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PubMed2000

Effect of eugenol-containing sealer on marginal adaptation of dentine-bonded resin fillings.

AIM: Eugenol is claimed to interfere with the polymerization of composite resins and to affect shear bond strengths of dentine-bonded composite restorations. Eugenol-based sealers are used during root canal treatment in teeth that may require build-ups or extensive restorations. Unfortunately, the adverse effect of eugenol has mostly been assessed in shear bond tests and this variable may be clinically inappropriate. The current study evaluate the effect of eugenol in a eugenol-based endodontic sealer on marginal adaptation of composite resin restorations with and without thermo-mechanical stress. METHODOLOGY: Thirty Class V cavities with half of the cavity margins in dentine and half of the cavity margins in enamel were prepared in extracted human premolars and then divided into 5 groups. Teeth in group 1 were not contaminated with eugenol. Cavities in groups 2-4 were contaminated with a eugenol-based sealer (Tubli-Seal, Kerr) and cleaned with: (i) sandblasting, (ii) bur finishing alone or (iii) bur finishing combined with swabbing with alcohol. These 4 groups were temporized for 6 weeks (Ketac, ESPE), whilst group 5 received no eugenol, was not temporized and acted as the control. Cavities were restored with Tetric Ceram using Syntac Classic (Vivadent) as a dentine-bonding agent. The specimens were then thermo-mechanically stressed. The percentages of marginal adaptation in dentinal and enamel margins were assessed in a SEM at x200 magnification before and after stress using a replica method. Mean percentages of marginal adaptation were calculated and compared using a two way-ANOVA (influence of eugenol and cleaning procedure) and non-parametric tests. RESULTS: Marginal adaptation in enamel exceeded 95% and 92% in all specimens before and after thermo-mechanical stress, respectively. Before stress, marginal adaptation in dentine ranged from 92.3 +/- 7.9% to 95.7 +/- 6.2% in groups 1-5. After stress, the percentage of marginal adaptation in dentine decreased significantly overall (P < 0.05, range 39.8 +/- 21.1% to 82.9 +/- 13.7%). The effect of contamination with eugenol was not significant (P > 0.05): in contrast, there was a significantly beneficial effect when the entire cavity was finished with burs (P < 0.01). CONCLUSIONS: Under the conditions of this study, the eugenol containing sealer did not significantly impair marginal adaptation in dentinal margins of mixed Class V restorations when bur finishing was employed before placement. However, no other cleaning method was sufficient to produce acceptable figures of marginal adaptation.

Analysis of Variance↗
PubMed2003

Maternal adaptation during childbearing in Norway, Sweden and the United States.

The purpose of the study of 147 healthy primiparous women is to investigate the relationship between maternal adaptation during pregnancy and postpartum. This report is part of a larger study of relationships between family dynamics and maternal adaptation during childbearing in Norway, Sweden and the US. Variables included maternal adaptation, age, social status, mother's employment, type of birth, length of hospitalization and mother infant time together in the hospital. Mothers reporting greater adaptation during pregnancy reported greater adaptation postpartum. Mothers who believed themselves adapted indicated that they were better prepared for labour, had more control over their birth experience, a better relationship with their partner, and perceived greater participation in child care from their partner. Few differences were found in maternal adaptation among all mothers, and few relationships were found among selected sociodemographic variables and maternal adaptation. Formation of maternal identity and mother's confidence in her ability to cope with the tasks of motherhood was affected by mothers' prenatal identification with the motherhood role, supporting the notion that knowing what to expect provides a sense of control. Mothers' prenatal identification with the motherhood role directly or indirectly affected her satisfaction with motherhood. Nurses may want to develop practice strategies to support these findings.

Adaptation, Psychological↗
PubMed1999

Simple method to observe the adaptive response of Listeria monocytogenes in food.

A simple, novel method for determining stress-adaptive response of Listeria monocytogenes in food systems is presented. The method involves plating samples on Listeria-selective agar (LSA) acidified to pH 5.25 with incubation at 36 degrees C for 60 h to detect acid adaptation and plating on LSA with 70 gl-1 NaCl and incubation at 7 degrees C for 7 d to detect cold-osmotic adaptation. Adapted cells produced larger colonies (> 1 mm) under these conditions than unadapted cells. Scot A (97%) and Brie-1 (100%) cells incubated in milk at pH 5 for 3 h manifested the acid-adapted colony type compared with 6% and 21% of viable cells in the unstressed control population. After a 5-d adaptation period at 4 degrees C in milk with 80 gl-1 salt, 29% of Scot A and 91% of Brie-1 viable cells exhibited the adapted colony type compared with < 1% of the unstressed control population. Stress-adapted L. monocytogenes were isolated from soft cheese held for 42 d at 10 C.

Adaptation, Physiological↗
PubMed1980

The adaptation of digestive enzymes to the diet: its physiological significance.

Digestive enzymes adapt to the diet when substrate intake is altered. An analysis of experimental works shows that this process includes many enzymes. The intestinal step of digestion is the most important in the enzyme breakdown of dietary components. In the first part of this paper, I have pooled the data on the adaptive potency of pancreatic and intestinal enzymes. When protein, carbohydrate and lipid digestions are considered successively, it is clear that the enzymes involved adapt to any change in substrate intake. For instance, when the amount of starch intake increases, the specific activity of pancreatic amylase is stimulated. At the same time, augmenting the disaccharide level leads to an increase in specific disaccharidase activity, and the absorption rate of some simple hydrolytic products, such as fructose, increases. It thus appears that altering the amount of starch intake leads to a parallel change in the activity of all the enzymes involved in the sequential hydrolysis of the dietary carbohydrates. The second part of the paper discusses the physiological significance of this adaptation in terms of utility to the animal. Two situations are considered in which (i) the nutritional requirements are supplied by food or (ii) they are not supplied either because of a dietary or an enzyme deficiency. When the nutritional requirements, particularly that of protein, are met, adaptation is apparently not useful to the animal. Nevertheless, the role of this adaptation on the hydrolysis rate of different substrates can be supposed. When nutritional requirements are not met, some data show that enzyme adaptation may be advantageous to the animal. If dietary restriction is not too severe and thus the biosynthesis of all the enzymes markedly decreases, then digestive secretions would export considerable nitrogenous material into the gastrointestinal lumen; this material could be a substrate compensating for the essential components lacking in the diet. Any enzyme deficiency leading to substrate decrease is similar to a dietary deficiency. Many experimental studies have shown that in pancreatic deficiency the adaptive potency of the organism is responsible for establishing digestive compensation.

Adaptation, Physiological↗
PubMedDate not supplied

[Significance of uterine contractions for adaptation of the newborn infant before cesarean section].

UNLABELLED: There are quite a few publications on the influence of labour on the adaptation of neonates after elective cesarean sections. Many authors recommend the induction of labor prior to the cesarean section. They found that this improves the adaptation of the infants. MATERIAL AND METHOD: All cesarean sections between 1991 and 1996 are recorded. Mature neonates (> 36 weeks of pregnancy) were evaluated separately from premature infants (< 36 weeks of pregnancy). As target-parameters we chose 1. the condition of the neonates (characterized by the Apgar-Score, the pH of the umbilical cord artery, and the requirement of artificial respiration). 2. the necessity of transfer to the neonatologic intensive care unit. Concerning these parameters, the immature neonates (> 36 weeks of pregnancy) were evaluated separately from the mature infants (< 36 weeks of pregnancy). In the latter group we finally evaluated the data of those who were not delivered by a cesarean section because of intrauterine fetal distress. RESULTS: The adaptation of the premature neonates was so closely related to the gestational age that all the other variables were of no statistically significant influence. Thus also the factor "labour" was of no influence. The results in the group of the mature infants were completely different. Between week 36 und 42 of pregnancy the gestational age was of no influence on the adaptation of the neonates. Statistically noticeable however was the influence of preoperative labour: The adaptation of infants delivered by cesarean-section after labour was remarkably worse than the adaptation of those who were delivered without labour prior to the operation. This statement is also correct when one rules out those infants who were delivered by a so called emergency cesarean section. When evaluating the group of neonates in which the cesarean section was not performed because of intrauterine fetal distress we could find no influence of preoperative labour on the adaptation of the infants. All other variables examined (e.g. maternal age, parity, duration of labour, method of anaesthesia, twin-pregnancy) were no factors of influence on the adaptation of the babies. CONCLUSION: From our results we cannot support the recommendation to induce labour prior to any elective cesarean section by infusion of oxytocin or to wait for the spontaneous onset of labour. There ist no reason to change our policy to perform an elective cesarean section as near as possible to term before the onset of labour.

Adaptation, Physiological↗
PubMed2005

Adaptation to spiral motion in crowding condition.

When a single, moving stimulus is presented in the peripheral visual field, its direction of motion can be easily distinguished, but when the same stimulus is flanked by other similar moving stimuli, observers are unable to report its direction of motion. In this condition, known as 'crowding', specific features of visual stimuli do not access conscious perception. The aim of this study was to investigate whether adaptation to spiral motion is preserved in crowding conditions. Logarithmic spirals were used as adapting stimuli. A rotating spiral stimulus (target spiral) was presented, flanked by spirals of the same type, and observers were adapted to its motion. The observers' task was to report the rotational direction of a directionally ambiguous motion (test stimulus) presented afterwards. The directionally ambiguous motion consisted of a pair of spirals flickering in counterphase, which were mirror images of the target spiral. Although observers were not aware of the rotational direction of the target and identified it at chance levels, the direction of rotation reported by the observers during the test phase (motion aftereffect) was contrarotational to the direction of the adapting spiral. Since all contours of the adapting and test stimuli were 90 degrees apart, local motion detectors tuned to the directions of the mirror-image spiral should fail to respond, and therefore not adapt to the adapting spiral. Thus, any motion aftereffect observed should be attributed to adaptation of global motion detectors (ie rotation detectors). Hence, activation of rotation-selective cells is not necessarily correlated with conscious perception.

Adaptation, Physiological↗
PubMed2000

The SOS response regulates adaptive mutation.

Upon starvation some Escherichia coli cells undergo a transient, genome-wide hypermutation (called adaptive mutation) that is recombination-dependent and appears to be a response to a stressful environment. Adaptive mutation may reflect an inducible mechanism that generates genetic variability in times of stress. Previously, however, the regulatory components and signal transduction pathways controlling adaptive mutation were unknown. Here we show that adaptive mutation is regulated by the SOS response, a complex, graded response to DNA damage that includes induction of gene products blocking cell division and promoting mutation, recombination, and DNA repair. We find that SOS-induced levels of proteins other than RecA are needed for adaptive mutation. We report a requirement of RecF for efficient adaptive mutation and provide evidence that the role of RecF in mutation is to allow SOS induction. We also report the discovery of an SOS-controlled inhibitor of adaptive mutation, PsiB. These results indicate that adaptive mutation is a tightly regulated response, controlled both positively and negatively by the SOS system.

Adaptation, Physiological↗
PubMed1991

Growth in high serum concentrations leads to rapid deadaptation of cells previously adapted to growth in an extremely low concentration of serum.

A subline of NIH 3T3 cells adapted to multiply in 0.25% calf serum (CS) by frequent passage (every 2-3 days) at low population density in 0.25% CS was deadapted by frequent successive passages of the cells in 10% CS for 3 weeks. The cells adapted to 0.25% CS multiplied with an average doubling time of 16.9 hr in 10% CS, and cells that had always been kept in 10% CS multiplied with an average doubling time of 14.6 hr, so there was weak selection for the latter in the higher serum concentration. When adapted cells were subjected to two passagers in 10% CS prior to assay of growth in 0.25% CS, a 4-day lag period was evident before commencement of exponential growth, and there was a decrease in saturation density. Further delay of growth in 0.25% CS developed as the number of passages of cells in 10% CS increased. The marked delay of growth in 0.25% CS of the bulk population after a few days in 10% CS argued against selection in 10% CS of rare nonadapted mutants from the adapted population and for an epigenetic origin of the change. Reconstruction experiments utilizing adapted cells mixed with non-adapted cells in 0.25% CS buttressed this explanation. Eight clones of the adapted population exhibited some loss of growth capacity in 0.25% CS after a single passage in 10% CS, though the extent of loss varied from clone to clone. The results support the idea that all cells in the adapted population respond to the lifting of growth constraints with loss of their growth potential under highly constrained conditions. They are consistent with the concept of progressive state selection in which selection operates on fluctuating metabolic states of individual cells rather than on genetic variants.

3T3 Cells↗
PubMed2006

Relationship between bond strength and marginal and internal adaptation of composite restorations photocured by different methods.

OBJECTIVE: This study evaluated the relationship between bond strength and marginal and internal adaptation of composite restorations photocured using different methods with a quartz-tungsten-halogen light. MATERIAL AND METHODS: A push-out test was performed to evaluate bond strength of conical restorations in 50 bovine incisors. To evaluate marginal (external) and internal restoration adaptation, 50 circular all-enamel margin preparations were done in bovine incisors. For both tests, the preparations were filled with Esthet*X resin composite. Specimens were distributed into 5 groups (n=10) depending on photoactivation method: G1: continuous light 700; G2: continuous light 150; G3: soft-start; G4: intermittent light; and G5: pulse-delay. The energy density for each method was standardized: 14 J/cm2. Caries Detector (Kuraray) was placed in restoration margins for detection of marginal adaptation. The percentage of interfaces present as gaps was determined using digital images. Specimens were then sectioned, stained, and the internal adaptation was recorded in a similar manner. Data were submitted to ANOVA and the Tukey HSD test, pre-set alpha = 0.05. RESULTS: Bond strength G5 (7.2 MPa+/-1.3) was significantly greater (p=0.00280) than G1 (4.6 MPa+/-1.5). G2, G3, and G4 showed equivalent, intermediate strength values. No significant difference was found in marginal adaptation of any of the groups (p=0.16911). Internal adaptation results were the inverse of strength results: G5 (2.8%+/-4.9) showed significantly less (p=0.00979) gap formation compared to G1 (10.1%+/-6.2). CONCLUSION: Some modulated photocuring methods can increase bond strength while decreasing internal gap formation. An inverse relationship was found between push-out bond strength and internal adaptation. Marginal adaptation was not affected by any photoactivation method.

Acrylic Resins↗
PubMed2002

Acculturation attitudes, need for cognitive closure, and adaptation of immigrants.

The author validated Berry's model of acculturation (J. W. Berry, 1990a, 1990b, 1991; J. W. Berry, U. Kim, S. Power, M. Young, & M. Bujaki, 1989) and examined the relation between acculturation attitudes and sociocultural and psychological adaptation among Croatian and Polish immigrants to Italy, 2 groups whose cultures are not very different from the Italian culture. Moreover, the author investigated the relation between the need for cognitive closure (NCC; M. D. Webster & A. W. Kruglanski, 1994) and psychological and sociocultural adaptation. The participants completed a questionnaire including measures of sociocultural adaptation, psychological adaptation, social relationships, acculturation attitudes, and NCC. The results of a multivariate analysis of variance revealed main effects of acculturation strategies for both forms of adaptation and a main effect of NCC for psychological adaptation. The Croatian and Polish immigrants differed in the level of sociocultural adaptation but not in the level of psychological adaptation.

Adaptation, Psychological↗
PubMed1989

Levels of adaptation and narcissistic psychopathology.

Why, one might reasonably query, do some narcissistic characters serve time as seemingly successful presidents of corporations while others serve time as seemingly impaired inpatients on psychiatric units? I will offer some observations on this unusual clinical phenomenon and suggest that it is useful to distinguish between two clinical presentations of narcissistic character psychopathology, which I will call, for the sake of expedience, Level 1 and Level 2. I will then examine 1) how an understanding of the dimensions of empathic abilities, paranoia, levels of depression, grandiosity, and defensive uses of denial and disavowal can lend a broad explanatory range to the understanding of these levels, and 2) how we can assess both successful and unsuccessful adaptation to the outer world and the inner world in narcissistic disorders. Moreover, it is important to distinguish between being well adapted and being emotionally healthy, which are quite different in meaning and intent. I use the term Level 1 to refer to the more poorly adapted presentation, and the term Level 2 to refer to the more successfully adapted narcissistic presentation. Characteristics of Level 1 narcissistic pathology dispose a patient to an adaptation that is similar to the description of the narcissistic patient who is often described as borderline; characteristics of Level 2 narcissistic pathology dispose a patient to a high-flying and superficially successful adaptation in which the patient can competently navigate the occupational and social demands of an external world despite the presence of severe object relational impairments. While a difference in adaptation is highlighted, emotional well-being is not within the exclusive province of either's characteristic adaptive skills.

Adaptation, Psychological↗
PubMed1989

Induction of the adaptive response by X-rays is dependent on radiation intensity.

Human lymphocytes pretreated with low (0.01 Gy) but not high (0.5 Gy) doses of X-rays become somewhat refractory to the induction of chromatid deletions by subsequent exposure to high (1.5 Gy) doses of X-rays (i.e. the yield of chromatid deletions is less than the sum of the yields induced by the pre-exposure and the subsequent challenge doses). This adaptive response can also be induced by pretreating the cells with very low, or even high, concentrations of tritiated thymidine. Because high concentrations of tritiated thymidine result in high doses of radiation that are delivered at very low dose-rates (i.e. less than 0.01 Gy/min), the lack of adaptation following high pre-treatment doses of X-rays could be attributed to their higher dose-rates. To test the effect of X-ray intensity on the induction of the adaptive response, lymphocytes were irradiated with 0.5 Gy of X-rays at 0.005-0.5 Gy/min at 28-30 h of culture, and then irradiated with 1.5 Gy at 48 h. Chromatid deletions were measured 6 h later. The results show that 0.5 Gy of X-rays given at low dose-rates (0.005 or 0.01 Gy/min), but not at high dose-rates (0.1, 0.2, or 0.5 Gy/min), are capable of inducing the adaptive response. Furthermore, experiments in which a male subject's cells exposed to 0.5 Gy given at 0.005 Gy/min were cocultivated with a female subject's cells irradiated with 0.5 Gy at 0.5 Gy/min showed that cells exposed to radiation at low and high intensity progress to metaphase equally and, therefore, that the lack of an adaptive response at high dose-rates cannot be attributed to selection of radioresistant cells. Although the induction of the adaptive response at higher X-ray doses occurs at low radiation intensity, there seems to be a minimum dose required for this effect; e.g., 0.01-Gy pretreatments induced the adaptive response when given at 0.2 Gy/min, but not at 0.005 Gy/min. Thus, the adaptive response is dependent both on the total dose of the pretreatment and on the rate at which the dose is given.

Adaptation, Physiological↗
PubMed1994

Calcium antagonist, TMB-8, prevents the induction of adaptive response by hydrogen peroxide or X-rays in human lymphocytes.

Treatment of human lymphocytes with hydrogen peroxide (10 microM, 30 min, 37 degrees C in PBS) or with 1 cGy X-rays evoked about a 30% decrease in the frequency of micronuclei upon subsequent X-irradiation (1.5 Gy). In addition to a lower micronuclei frequency, we also found an increase in the sedimentation distance of the nucleoids, when measured 90 min (duration of the isolation procedure carried out at 4 degrees C) after the adaptive dose (hydrogen peroxide or X-rays) and preceding the challenge dose. To test whether Ca2+ is involved in the induction of the adaptive response pathway, we treated cells with the calcium chelator, EGTA. When EGTA was given at the same time as the adaptive dose, it prevented the development of the adaptive response. In addition, the calcium antagonist, TMB-8, also prevented the development of the adaptive response as it prevented the reduction of both micronuclei and increased nucleoid sedimentation. Cellular treatment with TMB-8 increased the free [Ca2+] by 40%, when given together with hydrogen peroxide. The faster sedimenting nucleoids from adapted cells were also examined by ethidium bromide titration; there was no indication of any change in supercoil density or loop size. Psi-tectorigenin, an inhibitor of phosphatidylinositol turnover, did not modify the adaptive response, indicating that inositol (1,4,5)-trisphosphate is not involved in the induction of the adaptive response, but free Ca2+ ions are.

Adaptation, Physiological↗
PubMed1980

Cyclic 3',5'-AMP relay in Dictyostelium discoideum IV. Recovery of the cAMP signaling response after adaptation to cAMP.

In dictyoselium discoideum, an increase in extracellular cAMP activates adenylate cyclase, leading to an increase in intracellular cAMP and the rate of cAMP secretion. Cells adapt to any constant cAMP stimulus after several minutes, but still respond to an increase in the concentration of the stimulus. We have now characterized the decay of adaptation (deadaptation) after the removal of cAMP stimuli. Levels of adaptation were established by the perfusion of [(3)H]adenosine-labeled amoebae with a defined cAMP stimulus. After a variable recovery period, the magnitude of the signaling response to a second stimulus was measured; its attenuation was taken as a measure of residual adaption to the first stimulus. The level of adaptation established by the first stimulus depended on both its magnitude and duration. Deadaptation began as soon as the first stimulus was removed. The magnitude of the response to the second stimulus increased with the recovery time in a first-order fashion, with a t(1/2)=3-4 min for stimuli of 10(-8) M to 10(-5) M cAMP. Responses to test stimuli, although reduced in magnitude, had an accelerated time-course when they closely followed a prior response that had not completely subsided. This effect is called priming; we believe it reveals a reversible, rate-limiting step that modulates the onset and termination of the signaling responses of amoebae that have not recently responded to a cAMP stimulus. We have suggested that the cAMP signaling response is controlled by two antagonistic cellular processes, excitation and adaptation. The data reported here imply that both the rate of rise in the adaptation process and the final level reached depend on the occupancy of cAMP surface receptors and that the decay of adaptation when external cAMP is removed proceeds with first-order kinetics.

Adaptation, Physiological↗
PubMed1997

Light adaptation in Pecten hyperpolarizing photoreceptors. Insensitivity to calcium manipulations.

The ability of scallop hyperpolarizing photoreceptors to respond without attenuation to repetitive flashes, together with their low light sensitivity, lack of resolvable quantum bumps and fast photoresponse kinetics, had prompted the suggestion that these cells may be constitutively in a state akin to light adaptation. We here demonstrate that their photocurrent displays all manifestations of sensory adaptation: (a) The response amplitude to a test flash is decreased in a graded way by background or conditioning lights. This attenuation of the response develops with a time constant of 200-800 ms, inversely related to background intensity. (b) Adapting stimuli shift the stimulus-response curve and reduce the size of the saturating photocurrent. (c) The fall kinetics of the photoresponse are accelerated by light adaptation, and the roll-of of the modulation transfer function is displaced to higher frequencies. This light-induced desensitization exhibits a rapid recovery, on the order of a few seconds. Based on the notion that Ca mediates light adaptation in other cells, we examined the consequences of manipulating this ion. Removal of external Ca reversibly increased the photocurrent amplitude, without affecting light sensitivity, photoresponse kinetics, or susceptibility to background adaptation; the effect, therefore, concerns ion permeation, rather than the regulation of the visual response. Intracellular dialysis with 10 mM BAPTA did not reduce the peak-to-plateau decay of the photocurrent elicited by prolonged light steps, not the background-induced compression of the response amplitude range and the acceleration of its kinetics. Conversely, high levels of buffered free [Ca]i (10 microM) only marginally shifted the sensitivity curve (delta sigma = 0.3 log) and spared all manifestations of light adaptation. These results indicate that hyperpolarizing invertebrate photoreceptors adapt to light, but the underlying mechanisms must utilize pathways that are largely independent of changes in cytosolic Ca. The results are discussed in terms of aspects of commonalty to other ciliary sensory receptor cells.

Adaptation, Physiological↗
PubMed2005

Adaptation: "a critique of some current evolutionary thought".

In his classic Adaptation and Natural Selection: A Critique of Some Current Evolutionary Thought (1966), George Williams showed definitively that our understanding of adaptation, a central concept of evolutionary theory, must be gene-centered. The purpose of adaptations is to further the replication of genes. Genes are machines for turning out more genes; and adaptations are the means by which genes pluck resources from the world to promote this self-replication. Thus adaptations transform potential resources from part of the indifferent world-at-large into tailor-made environments, environments brimming with resources for organisms' distinctive adaptive needs. Systematically dif ferent adaptive problems therefore give rise to different environments; and so different species, for example, have different environments. Thus a gene-centered analysis of adaptations implies a gene-centered theory of environments. Without genes to specify what constitutes an environment, environments would not exist. Rather than being separate from biology, an autonomous, independent force, environments are themselves the products of biology. So a gene-centered view, far from depreciating the environment, furnishes a rich and precise understanding of its importance.

Adaptation, Physiological↗
PubMed2000

Responsiveness of dark-adaptation threshold to vitamin A and beta-carotene supplementation in pregnant and lactating women in Nepal.

BACKGROUND: Impaired dark adaptation occurs commonly in vitamin A deficiency. OBJECTIVE: We sought to examine the responsiveness of dark-adaptation threshold to vitamin A and beta-carotene supplementation in Nepali women. DESIGN: The dark-adapted pupillary response was tested in 298 pregnant women aged 15-45 y in a placebo-controlled trial of vitamin A and beta-carotene; 131 of these women were also tested at 3 mo postpartum. Results were compared with those for 100 nonpregnant US women of similar age. The amount of light required for pupillary constriction was recorded after bleaching and dark adaptation. RESULTS: Pregnant women receiving vitamin A had better dark-adaptation thresholds (-1.24 log cd/m(2)) than did those receiving placebo (-1.11 log cd/m(2); P: = 0. 03) or beta-carotene (-1.13 log cd/m(2); P: = 0.05) (t tests with Bonferroni correction). Dark-adaptation threshold was associated with serum retinol concentration in pregnant women receiving placebo (P: = 0.001) and in those receiving beta-carotene (P: = 0.003) but not in those receiving vitamin A. Among women receiving placebo, mean dark-adaptation thresholds were better during the first trimester (-1.23 log cd/m(2)) than during the second and third trimesters (-1.03 log cd/m(2); P: = 0.02, t test). The mean threshold of nonpregnant US women (-1.35 log cd/m(2)) was better than that of all 3 Nepali groups (P: < 0.001, t test, for all 3 groups). CONCLUSIONS: During pregnancy, pupillary dark adaptation was strongly associated with serum retinol concentration and improved significantly in response to vitamin A supplementation. This noninvasive testing technique is a valid indicator of population vitamin A status in women of reproductive age.

Adolescent↗
PubMed2002

Long-lasting amelioration of visuospatial neglect by prism adaptation.

It has been shown that unilateral left neglect can be significantly improved for a short time after a short period of adaptation to a prismatic shift of the visual field to the right. In neuropsychological studies, however, there is no evidence demonstrating long-lasting effects following treatment by prism adaptation (PA). The first aim of the present study was to find out whether the short-term amelioration found after prismatic adaptation could be converted into long-term therapeutic improvement. Secondly, we investigated whether the improvement of neglect in standard tests could be generalized to ecological visuospatial tests. Thirdly, the effects of prism adaptation on different spatial domains (far, near and personal space) were evaluated. Fourthly, the influence of PA on high-order visuospatial functions, such as spatial representation, and on a low-order factor, i.e. sensory--motor bias, was investigated. Finally, we investigated the possible correlation between neglect amelioration, the adaptation effect and the visuomotor after-effect, as assessed by a pointing task during and after PA. Seven patients with right hemisphere lesion and left visuospatial neglect were treated with prismatic lenses in twice-daily sessions over a period of 2 weeks. In each training session, patients were required to perform a pointing task wearing base-left wedge prisms inducing a shift of the visual field to the right by 10. The presence of visual neglect and the duration of the amelioration achieved were assessed before the treatment and 2 days, 1 week and 5 weeks after treatment by using a standardized battery that included a series of behavioural and ecological visuospatial tests. Six control, untreated patients, matched to the experimental group for gravity and duration of illness, were submitted to the same tests at the same intervals as the experimental patients. The results showed an improvement in the experimental patients' performance after PA, which was maintained during the 5-week period after treatment. The amelioration of neglect was found in standard as well as in behavioural tests and in all spatial domains. In contrast, control patients did not show any improvement in neglect. The amelioration of neglect occurred only in patients who showed the adaptation effect and the after-effect in the pointing task. Neglect amelioration did not occur in one patient who did not show the adaptation effect and had an unstable after-effect. In conclusion, these findings show that prism adaptation is a productive way of achieving long-lasting improvements in neglect treatment.

Adaptation, Physiological↗