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PubMed1978

Axonal adaptation to osmotic and ionic stress in an invertebrate osmoconformer (Mercierella enigmatica Fauvel). III. Adaptations to hyposmotic dilution.

The giant axons of this extreme osmoconformer were adapted, in vitro, to progressive hyposmotic dilution of the bathing medium (from 1024 m-Osmol to concentrations as low as 76.8 m-Osmol). Hyposmotic adaptation is associated with reductions in the intracellular concentrations of both sodium and potassium ions. These reductions do not appear to result from appreciable axonal swelling. The different electrical responses to isosmotic and hyposmotic dilution suggest that reduction in [Na+]1 results from ouabain-dependent sodium extrusion, in response to ionic dilution, and that reduction in [K+]1 is induced by a combination of ionic and osmotic dilution. The reduced level of intracellular potassium achieved during hyposmotic adaptation represents a balance between the necessity to contribute to osmotic equilibration and to maintain a potassium gradient across the axon membrane sufficient to produce appreciable axonal hyperpolarization during dilution of the bathing medium. This hyperpolarization tends to maintain the amplitude of the action potential, by compensating for reduction in overshoot (with decline in E(Na), and by reducing sodium inactivation. This, together with the reduction in [Na+]1, enables overshooting action potentials of relatively large amplitude and rapid rise time to be maintained during more than tenfold dilution of the ionic and osmotic concentration of the bathing medium.

Action Potentials↗
PubMed1991

Response properties of the periodontal mechanosensitive neurons in the thalamus of the cat: a comparison between the slowly adapting and rapidly adapting neurons.

Slowly adapting (SA) and rapidly adapting (RA) types of the periodontal mechanosensitive units (PM units) were recorded in the thalamus and their response properties were examined in the cat. Both types of the PM units were located in the medial area (PM area) of the nucleus ventralis posteromedialis (VPM) of the thalamus. The SA units were located in a rostro-medial part of the PM area, while the RA units were distributed in the caudo-lateral part. An incidence of the SA and RA units was 45.5 and 54.5%, respectively. The single-tooth units were found in 23.5% of the SA units and in 14.9% of the RA units, and they responded chiefly to mechanical stimulation of the contralateral canine tooth. The multi-tooth units of the SA type had smaller receptive fields than those of the RA type, because the majority of the RA units had their receptive fields at the bilateral and/or bimaxillary area. In total, the units having the contralateral receptive fields were also dominant in both adaptation types. The latency of the neuronal discharges to electrical stimulation of the receptive field was fairly shorter in the SA units than in the RA units. These findings suggest that the SA units of the thalamus receive periodontal inputs directly from the trigeminal nuclear complex (Vcomp) of the brain stem, while the RA units receive them polysynaptically from the Vcomp via other pathways.

Adaptation, Physiological↗
PubMed2004

Throwing accuracy during prism adaptation: male advantage for throwing accuracy is independent of prism adaptation rate.

Previous studies have found that men are more accurate at throwing an object at a target than are women, independent of experience. However, these studies' results are based on average scores from multiple trials. As such, it is unknown whether the male advantage results from superior throwing accuracy or from a superior ability to calibrate subsequent throws. This study examined whether men can calibrate repeated throws more quickly and accurately than women, 25 men and 30 women were required to throw velcro-covered balls at a carpet-covered target, both with and without 10-diopter prism lenses. Participants had multiple trials in both conditions. Analyses examined whether there was a sex difference in the rate of adaptation to the prism lenses (as indicated by calibration of subsequent throws), instead of simply averaging all throwing accuracy scores and looking for an overall sex difference. Men threw the balls significantly more accurately than women, both with and without the prism lenses. However, there was no significant sex difference found on the rate of prism adaptation, as measured by improvement across the trials, i.e., calibration. Although men were more accurate at throwing balls overall, there was no sex difference in calibration of subsequent throws in adapting to the prism lenses, therefore indicating that the male advantage in throwing accuracy does not result from superior ability to calibrate subsequent throws but rather from superior throwing accuracy overall.

Accommodation, Ocular↗
PubMedDate not supplied

Predictors of prism response during prism adaptation. Prism Adaptation Study Research Group.

Results of the Prism Adaptation Study (PAS) indicate that prism adaptation improves the success rate of strabismus surgery for patients with acquired esotropia. Patients who show a fusion response to the prisms benefit most from this preoperative treatment. This study analyzes the characteristics of those patients who were and were not prism responders in the PAS. Significant factors predicting a prism response included: patients who were older at the time of onset of their esodeviation (P = .007), duration of deviation less than 1 year (P = .04), alternating fixation (P = .003), fusion on the Worth four-dot test at near with prism neutralization (P = .008), and equal vision (P = .009). Demographic characteristics were similar for both responders and nonresponders except that non-Hispanic patients were significantly more likely to respond to prisms than Hispanic patients (P less than .002). No test or characteristic was found which could reliably predict the prism response. Therefore, all patients with acquired esodeviations should be considered candidates for prism adaptation prior to strabismus surgery.

Adaptation, Ocular↗
PubMed1975

The role of the parathyroids for the adaptation to a low calcium intake. 3. The long-term effect of parathyroidectomy on the adaptation to a low calcium intake in adult rats with special reference to plasma calcium, bone tissue and adrenal glands.

One-year-old selectively parathyroidectomized rats responded with a plasma calcium reduction to below 4.1 mEq./1 in 86 per cent at a normal and in 100 per cent at a low dietary calcium intake. Among the former, 17 per cent normalized their plasma calcium level within 8 weeks and another 40 per cent between the 8th ana 27th week of observation. Among the latter, only 10 per cent showed a normalization and first after the long-term period of observation. On the normal level of dietary calcium the parathyroidectomized animals with persistently reduced plasma calcium showed a significantly increased bone mass which was paradoxical in view of their inability of adaptation. On the low level of dietary calcium a normal bone resorptive activity was maintained despite parathyroidectomy possibly through the action of increased levels of 1,25-dihydroxycholecalciferol provoked by the profoundly reduced plasma calcium. This was, however, insufficient for adaptation and no osteoporosis developed. For the adaptation to a reduced calcium intake skeletal calcium reserves had to become mobilized through the action of the parathyroids with resulting osteoporosis. This was brought about by increased mobilization of skeletal calcium with resulting osteoporosis, a phenomenon which could be seen also among the parathyroidectomized animals on a low dietary calcium and with a normalized plasma calcium level. This osteoporosis was similar to that found in the calcium deficient intact animals. The described bone changes were progressing in character and there was no major influence by any eventual effect on bone growth. At histological and morphometric analyses of the adrenal cortex no apparent changes were found after parathyroidectomy.

Adaptation, Physiological↗
PubMedDate not supplied

[Aggressive behavior, its adaptive function and mechanisms of development of psychosomatic disorders and diseases of adaptation].

A correlation between physiologic and behavioral responses to emotional stress and agonistic conflict (triad model), as well as ideas of autonomic-humoral support of subsequent activity suggest that motor activity and situational aggressive behavior are essential final stages of stress reaction and, therefore, mechanisms of adaptation. Failure in final the stage of adaptive response causes mobilization changes to be directed against the host organism itself. This phenomenon forms the basis for psychosomatic disorders. Aggression seems to be an adaptive response not only from ethologic, but from physiologic point of view as well. It has some elements of homeostatic control (together with non-homeostatic functions). Homeostatic role of aggression may be in "elimination" of mobilization metabolic changes caused by stress reaction and physical activity by means of expressive emotional response. Aggression as a non-homeostatic factor has an ethologic function.

Adaptation, Physiological↗
PubMed1990

[Molecular basis of retrovirus adaptation: nucleotide sequence of Rous sarcoma virus adapted to duck cells].

The host range of retroviruses is rather complex and specific. It is controlled by the products of viral structural genes that interact with the determinants both on the surface and within the cell. The possibility to infect and transform duck embryo fibroblasts is shown for the Prague strain of chicken Rous sarcoma virus (subgroup C), though virus production in these cells is restricted. However, after the 6th passage the "adapted" virus gave the titre practically the same as it was for chicken embryo fibroblasts. Provirus of RSV adapted to the duck embryo fibroblasts and integrated into host DNA was isolated from the library of nucleotide sequences of duck embryo fibroblasts transformed by this virus. The nucleotide sequence of such provirus was determined. The alterations in gp85 coding region of the env gene which proved to be the result of recombination with endogeneous RAV-0 sequences were shown. The formation of viral particles with rather high titre was induced by the proviral transfection on both chicken and duck embryo fibroblasts. The contribution of the revealed alterations in the genome of transformation active virus and possible participation of its td mutant in the adaptation to the new host are discussed.

Adaptation, Physiological↗
PubMed1989

[Modification of the toxic effects of phenylmercury by adaptive reactions of the rat kidney. 2. Adaptation to phenylmercury acetate, cadmium chloride and cupric chloride].

ICO:WIST rats were pretreated over 20 days, using oral administration of subtoxic doses of 1.5 mg/kg body weight of phenylmercury acetate (PMA) 15 mg/kg of CdCl2 and 15 mg/kg of CuCl2, to investigate correlations between nephrotoxic effects of PMA, on the one hand, and buildup through various extraneous substances of adaptive reactivity, on the other. This was followed by application of an acutely toxic dose of 15 mg/kg of PMA. Its effect was compared by morphological and functional investigations with conditions in unchallenged animals. The method, according to all findings, did not cause major renal damage, on completion of PMA, CdCl2, and CuCl2 pretreatment. Nephrotoxic effects induced to pretreated animals (1.5 mg/kg of PMA) by 15 mg/kg of PMA were clearly below those induced to untreated animals. However, PMA effectiveness on kidneys was much higher in animals which had received CdCl2 or CuCl2 pretreatment. Such possible controllability of toxic PMA efficacy through adaptation to various extraneous substances is likely to underline the need for differentiated assessment of progressive and regressive elements related to adaptive reaction.

Adaptation, Physiological↗
PubMed1983

A canonical correlation between adaptive and maladaptive aspects of adaptive behavior.

The relationship between the adaptive and the maladaptive aspects of the construct of adaptive behavior was examined by means of a canonical correlation between Part One and Part Two of the AAMD Adaptive Behavior Scale (ABS). The sample consisted of 439 institutionalized mentally retarded persons. Four significant canonical correlations (.68, .49, .39, .28) were derived, three of which were interpretable. The redundancy index was 30 percent with Part One as the criterion and 14 percent with Part Two as the criterion. A redundancy of about 30 percent was calculated. An analysis of the pattern of canonical components suggested that the three major dimensions responsible for the overlap between ABS Parts One and Two are intellectual ability, sociability, and physical ability. An attempt to cross validate these results was made using another sample of 157 mentally retarded persons. Considerable shrinkage was observed on three of the roots.

Adaptation, Psychological↗
PubMed1980

[Modifying influence of extreme temperature on the radiation effect depending on body adaptation to heat. II. An analysis of the potential damages in a line adapted to heat].

The high temperature (33, 35, 37 and 38 degrees C) following the irradiation (X-rays, 3000r) is shown to increase the effect of radiation (on the loss of X-chromosomes) in non-adapted to high temperature Canton-S stock. This effect is due to the inhibition of repair processes and to the rising of probability of potential damage realization. The adapted to high temperature (32 degrees C) T-32 stock did not produce such effect at 33 and 35 degrees C. It seems that the heart-resistance of reparation of the enzymes of T-32 stock is higher than in non-adapted one. Temperature of 37 and 38 degrees C is effective in both stocks.

Adaptation, Physiological↗
PubMed2006

Role of lysine versus arginine in enzyme cold-adaptation: modifying lysine to homo-arginine stabilizes the cold-adapted alpha-amylase from Pseudoalteramonas haloplanktis.

The cold-adapted alpha-amylase from Pseudoalteromonas haloplanktis (AHA) is a multidomain enzyme capable of reversible unfolding. Cold-adapted proteins, including AHA, have been predicted to be structurally flexible and conformationally unstable as a consequence of a high lysine-to-arginine ratio. In order to examine the role of low arginine content in structural flexibility of AHA, the amino groups of lysine were guanidinated to form homo-arginine (hR), and the structure-function-stability properties of the modified enzyme were analyzed by transverse urea gradient-gel electrophoresis. The extent of modification was monitored by MALDI-TOF-MS, and correlated to changes in activity and stability. Modifying lysine to hR produced a conformationally more stable and less active alpha-amylase. The k(cat) of the modified enzyme decreased with a concomitant increase in deltaH# and decrease in K(m). To interpret the structural basis of the kinetic and thermodynamic properties, the hR residues were modeled in the AHA X-ray structure and compared to the X-ray structure of a thermostable homolog. The experimental properties of the modified AHA were consistent with K106hR forming an intra-Domain B salt bridge to stabilize the active site and decrease the cooperativity of unfolding. Homo-Arg modification also appeared to alter Ca2+ and Cl- binding in the active site. Our results indicate that replacing lysine with hR generates mesophilic-like characteristics in AHA, and provides support for the importance of lysine residues in promoting enzyme cold adaptation. These data were consistent with computational analyses that show that AHA possesses a compositional bias that favors decreased conformational stability and increased flexibility.

Amino Acid Sequence↗
PubMed2006

Finding the genes underlying adaptation to hypoxia using genomic scans for genetic adaptation and admixture mapping.

The complete sequencing the human genome and recent analytical advances have provided the opportunity to perform genome-wide studies of human variation. There is substantial potential for such population-genomic approaches to assist efforts to uncover the historical and demographic histories of human populations. Additionally, these genome-wide datasets allow for investigations of variability among genomic regions. Although all genomic regions in a population have experienced the same demographic events, they have not been affected by these events in precisely the same way. Much of the variability among genomic regions is simply the result of genetic drift (i.e., gene frequency changes resulting from the effects of small breeding-population size), but some is also the result of genetic adaptation, which will only affect the gene under selection and nearby regions. We have used a new DNA typing assay that allows for the genotyping of thousands of SNPs on hundreds of samples to identify regions most likely to have been affected by genetic adaptation. Populations that have inhabited different niches (e.g., high-altitude regions) can be used to identify genes underlying the physiological differences. We have used two methods (admixture mapping and genome scans for genetic adaptation) founded on the population-genomic paradigms to search for genes underlying population differences in response to chronic hypoxia. There is great promise that together these methods will facilitate the discovery of genes influencing hypoxic response.

Alleles↗
PubMed1989

Psychometric validity and clinical usefulness of the Vineland Adaptive Behavior Scales and the AAMD Adaptive Behavior Scale for an autistic sample.

Two prominent assessment measures of adaptive behavior were compared and evaluated in terms of their psychometric properties and their clinical usefulness for autistic children and adolescents. The AAMD Adaptive Behavior Scale-School Edition (Lambert & Windmiller, 1981) and the Vineland Adapative Behavior Scales (Sparrow, Balla, & Cicchetti, 1984) were compared in 15 autistic persons aged 8 to 18. Correlations between the two instruments revealed good concurrent validity. The psychometric properties of the tests were similar to those found in samples of mentally retarded persons. The use of adaptive behavior measures for autistic children and adolescents is encouraged. Clinical advantages and disadvantages of the two tests are discussed.

Activities of Daily Living↗
PubMed2006

Adaptation of a velogenic Newcastle disease virus to vero cells: assessing the molecular changes before and after adaptation.

A velogenic Newcastle disease virus isolate was passaged 50 times in Vero cell culture and the virus was assessed for the molecular changes associated with the passaging. At every 10th passage, the virus was characterized conventionally by mean death time (MDT) analysis, intracerebral pathogenicity index (ICPI) and virus titration. At increasing passage levels, a gradual reduction in the virulence of the virus was observed. Molecular characterization of the virus included cloning and sequencing of a portion of the fusion gene (1349 bp) encompassing the fusion protein cleavage site (FPCS), which was previously amplified by reverse transcription-polymerase chain reaction. Sequence analysis revealed a total of 135 nucleotide substitutions which resulted in the change of 42 amino acids between the velogenic virus and the 50th passage virus. The predicted amino acid motif present at the cleavage site of the virulent virus was (109)SRRRRQRRFVG(119) and the corresponding region of the adapted adapted virus was (109)SGGRRQKRFIG(119). Pathogenicity studies conducted in 20-week-old seronegative birds revealed gross lesions such as petechial haemorrhages in the trachea, proventricular junction and intestines, and histopathological changes such as depletion and necrosis of the lymphocytes in thymus, spleen, bursa and caecal tonsils in the birds injected with the velogenic virus and absence of the lesions in birds injected with the adapted virus. The 50th-passage cell culture virus was back-passaged five times in susceptible chickens and subjected to virulence attribute analysis and sequence analysis of the FPCS region, with minor difference found between them.

Amino Acid Sequence↗
PubMed2006

Adaptive regularization network based neural modeling paradigm for nonlinear adaptive estimation of cerebral evoked potentials.

In this paper we report an adaptive regularization network (ARN) approach to realizing fast blind separation of cerebral evoked potentials (EPs) from background electroencephalogram (EEG) activity with no need to make any explicit assumption on the statistical (or deterministic) signal model. The ARNs are proposed to construct nonlinear EEG and EP signal models. A novel adaptive regularization training (ART) algorithm is proposed to improve the generalization performance of the ARN. Two adaptive neural modeling methods based on the ARN are developed and their implementation and performance analysis are also presented. The computer experiments using simulated and measured visual evoked potential (VEP) data have shown that the proposed ARN modeling paradigm yields computationally efficient and more accurate VEP signal estimation owing to its intrinsic model-free and nonlinear processing characteristics.

Algorithms↗
PubMedDate not supplied

The effect of stereotypies on adaptive skills as assessed with the DASH-II and Vineland Adaptive Behavior Scales.

The relationship of the Stereotypy subscale of the Diagnostic Assessment for the Severely Handicapped-II (DASH-II) to adaptive functioning was investigated. Differences in adaptive skills measured with the Vineland Adaptive Behavior Scales (VABS) for individuals scoring at or above the cutoff of the Stereotypy scale and below the cutoff of the scale were analyzed. Individuals with high stereotypy scores had significantly lower VABS scores. Implications of these findings for assessment and treatment are discussed.

Humans↗
PubMed2003

The bacterial adaptive response gene, barA, encodes a novel conserved histidine kinase regulatory switch for adaptation and modulation of metabolism in Escherichia coli.

Histidine kinases are important prokaryotic determinants of cellular adaptation to environmental conditions, particularly stress. The highly conserved histidine kinase, BarA, encoded by the bacterial adaptive response gene, barA, is a member of the family of tripartite histidine kinases, and is involved in stress adaptation. BarA has been implicated to play a role during infection of epithelial cells. Homologues and orthologues of BarA have been found in pathogenic yeast, fungi, mould and in plants. The primary aim of this review is to assimilate evidence present in the current literature linking the role of BarA in stress response, and to support it with preliminary experimental evidence indicating that, it is indeed a global response regulator. In particular, the review focuses on the unusual domain structure of the BarA protein, its role in oxidative, weak acid, and osmotic stress responses and its role in biofilm formation. A preliminary genomic approach to identify downstream genes regulated by the BarA signaling pathway, using DNA microarray, is reported. The results demonstrate that BarA plays a global response regulatory role in cell division, carbon metabolism, iron metabolism and pili formation. The evolutionary significance of these types of histidine kinase sensors is reviewed in light of their roles in pathogenesis.

Acclimatization↗
PubMed2000

A novel adapter protein employs a phosphotyrosine binding domain and exceptionally basic N-terminal domains to capture and localize an atypical protein kinase C: characterization of Caenorhabditis elegans C kinase adapter 1, a protein that avidly binds protein kinase C3.

Atypical protein kinase C isoforms (aPKCs) transmit regulatory signals to effector proteins located in the cytoplasm, nucleus, cytoskeleton, and membranes. Mechanisms by which aPKCs encounter and control effector proteins in various microenvironments are poorly understood. By using a protein interaction screen, we discovered two novel proteins that adapt a Caenorhabditis elegans aPKC (PKC3) for specialized (localized) functions; protein kinase C adapter 1 (CKA1, 593 amino acids) and CKA1S (549 amino acids) are derived from a unique mRNA by alternative utilization of two translation initiation codons. CKA1S and CKA1 are routed to the cell periphery by exceptionally basic N-terminal regions that include classical phosphorylation site domains (PSDs). Tethering of PKC3 is mediated by a segment of CKA1 that constitutes a phosphotyrosine binding (PTB) domain. Two aromatic amino acids (Phe(175) and Phe(221)) are indispensable for creation of a PKC3-binding surface and/or stabilization of CKA1.aPKC complexes. Patterns of CKA1 gene promoter activity and CKA1/CKA1S protein localization in vivo overlap with patterns established for PKC3 expression and distribution. Transfection experiments demonstrated that CKA1/CKA1S sequesters PKC3 in intact cells. Structural information in CKA1/CKA1S enables delivery of adapters to the lateral plasma membrane surface (near tight junctions) in polarized epithelial cells. Thus, a PTB domain and PSDs collaborate in a novel fashion in CKA1/CKA1S to enable tethering and targeting of PKC3. Avid ligation of a PKC isoform is a previously unappreciated function for a PTB module.

Adaptor Proteins, Signal Transducing↗