roe were measured to be approximately 3 pg/g lipid in salmon from the Great Central Lake sockeye stock and estimated to range between 1.5 pg/g lipid for the shortest-migrating stocks and 7 pg/g lipid for the longest-migrating stocks. Concentrations in certain stocks approach or exceed the concentration of 3 pg/g lipid associated with 30% egg mortality in Oncorhynchus mykiss. This indicates the potential for population-level effects of current contaminant levels. It also suggests that historic contaminant concentrations, which were greater than current concentrations, may have contributed significantly to the decline of certain Pacific salmon stocks in British Columbia.

Animal Migration↗
PubMed2003

Macrophage migration inhibitory factor exhibits a pronounced circadian rhythm relevant to its role as a glucocorticoid counter-regulator.

In humans, maximal expression of T helper 1 cytokines coincide with the nocturnal nadir of plasma cortisol, whereas T helper 2 cytokine responses are dominant during day-time. The pro-inflammatory cytokine, macrophage migration inhibitory factor counter-regulates glucocorticoid-mediated immune suppression. To determine the relationship between cortisol and macrophage migration inhibitory factor, healthy volunteers had blood drawn hourly for 24 h for measurement of plasma cortisol and basal- and stimulated-macrophage migration inhibitory factor. Similar to cortisol, macrophage migration inhibitory factor peaked during the late morning whereas interferon-gamma, tumour necrosis factor-alpha, interleukin-1 and interleukin-12 demonstrated a nocturnal peak. After oral cortisone, plasma macrophage migration inhibitory factor rose 2-4-fold, whereas the other cytokines decreased. There was no correlation between cortisol during the insulin tolerance test and plasma macrophage migration inhibitory factor. The late morning peak of macrophage migration inhibitory factor, by antagonizing cortisol-mediated pro-inflammatory cytokine suppression may prolong the duration of early morning inflammation. These observations explain the beneficial role of macrophage migration inhibitory factor neutralization in models of inflammatory arthritis.

Adult↗
PubMed1974

Migration enhancement factor: a new lymphokine.

Production of human migration inhibitory factor by lymphocytes exposed to antigen was studied at intervals over a 7-day period. Migration inhibitory factor was measured by an agarose gel method, with buffycoat leukocytes as indicator cells. Lymphocyte supernatants from 7-day cultures consistently showed migration inhibitory factor activity; by contrast, enhancement of migration was frequently noted when effector cells were exposed to supernatants from 2- to 5-day cultures. Enhancement activity was manifested either by enhanced migration or by a sequential reduction in inhibitory activity consistent with a factor opposing the action of migration inhibitory factor. When supernatants were subjected to polyacrylamide gel electrophoresis, enhancement activity was regularly found in the beta-globulin region and migration inhibitory factor in the albumin fraction of the gel. The enhancement activity was heat-stable and nondialyzable. These findings characterize a hitherto unreported lymphokine, migration enhancement factor.

Cell Migration Inhibition↗
PubMed2006

Migration dynamics for the ideal free distribution.

This article verifies that the ideal free distribution (IFD) is evolutionarily stable, provided the payoff in each patch decreases with an increasing number of individuals. General frequency-dependent models of migratory dynamics that differ in the degree of animal omniscience are then developed. These models do not exclude migration at the IFD where balanced dispersal emerges. It is shown that the population distribution converges to the IFD even when animals are nonideal (i.e., they do not know the quality of all patches). In particular, the IFD emerges when animals never migrate from patches with a higher payoff to patches with a lower payoff and when some animals always migrate to the best patch. It is shown that some random migration does not necessarily lead to undermatching, provided migration occurs at the IFD. The effect of population dynamics on the IFD (and vice versa) is analyzed. Without any migration, it is shown that population dynamics alone drive the population distribution to the IFD. If animal migration tends (for each fixed population size) to the IFD, then the combined migration-population dynamics evolve to the population IFD independent of the two timescales (i.e., behavioral vs. population).

Animal Migration↗
PubMed1981

Leukocyte migration inhibition factor production in marasmic infants.

Production of leukocyte migration inhibition factor was measured in vitro with purified protein derivative and phytohemagglutinin in 14 marasmic infants 6 to 18 months of age. Twenty-seven well-nourished infants served as controls. All the children had received BCG vaccine in the neonatal period. Tuberculin reaction was positive in four of 14 of the marasmic infants and 13 of 27 of the controls. When leukocyte migration inhibition factor was induced with purified protein derivative, the four tuberculin positive malnourished subjects had a mean migration inhibition index of 55.7% which was significantly higher than the mean migration inhibition index of 38.2% in the tuberculin positive controls. In the tuberculin negative subjects the mean migration inhibition index was 24.7 and 16.6% in the marasmic and control groups, respectively. The difference was not statistically significant. Phytohemagglutinin-induced migration inhibition was comparable in malnourished and control infants. There was no correlation between leukocyte migration inhibition factor production and biochemical indices of iron nutrition, erythrocyte or serum folate, vitamin A, carotene, or serum zinc levels in either group. It is suggested the capacity of lymphocytes to produce leukocyte migration inhibition factor is unchanged in marasmus.

Blood Proteins↗
PubMedDate not supplied

Inhibition of lens epithelial cell migration by an acrylic intraocular lens in vitro.

We developed a new in vitro system to evaluate the effect of intraocular lenses (IOLs) on the migration of lens epithelial cells (LECs) and determined how acrylic and other IOLs influence LEC migration using this model. In an in vitro system, porcine LECs were cultured in a cell culture chamber insert, containing a collagen membrane, for 10 days with no IOL or with various types of IOLs. Migration of LECs beneath each IOL optic was observed with an inverted-phase microscope. The cell-free areas under the IOL optic, where the LECs had not migrated, were measured. Without IOL, LECs completely covered the collagen membrane within 5 days after plating (5.0 +/- 0.0 days). Complete coverage was slowed by a silicone IOL (6.7 +/- 1.2 days, p = 0.0305). LECs cultured with acrylic or with round- or sharp-edged polymethylmethacrylate (PMMA) IOLs did not completely cover the area. Ten days after initiating cultures, the cell-free areas under IOLs with sharp edges (acrylic, 41.1 +/- 8.0%; sharp-edged PMMA, 60.9 +/- 39.0%) were significantly larger than under IOLs with round edges (silicone, 0.0 +/- 0.0%; round-edged PMMA, 1.5 +/- 1.2%). A sharp edge may act as a barrier to LEC migration. Moreover, LEC migration under the acrylic IOL slowed after the LECs had crossed the barrier of the optic edge, perhaps due to acrylic adhesive properties. Only a few LECs reached the collagen membrane beneath the central 3 mm of the acrylic IOL. This new in vitro model was useful in evaluating the effect of various IOLs on LEC migration. Acrylic IOLs inhibited LEC migration by not only a sharp edge but also other factors, such as adhesive properties.

Acrylic Resins↗
PubMed2005

Modeling of the migration of the European glass eel.

The characteristics of glass eel migration at the mouth of river Bojana have been investigated by seasonal field studies from February to April 1998. Samples were collected by two fyke nets, one on each riverside, for 12 hours each night. A total of about 3,300 individuals were caught. In this work we present the results obtained from three successive migration waves in 1998. The data obtained on the number of eels caught during one migration wave, as a function of time, had two components: a bell-shaped curve, lasting 7-14 days, over which an impulse (sudden burst in the number of caught eels, during 1-2 days) was observed. We propose a mathematical model for total number of captured eels within one migration wave. Impulse components were observed during the first and second migration waves. After their removal, the remaining experimental data of the three migration waves were fitted with normal distribution functions. A decrease in the values of fitting parameters as a function of time (migration wave number) was obtained. Our data indicate multiple causes for the observed migration waves.

Animal Migration↗
PubMed2000

TNF-alpha associated with extracellular matrix fibronectin provides a stop signal for chemotactically migrating T cells.

The migration of T cells into extravascular sites of inflammation is regulated by information derived from the molecular structure of the invaded tissue and from chemokine and cytokine gradients in the context of the extracellular matrix (ECM). Although recent studies have highlighted the role of particular chemoattractants in leukocyte migration, to date little is known about how specific combinations of contextual signals control the migration of leukocytes and their localization at sites of inflammation. Here we studied the interplay between a pleiotropic cytokine, TNF-alpha, and two prototypic chemoattractants, RANTES and stromal cell-derived factor-1alpha (SDF-1alpha), on human CD45RO+ T cells migrating within an ECM-like context. For this purpose, we used a newly constructed three-dimensional gel system designed to follow, in real time, the migration of individual leukocytes along chemotactic gradients in vitro. We found that TNF-alpha, which binds the ECM protein fibronectin and lacks adhesion- and migration-promoting effects of its own, can act as a proadhesive cytokine on T cells exposed to RANTES and SDF-1alpha. Furthermore, fibronectin-complexed TNF-alpha provided anchorage signals to the T cells as they moved directionally along chemoattractive gradients. This effect of TNF-alpha required an intact TNF-alpha receptor II subtype on the migrating T cells. The anchoring effect of TNF-alpha appears to be specific; IL-2, an integrin-activating proadhesive cytokine, does not transmit stoppage signals to T cell migration induced by RANTES. Thus, TNF-alpha present in the ECM at sites of inflammation may function to anchor T cells recruited to these sites by chemotactic signals.

Adjuvants, Immunologic↗
PubMed1999

Transendothelial migration of lymphocytes in chronic lymphocytic leukaemia is impaired and involved down-regulation of both L-selectin and CD23.

Chronic lymphocytic leukaemia (B-CLL) is characterized by a progressive accumulation of B lymphocytes in blood and bone marrow and high concentrations of soluble CD23 and L-selectin are found in the serum of these patients. In this study lymphocytes from normal subjects and patients with B-CLL were allowed to undergo transendothelial migration across confluent layers of human umbilical vein endothelial cells. Lymphocytes in B-CLL samples showed an impaired capacity to migrate while the minor proportion of normal T cells was enriched by a mean of 2.5-fold in the transmigrated lymphocytes. In contrast, the ratio of B to T lymphocytes in normal preparations was unchanged in the transmigrated population. The expression of adhesion molecules on B-CLL lymphocytes before and after transendothelial migration was studied by flow cytometry which showed that 71 +/- 5% of L-selectin was lost from the surface of transmigrated lymphocytes. T and B cells from normal subjects also showed a major loss of L-selectin after transmigration. B-CLL lymphocytes and normal B cells expressed CD23 but this molecule was down-regulated following transendothelial migration, whereas the expression of VLA-4, ICAM-1, LFA-1 and CD44 was unchanged. Lymphocytes incubated with oxidized ATP, an irreversible inhibitor of P2Z/P2X7 purinoceptors, retained their capacity for transendothelial migration and showed the same loss of L-selectin as control leukaemic lymphocytes. Our results show that B-CLL lymphocytes have impaired ability for transendothelial migration compared to normal peripheral blood lymphocytes. Moreover, transendothelial migration involves a universal loss of L-selectin and CD23 from lymphocytes which suggests that the high serum levels of soluble L-selectin and CD23 observed in B-CLL may be generated by shedding during the process of transendothelial migration.

B-Lymphocytes↗
PubMed2000

The role of peritoneal dialysis catheter configuration in preventing catheter tip migration.

Migration of the peritoneal dialysis (PD) catheter from the pelvis to the upper abdomen frequently results in peritoneal dialysis failure and removal of the catheter. Previous studies compared PD catheter survival in various catheter configurations. These studies included single-cuff and double-cuff, straight-end and curled-end catheters, and showed an incidence of catheter migration ranging from 5%-35% depending on the catheter type. Recent studies demonstrated that the double-cuff, Swan-neck, curled-end configuration is associated with a considerably lower incidence of migration. Most of these studies, however, had a small patient sample or no control group, or they compared nonequivalent catheters (for example, Swan-neck, curled-end versus straight, non-curled-end). Over a six-year period, we examined two similar double-cuff, curled-end catheters: Group I catheters had a straight segment between the two cuffs, and Group II catheters had a 60 degrees Swan-neck bend between the two cuffs (Quinton Instrument Co., Bothell, WA, U.S.A.). The two catheters were identical, except for the presence or absence of the Swan-neck bend. All catheters were placed by the closed laparoscopic technique. In the two groups of patients in whom the catheters were implanted, no statistically significant difference was observed in primary disease, age, sex, race, weight, prior abdominal surgery, or duration of dialysis before catheter migration. In group I, 33 of the 219 patients developed catheter migration (15%); in group II, 2 patients of 243 patients developed catheter migration (less than 1%, p = 0.002). In conclusion, the Swan-neck configuration presents an independent factor in preventing PD catheter migration. Review of previous studies and the data from our study, show that double-cuff, curled-end, Swan-neck PD catheters are superior to other catheters in regard to prevention of catheter migration and should be the catheter of choice in PD patients.

Adolescent↗
PubMedDate not supplied

[Incidence and relation of endoscopic sphincterotomy to the proximal migration of biliary prostheses].

BACKGROUND: Endoprostheses are commonly used in the treatment of biliary disorders. The frequency of and potential risk factors for stent migration, however, remain largely unknown. OBJECTIVE: To determine how often biliary duct stents migrate proximally and to quantify the influence of specific risk factors on the occurrence of stent migration. PATIENTS METHODS AND RESULTS: We analyzed the occurrence of stent migration among the 410 stents for which follow-up data were available between January 1995 to December 1998. In 272 cases, we performed endoscopic sphincterotomy. Results demonstrated incidence rates of 4.4% for proximal biliary stent migration iatrogenic strictures were significantly associated with proximal biliary stent migration. CONCLUSIONS: Iatrogenic strictures were significantly associated with proximal common bile duct migration and the association between sphincterotomy and proximal migration failed to reach statistical significance.

Bile Ducts↗
PubMed1976

Studies on delayed hypersensitivity pleural exudates in guinea-pigs. II. The interrelationship of monocytic and lymphocytic cells with respect to migration activity.

The in vitro migration activity of monocytic cells and the effect of lymphocytes in the delayed hypersensitivity (DH) reaction induced by intrapleural injection of PPD into FCA-sensitized guinea-pigs was investigated. The in vitro migration of exudate mononuclear cells was lower than that of comparable blood cells, and continued to decrease as the reaction progressed. An inverse relaationship was observed between the migration area and cell volume of mononuclear cells from both blood and exudate. Similar experiments were performed on the reversed passive Arthus (RPA) reaction in the pleural cavity of guinea-pigs. For 6-h exudate, the mononuclear cell migration exceeded that for blood mononuclear cells. However, the migration of mononuclear cells from 18-h exudates was markedly reduced. As with DH, an inverse relationship between the migration area and cell volume was observed with the mononuclear cells of RPA exudates. Following the addition of antigen, the migration of DH exudate mononuclear cells was inhibited whereas the exudate mononuclear cells of the RPA reaction remained unaffected. For DH, the inhibition of migration induced by antigen appeared to be related to the non-adherent cells of 6-h exudates, and both the adherent and non-adherent cells of 18-h exudates.

Animals↗
PubMed2005

Evolution of migration under kin selection and local adaptation.

We present here a stochastic two-locus, two-habitat model for the evolution of migration with local adaptation and kin selection. One locus determines the migration rate while the other causes local adaptation. We show that the opposing forces of kin competition and local adaptation can lead to the existence of one or two convergence stable migration rates, notably depending on the recombination rate between the two loci. We show that linkage between migration and local adaptation loci has two antagonist effects: when linkage is tight, cost of local adaptation increases, leading to smaller equilibrium migration rates. However, when linkage is tighter, the population structure at the migration locus tends to be very high because of the indirect selection, and thus equilibrium migration rates increases. This result, qualitatively different from results obtained with other models of migration evolution, indicates that ignoring drift or the detail of the genetic architecture may lead to incorrect conclusions.

Adaptation, Biological↗
PubMed1978

Migration inhibition of T lymphocytes from human peripheral blood by specific antigen and lymphokines.

The inhibition of migration of human peripheral blood cells in the presence of PPD was studied. It was found that migration inhibition of peripheral blood mononuclear cells (MN) from Mantoux-positive donors was far greater than the migration inhibition of peripheral blood leucocytes (PBL). Moreover, MN cells and T lymphocytes showed larger and more uniform areas of migration. In contrast, the migration of B lymphocytes and monocytes was poor. Further analysis using purified subpopulations of MN cells showed that PPD inhibited the migration of T lymphocytes but not of B lymphocytes and monocytes. Corresponding to these findings, lymphokine-containing supernatants also inhibited the migration of purified T cells from Matoux-negative donors. It was concluded that the T lymphocyte was the predominant cell in the MN cell population, which migrated, and was subject to inhibition by PPD or lymphokines. These results imply that the movement of human T lymphocytes may be influenced by soluble factors from antigen-activated sensitized cells.

Adult↗
PubMed1997

Interregional migration in socialist countries: the case of China.

"This paper analyzes changing interregional migration in China and reveals that the recent eastward migration reverses patterns of migration under Mao. It finds that investment variables are more important than the conventional variables of income and job opportunities in determining China's recent interregional migration. It suggests that both state policy and the global force influence interregional migration, challenging the popular view that the socialist state is the only critical determinant. This paper also criticizes Mao's approach to interregional migration and discusses the impact of migration on development."

Asia↗
PubMed1996

A model of temporary migration: the Egyptian case.

"In this article, a family migration model is introduced where differences in regional amenities and wage rates can result in voluntary, temporary migration. A household production model of temporary migration will be developed and tested to analyse Egyptian temporary migration to the Gulf region. The theoretical model will be a two-period model of temporary migration and will be empirically tested using the well known and comprehensive 1982 Egyptian Fertility Survey, which is part of the World Fertility Survey and covers a period for which temporary migration from Egypt was at or near its peak. This was also before the Gulf War, after which patterns of migration were different." (SUMMARY IN FRE AND SPA)

Africa↗
PubMed1991

Determinants of migration in the Nordic labor market.

"Migration flows in the integrated Nordic labor market are heavily dominated by Finnish migration to Sweden. Differences in migration behavior across the Nordic populations are identified. Elasticities of migration are obtained from a logistic human capital model estimated as seemingly unrelated regressions. Differences in migration behavior are shown to exist, but the elasticities are not systematically higher for the Finns as could be expected. The domination of Finnish migration to Sweden is instead explained by real wage differences and since these have narrowed, major migration flows should not be expected in the future, unless large differences in labor market performance arise."

Demography↗