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PubMed1990

Importance of rotavirus and adenovirus types 40 and 41 in acute gastroenteritis in Korean children.

To examine the role of rotavirus (Rv) and adenovirus types 40 and 41 (Ad40/41) in Korean children with acute gastroenteritis, we evaluated 345 children with acute gastroenteritis and 90 children without acute gastroenteritis in Seoul, Korea, during a 29-month period. Stools were tested for group A Rv antigen and for Ad40/41 by using monoclonal antibody (MAb)-based assays. Rv was found in 68% of the ill children and 19% of the controls (P less than 0.001), whereas Ad40/41 was detected in 9% of the ill children and 2% of the controls (P less than 0.05). Also, 6% of the ill children and 0.01% of the controls excreted Rv and Ad40/41 simultaneously. Among the ill children, 96% of children with Rv and 94% of those with Ad40/41 were younger than 24 months. Although a peak of Rv infection was detected in early winter in both years of the study, there was no apparent seasonal trend with Ad40/41. Diarrhea with more than 10 stools per day, vomiting, or fever was most strongly associated with Rv shedding, whereas the first two manifestations were associated with coinfection of Rv and Ad40/41. To investigate the genetic and serotypic diversity of Rv strains, we tested 195 and 144 fecal Rv specimens isolated from the gastroenteritis cases, respectively, by polyacrylamide gel electrophoresis of the segmented RNA genome and by an enzyme-linked immunosorbent assay with serotype-specific MAbs. Of the 195 specimens, 154 yielded RNA patterns characteristic of group A Rv: 18% had short electrophoretic migration patterns, 81% had long patterns, and 1% had a mixture of short and long patterns. Of the 144 specimens, serotype specificity was determined in 51%: 89% were serotype 1, 10% were serotype 2, and 1% were serotype 3. Analysis of the specimens for which electropherotypes and serotypes were available indicated that a given RNA pattern corresponded to a particular serotype, except in one strain that showed short patterns but serotype 1. We suggest that Rv and Ad40/41 in stools be accepted critically as an important cause of diarrhea among young children in Korea.

Acute Disease↗

PubMed1998

Sensory development and its relation to habitat change in three species of sciaenids.

Visual and mechanosensory development of three sciaenid species was investigated to examine possible correlations between sensory morphology and patterns of habitat use. Although the three species have different migration patterns as early larvae, few differences in sensory morphology occurred between species until late in the larval period. Atlantic croaker, Micropogonias undulatus, were distinguished by enhancements of visual morphology (large eyes, abundant photoreceptors, and best summation of the three species). Croaker arrive inshore later in the larval period and, after settlement, appear to use deeper water habitats than do the other two species. Spotted seatrout, Cynoscion nebulosus, had the fewest enhancements of visual morphology but had more free neuromasts than the other two species late in the larval period. After settlement, seatrout are primarily associated with seagrass habitats. Red drum, Sciaenops ocellatus, did not have pronounced specialization of one sensory system, as did the other two species. For part of the larval period, neuromast numbers were higher in red drum than in the other two species. Later, enhancements of visual morphology did occur, but only eye and lens size were the same as those of Atlantic croaker. Red drum larvae appear to use a wider variety of habitats than do the other two species. In none of the species examined did sensory changes correlate with offshore to inshore movements, and only initial rod formation occurred prior to settlement. Distinct sensory changes did not occur concurrent with habitat changes, probably due to constructional and phylogenetic constraints. Rather, sensory differences are related to the environmental conditions in the predominant inshore habitat occupied by each species after settlement, when morphological limitations are less severe.

Animals↗

PubMed1989

Population migration and economic restructuring in the United States.

"This article demonstrates that sectoral employment shifts associated with the migration pattern changes of the 1970s are very different than those for the period 1955-60 to 1965-70. Changing competitiveness for jobs in manufacturing and other traditional basic sectors of the economy cannot account for the greatly accelerated levels of core-periphery net outflow that have been the dominant characteristic of interstate movement during the 1970s and 1980s. Instead, an interconnected set of activities that includes government, services, trade, and construction is associated with the broadscale shifts in the geographic pattern of the United States' population. The causal linkage from migration to employment change assumed heightened importance during the 1970s."

Americas↗

PubMed1994

Determinants of the demographic impact of HIV-1 in sub-Saharan Africa: the effect of a shorter mean adult incubation period on trends in orphanhood.

Recent evidence suggests that the adult HIV-1 incubation period may be shorter in some sub-Saharan African populations than in Western populations. In this article we use mathematical-model-based simulations to show that, other things being equal, a shorter incubation period can result in smaller but more pronounced HIV-1 epidemics and faster, more acute, changes in demographic features, such as adult mortality, orphanhood and population structure. Empirical studies of orphanhood reveal similar patterns to those found in the simulations, but suggest that migration patterns and structural factors can give rise to greater concentrations of orphans in areas of relatively low HIV-1 prevalence.

Adolescent↗

PubMed1999

Migradollars and mortality: the effects of migration on infant survival in Mexico.

We apply multilevel methods to data from Mexico to examine how village migration patterns affect infant survival outcomes in origins. We argue that migration is a cumulative process with varying health effects at different stages of its progression, and test several related hypotheses. Findings suggest higher rates of infant mortality in communities experiencing intense U.S. migration. However, two factors diminish the disruptive effects of migration: migradollars, or migrant remittances to villages, and the institutionalization of migration over time. Mortality risks are low when remittances are high and decrease as migration becomes increasingly salient to livelihoods of communities. Together, the findings indicate eventual benefits to all infants, irrespective of household migration experience, as a result of the development of social and economic processes related to U.S. migration.

Adult↗

PubMed1992

Immigration history and the future of international migration.

"International migration must be understood as a permanent phenomenon rather than as a temporary movement. In this article, the author proceeds from the premise that in appreciating the relation between the past and the present, we may be able to draw on 'lessons of the past' to modify our definition and perception of current problems and to analyze possible policies and decisions. The article is divided into several sections, historical changes within migration patterns including different categories of migrants, various phases within the migration process in recent history, theoretical considerations in analysis, distinct types of immigration policies pursued by various states, and current and possible future trends."

Demography↗

PubMedDate not supplied

Calcium: a potential central regulator in wound healing in the skin.

Calcium has an established role in the normal homeostasis of mammalian skin and serves as a modulator in keratinocyte proliferation and differentiation. Gradients of calcium concentration increasing from 0.5 mM in the basal layer to > 1.4 mM in the stratum granulosum are consistent with migration patterns in response to minor abrasion (normal wear). Dermal fibroblasts require calcium but are approximately 100 times less sensitive than keratinocytes. Normal calcium metabolism in the skin is dependent on cell membrane and cytosolic calcium binding proteins (calmodulin, cadherins, etc.), but their modulation through parathyroid hormone, vitamin D or growth factors in normal or damaged tissue is not well documented. In wound repair, calcium is predominantly involved as Factor IV in the hemostatic phase, but it is expected to be required in epidermal cell migration and regeneration patterns in later stages of healing. Calcium alginate dressings are designed to liberate calcium early in the acute phase to promote hemostasis, but it is presently unclear whether the supplementary calcium influences the intracellular environment at later stages of wound repair, notably during the remodeling phase. Although experimental studies suggest that control of calcium is obligatory in wound management, we know very little as to how calcium in the wound bed is modulated through hormones, vitamin D, or various growth factors. Also, there is limited information as to how calcium released either from dressings, platelets, or from the circulation through the action of parathyroid hormone, growth factors or other modulators influences cell migration and remodeling in skin wounds, although experimental models suggest that management of calcium is essential in wound management.

Animals↗

PubMed1997

Characterisation of the immune response in a neural xenograft rejection paradigm.

We have looked at both donor and host MHC expression in a neural xenograft rejection paradigm. Grafts of either mouse corpus callosum or an SV40 large T transformed astrocytic cell line were placed in the mid-brain of neonatal rats. Three weeks later graft rejection was induced by the application of a skin graft of the same donor origin. MHC expression in the neural graft and the host brain was examined histologically four and ten days after the animals had received a skin graft. Donor MHC expression was detected in the corpus callosal grafts at both time points and preceded host MHC expression and the lymphocytic infiltrate. The grafts of the transformed cell line could not be induced to express MHC antigens under the experimental protocol used nor were they rejected. The migratory patterns of the transformed cells were compared to the well characterised migration patterns of astrocytes from the corpus callosal grafts.

Animals↗

PubMed1999

Capillary electrophoresis of N-acetylneuraminic acid polymers and hyaluronic acid: correlation between migration order reversal and biological functions.

High-resolution analysis of polymers of N-acetylneuraminic acid and hyaluronic acid was performed by capillary electrophoresis in a buffer containing a neutral polymer. Both polysaccharides having more than 100 monosaccharide residues were well separated into their molecular species by capillary electrophoresis using a combination of a chemically modified capillary and a buffer containing poly(ethylene glycol) as an additive. During optimization of the separation conditions, small oligomers of both polysaccharides were observed to migrate in the reverse order of their molecular masses on the electropherograms. However, oligomers larger than pentamer and decamer for N-acetylneuraminic acid polymers and hyaluronic acid, respectively, migrated in the order of their molecular masses. We propose that these unusual migration patterns are closely related to the stereochemical structures and the oligomer migrating the fastest is the minimum unit that forms the regular three-dimensional structure required for the biological function.

Carbohydrate Sequence↗

PubMed1994

Enhanced T cell migration to sites of microscopic CNS disease: complementary treatments evaluated by 2- and 3-D image analysis.

Novel therapies are being developed to attack tumour or other abnormal cells within the brain. A general problem is the need for delivery to sites of microscopic disease. Leukocytes offer an attractive solution; they are able to both move through tissue and recognize abnormal targets. Leukocytes may act as effectors, or as vehicles for drugs, retroviral vectors or other agents. Here, we illustrate complementary ways of enhancing leukocyte migration to sites of microscopic central nervous system (CNS) disease. Enhanced T cell migration to sites of disseminated tumour is used as the example. Computer-assisted image analysis is used to evaluate migration patterns in 2 and 3 dimensions. Shared regulatory features in the migration of tumour and responding cells, and the opportunities and questions they imply, are discussed.

Brain Diseases↗

PubMed1992

Effects of epidermal growth factor, fibroblast growth factor, and transforming growth factor-beta on corneal cell chemotaxis.

The effects of recombinant basic fibroblast growth factor (FGF), epidermal growth factor (EGF), and transforming growth factor-beta (TGF-beta) on migration of human and bovine corneal cells were determined using checkerboard analysis in Boyden chambers. EGF, FGF, and TGF-beta each stimulated high levels of chemotactic migration. Each growth factor, however, induced a different dose-response pattern. Migration stimulated by FGF reached a plateau at a concentration between 100 and 200 ng/ml for endothelial, epithelial, and stromal fibroblasts. By contrast, chemotactic responses to EGF peaked between 10 and 50 ng/ml, then decreased at higher concentrations. TGF-beta also stimulated a peak in migration in all three corneal cells, but the peak of migration occurred at an approximately 1000-fold lower concentration (1 pg/ml) than for EGF. Checkerboard analysis demonstrated that FGF and EGF, but not TGF-beta, stimulated chemokinesis of bovine, stromal, and endothelial cells. These results demonstrate that FGF, EGF, and TGF-beta induce migration in pure populations of bovine and human corneal cells and support the concept that these growth factors may play key roles in corneal wound healing by regulating migration of corneal cells.

Animals↗

PubMed1981

In vitro migration of potential hemopoietic precursors from the murine fetus.

An in vitro migration system demonstrated the presence in murine fetal tissues of cells that migrate to thymus, spleen or lymph node. Preincubation of these cells with facteur thymique sérique, a factor derived from the thymus, produced changes in the migration patterns, suggesting a maturation sequence in fetal hemopoietic precursor-cell migration capacity, with migration to the thymus as the initial potential homing target, followed in order by a potential to migrate to the spleen, than to lymph-node tissue.

Animals↗

PubMed2004

LEGO bricks used as chemotactic chambers: evaluation by a computer-assisted image analysis technique.

One of the main techniques used to explore neutrophil motility, employs micropore filters in chemotactic chambers. Many new models have been proposed, in order to perform multiple microassays in a rapid, inexpensive and reproducible way. In this work, LEGO bricks have been used as chemotactic chambers in the evaluation of neutrophil random motility and chemotaxis and compared with conventional Boyden chambers in a "time-response" experiment. Neutrophil motility throughout the filters was evaluated by means of an image-processing workstation, in which a dedicated algorithm recognizes and counts the cells in several fields and focal planes throughout the whole filter; correlates counts and depth values; performs a statistical analysis of data; calculates the true value of neutrophil migration; determines the distribution of cells; and displays the migration pattern. By this method, we found that the distances travelled by the cells in conventional chambers and in LEGO bricks were perfectly identical, both in random migration and under chemotactic conditions. Moreover, no interference with the physiological behaviour of neutrophils was detectable. In fact, the kinetics of migration was identical both in random migration (characterized by a gaussian pattern) and in chemotaxis (characterized by a typical stimulation peak, previously identified by our workstation). In conclusion, LEGO bricks are extremely precise devices. They are simple to use and allow the use of small amounts of chemoattractant solution and cell suspension, supplying by itself a triplicate test. LEGO bricks are inexpensive, fast and suitable for current diagnostic activity or for research investigations in every laboratory.

Cell Culture Techniques↗

PubMed2006

Cranial neural crest cell migration in cockatiel Nymphicus hollandicus (Aves: Psittaciformes).

Parrots have developed unique jaw muscles in their evolutionary history. The M. pseudomasseter, which completely covers the lateral side of the jugal bar, is regarded as a jaw muscle unique to parrots. In a previous study, I presented a hypothesis on the relevance of modifications in the regulation of cranial neural crest cell (NCC) development to the generation of this novel jaw muscle based on histological analyses (Tokita [2004] J Morphol 259:69-81). In the present study, I investigated distribution and migration patterns of cranial neural crest cells (NCCs) through parrot embryogenesis with immunohistochemical techniques to further understand the role of cranial NCCs in the evolution of the M. pseudomasseter, and to provide new information on the relative plasticity in cranial NCC migration at early stages of avian development. The basic nature of cranial NCC development was mostly conserved between chick and parrot. In both, cranial NCCs migrated from the dorsal tip of the neural tube in a ventral direction. Three major populations were identified in their cranial NCCs. Migration pathways of these cells were almost identical between chick and parrot. The principal difference was seen in the relative timing of cranial NCC migration. In the parrot, cranial NCC migration into the first pharyngeal arch was more advanced than in the chick at early stages of development. Such a temporal shift in cranial NCC migration might influence architectural patterning of parrot jaw muscles that generates new muscle like M. pseudomasseter.

Animals↗

PubMed1994

Genomic characterization of rotavirus strains obtained from hospitalized children with diarrhoea in Bangladesh.

Faecal samples were obtained from 111 children hospitalized with acute watery gastroenteritis in a children's hospital in Bangladesh from January to December, 1989. Rotavirus was detected as the aetiologic agent in 35 (32%) of these patients. The electrophoretic pattern of ds-RNA extracted from the rotaviruses showed 11 different migration patterns (six short and five long), as well as some short and long mixed profiles. All four major G serotypes were identified by amplification of a segment of the gene for VP7 using the polymerase chain reaction. A specific serotype could be assigned in 32 (91%) cases. Serotypes G1-G4 accounted for 11%, 37%, 11%, and 23% of isolates respectively. Three (9%) mixed serotypes were identified by this method and were found to be mixtures of serotypes G1 and G4, G2 and G4, and G3 and G4.

Adolescent↗

PubMed2001

Active site characteristics of CYP4B1 probed with aromatic ligands.

The active site topography of rabbit CYP4B1 has been studied relative to CYP2B1 and CYP102 using a variety of aromatic probe substrates. Oxidation of the prochiral substrate cumene by CYP4B1, but not CYP2B1 or CYP102, resulted in the formation of the thermodynamically disfavored omega-hydroxy metabolite, 2-phenyl-1-propanol, with product stereoselectivity for the (S)-enantiomer. Reaction of CYP4B1, CYP2B1, and CYP102 with phenyldiazene produced spectroscopically observable sigma-complexes for each enzyme. Subsequent oxidation of the CYP2B1 and CYP102 complexes followed by LC/ESI--MS analysis yielded heme pyrrole migration patterns similar to those in previous literature reports. Upon identical treatment, no migration products were detected for CYP4B1. Intramolecular deuterium isotope effects for the benzylic hydroxylation of o-xylene-alpha-(2)H(3), p-xylene-alpha-(2)H(3), 2-(2)H(3),6-dimethylnaphthalene, and 4-(2)H(3),4'-dimethylbiphenyl were determined for CYP4B1 and CYP2B1 to further map their active site dimensions. These probes permit assessment of the ease of equilibration, within P450 active sites, of oxidizable methyl groups located between 3 and 10 A apart [Iyer et al. (1997) Biochemistry 36, 7136--7143]. Isotope effects for the CYP4B1-mediated benzylic hydroxylation of o- and p-xylenes were fully expressed (k(H)/k(D) = 9.7 and 6.8, respectively), whereas deuterium isotope effects for the naphthyl and biphenyl derivatives were both substantially masked (k(H)/k(D) approximately equal to 1). In contrast, significant suppression of the deuterium isotope effects for CYP2B1 occurred only with the biphenyl substrate. Therefore, rapid equilibration between two methyl groups more than 6 A apart is impeded within the active site of CYP4B1, whereas for CYP2B1, equilibration is facile for methyl groups distanced by more than 8 A. Collectively, all data are consistent with the conclusion that the active site of CYP4B1 is considerably restricted relative to CYP2B1.

Animals↗

PubMed1981

"Money illusion" and migration decisions: an international comparison of the United States and Canadian experiences.

"This paper argues that migrant behaviour should be, in the absence of 'money illusion', sensitive to geographic living-cost differentials. The empirical findings of this paper strongly imply that, in the United States and Canada, the cost of living is an important determinant of migration patterns and that omission of the living-cost variable from the migration regression constitutes a specification error." The study is based on net migration data for 36 SMSAs in the United States and 22 CMAs (Central Metropolitan Areas) in Canada (SUMMARY IN FRE, GER)

Americas↗

PubMed1983

Isolation of a cell surface receptor protein for laminin from murine fibrosarcoma cells.

We used affinity chromatography to isolate a specific laminin-binding protein from murine fibrosarcoma cells. These cells bind exogenous laminin to their surface with high affinity (Kd = 2 X 10(-9)M for laminin) with approximately 5 X 10(4) sites per cell. Laminin affinity chromatography of [35S]methionine-labeled cell extracts produced two distinct proteins. One was identified as Type IV (basement membrane) collagen based on its migration pattern on SDS gels and bacterial collagenase sensitivity. The other protein, which migrates as a single band or closely spaced doublet on reduced SDS gels, has a reduced molecular weight of 69,000. Using a nitrocellulose filter disk assay, we found that the latter protein specifically bound 125I-laminin with the same high affinity (Kd = 2 X 10(-9)M for laminin) as did intact fibrosarcoma cells. By iodinating intact cells, we demonstrated that this laminin-binding protein is on the cell surface. We conclude that this protein with reduced molecular weight of 69,000 is a subunit or component of a larger cell surface receptor protein for laminin in this fibrosarcoma model. This laminin receptor may mediate the interaction of the cell with its extracellular matrix.

Animals↗