Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Local adaptation”

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 1,189 records · Page 66Linked to original sources
PubMed1975

Population genetics of allozyme variation in Neurospora intermedia.

Electrophoretically detectable variation in the fungus Neurospora intermedia has been surveyed among isolates from natural populations in Malaya, Papua, Australia and Florida. The principal result is a pattern of genetic variation within and between populations that is qualitatively no different than the well documented patterns for Drosophila and humans. In particular, there is a high level of genetic variation, the majority of which occurs at the level of local populations. Evidence is presented which argues that N. intermedia has a population structure analogous to that of an annual vascular plant with a high level of vegetative reproduction. Sexual reproduction appears to be a regular feature in the biology of the species. Substantial heterokaryon function seems unlikely in natural populations of N. intermedia. Theoretical considerations concerning the mechanisms underlying the observed pattern of variation most likely should be consistent with haploid selection theory. The implications of this constraint upon the theory are discussed in detail, leading to the presentation of a model based upon the concept of environmental heterogenicity. The essence of the model, which is equally applicable to haploid and diploid situations, is a shifting distribution of multiple adaptive niches among local populations such that a given population has a small net selective pressure in favor of one allele or another, depending upon its particular distribution of niches. Gene flow among neighboring populations with differing net selective pressures is postulated as the principal factor underlying intrapopulational allozyme variation.

Acid Phosphatase↗
PubMed2003

[Physiologic basis of human adaptation to cold].

Intermittent exposures to cold (15 head out immersions into 14 degrees C water, for 1 h, within 3 weeks) induce physiological changes leading to the restriction of heat loss from the body, due to hypothermia and vasoconstriction. These adaptational changes may save more than 25% of energy during 1 hour cold test. Insulative adaptation due to increased amount of the subcutaneous fat is less prominent. Winter swimmers show similar mechanisms of cold adaptationn as humans adapted by intermittent cold exposures in the laboratory. Additionally, winter swimmers exert a greater capacity of nonshivering thermogenesis than nonadapted controls. Thus, adaptation of humans to cold involves hypothermic, metabolic and insulative mechanisms. Time courses of development of individual mechanisms of adaptation differ. Intermittent local cold exposures (20 immersions of legs into 12 degrees C water, for 45 min, within 4 weeks lower sympathetic tone and induce redistribution of cardiac output, in order to ensure preferential warming of central parts of the body. Basal metabolism and cold induced thermogenesis are increased, but the threshold for induction of cold thermogenesis is not influenced. In contrast to changes induced by repeated whole body immersions, these changes may not ensure greater resistance to the cold stress.

Adaptation, Physiological↗
PubMed1980

Motion and vision. III. Stabilized pattern adaptation.

It has been suggested that local variations of retinal sensitivity may be responsible for elevating the threshold in pattern-adaptation experiments of the Blakemore-Campbell type. Subjects are unable to scan high-contrast gratings uniformly enough to eliminate this possibility. To control this effect, we performed grating-adaptation experiments under stabilized-image conditions, while both adapting and test targets were moved at retinal velocities determined by the experimenter. By means of an afterimage technique, we also measured the strength of the retinal sensitivity mask that forms under these conditions. Varying the spatial frequency and velocity of the adapting stimulus, we inferred the spatial and temporal properties of the principal mechanism that contributes to the afterimage. We found that the Blakemore-Campbell effect persists at adapting velocities that are fast enough to rule out local variations of retinal sensitivity. More surprisingly, even the clearly visible afterimages that occur at a retinal velocity of 0.1 deg/s seem to have no effect on pattern adaptation. (Sensitivity masking can raise the adapted threshold, but only at adapting velocities slower than normal eye movements). By manipulating the image velocity, we were able to shift the spatial frequencies of some threshold-elevation curves, but these shifts were not great enough to suggest that velocity tuning plays important role in pattern adaptation.

Adaptation, Ocular↗
PubMed1994

[Environments and handicaps].

Chronic deficiencies have been known ever since man left traces of his own existence but have increased since the 19th century. The number of people with chronic deficiencies in France is close to five millions, of which 1,2 million are very severe. This figure does not include occasional deficiencies due to age or "normal" transitory situations of life. These deficiencies engender disabilities which themselves create a handicap. Particular attention to environmental conditions is required to cope with such situation and try and equalize opportunities and reduce exclusion. This is a part of the scope of medicine if the aim is, as Pr. B. Glorion reminded us recently "to treat and cure but also maintain the patients physical and moral equilibrium". Reeducation is concerned with the person, rehabilitation with the adaptation of the individual and collective environment. It is in intervening in this area, that it becomes possible to reduce otherwise overwhelming inequalities. "What constitutes real democracy is not to recognise equals but to make them equal" (Gambetta). While it remains necessary to answer to the requirements of individual situations, it is on the wider and collective front that solutions must be found in order to deal with the greater situational difficulties of collective life. To be efficient, the principles of action must leave behind conventional classifications and attempt to solve the functional difficulties: daily life activities, transportation, work, education, access to social life. Given pressure from individuals, often grouped in associations, and from medical practitioners sensitive to these problems, laws have been passed and local authorities have adapted infrastructures.(ABSTRACT TRUNCATED AT 250 WORDS)

Persons with Disabilities↗
PubMed1990

Crossbreeding as a tool for genetic improvement of chickens in suboptimum environments.

A 2-phase crossbreeding study was undertaken to explore prospects of improving the performance of chickens under extensive production conditions in Tanzania. The first phase was carried out under reasonably good feeding and housing conditions and involved one imported meat and egg type each as well as a local breed and their crosses. In the second phase, 15 genetic groups with graded proportions of inheritance from the 3 parental breeds were compared for their performance under relatively poor conditions of feeding and general management. The results revealed that under good production conditions the performance in a particular trait increased with increasing levels of inheritance from the exotic breed which had been developed mainly for that trait. Under poor management conditions, the trend was rather obscure, with the superiority of germ plasma from the exotic breeds expressed in the crosses rather than in the parental breeds. The disparity between the results obtained in the two phases is attributed to genotype x environmental interaction, heterosis, heterosis x environment interaction, and maternal and sex-linked influences. It is concluded that the genetic disposition of the high performers should be adapted to the local production conditions by forming synthetic breeds based on crossbreeding.

Animals↗
PubMed2004

The relationship between specialization and local abundance: the case of helminth parasites of birds.

Positive relationships are commonly observed between the abundance of a species in a locality and the frequency of its occurrence among localities on a larger scale. This pattern may not hold for parasitic organisms when the average abundance of a parasite among its hosts is related to the number of host species in which it occurs, because of the additive investment in specific adaptations to counter host immune responses required for each host species in a parasite's repertoire. For a rigorous test of the hypothesis that there is a trade-off between the number of host species that can be successfully exploited and the average abundance of parasites in those hosts, one needs to take into account the phylogenetic (or taxonomic) distances among the host species used by a parasite. Differences in immune responses are likely to increase with increasing phylogenetic distances. The trade-off hypothesis was tested in a comparative analysis of 393 species of trematodes, cestodes and nematodes parasitic in birds surveyed from the same geographical area, using an index of host specificity that measures the average taxonomic distances between a parasite's known host species. After correcting for the influences of parasite phylogeny and other potential confounding variables, mean abundance was negatively correlated with the average taxonomic distance among host species for nematodes, and with the variance in taxonomic distances among hosts for cestodes. In the case of trematodes, these variables covaried positively. The trade-off between average infection success and how taxonomically distant a parasite's host species are from each other was only found in two of the three groups of helminths investigated, possibly because of compensating features in trematodes, such as their ability to multiply asexually in intermediate hosts. These results provide empirical evidence consistent with the hypothesis that specialization allows greater local adaptation and therefore greater local population abundance, supporting key predictions regarding the evolution of ecological specialization.

Analysis of Variance↗
PubMedDate not supplied

Increasing capacity for innovation in bureaucratic primary care organizations: a whole system participatory action research project.

PURPOSE: We wanted to identify what organizational features support innovation in Primary Care Groups (PCGs). METHODS: Our study used a whole system participatory action research model. Four research teams provided complementary insights. Four case study PCGs were analyzed. Two had an intervention to help local facilitators reflect on their work. Data included 70 key informant interviews, observations of clinical governance interventions and committee meetings, analysis of written materials, surveys and telephone interviews of London Primary Care Organizations, interviews with 20 nurses, and interviews with 6 finance directors. A broad range of stakeholders reviewed data at annual conferences and formed conclusions about trustworthy principles. Sequential research phases were refocused in the light of these conclusions and in response to the changing political context. RESULTS: Five features were associated with increased organizational capacity for innovation: (1) clear structures and a vision for corporate and clinical governance; (2) multiple opportunities for people to reflect and learn at all levels of the organization, and connections between these "learning spaces"; (3) both clinicians and managers in leadership roles that encourage participation; (4) the right timing for an initiative and its adaptation to the local context; and (5) external facilitation that provides opportunities for people to make sense of their experiences. Low morale was commonly attributed to 3 features: (1) overwhelming pace of reform, (2) inadequate staff experience and supportive infrastructure, and (3) financial deficits. CONCLUSIONS: These features together may support innovation in other primary care bureaucracies. The research methodology enabled people from different backgrounds to make sense of diverse research insights.

Group Practice↗
PubMed2005

Challenges for control of taeniasis/cysticercosis in Indonesia.

Taeniasis/cysticercosis has been reported from several provinces of Indonesia: Papua (=former Irian Jaya), Bali, North Sumatra, East Nusa Tenggara, South East Sulawesi, Lampung, North Sulawesi, Jakarta, West Kalimantan, and East Java. The highest level of endemicity of taeniasis/cysticercosis has been found in Papua. Recent surveys in Jayawijaya District of Papua in 2000 and 2001 showed that 5 of 58 local people (8.6%) harbored the adult tapeworm, Taenia solium, whereas 44 of 96 people (45.8%), 50 of 71 pigs (70.4%), and 7 of 64 local dogs (10.9%) were seropositive for T. solium cysticercosis. Current surveys in Bali and Samosir District, North Sumatra during 2002-2005 revealed that Taenia saginata taeniasis has increased in incidence whereas T. solium cysticercosis is now rather rare compared to one-two decades ago in Bali. Taenia asiatica taeniasis is still common in Samosir District. Data from other provinces of Indonesia are very limited or unavailable. Control of these diseases is not a priority in the health or veterinary services, neither at central or local government levels. However, limited efforts toward control of the diseases have been implemented such as training of health personnel, community education on disease prevention, and provision of anthelminthics. A working group for control of the disease in Indonesia and an international collaboration have been established among Ministry of Health, Indonesia; University of Indonesia; and Asahikawa Medical College, Asahikawa, Japan since 1996. Future goals include implementation of active case finding (active surveillance) and treatment of tapeworm carriers, sustainable public health education, establishment of a system to check the quality of beef/pork and determine the distribution of infected animals and strengthening of laboratory capacity. Efforts to motivate provinces and districts should be implemented in developing the strategic plan to control of the disease. Given the considerable differences in cultures, religions, levels of education, socio-economic levels, daily habits and behaviour etc., control programmes must be adapted to the local situations.

Animals↗
PubMed2004

Human birthweight evolution across contrasting environments.

We explore from both theoretical and empirical perspectives the hypothesis that a significant part of the worldwide variability in human birthweight results from adaptive responses to local selective pressures. We first developed an agent-based model to simulate the process of evolutionary selection on life history strategy, and then we performed a comparative analysis across 89 countries worldwide. The model illustrates that optimal birthweight depends on which fitness-reducing risk locally predominates (somatic diseases, parasitic diseases or adverse environmental conditions). When fitness variations between individuals mainly result from somatic diseases (e.g. industrialized countries), or conversely from infectious and parasitic diseases (e.g. developing countries), selection is expected to favour individuals producing larger children. Conversely, when environmental risks increase in relative importance, selective pressures for producing children with high birthweight are reduced. The comparative analysis supports these theoretical expectations, in particular the finding that birthweight is higher than predicted in highly parasitized countries.

Adaptation, Physiological↗
PubMed2003

Plasticity in human sound localization induced by compressed spatial vision.

Auditory and visual target locations are encoded differently in the brain, but must be co-calibrated to maintain cross-sensory concordance. Mechanisms that adjust spatial calibration across modalities have been described (for example, prism adaptation in owls), though rudimentarily in humans. We quantified the adaptation of human sound localization in response to spatially compressed vision (0.5x lenses for 2-3 days). This induced a corresponding compression of auditory localization that was most pronounced for azimuth (minimal for elevation) and was restricted to the visual field of the lenses. Sound localization was also affected outside the field of visual-auditory interaction (shifted centrally, not compressed). These results suggest that spatially modified vision induces adaptive changes in adult human sound localization, including novel mechanisms that account for spatial compression. Findings are consistent with a model in which the central processing of sound location is encoded by recruitment rather than by a place code.

Acoustic Stimulation↗
PubMed1994

The design of a community-based health education intervention for the control of Aedes aegypti.

This report describes the process used to develop locally appropriate educational materials and to implement the education component of a community-based Aedes aegypti control program in Merida, Yucatan, Mexico. The process is broken into five stages: formative research, developing recommendations for behavior change, development of educational messages, development and production of educational materials, and distribution of the materials. Appropriate terminology and taxonomies for dengue were obtained from open in-depth interviews; baseline data from a knowledge, beliefs, and practices questionnaire served to confirm this information. A larval survey of house lots was carried out to identify the Ae. aegypti larval production sites found on individual house lots. This enabled the program to target the most important larval habitats. Community groups were organized to work on the development of messages and production of the educational materials to be used. The education intervention was successful in stimulating changes in both knowledge and behavior, which were measured in the evaluations of the intervention. To be successful, community-based strategies must be flexible and adapted to the local setting because of ecologic, cultural, and social differences between localities.

Aedes↗
PubMed1994

Functional and histologic characteristics of chronic renal allograft rejection.

Chronic allograft rejection very probably results from the interactions between allogeneic immune injury, tissue reactions in response to injury, and local intragraft hemodynamic adaptations to the progressive loss of functioning organ mass. We examined each of these components in a rat model of chronic renal allograft rejection. Although immunofluorescence studies of renal allografts with chronic rejection usually reveal nondiagnostic patterns of immunoglobulin deposits, we found, using Western blot analysis, donor-directed antibodies against novel glomerular basement membrane antigens in the sera of animals with chronic rejection-associated transplant glomerulopathy. Stop-flow micropuncture studies have shown that the glomerular capillary pressure in transplanted kidneys resembles that of the donor strain kidney in response to renal ablation. Northern blots for growth factor transcripts showed induced expression of mRNA levels for various growth factors in long-surviving renal transplants. Reduction in intraglomerular pressure was associated with increased recipient survival, preservation of renal function, decreased amounts of proteinuria, and less severe structural lesions in the glomeruli. We conclude that the glomerular lesions of chronic rejection may arise from a combination of antiglomerular (allo) antibodies in conjunction with increased intraglomerular pressures and local production of growth factors. The vascular lesions and interstitial scarring of chronic rejection may arise from previous episodes of graft vasculitis and interstitial inflammation, respectively.

Animals↗
PubMed1991

[Contact eczema and "standard test"--do "International Standard Test Series" coincide with Austrian local characteristics?].

Testing with a "standard" group of substances has proved of great value when allergic contact dermatitis is suspected and the offending agent cannot be pinpointed by careful history-taking. But internationally standardized series do not take into account locally important and individual factors, changing consumer habits or economic aspects. We have, thus, compared the suitability of two standard series, the ICDRG-European and the DKG-German standard, for Austrian purposes. 1,478 patients with a clinical diagnosis of contact dermatitis were patch tested between 11/88 and 4/90 with the ICDRG allergens; the second collective of 505 patients was tested between 5/90 and 1/91 with the DKG series. Only 12 out of the 27 substances of the ICDRG series exceeded the critical incidence of 1%; 6 were below this limit but positive in more than 0.5% and 9 hardly ever aroused positive reactions. In the DKG series, 17 out of 23 substances surpassed the limit, 2 were positive in more than 0.5%, and 4 caused virtually no reactions. However, 4 allergens with frequent sensitization rates were included neither in the ICDRG nor in the DKG series and 2 others were missing in the over-dimensioned ICDRG standard. Our results demonstrate that internationally established standard series have to adapted for the local situation in Austria, and that a constant review is essential with replacement of allergens as necessary according to changing production techniques and consumer habits. Suggestions for an "Austrian standard patch test series" are proposed on the basis of our results but in spite of being helpful in general terms interpretation of such a test in the individual patient with eczema remains problematic.

Allergens↗
PubMed1998

[Popular perceptions about childhood diarrheas: diversity and unity].

Sickness is defined by culture: each society has its own way of labelling, explaining and treating symptoms. In the case of childhood diarrhea, each population selects some signs and considers them as symptoms, defines a limit between normal and pathologic, arranges symptoms in order to build syndromes that make up a local nosology. Examples from Thailand, China, Algeria, Nicaragua and Burkina Faso show the diversity of popular beliefs about diarrhea. These beliefs depend upon the epidemiological context, but they do not reflect it exactly: thus in Burkina Faso, AIDS has not been integrated in popular beliefs about childhood diarrhea. The examples discussed in this article show how popular beliefs evolve, especially under the influence of biomedicine. Moreover, every individual understands differently the popular nosology according to his (or her) social status and to the level of his (her) knowledge. To the unity of biomedical knowledge responds a great diversity of popular beliefs. In France, contemporary popular beliefs about childhood diarrhea have been seldom studied by social sciences. They seem to be close to biomedical knowledge and share some essential elements with it, but they also show some features--such as the belief that diarrhea is benign when simultaneous to teething--that relate them to popular beliefs which have been described in other cultures. By describing and analysing these popular beliefs, medical anthropology makes it possible to adapt medicine to local knowledges.

Acquired Immunodeficiency Syndrome↗
PubMed2006

Differential regulation of glucocorticoid synthesis in murine intestinal epithelial versus adrenocortical cell lines.

Glucocorticoids are steroid hormones with important functions in development, immune regulation, and glucose metabolism. The adrenal glands are the predominant source of glucocorticoids; however, there is increasing evidence for extraadrenal glucocorticoid synthesis in thymus, brain, skin, and vascular endothelium. We recently identified intestinal epithelial cells as an important source of glucocorticoids, which regulate the activation of local intestinal immune cells. The molecular regulation of intestinal glucocorticoid synthesis is currently unexplored. In this study we investigated the transcriptional regulation of the steroidogenic enzymes P450 side-chain cleavage enzyme and 11beta-hydroxylase, and the production of corticosterone in the murine intestinal epithelial cell line mICcl2 and compared it with that in the adrenocortical cell line Y1. Surprisingly, we observed a reciprocal stimulation pattern in these two cell lines. Elevation of intracellular cAMP induced the expression of steroidogenic enzymes in Y1 cells, whereas it inhibited steroidogenesis in mICcl2 cells. In contrast, phorbol ester induced steroidogenic enzymes in intestinal epithelial cells, which was synergistically enhanced upon transfection of cells with the nuclear receptors steroidogenic factor-1 (NR5A1) and liver receptor homolog-1 (NR5A2). Finally, we observed that basal and liver receptor homolog-1/phorbol ester-induced expression of steroidogenic enzymes in mICcl2 cells was inhibited by the antagonistic nuclear receptor small heterodimer partner. We conclude that the molecular basis of glucocorticoid synthesis in intestinal epithelial cells is distinct from that in adrenal cells, most likely representing an adaptation to the local environment and different requirements.

Adrenal Cortex↗
PubMed2004

Adaptation of the ACE for a Malayalam speaking population in southern India.

OBJECTIVE: To adapt the Addenbrooke's Cognitive Examination (ACE) as a dementia-screening tool in a community in south India. To establish that items in the adapted version are equivalent to that in the original. METHODS: The ACE was adapted into the local language, Malayalam (m-ACE), following cultural/linguistic modifications. To establish equivalence, qualitative comparisons were made (on the distribution of scores, percentage scoring at ceiling, and relative difficulty across items) between a UK sample receiving the ACE (n = 50; mean age = 67.9 +/- 7.4; education >/= 9, mean = 10.9 +/- 2.5) and a community-based educationally-stratified Indian sample receiving the m-ACE: 'India >/= 9' (n = 50; mean age = 67.8 +/- 5.2; education >/= 9, mean = 13.9 +/- 2.7) and 'India </= 8' (n = 50; mean age = 67.1 +/- 5.3; education </= 8, mean = 3.1 +/- 2.0). RESULTS: Most ACE items were retained. The score distribution (mean +/- 1SD), percentage at ceiling, and relative difficulties across items is comparable between the UK and the educationally equivalent India >/= 9 groups. Language, Naming, Attention and Orientation are relatively easy (>/= 80% at ceiling) and Recall and Verbal fluency are relatively difficult (</= 22% at ceiling). Although the percentage at ceiling were lower for the India </= 8 group, the order of relative difficulty was similar and the percentage scoring at floor was </= 10% on all except visuospatial item. CONCLUSIONS: The m-ACE provides a culture-fair Malayalam adaptation of the ACE with component items of equivalent difficulty.

Aged↗
PubMed2002

[Analyses of responsible factors for the delay effect produced by prolonged viewing in recognizing Kanji characters].

Ninose & Gyoba (1996) examined delays in the recognition of Kanjis following prolonged viewing. They suggested that a Kanji pattern may be internally represented as a whole and the prolonged viewing may produce an adaptation effect specific to such a representation. The present study examined responsible factors producing the delay effect more in detail by manipulating figural components of adaptation and test Kanjis. The delay occurred only when the test Kanji was the same pattern as the adaptation Kanji in all local details. In contrast, the delay were not observed either when the global pattern of the test Kanji was similar to that of the adaptation Kanji, or when a part of the test Kanji was the same pattern as the whole configuration of the adaptation Kanji. These results indicate that the delay effect is produced by prolonged viewing of the adaptation Kanji with exactly the same local and global configurations as the test Kanji, while the previous studies have revealed that the delay effect occurs independent from Kanji's size and orientation in some ranges.

Adaptation, Psychological↗
PubMed2003

Adaptation of Cucumber mosaic virus soybean strains (SSVs) to cultivated and wild soybeans.

Cucumber mosaic virus soybean strains formerly called soybean stunt virus (SSV) were inoculated onto 23 wild soybeans collected from four Asian countries to investigate their infectivity in order to improve understanding of the co-evolution of SSVs and soybean. SSV inoculation resulted in systemic infection in most of the wild soybeans used. However, an SSV strain (SSV-In), which was isolated in Indonesia, did not result in systemic infection of many of the wild soybeans distributed in southern Japan. This exceptional infectivity of SSV-In may be due to its specific adaptation to the local soybean population(s) of Indonesia, which has rarely been affected by gene flows from wild soybean. In the present study, the nucleotide sequences of the 3a and CP genes of SSV were determined, and the data were used to classify seven SSV isolates among known Cucumber mosaic virus (CMV) strains. The phylogenetic analysis showed that the seven SSVs formed a distinct cluster separated from the other CMV strains despite their different geographical origins; SSV-In was the most divergent of the seven isolates. Comparison of the rates of synonymous and nonsynonymous substitutions revealed that the SSV group had evolved faster than subgroup IA. The implications of the findings are discussed in relation to the so-called Red Queen hypothesis.

Adaptation, Physiological↗