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At least 19 recordsLinked to original sources
PubMed1979

Cold-adapted variants of influenza A virus: evaluation in adult seronegative volunteers of A/Scotland/840/74 and A/Victoria/3/75 cold-adapted recombinants derived from the cold-adapted A/Ann Arbor/6/60 strain.

Influenza A/Scotland/74 (H3N2) and A/Victoria/75 (H3N2) cold-adapted (ca) recombinant viruses, prepared by mating the A/Ann Arbor/6/60 (H2N2) ca donor virus and influenza A wild-type virus, were evaluated in adult seronegative volunteers (serum hemagglutination-inhibiting antibody titer, </=1:8) for level of attenuation, antigenicity, and genetic stability of the temperature-sensitive and ca phenotypes. At 10(7.0) to 10(7.5) 50% tissue culture infective doses the A/Scotland/74 and A/Victoria/75 ca recombinant viruses were clearly attenuated and antigenic. However, one of eight vaccinees infected with 10(7.5) 50% tissue culture infective doses of the A/Scotland/74 ca recombinant had a febrile reaction (39 degrees C). At a 10-fold higher dose (10(8.5) 50% tissue culture infective doses), 4 of 12 A/Scotland/74 vaccinees had a febrile and/or systemic reaction. Febrile reactions were not observed in volunteers who received the A/Victoria/75 ca recombinant virus, whereas 3 of the 12 vaccinees had mild upper respiratory tract symptoms, in one instance associated with mild systemic manifestations. Significantly, the serum hemagglutination- and neuraminidase-inhibiting antibody responses were comparable to those induced by wild-type virus. Both ca recombinant viruses were shed in low titer for a short period of time. Each isolate retained the temperature-sensitive phenotype. However, there was evidence of genetic instability of the ca marker in that 7 of 24 isolates exhibited some loss of the ca property, and one isolate completely lost the capacity to produce plaques at 25 degrees C. The retention of a low level of residual reactogenicity in the A/Scotland/74 ca recombinant suggests that acquisition of the ca and temperature-sensitive phenotypes by a ca recombinant virus may not always bring about a satisfactory level of attenuation for individuals lacking hemagglutinin immunity.

Adaptation, Physiological↗
PubMed1974

On the mechanism of adaptation to protein synthesis inhibitors by Tetrahymena. Facilitation, cross adaptation, and resensitization.

Tetrahymena is able to adapt to the presence of sublethal concentrations of many drugs which inhibit a wide variety of cellular functions. In spite of the generality of this phenomenon in Tetrahymena, the mechanism of adaptation at the cellular and molecular levels is unknown. This study deals mainly with adaptation to the protein synthesis inhibitors, cycloheximide and emetine. The physiological response of Tetrahymena to sublethal concentrations of these drugs is an immediate cessation of cell division for a period of time dependent on the drug concentration, followed by an abrupt resumption of exponential growth at a constant rate. By measuring the length of the growth lags under a variety of experimental conditions, we have confirmed several observations made by Frankel and coworkers, and provide evidence for two new phenomena associated with adaptation to cycloheximide: (a) adaptation to cycloheximide also results in adaptation of cells to emetine, another protein synthesis inhibitor not closely related structurally to cycloheximide. We have termed this phenomenon cross adaptation, (b) exposure to concentrations of cycloheximide too low to cause any growth lags or inhibition of protein synthesis significantly shortens the time required by cells to adapt to higher concentrations of cycloheximide. We have termed this phenomenon facilitation. Facilitation shows some degree of specificity in that facilitation with cycloheximide has no effect on adaptation to emetine. From this, we infer the existence of two distinct systems involved in adaptation to cycloheximide, one of which shows a higher degree of specificity towards cycloheximide than the other. We also show that transfer of adapted or facilitated cells to drug-free medium results in a gradual but complete resensitization. The kinetics of resensitization suggest that the cellular machinery responsible for adaptation and facilitation does not leave the cell, but is simply diluted out during cell division.

Adaptation, Physiological↗
PubMed1988

Color perception under chromatic adaptation: red/green equilibria with adapted short-wavelength-sensitive cones.

Chromatic adaptation can dramatically alter the color appearance of a light. The specific effect of adapting short-wavelength-sensitive (SWS) cones is examined by using two adapting wavelengths that lie on a tritanopic confusion line. The change in color appearance caused by signals from adapted SWS cones is isolated by restricting the wavelengths of the test light to 550 nm or longer. Thus the test negligibly stimulates SWS cones, so their sensitivity does not affect the test's appearance. The results show that adapted SWS cones contribute redness to the appearance of a superimposed test light, while not affecting sensitivity of MWS and LWS cones. Quantitatively, the redness from SWS cones illuminated by a large adapting field approaches physical admixture of test and adapting lights. This is very different from an adapting field that stimulates only MWS and LWS cones which, due to a postreceptoral process, contributes much less redness to a small superimposed test than expected from admixture. The difference between the adapted SWS-cone and the adapted MWS/LWS-cone contributions to the color of a small test explains a surprising result: a bluish-green (491 nm) adapting field contributes redness to a superimposed test light.

Adaptation, Ocular↗
PubMed1985

Effect of localized grating adaptation as a function of separation along the length axis between test and adaptation areas.

Aftereffect following adaptation to localized gratings was measured as a function of the separation along the length axis between test and adaptation gratings. When the adaptation gratings were located on or near the retinal area occupied by the test grating, contrast sensitivity greatly decreased. When the adaptation gratings were spatially separated from the test grating, contrast sensitivity significantly increased. This property is similar to that which was observed in our previous study, in which the adaptation gratings were displaced from a test grating along the modulation axis. The facilitatory aftereffect of the grating adaptation can be accounted for by assuming that there may exist two mechanisms involved in the adaptation process; one is a center mechanism responsible for the detection of a test pattern, its adaptation producing a reduction in responsiveness; the other is a surround mechanism which tonically inhibits the center mechanism, its adaptation resulting in an increase in the sensitivity of the center mechanism by releasing the tonic inhibition. The spatial property of the adaptation effect may reflect the nature of spatial integration process of the center and surround mechanism.

Adaptation, Ocular↗
PubMedDate not supplied

[Change in adaptability and kinetics of T-lymphocyte adaptation to hypotonia in pathological states of mammals].

The kinetics of adaptation of the volume of T-lymphocytes and their membrane potential in a hypotonic medium is investigated. It is shown to have a quasiperiodic character. The shortest adaptation period T = 2 min characterizes the adaptation of T-lymphocytes test animals, the most complete adaptation of the volume and the membrane potential in hypotonic medium. Upon adaptation their values are only 6% higher than respective values in an isotonic medium. If an aseptic inflammatory process develops in a mammalian organism, the adaptation period increases to T = 2.5 min, while the volume and the membrane potential remains 28% higher than in an isotonic medium. In the course of development of induced cancerogenesis, 10 min after the cells have been placed in a hypotonic medium, their size is equal to that at the point of maximal swelling, while the membrane potential is 20% lower than that in an isotonic medium. The reason for the varying adaptability of T-lymphocytes is, in our opinion, that, as the inflammation develops, the concentration of corticosteroids increases, the concentration of intracellular K+ decreases, the concentration of macromolecules increases and the potential of the plasmatic membrane of the cell rises, thus leading to the slowing down of the process of adaptation and its decreased extent. The lack of regulation of the volume by T-lymphocytes of mammals in the organisms of which cancerogenesis develops, testifies to the fact that, in such a case, cells lose their adaptability to changing external conditions. Therefore, the disappearance of adaptability of T-lymphocytes on the third day of development of cancerogenesis represents an early test of the process.

Adaptation, Physiological↗
PubMed1991

[Studies on the changes of adaptation with children in the dental setting. The relationship between the changes of adaptation and various psychological tests].

The purpose of this study was to discover the changes in the adaptation of children to the Dental setting, and to discover the relationship between the adaptation, and the personality of the child, the personality of the mother, as well as the relationship between the mother and child. The subjects were 60 two to six year old children and their mothers who visited at the Department of Pedodontics, School of Dentistry, Showa University. The results were as follows: 1) The changes of adaptation were classified in groups of four classes. Four groups: Continuous Adaptability (45.0%) Acquired Adaptability (18.3%) Continuous Inadaptability (16.7%) Extreme Inadaptability (20.0%) 2) The inadaptability groups (Continuous Inadaptability and Extreme Inadaptability) of the two to three year old children did not correlate to the change of adaptation and personality of the child, and the relationship between the mother and child. 3) The extreme inadaptability group with the four year old children showed a connection with the change of adaptation and the various Psychological Tests. Concerning personality, the children showed elements of "dependence" "retrogression" and "maladaptation to school (kindergarten)". Concerning the mother child relationship, there were elements of "anxiety" "dotage" "follow blindly" "disagreement". 4) Nobody showed extreme inadaptability in the group of five to six year old children. Continuous Inadaptability group with the five to six year old children showed scarcely any problems. 5) The Personality of mother did not correlate to the change of adaptation of children in the dental setting.

Adaptation, Psychological↗
PubMed1986

Studies on the genetic determinants of influenza virus pathogenicity for mice with the use of reassortants between mouse-adapted and non-adapted variants of the same virus strain.

The original influenza virus strain A/USSR/90/77 (H 1 N 1) and its mouse-adapted variant, differing in their reactivity with anti-hemagglutinin monoclonal antibodies HC 22 and HC 124, were crossed in MDCK cells and in chicken embryos, and 21 clones were isolated by non-selective random cloning. In all the clones the virulence for mice was found to be linked to the antigenic specificity of hemagglutinin (HA). An independent marker, formation of filamentous forms, was reassorted with an expected frequency. In the crosses between UV-irradiated mouse-adapted variant and live non-adapted strain, with selection of clones by a mixture of monoclonal antibodies discriminating between HA of the two variants, virulence also was linked to HA gene. On the contrary, in the experiments with A/Aichi/2/68 (H 3 N 2) strain and its mouse-adapted highly virulent variant these two characteristics--virulence and HA antigenic specificity--could be dissociated. A pathogenic clone having HA of the non-adapted strain was readily obtained; its virulence, however, was weaker than that of the mouse-adapted parent. In the inter-subtypic crosses between A/USSR/90/77 and A/Aichi/2/68 the transfer of the HA gene of the mouse-adapted A/Aichi/2/68 did not confer virulence to the reassortant. The results are discussed in terms of the genetic basis of virulence acquired in the course of influenza virus adaptation to a new host.

Animals↗
PubMed1991

Adaptation and recovery from adaptation in single fiber responses of the cat auditory nerve.

This study examined the time course of adaptation and recovery from adaptation of single auditory-nerve fiber responses. The conditions studied were: (1) adaptation response using low level, 800 Hz or characteristic frequency (CF) stimuli; and (2) onset recovery and whole tone response recovery of a probe tone following a masker of equal frequency with variable silent intervals between the masker offset and probe onset. Single unit responses to 290 ms long, 800 Hz or CF tones presented at 10-30 dB SL were recorded from the auditory nerve of the cat. Adaptation properties were determined and fit to the equation: A(tp) = Yre(-tp/tau Rr) + Yse(-tp/tau Rs) + Ass. Recovery from adaptation was determined by recording the response of a probe tone following a 100-ms masker tone equal in frequency to the probe, and with amplitudes ranging from 20- to 30-dB relative to the probe amplitude. Both the onset recovery and the whole tone recovery were determined for the single unit responses. The onset data were analyzed and fit to either the equation: A (delta xt,tp) = Ass - Yre(-tp/tau Rr) - Yse(- delta t/tau Rs) or A (delta t,tp) = Ass - Yre(- delta t/tau R). The whole tone response showed two distinctive time patterns that could be fit to either an adaptation equation or to the two-time-constant recovery equation, depending on the relative amplitude of the masker and the length of the silent interval between masker offset and probe onset. The results of this study indicate that single fiber time constants are comparable to those measured in previous studies using the auditory-nerve neurophonic (ANN). Likewise, the pattern of recovery of the whole tone response for single fiber responses is comparable to the ANN. Possible sites and mechanisms for adaptation and recovery from adaptation taking into account recent data from electrical stimulation studies and receptor channel morphology and kinetics are discussed.

Animals↗
PubMed1990

Efficacy of prism adaptation in the surgical management of acquired esotropia. Prism Adaptation Study Research Group.

Prism adaptation, the preoperative use of prisms in acquired esotropia to determine the maximum angle of strabismus and to estimate fusional potential, has been suggested as a method of improving the results of initial surgery and minimizing the rate of reoperation. We performed a prospective, randomized, multicenter clinical trial of the effectiveness of prism adaptation. Two levels of randomization were used. Sixty percent of the patients underwent prism adaptation and 40% did not. Of those who responded to prisms with motor stability and sensory fusion, half underwent a conventional amount of surgery and half underwent augmented surgery based on the prism-adapted angle of deviation. Success rates were highest (54 [89%] of 61 patients) in prism adaptation responders who underwent augmented surgery and lowest (92 [72%] of 127 patients) in patients who did not undergo prism adaptation. Prism responders had better results with augmented surgery than with conventional surgery (54 [89%] of 61 patients vs 53 [79%] of 67 patients, P = .23). Our results indicated a significant beneficial overall effect of prism adaptation in patients with acquired esotropia (success rates, 83% vs 72%, P = .04). Although the process requires some additional time and effort, it appears to result in a higher rate of satisfactory alignment.

Adaptation, Ocular↗
PubMed1985

Correlation of Na+,K+-ATPase content and plasma membrane surface area in adapted and de-adapted salt glands of ducklings.

During salt-water adaptation, an increase occurs in Na+,K+-ATPase content and surface area of the basolateral plasma membrane of the principal cell of the duck salt gland. To determine the degree to which these changes are correlated, accepted morphometric methods were used to determine numerical cell densities and plasma membrane surface densities of peripheral and principal cells. After adaptation, the plasma membrane surface area per principal cell was five times greater than in controls. Following de-adaptation, the plasma membrane content in principal cells returned to 1.9 times control levels. Two other cell constituents, mitochondria and lipid droplets, displayed similar quantitative changes. Na+,K+-ATPase content increased about fourfold with adaptation and decreased to near control levels with de-adaptation. Thus, changes in Na+,K+-ATPase content and basolateral plasma membrane surface area in adapting and de-adapting secretory epithelia of the salt gland occur nearly in parallel. These quantitative data enable Na+,K+-ATPase synthesis and degradation to be investigated in relation to membrane biogenesis.

4-Nitrophenylphosphatase↗
PubMed1985

Photoconversion from the light-adapted to the dark-adapted state of bacteriorhodopsin.

Dark and light adaptation of bacteriorhodopsin in purple membrane multilayers at less than 100% relative humidity differs from that seen in suspensions. Equilibrium between the two bacteriorhodopsin isomers (bR cis 550 and bR trans 570) in the light-adapted state becomes dependent on the wavelength of actinic light. Excitation at the red edge of the visible absorption band causes dark adaptation in a light-adapted sample. Using polarized actinic and measuring light, we show that acceleration of the dark adaptation through heating by actinic light cannot explain this observation. A light-driven bR trans 570 to bR cis 550 reaction that competes with the well-known 13 cis-to-all-trans light adaptation reaction must exist under our experimental conditions. Trans-to-cis conversion is a one-photon process distinct from the two photon process observed by others in purple membrane suspensions (Sperling, W., C. N. Rafferty, K. D. Kohl, and N. A. Dencher, 1978, FEBS (Fed. Eur. Biochem. Soc.) Lett. 97:129-132). Its quantum efficiency increases monotonously on reducing the hydration level, and is paralleled by an increase in the lifetime of the M410 intermediate of the trans photocycle. We suggest that at this point a branch leads from the all-trans into the 13-cis photocycle. It is probably the same reaction that causes the reduced light adaptation in monomeric bacteriorhodopsin (Casadio, R., H. Gutowitz, P. Mowery, M. Taylor, and W. Stoeckenius, 1980, Biochim. Biophys. Acta. 590:13-23; Casadio, R., and W. Stoeckenius, 1980, Biochemistry. 19:3374-3381).

Bacteriorhodopsins↗
PubMed2025

Adaptive Evolution for Freshwater Adaptation in Coilia nasus by Directional Selection on Osmoregulation Genes.

The molecular mechanisms underlying the adaptation to freshwater habitats in fish of marine origin remain unclear. Grenadier anchovies, such as Coilia nasus, originate from marine environments and include both anadromous and freshwater-resident conspecifics, making them ideal for studying adaptive evolution from marine to freshwater habitats. We conducted a comparative population genomic and transcriptome analysis of two distinct C. nasus lineages, one anadromous and the other freshwater-resident, collected from mainstream and estuarine regions of the Yangtze River, China. By genome-wide genotyping of the anadromous and the freshwater-resident populations, we observed significant divergence in osmoregulation, energy metabolism, and immune response pathways associated with ecological adaptation and energy expenditure for migration. Some ion transport genes such as CAMK1, ATP1&#x3b1;3, KCNJ1 and SLC30A2 were identified that may contribute to freshwater adaptation. Notably, numerous mineralocorticoid signalling genes (e.g., NR3C2, SGK1, ATP1&#x3b1;3, KCNJ1) exhibit dynamic change between the anadromous and freshwater populations, suggesting an important role for the hormone cortisol in regulating salinity acclimation in euryhaline fish. Among these genes, the ion channel ATP1&#x3b1;3 experienced adaptive amino acid substitutions (Val317Ile and Thr329Ser), which appear to be evolutionary hotspots across migratory species based on ortholog comparisons. These variants may facilitate sodium/potassium transport and highlight salinity tolerance as a key driver of divergence in anadromous fish transitioning to freshwater. These results enhance our understanding of the genetic basis underlying freshwater adaptation for an anadromous fish across osmotic boundaries.

Animals↗
PubMed1992

Adaptation and recovery from adaptation of the auditory nerve neurophonic (ANN) using long duration tones.

The time course of the interaction between adaptation and the recovery from adaptation of the auditory nerve neurophonic (ANN) responses was examined. The interaction between the process of recovery and the adaptation process of long probe tones which follow a masker, the so called whole tone recovery, was determined for the ANN response for different silent intervals between masker offset and probe onset. The auditory nerve neurophonic (ANN) reflects the ensemble response of phase-locked firing in single auditory nerve fibers to sustained signals. Consequently, neural response properties such as adaptation and recovery from adaptation of these coherent, time-locked responses can be studied. Recovery from adaptation was determined by recording the response of a 290 ms duration probe tone following a 100 ms masker tone, equal in frequency to the probe, ranging from -5 to 20 dB relative to the probe amplitude. Two different time patterns of the whole tone recovery were observed. If short silent intervals and/or loud maskers were used, the time course of the probe tone can be described as an exponential increase in amplitude toward a steady state expressed by the equation: A(tp) = Ass-Yr e(-tp/tau Rr)-Ys e(-tp/tau Rs) ('ascending exponential'). For longer silent intervals and/or fainter maskers, the time course of the probe tone can be described by an exponential decrease expressed by the equation: A(tp) = Yr e(-tp/tau Rr) +Ys e(-tp/tau Rs) +A(ss) ('declining exponential').

Acoustic Stimulation↗
PubMed1990

Spectral sensitivity and adaptation characteristics of cone mechanisms under white-light adaptation.

Increment-threshold spectral-sensitivity (ITSS) functions and threshold-versus-intensity (tvi) curves were measured under white-light adaptation in rhesus monkeys. The tvi curves showed shape and test wavelength invariance, implying that three cone mechanisms were mediating detection. In general, the results were in agreement with the differential adaptation hypothesis proposed by Stiles that predicted spectral shape invariance of the cone mechanisms but overall changes in the shape of the spectral-sensitivity function with increases in the intensity of the adapting field. The principal changes occurring in the ITSS function as the level of adaptation increased involved a smaller loss in sensitivity of the short-wavelength and the long-wavelength peaks compared with the corresponding loss in sensitivity of the middle-wavelength peak. A three-channel model with an opponent L-M mechanism and a nonopponent L-M mechanism (both with S-cone input) and an independent S-cone mechanism described the ITSS data as well as other increment-threshold and suprathreshold data. The model values for the ITSS functions, along with parameters derived from the transformation of these data to cone-contrast coordinates, permitted the factoring out of first-site adaptation, second-site adaptation, and the relative strengths of contribution of the L and M cones within the opponent and nonopponent L-M channels.

Adaptation, Ocular↗
PubMed1990

Individualized adaptation of clothes for impaired persons. A comparison of two groups with and without experience of adapted clothes.

Impaired persons often have difficulties in obtaining suitable clothing. Questionnaires on this subject were sent to a consecutive series of impaired persons. Group 1 (n = 50) had received adapted clothes and group 2 (n = 81) had not. Questionnaire A (both groups) contained general questions on clothes and questionnaire B (Group 1) contained questions on adapted clothes. The result of the study shows a significant difference (p less than 0.01) between the need for adapted clothing in group 1 and group 2. No significant difference was found between the groups regarding the reason for obtaining and using adapted clothes. It was difficult for 94% in group 1 and 85% in group 2 to obtain clothes which were suitable for the individual's impairment and which made their daily activities easier. In group 1 the adapted garments were of most value when dressing and undressing (86%). They also reduced the time needed, by 31% for the individual, by 43% for a helper; and by 62% when going to the toilet. The adapted garments were considered smarter and more comfortable by 64%. Eighteen per cent considered that wearing them had increased their self-confidence.

Activities of Daily Living↗
PubMed1978

Olfactory self- and cross-adaptation: effects of time of adaptation on perceived odor intensity.

The time-course of self- and cross-adaptation of the olfactory system was investigated for two constant concentrations of three odorous substances. The substances (hydrogen sulfide, dimethyl disulfide, and pyridine) were matched, in a pilot experiment, with regard to perceived odor intensity. The time of adaptation was controlled by the number of inhalations (1-10). A two-step scaling method, involving cross-modality matching and numerical scaling of the matching continuum, was used for measuring perceived odor intensity during adaptation. The results show that the time-course function for self-adaptation seems to be an exponential function for two of the substances (H2S, DMDS), while for the third (pyridine) the form of the function is less distinct. Cross-adaptation between substances was found for the high concentrations, while for the low concentrations, hydrogen sulfide and dimethyl disulfide gave rise to pronounced cross-facilitation. The latter effect increased with time of adaptation.

Adaptation, Physiological↗
PubMed1990

Laboratory properties of cold-adapted influenza B live vaccine strains developed in the US and USSR, and their B/Ann Arbor/1/86 cold-adapted reassortant vaccine candidates.

The adaptation of two influenza B strains (B/Leningrad/14/55 and B/Ann Arbor/1/66) to replication at 25 degrees C is described. Comparison of the two viruses indicates that both also exhibit temperature sensitive phenotypes, although that of the virus B/Leningrad/14/55 is less pronounced. When inoculated into ferrets both viruses replicate well in the trachea, but only the B/Leningrad/14/55 cold-adapted virus replicates in the lungs. This virus exhibited a moderate level of attenuation in the animals, in contrast to the B/Ann Arbor/1/66 cold-adapted virus, which was fully attenuated. Reassortant viruses deriving the surface antigens of the contemporary wild type virus B/Ann Arbor/1/86 and most or all of their other genes, from one or other cold-adapted parent, were virtually indistinguishable from their respective cold-adapted parents. The B/Leningrad/14/55 reassortant was slightly more attenuated than its cold-adapted parent in ferrets. These studies extend knowledge of the properties of viruses used to prepare experimental live influenza B human vaccines.

Animals↗