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At least 127 records · Page 7Linked to original sources
PubMed2005

Adaptation of estrogen-regulated genes in long-term estradiol deprived MCF-7 breast cancer cells.

First line treatment of hormone dependent breast cancer initially causes tumor regression but later results in adaptive changes and tumor re-growth. Responses to second line treatments occur but tumors again begin to progress after a period of 12???18??months. In depth understanding of the adaptive process would allow the identification of targets to abrogate the development of hormonal resistance and prolong the efficacy of endocrine therapy. We have developed a model system to examine adaptive changes in human MCF-7 breast cancer cells. Upon deprivation of estradiol for a prolonged period of time, a maneuver analogous to surgical oophorectomy in pre-menopausal women and use of aromatase inhibitors in post-menopausal patients, tumor cells adapt and become hypersensitive to estradiol. We reasoned that the expression pattern of multiple genes would change in response to estradiol deprivation and that cDNA microarrays would provide an efficient means of assessing these changes. Accordingly, we examined the transcriptional responses to estradiol in long-term estradiol deprived (LTED) MCF-7 cells with a cDNA microarray containing 1901 known genes and ESTs. To assess the changes induced by long-term estradiol deprivation, we compared the effects of estradiol administration in LTED cells with those in MCF-7 cells, which we had previously reported, and confirmed with real time PCR using the parental and LTED cells. Seven genes and one EST were induced by estradiol in LTED but not in wild type MCF-7 cells, whereas ten genes were down-regulated by estradiol only in LTED cells. The expression of seven genes increased concurrently and five decreased in response to estradiol in both cell types. From these observations, we generated testable hypotheses regarding several genes including DKFZP, RAP-1, ribosomal protein S6, and TM4SF1. Based upon the known functions of these genes and the patterns of observed changes, we postulate that divergent regulation of these genes may contribute to the different biologic responses to estrogen in these cell lines. These results provide targets for further mechanistic studies in our experimental system. Our findings indicate that long-term estradiol deprivation causes expression changes in multiple genes and emphasizes the complexity of the process of cellular adaptation.

Adaptation, Physiological↗
PubMed1976

Gingival architectural forms in periodontal diseases.

Changes in the gingival architectural form and the incidence were observed on 1,700 interdental papillae and 3,791 parts of the gingival margin of 89 patients, both males and females, with periodontal diseases. The effects of improperly adapted restoration, tooth irregularity, depth of periodontal pocket and degree of bone loss on the gingival changes were also examined. Of the four types of changes observed in the marginal gingiva, the recessed form occurred most frequently. Next in order of frequency of occurrence were the ledged, festoon and cleft forms. The greater part of the gingival changes observed in the interdental papilla were both of the blunted and enlarged forms. In the interdental papilla, the blunted and cratered forms increased and the enlarged form decreased according to the degree of bone loss. Improperly adapted restoration and tooth irregularity influenced the gingival changes observed. The depth of the periodontal pocket was not found to influence the gingival form.

Adolescent↗
PubMed2006

Computer-generated holograms of a real three-dimensional object based on stereoscopic video images.

A novel method of using stereoscopic video images to synthesize the computer-generated hologram (CGH) patterns of a real 3D object is proposed. Stereoscopic video images of a real 3D object are captured by a 3D camera system. Disparity maps between the captured stereo image pairs are estimated and from these estimated maps the depth data for each pixel of the object can be extracted on a frame basis. By using these depth data and original color images, hologram patterns of a real object can be computationally generated. In experiments, stereoscopic video images of a real 3D object, a wooden rhinoceros doll, are captured by using the Wasol 3D adapter system and its depth data are extracted from them. Then, CGH patterns of 1280 pixels x 1024 pixels are generated with these depth-annotated images of the wooden rhinoceros doll, and the CGH patterns are experimentally displayed via a holographic display system.

Journal Article↗
PubMed2005

A common mechanism for perceptual filling-in and motion-induced blindness.

Perceptual-filling-in (PFI) and motion-induced-blindness (MIB) are two phenomena of temporary blindness in which, after prolonged viewing, perceptually salient targets repeatedly disappear and reappear, amidst a field of distracters (i.e., non-targets). Past studies have shown that boundary adaptation is important in PFI, and that depth ordering between target and distracter pattern is important in MIB. Here we show that the reverse is also true; that boundary adaptation is important in MIB, and that depth ordering is important in PFI. Results corroborate our earlier conjecture that PFI and MIB are highly related phenomena that share a common underlying mechanism. We argue that this mechanism involves boundary adaptation, but also that the depth effect shows that boundary adaptation can be no more than a sufficient cause of PFI and MIB, and not a necessary one.

Adaptation, Physiological↗
PubMed1999

Stereopsis from contrast envelopes.

We report two experiments concerning the site of the principal nonlinearity in second-order stereopsis. The first exploits the asymmetry in perceiving transparency with second-order stimuli found by Langley et al. (1998) (Proceedings of the Royal Society of London B, 265, 1837-1845) i.e. the product of a positive-valued contrast envelope and a mean-zero carrier grating can be seen transparently only when the disparities are consistent with the envelope appearing in front of the carrier. We measured the energy at the envelope frequencies that must be added in order to negate this asymmetry. We report that this amplitude can be predicted from the envelope sidebands and not from the magnitude of compressive pre-cortical nonlinearities measured by other researchers. In the second experiment, contrast threshold elevations were measured for the discrimination of envelope disparities following adaptation to sinusoidal gratings. It is reported that perception of the envelope's depth was affected most when the adapting grating was similar (in orientation and frequency) to the carrier, rather than to the contrast envelope. These results suggest that the principal nonlinearity in second-order stereopsis is cortical, occurring after orientation- and frequency-selective linear filtering.

Adaptation, Ocular↗
PubMed2002

Selective inhibition of the epidermal growth factor receptor impairs intestinal adaptation after small bowel resection.

BACKGROUND: Prior indirect studies have suggested that a functional epidermal growth factor receptor (EGFR) appears to be indispensable for the adaptive response of the remnant intestine to massive small bowel resection (SBR). The recent availability of a specific pharmacologic EGFR inhibitor enabled us to more directly test the hypothesis that EGFR signaling is required for postresection intestinal adaptation. METHODS: Mice (C57B1/6, n = 26) underwent a 50% SBR or sham operation and were then given orogastric EGFR inhibitor (ZD1839, 50 mg/kg/day) or vehicle. After 3 days, indices of adaptation (wet weight, crypt depth, and villus height) and apoptotic index (number of apoptotic bodies per crypt) were calculated in the ileum. The expression of proliferating cell nuclear antigen (PCNA) and activated EGFR was measured by Western blotting. RESULTS: ZD1839 prevented EGFR activation and the normal postresection increases in ileal wet weight, villus height, and crypt depth. Enterocyte proliferation was reduced twofold in the SBR group by ZD1839. Although not statistically significant, rates of enterocyte apoptosis were the highest in the inhibitor-treated mice. CONCLUSION: Following massive SBR, pharmacologic inhibition of the EGFR attenuates proliferation and the normal adaptive response of the intestine. These results more directly confirm the requirement of a functional EGFR as a mediator of the postresection adaptation response. This study demonstrates an in vivo application of a novel selective EGFR inhibitor and offers a unique experimental model to gain mechanistic insight into understanding postresection intestinal adaptation.

Adaptation, Physiological↗
PubMedDate not supplied

Vitamin A status modulates intestinal adaptation after partial small bowel resection.

BACKGROUND: Intestinal adaptation after loss of functional small bowel surface area is characterized by cellular hyperplasia and increased absorptive function. Interventions to enhance the adaptive response are needed to decrease the morbidity and mortality associated with short bowel syndrome. Retinoic acid was shown to stimulate crypt cell proliferation in the adapting remnant rat ileum by 6 hours after resection. Thus, vitamin A, which is required for normal epithelial cell proliferation and differentiation and which can modulate programmed cell death, may play an important role in the adapting intestine. On the basis of these observations, the effects of vitamin A deficiency on intestinal morphology, epithelial cell proliferation, and apoptosis in the adapting intestine after resection were investigated. METHODS: Weanling male Sprague-Dawley rats fed either a vitamin A-deficient or -sufficient diet for 58 days underwent 70% proximal small bowel resection. The deficient rats were divided into cohorts that were either maintained on the experimental diet after surgery or replenished with vitamin A 20 hours before surgery and switched to the control diet after surgery. RESULTS: Ten days after resection, vitamin A-deficient rats exhibited a markedly blunted adaptive response. The adaptive increase in villus height and crypt depth was absent in the deficient rats. However, adaptive increases in crypt cell proliferation were not attenuated by vitamin A deficiency, and there were no differences in apoptotic indices. CONCLUSIONS: Vitamin A deficiency inhibits the adaptive response to partial small bowel resection, supporting a role for vitamin A in the adaptive process. Changes in cellular proliferation or programmed cell death are not sufficient to account for this inhibition. This model system will be useful for examining the role of other mechanisms, such as changes in cell-cell and cell-extracellular matrix interactions, and rates of epithelial cell migration and cell extrusion.

Adaptation, Physiological↗
PubMed2000

Issues and problems of adaptation of North Korean defectors to South Korean society: an in-depth interview study with 32 defectors.

The number of North Koreans defecting to South Korea is increasing rapidly. They are important people to South Korean society not only for humanitarian reasons, but also for their impact on the future Korean unification and the integration of the two different South and North Korean peoples. However, the defectors have experienced many difficulties in their adaptation to South Korean society due to their own characteristics and due to the misunderstandings of the South Korean people. To obtain comprehensive qualitative data about the characteristics and difficulties of North Korean defectors' adaptation to South Korean society, 58 semi-structured in-depth interviews were performed with 32 defectors who had entered South Korea from 1990 to 1997. Four categories of adaptation difficulties were encountered, which are related with the defectors' suspiciousness, different ways of thinking, searching for new sets of values, and with the prejudice of the South Korean people. Finally, three areas of suggestions for the more successful adaptation of the defectors to South Korean society were made; a need for more comprehensive perspectives on the defectors' adaptation, suggestions regarding educational programs and suggestions for educating the South Korean people.

Adaptation, Psychological↗
PubMed2000

Relationship of dorsoventral eyeshine distributions to habitat depth and animal size in mesopelagic decapods.

Eyeshine distribution patterns recorded from the eyes of 19 mesopelagic decapod species were examined and related to the depths at which the species are found. For most species examined, eyeshine was found to be brighter ventrally than dorsally. Deep-water decapod species that do not undergo diel vertical migrations had brighter dorsal eyeshine than migratory species. Eyeshine intensity increased with body size in five of the species examined and decreased in two. These changes in eyeshine intensity may be an adaptation to variations in depth distributions that occur with increasing body size. It is suggested that the depth and size-related changes reflect the importance of remaining camouflaged in the mesopelagic realm and are an example of ecologically functional development.

Animals↗
PubMed2003

Motion distorts perceived depth.

Two important tasks that the visual system has to perform are determining the direction of motion and the spatial location of objects. It has recently been shown that the perceived location of an object moving in the frontal-plane is displaced along the direction of motion (e.g. Nature 397 (1999) 610; Vision Research 31 (1991) 1619). The aim of the present study is to examine the extent of this interaction between motion and perceived location. The observers' task was to indicate which of two vertically separated moving stimuli was closer. The two stimuli were presented at various relative disparity offsets. The stimuli consisted of moving dot patterns (optic-flow) that simulated either fronto-parallel motion (all the dots moved one direction) or motion in depth. Motion of the dots towards the centre of the stimulus simulated object motion away from the observer and motion of the dots away from the centre of the stimulus simulated object motion towards the observer. Results indicate that motion-in-depth information can bias perceived stereoscopic-based depth. Simulated motion towards the observer made the object appear closer to the observer than the depth signalled by the disparity information and simulated motion away from the observer made it seem further away. The results of this study, when combined with those of previous studies, show that motion can distort our entire three dimensional representation of space.

Adaptation, Ocular↗
PubMed2002

Hearing visual motion in depth.

Auditory spatial perception is strongly affected by visual cues. For example, if auditory and visual stimuli are presented synchronously but from different positions, the auditory event is mislocated towards the locus of the visual stimulus-the ventriloquism effect. This 'visual capture' also occurs in motion perception in which a static auditory stimulus appears to move with the visual moving object. We investigated how the human perceptual system coordinates complementary inputs from auditory and visual senses. Here we show that an auditory aftereffect occurs from adaptation to visual motion in depth. After a few minutes of viewing a square moving in depth, a steady sound was perceived as changing loudness in the opposite direction. Adaptation to a combination of auditory and visual stimuli changing in a compatible direction increased the aftereffect and the effect of visual adaptation almost disappeared when the directions were opposite. On the other hand, listening to a sound changing in intensity did not affect the visual changing-size aftereffect. The results provide psychophysical evidence that, for processing of motion in depth, the auditory system responds to both auditory changing intensity and visual motion in depth.

Acoustic Stimulation↗
PubMed2006

The unique 16S rRNA genes of piezophiles reflect both phylogeny and adaptation.

In the ocean's most extreme depths, pressures of 70 to 110 megapascals prevent the growth of all but the most hyperpiezophilic (pressure-loving) organisms. The physiological adaptations required for growth under these conditions are considered to be substantial. Efforts to determine specific adaptations permitting growth at extreme pressures have thus far focused on relatively few gamma-proteobacteria, in part due to the technical difficulties of obtaining piezophilic bacteria in pure culture. Here, we present the molecular phylogenies of several new piezophiles of widely differing geographic origins. Included are results from an analysis of the first deep-trench bacterial isolates recovered from the southern hemisphere (9.9-km depth) and of the first gram-positive piezophilic strains. These new data allowed both phylogenetic and structural 16S rRNA comparisons among deep-ocean trench piezophiles and closely related strains not adapted to high pressure. Our results suggest that (i) the Circumpolar Deep Water acts as repository for hyperpiezophiles and drives their dissemination to deep trenches in the Pacific Ocean and (ii) the occurrence of elongated helices in the 16S rRNA genes increases with the extent of adaptation to growth at elevated pressure. These helix changes are believed to improve ribosome function under deep-sea conditions.

Adaptation, Physiological↗
PubMed2006

Influence of the site of small bowel resection on intestinal epithelial cell apoptosis.

Massive small bowel resection (SBR) results in a significant increase in intestinal epithelial cell (EC) proliferation as well as apoptosis. Because the site of SBR (proximal (P) vs. distal (D)) affects the degree of intestinal adaptation, we hypothesized that different rates of EC apoptosis would also be found between P-SBR and D-SBR models. Wild-type C57BL/6J mice underwent: (1) 60% P-SBR, (2) 60% D-SBR, or (3) SHAM-operation (transaction-reanastomosis) at the mid-gut point. Mice were sacrificed after 7 days. EC apoptosis was measured by TUNEL staining. EC-related apoptotic gene expression including intrinsic and extrinsic pathways was measured with reverse transcriptase-polymerase chain reaction. Bcl-2 and bax protein expression were analyzed by Western immunoblotting. Both models of SBR led to significant increases in villus height and crypt depth; however, the morphologic adaptation was significantly higher after P-SBR compared to D-SBR (P<0.01). Both models of SBR led to significant increases in enterocyte apoptotic rates compared to respective sham levels; however, apoptotic rates were 2.5-fold higher in ileal compared to jejunal segments (P<0.01). P-SBR led to significant increases in bax (pro-apoptotic) and Fas expression, whereas D-SBR resulted in a significant increase in TNF-alpha expression (P<0.01). EC apoptosis seems to be an important component of intestinal adaptation. The significant difference in EC apoptotic rates between proximal and distal intestinal segments appeared to be due to utilization of different mechanisms of action.

Adaptation, Physiological↗
PubMed2004

Bias to experience approaching motion in a three-dimensional virtual environment.

We used two-frame apparent motion in a three-dimensional virtual environment to test whether observers had biases to experience approaching or receding motion in depth. Observers viewed a tunnel of tiles receding in depth, that moved ambiguously either toward or away from them. We found that observers exhibited biases to experience approaching motion. The strengths of the biases were decreased when stimuli pointed away, but size of the display screen had no effect. Tests with diamond-shaped tiles that varied in the degree of pointing asymmetry resulted in a linear trend in which the bias was strongest for stimuli pointing toward the viewer, and weakest for stimuli pointing away. We show that the overall bias to experience approaching motion is consistent with a computational strategy of matching corresponding features between adjacent foreshortened stimuli in consecutive visual frames. We conclude that there are both adaptational and geometric reasons to favor the experience of approaching motion.

Adaptation, Physiological↗
PubMed1986

Visual processing of four kinds of relative motion.

Evidence is presented supporting the idea that the human visual system has several specific sensitivities to different kinds of relative motion. These specific sensitivities include: sensitivity to a velocity difference between two different points A and B on one eye's retinal image, the two velocities being directed along the line AB; sensitivity to the velocity difference at A and B between velocity components perpendicular to the line AB (i.e. shearing motion); sensitivity to rotary motion; sensitivity to the ratio between the velocities of the left and right retinal images of an object that is moving in depth. These specific sensitivities can be attributed to relatively hardwired neural filters that are "tuned" to different retinal image correlates of the three-dimensional structure and motion of solid objects in the environment. Such filters may be of use in distinguishing rigid nonrotating objects from nonrigid or rotating objects. They may also be of use in recovering information from the two-dimensional retinal image, including information about object boundaries, the three-dimensional structure of the environment, self-motion and object motion in depth. An alternative way of regarding certain of these specific sensitivities is that they might provide rough physiological equivalents of the values of div V and curl V at every point in the instantaneous velocity field of the retinal image and thus crudely analyze the retinal image flow pattern in terms of mathematical quantities that have the useful property of being relatively invariant against bodily translations of the whole retinal image caused by eye rotation.

Adaptation, Ocular↗
PubMed2004

The lived experience of oldest-old rural adults.

The author elicited the lived experience of 19 oldest-old adults (13 women, all White, mean age 90.7 years, range 85-98 years) who lived alone in the rural Midwest to describe their everyday activities, concerns and struggles, and adaptive strategies. In-depth interviews (59 total) were audiotaped, transcribed, and analyzed in an interpretive phenomenological tradition of thematic analysis, interpretation of paradigm cases, and interpretation of exemplars. Participants described how historical, cultural, and environmental contexts shaped their everyday thoughts, activities, and what was meaningful to them. Findings can guide health care professionals to evaluate and develop community services and help significant others (family, friends, neighbors) understand what oldest-old rural adults need to remain at home.

Activities of Daily Living↗