Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Return Migration”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 613 records · Page 34Linked to original sources
PubMed1995

Evidence that Spitzenkörper behavior determines the shape of a fungal hypha: a test of the hyphoid model.

Hyphae of the fungus Rhizoctonia solani have a characteristic Spitzenkörper in their growing tips and a cell shape described by the mathematical hyphoid equation. A mild disturbance of hyphae growing in a slide culture chamber on a microscope stage caused the Spitzenkörper to move away from its usual position next to the apical pole and wander briefly inside the apical dome. Hyphal elongation rate declined abruptly, and the apex became rounded and increased in diameter. As the Spitzenkörper migrated back to its polar position, rapid cell elongation resumed, and the contour of the growing hyphal tip returned to the typical hyphoid shape. The brief dislocation of the Spitzenkörper left a permanent bulge in the hyphal profile. This morphogenetic sequence was mimicked by computer simulation, based on the hyphoid equation which relates the generation of hyphal shape to the linear displacement of a vesicle supply center (VSC). The VSC was programmed to retrace the observed movements of the Spitzenkörper during the above sequence. The resulting similarity of shape between real and computer-simulated cells reinforces the mathematical prediction that the Spitzenkörper acts as a VSC and that its continuous linear advancement generates a typical hyphal tube with the characteristic hyphoid shape. Accordingly, the hyphoid model and its VSC concept provide a plausible hypothesis to explain the cellular basis of polarized growth of fungal hyphae.

Computer Simulation↗
PubMed2005

Physiological effects of thermomechanical newsprint mill effluent on Atlantic salmon (Salmo salar L.).

Anadramous Atlantic salmon (Salmo salar L.) returning to Exploits River, Newfoundland, Canada, to spawn encounter low concentrations of thermomechanical pulp (TMP) effluent as they migrate upstream past an integrated newsprint mill. Various physiological responses of adult Atlantic salmon from the Exploits River were studied under laboratory conditions. The effects of a 6-h exposure to 0%, 6%, 12%, or 25% (v/v) TMP effluent or an increasing concentration gradient of effluent (0-25%) on cardiac output (Q ), critical swimming performance (U(crit)), hematocrit, and blood glucose, cortisol, lactate, and osmolality were examined. Relative to other treatment groups, Q during routine and low-level activity was 7-10% higher in fish exposed to at least 12% effluent. The 25% exposure group had a distinctly lower U(crit) and scope for increase in Q than the other treatment groups. These findings suggest that effluent exposure elevates physiological maintenance and repair costs, resulting in a reallocation of energetic resources.

Animals↗
PubMed1996

Behavioral responses of Escherichia coli to changes in redox potential.

Escherichia coli bacteria sensed the redox state in their surroundings and they swam to a niche that had a preferred reduction potential. In a spatial redox gradient of benzoquinone/benzoquinol, E. coli cells migrated to form a sharply defined band. Bacteria swimming out of either face of the band tumbled and returned to the preferred conditions at the site of the band. This behavioral response was named redox taxis. Redox molecules, such as substituted quinones, that elicited redox taxis, interact with the bacterial electron transport system, thereby altering electron transport and the proton motive force. The magnitude of the behavioral response was dependent on the reduction potential of the chemoeffector. The Tsr, Tar, Trg, Tap, and CheR proteins, which have a role in chemotaxis, were not essential for redox taxis. A cheB mutant had inverted responses in redox taxis, as previously demonstrated in aerotaxis. A model is proposed in which a redox effector molecule perturbs the electron transport system, and an unknown sensor in the membrane detects changes in the proton motive force or the redox status of the electron transport system, and transduces this information into a signal that regulates phosphorylation of the CheA protein. A similar mechanism has been proposed for aerotaxis. Redox taxis may play an important role in the distribution of bacterial species in natural environments.

Bacterial Proteins↗
PubMed1997

Philopatry of male marine turtles inferred from mitochondrial DNA markers.

Recent studies of mitochondrial DNA (mtDNA) variation among marine turtle populations are consistent with the hypothesis that females return to beaches in their natal region to nest as adults. In contrast, less is known about breeding migrations of male marine turtles and whether they too are philopatric to natal regions. Studies of geographic structuring of restriction fragment and microsatellite polymorphisms at anonymous nuclear loci in green turtle (Chelonia mydas) populations indicate that nuclear gene flow is higher than estimates from mtDNA analyses. Regional populations from the northern and southern Great Barrier Reef were distinct for mtDNA but indistinguishable at nuclear loci, whereas the Gulf of Carpentaria (northern Australia) population was distinct for both types of marker. To assess whether this result was due to reduced philopatry of males across the Great Barrier Reef, we determined the mtDNA haplotypes of breeding males at courtship areas for comparison with breeding females from the same three locations. We used a PCR-restriction fragment length polymorphism approach to determine control region haplotypes and designed mismatch primers for the identification of specific haplotypes. The mtDNA haplotype frequencies were not significantly different between males and females at any of the three areas and estimates of Fst among the regions were similar for males and females (Fst = 0.78 and 0.73, respectively). We conclude that breeding males, like females, are philopatric to courtship areas within their natal region. Nuclear gene flow between populations is most likely occurring through matings during migrations of both males and females through nonnatal courtship areas.

Animals↗
PubMed2002

[Genetic demography of Ukrainian urban populations in the 1990's: ethnicity and birth places of migrants to the Poltava population].

Analysis of the birthplace and ethnicity of males and females contracting marriages in the city of Poltava in 1960, 1985, and 1995 revealed a trend towards return of Ukrainians from various regions of the former Soviet Union to their places of origin. In the migration flow, Russians were gradually substituted by Ukrainians, and the total proportion of Slavs increased. The isolation by distance (b) decreased from 0.00122 to 0.00075 in the period from 1960 to 1985 and then increased to 0.00098 by 1995. Positive association was found between the parent-offspring distance and marriage distance (the correlation coefficient r = 0.65-0.75).

Adult↗
PubMed2000

Donor and recipient leukocytes in organ allografts of recipients with variable donor-specific tolerance: with particular reference to chronic rejection.

We have attributed organ engraftment to clonal exhaustion-deletion of host-versus-graft and graft-versus-host reactions that are reciprocally induced and governed by migratory donor and recipient leukocytes. The so-called donor passenger leukocytes that migrate from the allograft into the recipients have been thoroughly studied (chimerism), but not the donor leukocytes that remain in, or return to, the transplanted organ. Therefore, using flow cytometry we determined the percentage and lineages of donor leukocytes in cell suspensions prepared from Lewis (LEW) cardiac allografts to 100 days posttransplantation. The LEW hearts were transplanted to naïve untreated Brown Norway (BN) recipients (group 2), to naïve BN recipients treated with a 28-day or continuous course of tacrolimus (TAC) (groups 3 and 4), and to drug-free BN recipients pretolerized by earlier bone marrow cell (BMC) or orthotopic LEW liver transplantation (groups 5 and 6). The findings in the heart cell suspensions were correlated with the results from parallel histopathologic-immunocytochemical studies and other studies of the grafts and of host tissues. Although the LEW heart allografts were rejected in 9.6 days by the unmodified recipients of group 2, all beat for 100 days in the recipients of groups 3 through 6. Nevertheless, all of the long-surviving cardiac allografts (but not the isografts in group 1) were the targets of an immune reaction at 5 days, reflected by dramatic increases in the ratio of leukocytes to nonleukocyte nucleated cells from normal values of 1:5-1:6 to 1:1-5:1 and by manifold other evidence of a major inflammatory event. The acute changes returned to baseline by 100 days in the chronic rejection (CR) free hearts of groups 4 and 6, but not in the CR-afflicted hearts of short-course TAC group 3 or the less-severely damaged hearts of the BMC-prime group 5. The freedom from CR in groups 4 and 6 was associated with a large donor contribution to the intracardiac leukocyte population at 5 days (28.6% and 22% in the respective groups) and at 100 days (30.5% in group 4 and 8.4% in group 6) compared with 2% and 1.2% at 100 days in the CR-blighted allografts of the partially tolerant animals of groups 3 and 5. Whether large or small, the donor leukocyte fraction always included a subset of class II leukocytes that had histopathologic features of dendritic cells. These class II(+) cells were of mixed myeloid (CD11b/c(+)) and lymphoid lineages; their migration was markedly inhibited by TAC and accelerated by donor-specific priming and TAC discontinuance. Although a large donor leukocyte population and a normal leukocyte/nonleukocyte cell ratio were associated with freedom from CR, these findings and the lineage profile of the intracardiac leukocytes were not associated with tolerance in the animals of groups 3 and 4 under active TAC treatment. The findings in this study, singly and in their entirety, are compatible with our previously proposed leukocyte migration-localization paradigm of organ allograft acceptance and tolerance.

Animals↗
PubMed1999

The impact of overseas labour migration on rural Thailand: regional, community and individual dimensions.

"This paper provides a case study of the impact at origin of recent labour migration from rural Thailand to East Asian destinations. It does so through survey information on 63 villages and detailed biographic interviews with recently returned workers. It is concluded that work abroad is regarded by migrants as a strategy of life support; it is sometimes life-enhancing, but only rarely life-changing."

Asia↗
PubMed1988

Migration Amendment Act 1987 (No. 133 of 1987), 16 December 1987.

This Act does the following, among other things: 1) requires that certain requests relating to entry permits, visas, and return endorsements are not considered to have been made unless in writing in accordance with the relevant approved forms and unless any fee payable has been made; 2) makes "operators," as well as charterers, liable for the carriage of persons to Australia without documentation; and 3) provides that international air operators shall pay immigration clearance fees payable by passengers whether or not the operator has collected the fees from the passengers.

Australia↗
PubMedDate not supplied

Evaluation of surgical repair of humeral condylar fractures using self-compressing orthofix pins in 23 dogs.

OBJECTIVE: To report short- and long-term clinical and radiographic outcomes in dogs with humeral condylar fractures repaired using self-compressing Orthofix pins. STUDY DESIGN: Retrospective evaluation with solicited long-term clinical and radiographic evaluations. ANIMALS: Twenty-three dogs with humeral condylar fractures. METHODS: Medical records and radiographs were reviewed. Owners were asked to return dogs for long-term clinical and radiographic evaluation. RESULTS: Dogs were aged 1.5-26 months (mean+/-SD, 5.8+/-5.0 months) with 20 dogs weighing <5 kg (mean, 3.6+/-2.8 kg). Of 21 dogs with immediate post-operative radiographs, 10 had anatomic reduction with the rest having either a step and/or gap at the articular surface. Kirschner wire migration and implant loosening were the most common post-operative complications. All fractures with adequate follow-up radiographic evaluations achieved union. Twelve of 13 dogs returned for long-term evaluation (mean, 19.0+/-18.5 months) were either sound (10 dogs) or had subtle, weight-bearing lameness (2). Fourteen dogs had radiographs >/=75 days after surgery (mean, 18.7+/-18.3 months), 8 dogs (57%) had no radiographic evidence of osteoarthritis (OA; mean OA score, 0.8; median 0), and all dogs had good or excellent limb function. CONCLUSIONS: Self-compressing Orthofix pins are suitable implants for the stabilization of humeral condylar fractures in small breed dogs. Implants were convenient and simple to use and complications were easily resolved. Dogs consistently had good long-term clinical and radiographic outcomes with no or minimal lameness and OA. CLINICAL RELEVANCE: Self-compressing Orthofix pins should be considered for the repair of humeral condylar fractures in small breed dogs.

Animals↗
PubMed2004

Suspected infant abuse: radiographic skeletal survey practices in pediatric health care facilities.

PURPOSE: To determine current national radiographic skeletal survey imaging practices, including migration to digital technologies, for evaluation of suspected infant abuse. MATERIALS AND METHODS: Of 155 children's health care facilities in the United States in which radiographic skeletal surveys are performed for suspected infant (<1 year old) abuse, 137 (88.4%) agreed to complete a questionnaire. Questions included facility type, imaging department volume, radiographic equipment, and details of skeletal survey imaging practices. Statistical analysis was performed with chi(2), Fisher exact, Pearson correlation, Spearman rank correlation, and Student t tests. RESULTS: One hundred seven completed questionnaires were returned. Forty-seven (43.9%) facilities used screen-film imaging; 60 (56.1%) used digital. Of screen-film users, 25 (53.2%) had already migrated or planned to migrate to digital within 1 year. Of screen-film users, 27 (60.0%) reported use of a high-detail imaging system, while 13 (21.7%) digital users employed a high-resolution technique (P < .001). Eighty-four (78.5%) facilities reported more than 10 images in their protocol, and 45 (42.0%) specified more than 15 images. Only one (0.9%) facility obtained fewer than three images. Upper extremities were imaged separately with at least two exposures in 81 (75.7%) facilities. Lower extremities were imaged separately with at least two exposures in 82 (76.6%) facilities. One hundred five (98.1%) facilities reported acquisition of lateral spinal views. CONCLUSION: Within U.S. pediatric health care facilities, most skeletal surveys in cases of suspected infant abuse include separate frontal views of the appendicular skeleton and frontal and lateral views of the axial skeleton. Imaging protocols and other image quality determinants vary widely, and as U.S. pediatric health care facilities migrate from film-based to digital imaging technology, imaging practices directly applicable to the digital environment are being retained; however, less attention is being paid to technical elements specific to digital imaging that affect high-detail image quality.

Bone and Bones↗
PubMed1990

The migration response to the economic turnaround in New England.

"This paper is an investigation of the dynamics of interstate migration flows to and from New England since 1975. The main goal of the research is to study the timing and volume of the lagged migration adjustment to the regional economic turnaround and the temporal stability of patterns of regional inflows and outflows. The paper is an examination of the responsiveness of interstate migration to changing regional economic conditions based on annual interstate migration data and a set of cross-sectional destination-specific Poisson regression models." The data are from a series developed by the Bureau of the Census based on Federal income tax returns.

Americas↗
PubMedDate not supplied

Differential effects of ninaC proteins (p132 and p174) on light-activated currents and pupil mechanism in Drosophila photoreceptors.

The Drosophila ninaC locus encodes two retinal specific proteins (p132 and p174) both consisting of a protein kinase joined to a myosin head domain and a C terminal with a calmodulin-binding domain. The role of p132 and p174 was studied via whole-cell recording and through measurements of the pupil mechanism, i.e. the pigment migration in the photoreceptor cells, in the ninaC mutants, P[ninaC delta 132] (p132 absent), P[ninaC delta 174] (p174 absent), and ninaCP235 (null mutant). Voltage-clamped flash responses in P[ninaC delta 174] and ninaCP235 showed delayed response termination. In response to steady light, plateau responses in both P[ninaC delta 174] and ninaCP235 were also large. In both cases the defect was significantly more severe in ninaCP235. Responses in P[ninaC delta 132] were apparently normal. P[ninaC delta 174] and ninaCP235 were also characterized by spontaneous quantum bump-like activity in the dark and by larger and longer light-induced quantum bumps. The turn-off of the pupil mechanism in P[ninaC delta 174] and ninaCP235 was also defective, although in this case the rate of return to baseline in both mutants was more or less the same. In all ninaC mutants, the amplitudes of the pupillary pigment migration were distinctly smaller than that in the wild type. The reduction of the amplitude was largest in P[ninaC delta 174]. The light sensitivity of the pupil mechanism of P[ninaC delta 174] compared to that of wild type was reduced by 1.3 log units. Remarkably, the light sensitivity of P[ninaC delta 132] and ninaCP235 was ca. 0.5 log units higher than that of the wild type. The results suggest that the p174 protein is required for normal termination of the transduction cascade. The diverse phenotypes observed may suggest multiple roles calmodulin distribution for controlling response termination and regulating pigment migration in Drosophila photoreceptors.

Animals↗
PubMed1981

Route of lymphocyte migration in pigs. I. Lymphocyte circulation in gut-associated lymphoid tissue.

Evidence is presented which indicates that recirculating lymphocytes originating from the intestine in pigs are returned to the blood circulation at the level of the mesenteric lymph nodes (MLN) and not via efferent intestinal lymph. This was demonstrated by three observations: (1) removal of all MLN resulted in a thirty-fold increase in lymphocyte numbers in efferent lymph of pigs, but not in rats; (2) there are about twenty-five times more lymphocytes in afferent intestinal lymph than efferent intestinal lymph in normal pigs; (3) 51Cr-labelled lymphocytes injected into afferent lymphatics are mostly recovered in the node tissue or efferent lymph of sheep, and very few in the venous drainage, whereas in pigs relatively few labelled cells are recovered in the node or in efferent lymph.

Animals↗
PubMed2001

Incomplete large bowel obstruction caused by a duodenal stent.

Gastric outlet obstruction secondary to benign or malignant disease can be treated with self-expanding metallic stents. This obviates the need for surgical bypass procedures and returns most patients to a normal diet. Prosthesis displacement is described as a late complication. A case of stent migration to the rectum, presenting with the symptoms and signs of incomplete large bowel obstruction, is described.

Colonic Diseases↗
PubMed1988

Cortical flow in animal cells.

A concerted flow of actin filaments associated with the inner face of the plasma membrane may provide the basis for many animal cell movements. The flow is driven by gradients of tension in the cell cortex, which pull cortical components from regions of relaxation to regions of contraction. In some cases cortical components return through the cytoplasm to establish a continuous cycle. This cortically located motor may drive cell locomotion, growth cone migration, the capping of antigens on a lymphocyte surface, and cytokinesis.

Actins↗
PubMed1990

A technique of acetabular reconstruction for uncemented total hip replacement.

A technique for performing uncemented total hip replacement in the presence of osteoarthritis with proximal femoral migration is detailed. The femoral head is used as an autograft. The center of rotation of the hip is returned to its anatomic location, and subchondral bone is preserved. Rigid fixation of the graft is accomplished with matching reamers and AO lag screw fixation. Simultaneous reaming of graft and host bone produces a seamless transition to ensure graft loading. The goals of restoration of anatomic hip center, rigid press fit, and complete cup coverage are accomplished.

Acetabulum↗
PubMedDate not supplied

[Morphogenesis of the brain of rats developing under conditions of weightlessness].

Macroscopic and light microscopic examinations of the brain of 18-day fetuses, and neonate 15-, 30- and 100- day rats whose embryonic development from day 13 to day 18 occurred in space flight on Cosmos-1514 did not reveal any changes in the brain structures of the fetuses or pups of the three ages. However, the brain of the 18-day fetuses that developed in flight showed signs of insufficient tissue oxygenation, trends toward delayed cell migration in the cortex and delayed differentiation of neurosecretory cells of the hypothalamic supraoptic nuclei. The cell differentiation rate returned to normal during continued embryogenesis after flight at 1 g.

Animals↗
PubMed1984

[Intestinal motility following jejunal resection: electromyography study in the rat].

The influences of massive resections on motility of the small intestine remain poorly known. The aim of our study was to determine the effects of jejunal resection on the pattern of occurrence of the migrating myoelectric complex and its postprandial inhibition. The experiments were performed over a period of 1 month after surgery. Transections were done on the jejunum or on the ileum in sham-operated animals. Ten days after resection, the motility of the anastomosed jejunal and ileal segments was dissociated. After one month, a functional continuity appeared through the anastomosis: the whole intestine worked synchronously at the same rhythm as the ileum. Food intake induced an increase in the frequency of the migrating myoelectric complexes measured 10 days after surgery. An adaptative phenomenon appeared after 30 days, the postprandial motor activity returning to its control level.

Animals↗