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PubMed1981

A serum C3-activating factor: its characterization and its presence in glomerular deposits.

A non-IgG C3 activating factor (C3AF) isolated from the serum and plasma of a patient with membranoproliferative glomerulonephritis with subendothelial and subepithelial deposits (type III) was studied to define its molecular structure, functional characteristics, and presence in renal biopsies. Alternative complement pathway (ACP) activation of C3 was comparable to that of zymosan, but significantly less than that of IgG C3 nephritic factor (C3NeF). Functionally active isolate contained beta 1H globulin (beta 1H) and the C3AF protein, which had a gamma-electrophoretic migration. beta 1H present in the isolate exhibited an altered gamma-beta electrophoretic mobility. The function of this complex is heat labile. Time/temperature studies demonstrated that inactivated preparations of this isolate show a return to the normal beta migration of beta 1H followed by the development of an alpha 2 electrophoretic migration of the previously gamma-migrating material of functionally active isolate. Normal human serums contain an alpha 2 protein that shows complete antigenic identity with the gamma protein of C3AF, but this alpha 2 protein lacks C3 activating function. On polyacrylamide gel electrophoresis, the C3AF isolate contains a high m.w. protein of 500,000 to 590,000 that is composed of 2 major subunits. Carbohydrate is not demonstrable, and the protein is antigenically distinct from plasma fibronectin. Immunofluorescence studies of renal biopsies of patients with types I and III MPGN revealed the presence of C3AF antigen in granular deposits in 10 of 16 cases. The presence of this antigen in glomerular deposits was associated with C3 and beta 1H, but was independent of Ig. These studies suggest that the mechanism of ACP activation by C3AF results from interference with beta 1H function. The presence of this material in renal biopsies from some MPGN patients further suggests a pathogenetic role in mediating glomerular pathology.

Chemical Precipitation↗
PubMed1995

Micro-enterprise development schemes as effective reintegration assistance programs for voluntarily-repatriated Vietnamese asylum seekers.

"From the creation of the Comprehensive Plan of Action (CPA) in 1989 through December 1994, about sixty-eight thousand asylum seekers have voluntarily repatriated to Vietnam. In response to this reverse migration, the international community has funded numerous reintegration assistance programs to facilitate the asylum seekers' return. This article examines reintegration assistance programs currently operating in Vietnam and presents an argument that small scale income generation projects constitute the most effective and efficient use of scarce repatriation funding."

Asia↗
PubMed2006

Full recovery of electron damage in glass at ambient temperatures.

An unusually complete recovery of extensive electron-beam-induced damage in a thin film of a CaO-Al2O3-SiO2 glass was discovered. Nanoscale measurements show that the Ca ions migrate about 10 nm away during irradiation and return during recovery. Oxygen atoms are trapped largely as molecular oxygen and do not migrate. Electron energy loss measurements demonstrate that the glass returns completely to the original compositional and structural state thus indicating that the glass is in a deep thermodynamic energy minimum.

Journal Article↗
PubMed1990

Two neglected categories of immigrants to Canada: temporary immigrants and returning Canadians.

Results are presented from an attempt to improve Canadian statistics on international migration so as to comply with U.N. guidelines by including data on long-term residents with temporary status and Canadian citizens and permanent residents returning from abroad. "The estimation procedures involve extensive operations on three Canadian administrative data systems: the Visitors Immigration Data System of Employment and Immigration Canada; the Family Allowances Files of Health and Welfare Canada; and the Customs and Excise Files of Revenue Canada. These data are used to produce the number of immigrants in both of the neglected categories, as well as to calculate the geographic (origin and destination) and demographic (sex, age, marital status) structures of these groups. Results of the analysis of estimates for the period 1982-1988 show that, due to their size and characteristics, both of these neglected categories of immigrants constitute a significant part of immigration to Canada, and their importance has and will continue to increase over time."

Americas↗
PubMed1984

Studies on the effects of ingestion of a single 500 mg oral dose of erythromycin stearate on leucocyte motility and transformation and on release in vitro of prostaglandin E2 by stimulated leucocytes.

Polymorphonuclear leucocyte (PMNL) and mononuclear leucocyte (MNL) migration to the leucoattractant endotoxin-activated serum as well as MNL mitogen-induced transformation were measured in normal adult volunteers before and 1 1/2 h and 96 h after the ingestion of a single oral dose of 500 mg of erythromycin stearate. Ingestion of the antibiotic was associated with a significant increase in PMNL migration at 1 1/2 h with a return to normal levels at 96 h. Slight but insignificant enhancement of MNL migration and of transformation to mitogens was detected after erythromycin. The mechanism of the slight stimulation of MNL transformation, which was consistently observed, was investigated further in vitro by measuring the effects of erythromycin base on the release of prostaglandin (PG) E2 by mitogen-stimulated MNL. Similar studies were performed using leuco-attractant-exposed PMNL. Inhibition of PGE2 release was observed for both MNL and PMNL with therapeutic concentrations of erythromycin. To assess the possible in-vivo significance of the immunopotentiating properties of the antibiotic the effect of a single intraperitoneal injection of 250, 500 or 1000 micrograms on the survival time of mice lethally infected with the erythromycin-resistant microorganism Candida albicans were investigated. Pre-treatment of the mice with erythromycin at each concentration used significantly increased the mean survival times. It is possible that these non-specific immunostimulatory properties of erythromycin potentiate in-vivo antimicrobial activity.

Adjuvants, Immunologic↗
PubMed1994

Quantitation of neutrophil migration in acute bacterial pneumonia in rabbits.

The circulating neutrophils must slow down, adhere to the vessel walls, and migrate out of the microvasculature into the tissue and air spaces to defend the lung against microorganisms. The present study was designed to provide quantitative information about each of these steps. Streptococcus pneumoniae was instilled into the left lower lobe of New Zealand White rabbits to induce a pneumonia, and this lobe was compared with the same region of the opposite lung. The distribution of blood flow was determined by using radiolabeled macroaggregated albumin, and the patterns of perfusion within the capillary bed were quantitated using Monastral blue. The number of neutrophils delivered to the pneumonic site was determined by multiplying the circulating neutrophil count and blood flow. The results show that retention of 51Cr-labeled neutrophils was increased in the pneumonic region 2, 4, and 8 h after instillation of the organisms. The number of intracapillary neutrophils was increased in the pneumonic regions at all time points and in the control regions at 1 and 4 h. Neutrophil migration occurred in the pneumonic site, but only 1-2% of the total neutrophils delivered to the region migrated out of the pulmonary vessels into the air space. We conclude that the circulating neutrophils undergo a generalized response that increases their margination throughout the lung, that increased margination in the pneumonic site changes the distribution of capillary flow, and that the majority of neutrophils delivered to a pneumonic site are returned to the circulation without migrating into the air space.

Acute Disease↗
PubMedDate not supplied

Migration status and investment in rural productive activities: evidence from Oyo State, Nigeria.

"This paper presents an attempt to investigate the differential contributions of return migrants and non migrants [in Nigeria] to rural economy with respect to their level of investment in rural productive activities. The study is [a] sequel to the controversy generated by the selectivity theory which tends to suggest that return migrants are superior to, and more enterprising than non migrants. The relevant data were collected from 363 returnees and non migrants.... An examination of the differential characteristics of the two groups shows that returnees are slightly superior to their non migrant counterparts. The differential characteristics seem to translate to differences in investment level and the general conclusion is that return migrants are likely to invest more in rural productive activities than non migrants." (SUMMARY IN FRE AND ITA)

Africa↗
PubMedDate not supplied

[Emigration of Quebec physicians: motivation for departure and return].

Since the 80's, outmigration of physicians from Quebec is steadily increasing. About 46 percent of outmigrating doctors explain their move by factors related to their occupational life (higher income, greater opportunity in the academic career, larger amount of resources devoted to the health care system). Nearly 40 percent relate their decision to personal factors (greater job opportunity for their wife/husband, quality of family life...). The factors linked to the context of the receiving place (political climate, linguistic regulations, income tax level...) play a minor role on the migration decision. As concerns the returning physicians, 80 percent explain their decision by personal factors. The factors linked to the occupational life have a lower role. It appears therefore that doctor outmigration from Quebec is not directly determined by manpower policies adopted by the Province during the last two decades, except the policies directly linked to the income level of professionals.

Adult↗
PubMed1985

Control of nematodes in dairy heifers by prophylactic treatments with albendazole in the spring.

The effect of 2 prophylactic anthelmintic treatments with albendazole (7.5 mg/kg) was evaluated in 2 groups of Holstein dairy replacement heifers treated 3 and 6 weeks after turnout to spring pasture on May 2, 1983. The lightweight group consisted of twelve 7- to 9-month-old heifers with a mean initial weight of 201.1 kg. The heavyweight group consisted of ten 11- to 15-month-old heifers with a mean weight of 319.4 kg. Within each group, the heifers were paired by initial weight, and one member of each pair was randomly assigned to the treatment group. Each of the 4 resulting groups grazed separate, contaminated pastures until winter housing on Oct 31, 1983. The albendazole-treated, lightweight heifers had bodyweight gains 28.9% greater than that of the control heifers at the end of 23 weeks (P less than 0.001). There was no significant difference in gain for the treated heavyweight heifers, which had a lower feeding rate/kg of bodyweight than did the lightweight heifers. At the end of the study, there was a sevenfold difference in mean pasture L3 counts between treatment (1,303 L3/kg) and control (9,153 L3/kg) replicates. It was concluded that it is desirable to treat all heifers in northern regions during their first spring at pasture. This strategy would likely provide substantial economic returns to the farmer in years with a wet summer, which would favor early migration of L3 to herbage, but would provide smaller returns in dry seasons, which would delay this pattern of migration.

Albendazole↗
PubMed2004

Navigation and seasonal migratory orientation in juvenile sea turtles.

Juvenile loggerhead and green turtles that inhabit inshore waters of North Carolina, USA undertake long seasonal migrations, after which they often return to specific feeding areas. In addition, juvenile turtles are capable of homing to specific sites after being displaced. As a first step towards investigating the navigational mechanisms that underlie these movements, juvenile turtles were captured in coastal waters of North Carolina and displaced 30-167 km along circuitous routes while deprived of visual cues. At the testing location, turtles were tethered in a circular arena and permitted to swim while their orientation was monitored. Between May and September, when juvenile loggerhead and green turtles inhabit feeding areas along the North Carolina coast, turtles oriented in directions that corresponded closely with the most direct route back to their capture locations. During October and November, however, both loggerhead and green turtles oriented southward, a direction consistent with the migratory paths of turtles beginning their autumn migration. The results demonstrate for the first time that both homing and migratory orientation can be elicited in juvenile turtles under laboratory conditions in which orientation cues can be readily manipulated. In addition, the results provide evidence that juvenile loggerheads can assess their position relative to a goal using local cues available at the test site and are therefore capable of map-based navigation.

Animal Migration↗
PubMed1972

Helminthic pseudotumours of the bowel: thirty-four cases of helminthoma.

Human infestation with nematode worms of the superfamily Strongyloidea has been recorded from time to time to give rise to serious surgical complications. Worms of the genus Oesophagostomum are most frequently responsible. These are common parasites of ruminants, monkeys, and apes in which their histotropic phase is confined to the bowel wall and sometimes results in multiple inflammatory nodules. Man is an accidental host and it seems an abnormal one. The worm fails to return to the bowel lumen, migrates further and persists in the tissues. The commonest manifestation is a solitary tumour-like inflammatory mass or abscess (;helminthoma') in the ileocaecal region. The ileum, transverse and sigmoid colons are affected less commonly and the lesions are occasionally multiple. Patients may also present with abscesses of the abdominal wall. The clinical diagnosis is difficult, even at laparotomy. Carcinoma, appendicitis, ileocaecal tuberculosis are frequently simulated and unnecessary radical surgery is often the result, particularly in expatriate Europeans. In this communication 34 cases from Uganda are reviewed with emphasis on histopathology as responsibility for the correct diagnosis is likely to fall on pathologists. Three characteristic appearances are described and related to phases in the natural history of the disease. Current knowledge on parasitology is reviewed. The disease affects Africans as well as Europeans and it is anticipated that cases will be seen in those returning from the tropics.

Abdominal Muscles↗
PubMed1987

[Time, cultures, and coexistence].

"In this essay, the authors try to illustrate the relevance of the sociology of time for the study of migration and inter-cultural relations. It is argued that by taking the time-dimension more explicitly into account, our insights in the dynamics of these relations can be [improved].... In connection with international migration processes, this relationship appears to be influenced by at least six different factors: 1) the sudden transition from a rural to an urban, industrial environment; 2) the perspective of the return to the homeland; 3) the confrontation with the culture of the host country and with other migrants' cultures; 4) the religious, ideological and political developments in the homeland; 5) the reactions of the host country and the problems these create; 6) the minority position of the migrants." (SUMMARY IN ENG)

Acculturation↗
PubMed2025

Tales of a Super Butterfly: Is Vanessa carye a Truly Migrant Species? Unraveling Migration Using Morphological and Genomics Approaches.

Among movement strategies, migratory behavior is particularly intriguing in insects. Home-breeding is often permanent, and return journeys can take several generations. Although migration is crucial to the ecological and evolutionary processes of the species involved, knowledge of insect migratory behavior needs to be better understood. Vanessa carye, a butterfly native to South America with a latitudinal range of ∼7,000 km, exemplifies this problem. This study analyzed samples collected across the species' range using single-nucleotide polymorphisms (SNPs) to assess population structure, genetic diversity, and geometric morphometrics to examine wing shape variation. Results indicate that V. carye forms a genetically homogeneous unit composed of only two potential populations spanning ∼5,000 km, geographically correlated with the Pacific Ocean and the Andes, maintaining constant gene flow, and with a mean heterozygosity of 5.74% (SE: ±0.048%). Geometric morphometrics detected no geographic differentiation in wing shapes and sizes across ∼7,000 km, suggesting an absence of local adaptation and indicating a conserved wing shape adapted to flight throughout the species' range. Our findings support V. carye as a migratory species with the longest migratory journey among American butterflies, revealing two migratory routes. With these approaches, we provide a consistent methodological framework for migratory studies in species with important gaps in knowledge of their natural history.

Animals↗
PubMed1980

The role of long distance migration in the rural renaissance, in gentrification, and in growth of the Sunbelt.

The author "has examined trends in interstate migration during the 1970s for the four regions of the United States and, in particular, explored the relationship of this migration with nonmetropolitan expansion and the return to the city movement. The data show that the former trend is a very real one which has persisted throughout the decade and that population growth through interstate migration in nonmetropolitan America is, on balance, the result of nonblacks moving to the South from elsewhere in the nation. Except in the West, central cities continue to experience substantial losses of population through interstate migration. Interstate migration continues to be directed toward suburbs, and is especially vigorous in the West." Data are from the March 1975 and March 1979 Current Population Surveys.

Americas↗
PubMed1980

Weather, host and vector--their interplay in the spread of insect-borne animal virus diseases.

The spread of insect-borne animal virus diseases is influenced by a number of factors. Hosts migrate, move or are conveyed over long distances: vectors are carried on the wind for varying distances in search of hosts and breeding sites; weather and climate affect hosts and vectors through temperature, moisture and wind. As parasites of host and vector, viruses are carried by animals, birds and insects, and their spread can be correlated with the migration of hosts and the carriage of vectors on winds associated with the movements of the Intertropical Convergence Zone (ITCZ) and warm winds to the north and south of the limits of the ITCZ. The virus is often transmitted from a local cycle to a migratory cycle and back again.Examples of insect-borne virus diseases and their spread are analysed. Japanese, Murray Valley, Western equine, Eastern equine and St Louis encephalitis represent viruses transmitted by mosquito-bird or pig cycles.THE AREAS EXPERIENCING INFECTION WITH THESE VIRUSES CAN BE DIVIDED INTO A NUMBER OF ZONES: A, B, C, D, E and F. In zone A there is a continuous cycle of virus in host and vector throughout the year; in zone B, there is an upsurge in the cycle during the wet season, but the cycle continues during the dry season; there is movement of infected vectors between and within zones A and B on the ITCZ and the virus is introduced to zone C by infected vectors on warm winds; persistence may occur in zone C if conditions are right. In zone D, virus is introduced each year by infected vectors on warm winds and the arrival of the virus coincides with the presence of susceptible nestling birds and susceptible piglets. The disappearance of virus occurs at the time when migrating mosquitoes and birds are returning to warmer climates. The virus is introduced to zone E only on occasions every 5-10 years when conditions are suitable. Infected hosts introduced to zone F do not lead to circulation of virus, since the climate is unsuitable for vectors. Zones A, B and C correspond to endemic and zones D and E to epidemic conditions.Similar zones can be recognized for African horse sickness, bluetongue, Ibaraki disease and bovine ephemeral fever - examples of diseases transmitted in a midge-mammal cycle. In zones A and B viruses are transported by infected midges carried on the wind in association with the movement of ITCZ and undergo cycles in young animals. In these zones and in zone C there is a continual movement of midges on the warm wind between one area and another, colonizing new sites or reinforcing populations of midges already present. Virus is introduced at times into fringe areas (zones D and E) and, as there is little resistance in the host, gives rise to clinical signs of disease. In some areas there is persistence during adverse conditions; in others, the virus is carried back to the endemic zones by infected midges or vectors.Examples of viruses maintained in a mosquito/biting fly-mammal cycle are Venezuelan equine encephalitis and vesicular stomatitis. These viruses enter a migratory cycle from a local cycle and the vectors in the migratory cycle are carried over long distances on the wind. Further examples of virus spread by movement of vectors include West Nile, Rift Valley fever, yellow fever, epizootic haemorrhagic disease of deer and Akabane viruses.In devising means of control it is essential to decide the relationship of host, vector and virus and the nature of the zone in which the area to be controlled lies. Because of the continual risk of reintroduction of infected vectors, it is preferable to protect the host by dipping, spraying or by vaccination rather than attempting to eliminate the local population of insects.

African Horse Sickness↗