Lesions localized to the eight nerve and abnormal threshold adaptation.
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Adult↗
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Results for “Local adaptation”
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[Variability of localization of retrotransposon copia ant its effect on adaptation in inbred strains of Drosophila melanogaster with the different rate of transposition].
Three sublines of an inbred laboratory line of Drosophila melanogaster with the initial copia transposition rate 2 x 10(-2), 2 x 10(-3), and 5 x 10(-4) per copy per generation were reared for several dozen generations under conditions of low effective population size (by full-sib crosses or in a small mass culture of 10 females x 10 males). All six lines were tested for the transposition rate, location pattern, and copy number of copia in euchromatic genome regions and for fitness inferred from the intraspecific competition index. The copia transposition rate remained constant in both versions of the lines with an initially lower rate and decreased by an order of magnitude in both versions of the line with an initially higher rate. New copia insertions behaved as selectively neutral and were accumulated in the genome. Each new copy decreased fitness by less than 1% on average. Some of the existing unfixed insertions remained segregating after long-term inbreeding and were assumed to provide a selective advantage to heterozygotes.
Adaptation, Biological↗
[Variability of local strains of Salmonella typhosa during its artificial adaptation to antibiotics].
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Adaptation, Physiological↗
[Adaptation ability of nasal mucosa in relation to local injury].
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Formaldehyde↗
Teleost chloride cell. II. Autoradiographic localization of gill Na,K-ATPase in killifish Fundulus heteroclitus adapted to low and high salinity environments.
The specific binding and inhibitory action of (3H)ouabain were employed to localize transport Na,K-ATPase in the euryhaline teleost gill, a NaCl-transporting osmoregulatory tissue in which both enzyme activity and transepithelial transport vary with environmental salinity. In killifish fully adapted to 10%, 100%, or 200% seawater, the gills were internally perfused and externally irrigated in situ. After suitable internal or external exposure to (3H)ouabain, individual gill arches were excised for Na,K-ATPase assay, measurement of radiolabel binding, or quantitative high-resolution autoradiography. Internal exposure to 50 muM ouabain resulted in essentially complete enzyme inhibition, and binding paralleled the increases in enzyme activity at higher salinities; in contrast, external exposure gave minimal and erratic results consistent with leakage of external ouabain into interstitial fluid. (3H)Ouabain autoradiographs demonstrated that, irrespective of exposure or salinity, most of the gill binding was associated with chloride cell. These cells increased in size and number with salinity and, at the subcellular level, the distribution pattern for bound ouabain was always identical to that for the amplified basal-lateral (tubular system) membrane. The combined physiologicmorphologic results constitute final direct proof that chloride cells are the primary site of gill Na,K-ATPase. More important, they provide convincing evidence for unexpected increases in basal-lateral enzyme at higher salinities and thus raise a fundamental objection to the long-postulated role of the Na pump in secretory NaCl transport.
Adenosine Triphosphatases↗
A minimum on the mean number of steps taken in adaptive walks.
I consider the adaptation of a DNA sequence when mutant fitnesses are drawn randomly from a probability distribution. I focus on "gradient" adaptation in which the population jumps to the best mutant sequence available at each substitution. Given a random starting point, I derive the distribution of the number of substitutions that occur during adaptive walks to a locally optimal sequence. I show that the mean walk length is a constant:L = e-1, where e approximately 2.72. I argue that this result represents a limit on what is possible under any form of adaptation. No adaptive algorithm on any fitness landscape can arrive at a local optimum in fewer than a mean of L = e-1 steps when starting from a random sequence. Put differently, evolution must try out at least e wild-type sequences during an average bout of adaptation.
Adaptation, Biological↗
Improving the local solution accuracy of large-scale digital image-based finite element analyses.
Digital image-based finite element modeling (DIBFEM) has become a widely utilized approach for efficiently meshing complex biological structures such as trabecular bone. While DIBFEM can provide accurate predictions of apparent mechanical properties, its application to simulate local phenomena such as tissue failure or adaptation has been limited by high local solution errors at digital model boundaries. Furthermore, refinement of digital meshes does not necessarily reduce local maximum errors. The purpose of this study was to evaluate the potential to reduce local mean and maximum solution errors in digital meshes using a post-processing filtration method. The effectiveness of a three-dimensional, boundary-specific filtering algorithm was found to be mesh size dependent. Mean absolute and maximum errors were reduced for meshes with more than five elements through the diameter of a cantilever beam considered representative of a single trabecula. Furthermore, mesh refinement consistently decreased errors for filtered solutions but not necessarily for non-filtered solutions. Models with more than five elements through the beam diameter yielded absolute mean errors of less than 15% for both Von Mises stress and maximum principal strain. When applied to a high-resolution model of trabecular bone microstructure, boundary filtering produced a more continuous solution distribution and reduced the predicted maximum stress by 30%. Boundary-specific filtering provides a simple means of improving local solution accuracy while retaining the model generation and numerical storage efficiency of the DIBFEM technique.
Algorithms↗
Vascular tree object segmentation by deskeletonization of valley courses.
In this paper, we propose a valley-course-based image segmentation technique for tree-like object delineation, as an alternative to the traditional centerline-based methods. This technique consists of valley-course extraction, skeleton pruning and deskeletonization. Valley courses, constructed from valley points that are obtained by star-pattern scanning over an image, offer a natural manner of identifying tree skeletons. Unattached segments are removed using morphological operations. A structured tree is then constructed from the skeletons by using a tree pruning/spanning algorithm. A fleshy tree-like object is obtained by a deskeletonization procedure, which consists of extracting tree boundary in vicinity of the skeletons in the original image. The tree boundary is determined by identifying paired edge points at a valley point. A derivative-free edge identification approach is proposed, which defines an edge point at a side-slope by a relative intensity drop with respect to the local background. An empirical formula using a logarithmic function of local intensity contrast offers desirable characteristics of adaptability and stability. The adaptability of edge points to the local background is attributed to the compression behavior of logarithmic function. Furthermore, stability to noise is resulted because derivative operations are not used. The segmentation technique was validated using coronary angiographic images.
Algorithms↗
[Clinical study on development of nontuberculous mycobacterial lung disease].
DEVELOPEMENT OF MAC LUNG DISEASE: An increase of nodular bronchiectatic type of MAC lung disease becomes a problem among respiratory physician today. The reason is still unknown, but it seems to be globally recognized that this type of MAC disease is developing particularly in middle-aged woman. Some papers mentioned the existence of such type of MAC lung disease already early in the 70s, in Japan. Yamamoto described that 17 cases of middle lobe type lung disease out of 154 non-photochoromogen cases, and 76.5% were female, in 1970. Shimoide also pointed such type of 39 cases out of 240 MAC lung disease and 84.6% were female, in 1980. Prince reported MAC lung disease seen in old and middle age female of 21 cases including lethality example of 4 cases without a precedent disease in 1989. After his report, the international consensus of this peculiar type of MAC lung disease seems to be spread. In 1989, we compared 72 cases of nodular bronchiectatic type of MAC lung disease and 56 cases of diffuse panbronchiolitis (DPB) that was a most typical chronic airway disease at that time in Japan. The average age of disease onset of DPB group was 37.0 +/- 16.3 years old and that of MAC group was 54.5 +/- 16.3 years old. The percentage of female was 32% in DPB group and 87.5% in MAC group. It was highly possible that two groups belong different parent population. We could grasp that nodular bronchiectatic type of MAC lung disease patients is a unique group. We observed the serial films of 21 cases of nodular bronchiectatic MAC lung disease, and divide the progression of the disease to sequential 7 steps as Fig. 1. Small nodules progress to cavities in mean about 10 years. However, why is MAC which is opportunistic pathogen with weak virulence, able to form a lesion at unimpaired lung parenchyma? Is there really normal site? Why dose it start from lingula? Why is MAC seen a lot in woman? While it is extremely pathognomonic clinical picture, and, is an extremely interesting problem, most are still unidentified. STUDY OF MAC LUNG DISEASE TREATMENT: It was known that Mycobacterium kansasii lung disease is healed with a chemotherapy like analog of anti-tuberculosis chemotherapy, already in those days. However, the results of MAC lung disease chemotherapy were extremely poor. We tried to express a physicians experience quantitatively as follows, in 1987. The results of 8 weeks sputum culture on Ogawa egg medium were converted semi-quantitatively to CFU numbers based on "Japanese standard guideline of Mycobacterium tuberculosis inspection". We exhibit the ratio of post-treatment consecutive 6 months culture yield to pre-treatment culture yield as response rate, about 110 pulmonary MAC cases. Through this study, we clarify the followings. The results of chemotherapy do not correlate susceptibility test for Mycobacterium tuberculosis. Multidrug regimen is more useful. Small extent of lesion is more responsive. Combination with aminoglycoside chemotherapy is more effective. These conclusions were almost same as the ATS guideline of 1990. New drugs such as, new macrolides and new quinolones appeared for pulmonary MAC treatment through the feedback from systemic MAC complicated AIDS treatments from the latter half of 90's. We measured the sensitive strain ratio at 2 mcg/ml of OFLX, CPFX, LVFX about 990 clinical isolates and could expect availability for M. kansasii or M. fortuitum, but these new quinolones are not enough effective for MAC. Also we examined MIC for various antimycobacterial agent by 50 MAC clinical isolates, and we could expect a certain availability of SPFX, GFLX, CPFX, CAM for MAC. The availability of clarithromycin (CAM) has been established through many randomized clinical trials for disseminated MAC complicated AIDS, but for pulmonary MAC, complete cure is still difficult if we use CAM including regimen. We performed surgical treatment for relatively young patients with localized lesions. We carry out the adaptation reference such as Table, now. The localization of the lesions become a problem at surgical resection. Through the study of our 55 surgical treatment cases, 8 cases (67%) relapsed out of 12 cases which had destructive airway structure in unresected lung field. On the other, only 1 case relapsed (10%) relapsed out of 10 cases without airway destruction in unresected lung. Therefore, even if there is a little dispersal focus without airway destruction in the other pulmonary lobe except purpose focus of resection, it seems that control is possible by post operational chemotherapy. LONG SURVIVAL: As overall consequence, we calculate the survival curves of 201 pulmonary MAC patients visited Tokyo National Hospital from 1953. The survival medium value was 7332 days. The prognosis of nodular bronchiectatic type was better than that of post-tuberculosis type. Extent of disease measured by chest X-ray examination at the time of first visit may be a most affecting factor to the survival rate.
Age Factors↗
Horizontal localization with bilateral hearing aids: without is better than with.
This paper studies the effect of bilateral hearing aids on directional hearing in the frontal horizontal plane. Localization tests evaluated bilateral hearing aid users using different stimuli and different noise scenarios. Normal hearing subjects were used as a reference. The main research questions raised in this paper are: (i) How do bilateral hearing aid users perform on a localization task, relative to normal hearing subjects? (ii) Do bilateral hearing aids preserve localization cues, and (iii) Is there an influence of state of the art noise reduction algorithms, more in particular an adaptive directional microphone configuration, on localization performance? The hearing aid users were tested without and with their hearing aids, using both a standard omnidirectional microphone configuration and an adaptive directional microphone configuration. The following main conclusions are drawn. (i) Bilateral hearing aid users perform worse than normal hearing subjects in a localization task, although more than one-half of the subjects reach normal hearing performance when tested unaided. For both groups, localization performance drops significantly when acoustical scenarios become more complex. (ii) Bilateral, i.e., independently operating hearing aids do not preserve localization cues. (iii) Overall, adaptive directional noise reduction can have an additional and significant negative impact on localization performance.
Acoustic Stimulation↗
Putative neurotransmitters in the red nucleus and their involvement in postlesion adaptive mechanisms.
A variety of putative neurotransmitters has been described in the red nucleus (RN). Measurement of neurotransmitter biochemical markers and study of their specific localizations using morphological techniques in lesion and deafferentation of the RN indicate the participation of glutamate (Glu) in corticorubral transmission and the presence of GABA in RN intrinsic neurones. The cerebellorubral projection may contain at least two populations of fibres, the one using acetylcholine and the other Glu as neurotransmitter. The presence of a serotoninergic input was also demonstrated. Selective deafferentations of the RN, particularly from its cerebellar input, result in biochemical and immunohistochemical responses indicative of increased corticorubral glutamatergic and local GABAergic transmission. These adaptive changes of neuronal transmission as well as the previously described sprouting of corticorubral nerve terminals may contribute to functional recovery after cerebellectomy in adult animals.
Animals↗
Spatially localized distortions of event time.
A fundamental question about the perception of time is whether the neural mechanisms underlying temporal judgements are universal and centralized in the brain or modality specific and distributed. Time perception has traditionally been thought to be entirely dissociated from spatial vision. Here we show that the apparent duration of a dynamic stimulus can be manipulated in a local region of visual space by adapting to oscillatory motion or flicker. This implicates spatially localized temporal mechanisms in duration perception. We do not see concomitant changes in the time of onset or offset of the test patterns, demonstrating a direct local effect on duration perception rather than an indirect effect on the time course of neural processing. The effects of adaptation on duration perception can also be dissociated from motion or flicker perception per se. Although 20 Hz adaptation reduces both the apparent temporal frequency and duration of a 10 Hz test stimulus, 5 Hz adaptation increases apparent temporal frequency but has little effect on duration perception. We conclude that there is a peripheral, spatially localized, essentially visual component involved in sensing the duration of visual events.
Adaptation, Physiological↗
[Development and evaluation of a local area network system to make drug information paper for inpatient--adaptation to characteristics of diseases, and expansibility to other hospitals and the Internet].
We developed and evaluated a local area network system to make drug information papers. Because pharmacists should explain drug information both orally and using papers to patients in response to their understanding and characteristics of their diseases. The merit of this system is as follows: pharmacists can use it without any education for its operation; most data can be inputted by selection from the lists and automatic reference; the data are adjustable for individuals; different contents are available for different wards; multiple users can access the same data file. Input data in this system are available for making explanation papers on the medical examination of outpatients, and making a plan for pharmaceutical care and guidance services. This system is also available in other hospitals, and on the internet. First, we surveyed the time required for preparing drug information papers. Making a hand written paper for typical patient takes 395 sec. for manuscript, 160 sec. with the system using text data only, and 178 sec. with the system using text and picture data. Next, we surveyed 27 patients' views on the addition of drug pictures to drug information papers, and with the result that 19 patients thought it very good. Last, we surveyed 13 ward pharmacists about their usage of this system. We found that 8 pharmacists used frequently this system, and 3 pharmacists used the same file in the same hours at the maximum.
Aged↗
Pattern-specific contrast threshold elevation.
Visual channels are defined psychophysically; stimuli that interact share information in the same channel, and those that do not interact are processed in different channels. Channels are often investigated by means of adaptation to one stimulus, testing contrast threshold elevation with one (or more) others. Much recent work has tested the tuning of channels for orientation and spatial frequency, using simple line gratings. This study examined the pattern-specificity of such adaptation, testing the hypothesis that the fundamental operators of the Lie Transformation Group Theory of Neuropsychology (LTG/NP) define psychophysical channels. In Experiment I the three basic pattern pairs of LTG/NP were used as adaptation and test stimuli in a conventional contrast threshold-elevation experiment. Threshold elevation was pattern-specific, thus supporting the hypothesis. In subsequent experiments various 'fractured' patterns, and patterns generated by combinations of Lie operators were used both for adaptation and test. The results were mixed; some supported the original hypothesis, but many did not. Relations between local contour orientations in adaptation and test patterns could explain some results, but not all. The hypothesis that adaptation occurs to the oriented spatial-frequency components of the test patterns, on the other hand, gave a good fit to the data. It is concluded that there is pattern-specificity in contrast threshold elevation, but it is a form of specificity that can be explained without recourse to a model of geometrical pattern processing, at least for the simple patterns used here.
Adaptation, Ocular↗
[Collagenolytic activity of human cervical tissue, following local application of prostaglandin E2 (PG E2), using a portio adapter (author's transl)].
A biological assay was used to determine collagenolytic activities in cervical tissue of 16 patients, who had received PG E2 treatment for cervical ripening, and of another 16 patients in whom cervical ripening had occurred spontaneously. The cervical tissue required for the assay was obtained by small biopsy after delivery. The first group of probands received 1.25 mg PG E2 in aqueous solution which was locally applied to the cervix through a portio adapter. Mean lysis, related to a tissue sample of 2 mm in diameter and following twelve hours of incubation, amounted to 7.82 +/- 2.58 mm2 in the treated group and to 5.39 +/- 1.06 mm2 in the untreated group. A statistically significant difference of p less than 0.005 was, accordingly, obtained by a Student-t test of unpaired observation. The results of the author's tests have shown that rise in collagenolytic activity was one of the major effects when prostaglandin was locally applied for cervical ripening.
Administration, Topical↗
The importance of being discrete: life always wins on the surface.
Many systems in chemistry, biology, finance, and social sciences present emerging features that are not easy to guess from the elementary interactions of their microscopic individual components. In the past, the macroscopic behavior of such systems was modeled by assuming that the collective dynamics of microscopic components can be effectively described collectively by equations acting on spatially continuous density distributions. It turns out that, to the contrary, taking into account the actual individual/discrete character of the microscopic components of these systems is crucial for explaining their macroscopic behavior. In fact, we find that in conditions in which the continuum approach would predict the extinction of all of the population (respectively the vanishing of the invested capital or the concentration of a chemical substance, etc.), the microscopic granularity insures the emergence of macroscopic localized subpopulations with collective adaptive properties that allow their survival and development. In particular it is found that in two dimensions "life" (the localized proliferating phase) always prevails.
Journal Article↗
Mechanisms for force adjustments to unpredictable frictional changes at individual digits during two-fingered manipulation.
Previous studies on adaptation of fingertip forces to local friction at individual digit-object interfaces largely focused on static phases of manipulative tasks in which humans could rely on anticipatory control based on the friction in previous trials. Here we instead analyze mechanisms underlying this adaptation after unpredictable changes in local friction between consecutive trials. With the tips of the right index and middle fingers or the right and left index fingers, subjects restrained a manipulandum whose horizontal contact surfaces were located side by side. At unpredictable moments a tangential force was applied to the contact surfaces in the distal direction at 16 N/s to a plateau at 4 N. The subjects were free to use any combination of normal and tangential forces at the two fingers, but the sum of the tangential forces had to counterbalance the imposed load. The contact surface of the right index finger was fine-grained sandpaper, whereas that of the cooperating finger was changed between sandpaper and the more slippery rayon. The load increase automatically triggered normal force responses at both fingers. When a finger contacted rayon, subjects allowed slips to occur at this finger during the load force increase instead of elevating the normal force. These slips accounted for a partitioning of the load force between the digits that resulted in an adequate adjustment of the normal:tangential force ratios to the local friction at each digit. This mechanism required a fine control of the normal forces. Although the normal force at the more slippery surface had to be comparatively low to allow slippage, the normal forces applied by the nonslipping digit at the same time had to be high enough to prevent loss of the manipulandum. The frictional changes influenced the normal forces applied before the load ramp as well as the size of the triggered normal force responses similarly at both fingers, that is, with rayon at one contact surface the normal forces increased at both fingers. Thus to independently adapt fingertip forces to the local friction the normal forces were controlled at an interdigital level by using sensory information from both engaged digits. Furthermore, subjects used both short- and long-term anticipatory mechanisms in a manner consistent with the notion that the central nervous system (CNS) entertains internal models of relevant object and task properties during manipulation.
Adaptation, Physiological↗
Habitat-specific pigmentation in a freshwater isopod: adaptive evolution over a small spatiotemporal scale.
Pigmentation in the freshwater isopod Asellus aquaticus (Crustacea) differed between habitats in two Swedish lakes. In both lakes, isopods had lighter pigmentation in stands of submerged vegetation, consisting of stoneworts (Chara spp.), than in nearby stands of reed (Phragmites australis). Experimental crossings of light and dark isopods in a common environment showed that pigmentation had a genetic basis and that genetic variance was additive. Environmental effects of diet or chromatophore adjustment to the background had minor influence on pigmentation, as shown by laboratory rearing of isopods on stonewort or reed substrates, as well as analyses of stable isotope ratios for isopods collected in the field. In both study lakes, the average phenotype became lighter with time (across generations) in recently established stonewort stands. Taken together, these results indicate that altered phenotype pigmentation result from evolutionary responses to local differences in natural selection. Based on the assumption of two generations per year, the evolutionary rate of change in pigmentation was 0.08 standard deviations per generation (haldanes) over 20 generations in one lake and 0.22 haldanes over two generations in the other lake. This genetic change occurred during an episode of population growth in a novel habitat, a situation known to promote adaptive evolution. In addition, stonewort stands constitute large and persistent patches, characteristics that tend to preserve local adaptations produced by natural selection. Results from studies on selective forces behind the adaptive divergence suggest that selective predation from visually oriented predators is a possible selective agent. We found no indications of phenotype-specific movements between habitats. Mating within stonewort stands was random with respect to pigmentation, but on a whole-lake scale it is likely that mating is assortative, as a result of local differences in phenotype distribution.
Adaptation, Physiological↗