Degree Of Individual Variation Research Articles

Изменчивость биохимических признаков Pinus sylvestris (Pinaceae) при адаптации форм в условиях избыточного увлажнения

Conifers are characterized by a certain degree of individual variability in the content of stress metabolites, which can be caused by genotypic variations or divergence in the growth conditions of individual trees. The purpose of the study is to evaluate the variation of biochemical traits of Scots pine, which are different in the color of male strobilus, during adaptation to the conditions of constant excessive moisture in the soil of the northern taiga. The dynamics of metabolic parameters of Pinus sylvestris L. were investigated in shrubsphagnum pine stands on marshy upland soils at the mouth of the Northern Dvina River (northern taiga subzone). From July to November 2018, needle samples from shoots were collected from 10 pine trees of each of the male strobilus types, differentiated by color. The contents of photosynthetic pigments, anthocyanins, ascorbic acid, proline, water-soluble proteins, and pH were measured under laboratory conditions. The synthesis of chlorophyll in the needles in the current year of formation decreased in trees of both forms during the dry summer period. A favorable temperature in the autumn period could promote an extension of photosynthetic pigment accumulation, which might negatively affect tree preparation for overwintering. There were no significant differences between f. erythranthera Sanio and f. sulfuranthera Kozubow in the needle content of chlorophyll and carotenoids, anthocyanins, ascorbic acid, free proline, water-soluble proteins, or pH. The similarities in the adaptation of the trees to the constant excessive soil moisture in northern taiga conditions were revealed. The seasonal factor had a considerable impact on the dynamics of biochemical parameters. Ascorbic acid, proline, and anthocyanin were more actively accumulated in the needles throughout the summer due to the high air temperature, resulting in an increase in antioxidant activity and the development of protective mechanisms aimed at reducing oxidative stress. The increase in water-soluble protein content in needles from October to November is one of the cryoprotective mechanisms of the trees for the winter period. Individual differences in ascorbic acid and proline contents in yellow microspore-bearing pine needles at the establishment of minus temperatures in November were considerably higher than in red microspore-bearing pine needles. This is regarded as the norm of the reaction for different types of trees to the influence of negative temperatures. For citation: Tarkhanov S.N., Pinaevskaya E.A., Aganina Y.E., Pakhov A.S. Variability of Biochemical Properties During Adaptation of Pinus sylvestris (Pinaceae) Forms to Excessive Moisture Conditions. Lesnoy Zhurnal = Russian Forestry Journal, 2023, no. 4, pp. 58–75. (In Russ.). https://doi.org/10.37482/0536-1036-2023-4-58-75

Identifying the dataset to define the optimal timing of histopathological examination for central nervous system toxicity in MPTP-induced Parkinson's disease monkey model.

Determining the optimal timing for histopathological examination following exposure to a test article is crucial for assessing neurotoxicity. However, no study has focused on identifying an ideal dataset to define the optimal timing for histopathological examination of central nervous system (CNS) toxicity in monkeys. Therefore, this study aimed to define a predictive endpoint that would guide us in selecting the optimal timing for histopathological examination of CNS toxicity in monkeys. Four cynomolgus monkeys were administered 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) intravenously at a dosage of 0.6 mg/kg twice at 1-week intervals. Necropsies were performed 1 week after the final dose. The Parkinsonian rating (PR) score and temporal changes in neurofilament light chain and glial fibrillary acidic protein concentrations in the cerebrospinal fluid (CSF) and serum were evaluated and compared with the histopathological findings in the brain. The PR score of all animals administered MPTP increased from days 10 to 11, with some degree of individual variability. Microscopically, all animals showed axonal swelling and vacuolation, with or without microgliosis in the nigrostriatal bundle. However, substantial neurodegenerative findings were observed only in animals with high PR scores at necropsy. A slight increase in CSF biomarker levels at necropsy was also observed in animals with high PR scores. However, their correlation with microscopic findings in these animals was unclear. These data suggest that comprehensive clinical observations, such as PR score alone or combined with other CSF biomarkers, could be further evaluated as potential indicators for triggering anatomic CNS evaluations in monkeys following toxic insults.

Personality maturation through sense of mastery? Longitudinal evidence from two education-to-work transition studies.

Why personality changes in young adulthood remains a critical theoretical and empirical question. We studied personality change during the education-to-work transition, including mean-level personality change and its specific timing, the degree of individual variability in change, and the link between sense of mastery and personality change. We used two intensive longitudinal studies. Study 1 included 5 waves of data across 2 years during the university-to-work transition (N=309; mean-aged 25). Study 2 included 3 waves of data across 8months during an internship-heavy teacher education program (N=317; mean-aged 22). We measured personality traits and work-related mastery with questionnaires and personality states and general mastery with the experience sampling method. First, we found no evidence for mean-level personality maturation but decreases in trait Conscientiousness. Second, young adults differed significantly in personality trait and state change. Third, young adults with higher levels of work-related sense of mastery showed more positive changes in trait Conscientiousness. Decreases in general sense of mastery predicted later decreases in state Emotional Stability and vice versa. Change in general sense of mastery correlated with personality state change. Sense of mastery seems to be part of a dynamic short-term process underlying personality change in young adulthood.

Time-dependent memory and individual variation in Arctic brown bears (Ursus arctos)

BackgroundAnimal movement modelling provides unique insight about how animals perceive their landscape and how this perception may influence space use. When coupled with data describing an animal’s environment, ecologists can fit statistical models to location data to describe how spatial memory informs movement.MethodsWe performed such an analysis on a population of brown bears (Ursus arctos) in the Canadian Arctic using a model incorporating time-dependent spatial memory patterns. Brown bear populations in the Arctic lie on the periphery of the species’ range, and as a result endure harsh environmental conditions. In this kind of environment, effective use of memory to inform movement strategies could spell the difference between survival and mortality.ResultsThe model we fit tests four alternate hypotheses (some incorporating memory; some not) against each other, and we found a high degree of individual variation in how brown bears used memory. We found that 71% (15 of 21) of the bears used complex, time-dependent spatial memory to inform their movement decisions.ConclusionsThese results, coupled with existing knowledge on individual variation in the population, highlight the diversity of foraging strategies for Arctic brown bears while also displaying the inference that can be drawn from this innovative movement model.

Heterogenous presence of neutrophil extracellular traps in human solid tumours is partially dependent on IL‐8

Neutrophil extracellular traps (NETs) are webs of extracellular nuclear DNA extruded by dying neutrophils infiltrating tissue. NETs constitute a defence mechanism to entrap and kill fungi and bacteria. Tumours induce the formation of NETs to the advantage of the malignancy via a variety of mechanisms shown in mouse models. Here, we investigated the presence of NETs in a variety of human solid tumours and their association with IL-8 (CXCL8) protein expression and CD8+ T-cell density in the tumour microenvironment. Multiplex immunofluorescence panels were developed to identify NETs in human cancer tissues by co-staining with the granulocyte marker CD15, the neutrophil marker myeloperoxidase and citrullinated histone H3 (H3Cit), as well as IL-8 protein and CD8+ T cells. Three ELISA methods to detect and quantify circulating NETs in serum were optimised and utilised. Whole tumour sections and tissue microarrays from patients with non-small cell lung cancer (NSCLC; n= 14), bladder cancer (n= 14), melanoma (n= 11), breast cancer (n= 31), colorectal cancer (n= 20) and mesothelioma (n= 61) were studied. Also, serum samples collected retrospectively from patients with metastatic melanoma (n= 12) and NSCLC (n= 34) were ELISA assayed to quantify circulating NETs and IL-8. NETs were detected in six different human cancer types with wide individual variation in terms of tissue density and distribution. At least in NSCLC, bladder cancer and metastatic melanoma, NET density positively correlated with IL-8 protein expression and inversely correlated with CD8+ T-cell densities. In a series of serum samples from melanoma and NSCLC patients, a positive correlation between circulating NETs and IL-8 was found. In conclusion, NETs are detectable in formalin-fixed human biopsy samples from solid tumours and in the circulation of cancer patients with a considerable degree of individual variation. NETs show a positive association with IL-8 and a trend towards a negative association with CD8+ tumour-infiltrating lymphocytes. © 2021 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland.

Characterizing population and individual migration patterns among native and restored bighorn sheep (Ovis canadensis).

Migration evolved as a behavior to enhance fitness through exploiting spatially and temporally variable resources and avoiding predation or other threats. Globally, landscape alterations have resulted in declines to migratory populations across taxa. Given the long time periods over which migrations evolved in native systems, it is unlikely that restored populations embody the same migratory complexity that existed before population reductions or regional extirpation.We used GPS location data collected from 209 female bighorn sheep (Ovis canadensis) to characterize population and individual migration patterns along elevation and geographic continuums for 18 populations of bighorn sheep with different management histories (i.e., restored, augmented, and native) across the western United States.Individuals with resident behaviors were present in all management histories. Elevational migrations were the most common population‐level migratory behavior. There were notable differences in the degree of individual variation within a population across the three management histories. Relative to native populations, restored and augmented populations had less variation among individuals with respect to elevation and geographic migration distances. Differences in migratory behavior were most pronounced for geographic distances, where the majority of native populations had a range of variation that was 2–4 times greater than restored or augmented populations. Synthesis and applications. Migrations within native populations include a variety of patterns that translocation efforts have not been able to fully recreate within restored and augmented populations. Theoretical and empirical research has highlighted the benefits of migratory diversity in promoting resilience and population stability. Limited migratory diversity may serve as an additional factor limiting demographic performance and range expansion. We suggest preserving native systems with intact migratory portfolios and a more nuanced approach to restoration and augmentation in which source populations are identified based on a suite of criteria that includes matching migratory patterns of source populations with local landscape attributes.

Interobserver agreement of digital dermatitis M-scores for photographs of the hind feet of standing dairy cattle

Digital dermatitis (DD) is the leading infectious cause of lameness in dairy cattle, and it affects their welfare and productivity worldwide. At the herd level, DD is often assessed while cows are standing in a milking parlor, and lesions are most commonly evaluated using the M-score. The objective of this study was to examine the interobserver agreement for M-scores of the feet of standing cattle, based on digital color photographs of dairy cattle hind feet. A total of 88 photographs and written descriptors of the M-score were sent to 11 scorers working at 10 different institutions in 5 countries. The scorers received no formal training immediately before scoring the photographs; however, all regularly used the M-score to score DD. The answers for 36 photographs were excluded from the analysis because the photograph either had more than 1 M-stage as mode or not all scorers assigned an M-score to it. The M-scores of the 11 scorers from 52 photographs were available for analysis. Interobserver agreement was tested using Gwet's agreement coefficient (AC1) and the mode was assumed correct. Overall, moderate agreement emerged for the M-score (AC1 = 0.48). For the individual M-stages, almost perfect agreement existed for M0 (AC1 = 0.99), M1 (AC1 = 0.92), and M3 (AC1 = 0.82), and substantial agreement for M2 (AC1 = 0.61), M4 (AC1 = 0.65), and M4.1 (AC1 = 0.71). This outcome indicates the degree of individual variation in M-scoring in this context by unstandardized, experienced European observers, particularly for the M2, M4, and M4.1 stages. Standardized training is likely to improve the consistency of M-scoring and thus the generalizability of future DD research results on this important endemic disease.

Effect of oil palm (Elaeis guineensis Jacq.) plantations on individual-level diet variation of Hylaeamys megacephalus (G. Fisher 1814) (Rodentia, Cricetidae) in eastern Amazon Forest

Abstract: In this study we described the diet of Hylaeamys megacephalus (G. Fisher, 1814) and investigated the degree of individual variation in the diet of this species among the Amazon Forest and the oil palm plantation. We analyzed the stomach contents of 36 individuals, of whom 11 were collected in the forest and 25 captured in the palm oil palm plantation. The H. megacephalus diet consisted of 18 food items, of which 12 were animal composition and eight were vegetable composition. The niche amplitude of the species was narrower in the forest area (Baforest = 0.013) compared to the palm tree plantation area (Bapalm = 0.478). This shows that individuals have greater niche overlap in forest areas, while in the plantation areas the animals expand their food niche. In addition, the values of the mean of the individual diet in relation to the diet of the entire population were lower in the palm oil palm plantation environment (ISpalm = 0.164) than in the Forest environment (ISforest = 0.357), indicating a high specialization in the palm oil plantation. These results indicate a population mechanism to reduce intraspecific competition in response to scarce resources.

Drivers of individual niche variation in coexisting species.

Although neglected by classic niche theory, individual variation is now recognized as a prevalent phenomenon in nature with evolutionary and ecological relevance. Recent theory suggests that differences in individual variation across competitors can affect species coexistence and community patterns. However, the degree of individual variation is flexible across wild populations and we still know little about the ecological drivers of this variation across populations of single species and, especially, across coexisting species. Here, we aimed to (a) elucidate the major drivers of individual niche variation in natural communities and (b) to determine how consistent this variation is across coexisting species and communities. We analysed natural patterns of individual-level niche variation in four species of coexisting generalist frogs across a wide range of tropical communities. Specifically, we used gut contents and stable isotopes (δ13 C and δ15 N) from frog species and their prey to quantify individual niche specialization. Then, we combined data on local community structure, availability of prey, phylogenetic relationships and predator-prey size models to test how this variation is related to four ecological factors which are predicted to be key drivers of individual specialization: intraspecific competition, interspecific competition, ecological opportunity (i.e., diversity of resources) and predation. We found that the degree of individual trophic specialization varied by up to ninefold across populations within the same species. This sizable variation in trophic specialization across populations was at least partially explained by gradients of density of competitors (both conspecifics and heterospecifics) and intraguild predation. However, the specific relationships between individual specialization and these ecological gradients were strongly species-specific. As consequences, the identity of the species with more individual variation changed among sites and there was typically no spatial correlation in the degree of individual specialization across coexisting species. Our results show that individual niche specialization within and across species can be strongly context-dependent and that hierarchies of individual variation among coexisting species are not necessarily consistent across communities. Recent theory suggests that this pattern could lead to concurrent changes in competitive interactions across sites and thereby could play a key role in species coexistence at the landscape level. Our results suggest that individual variation across and within coexisting species has the potential to affect not only species coexistence at local communities, but also regional diversity patterns.

Spectral patterns of the American English diphthong /aɪ/ as a function of coda voicing produced by native Korean speakers

This study aimed to investigate how native speakers of Korean who learned English as a second language realize spectral differences in the American English diphthong /ai/ as a function of coda voicing. Ten Korean learners of English and eight native speakers of American English participated in a production experiment. The monosyllabic words “bite” (/bait/) and “bide” (/baid/) were read along with filler words in isolation and in a carrier sentence. The native group demonstrated significantly smaller F1 and larger F2 before /t/ than /d/ both in the nucleus /a/ and in the offglide /i/ (Moreton 2004). The learner group did not show statistically significant spectral changes in the nucleus and the offglide. Also, the native group significantly reduced the temporal distance between the nucleus and the offglide, and showed spectral peripheralization in the offglide before /t/ than /d/ (Pycha and Dahan 2016). However, the learner group did not show native-like reduction of the temporal distance between the nucleus and the offglide and spectral peripheralization in the offglide. Although the non-native speakers in this study exhibited some durational changes as a function of coda voicing, they did not learn the fine phonetic details regarding the gestural timing and spectral patterns in the diphthong. A considerable degree of individual variation in the learner group and speaking context effects were also found. It was interpreted that the Hyperarticulation hypothesis (Thomas 2000; Moreton 2004) and the Gestural Timing hypothesis (Pycha and Dahan 2016) could provide indices modelling the non-native phenomena found in this study as not attaining native-like phonetic values and gradual approach to the values concerning the spectral and durational aspects in /ai/ as a function of coda voicing. (Ewha Womans University)

The dimensionality of individual niche variation.

The inherently multidimensional nature of the niche has not yet been integrated into the investigation of individual niche specialization within populations. We propose a framework for modeling the between- and within-individual components of the population niche as a set of variance-covariance matrices, which can be visualized with ellipses or ellipsoids. These niche components can be inferred using multiple response mixed models, and can incorporate diverse types of data, including diet composition, stable isotopes, spatial location, and other continuous measures of niche dimensions. We outline how considering both individual and population niches in multiple dimensions may enhance our understanding of key concepts in ecology and evolution. Considering multiple dimensions as well as the within-individual component of variation can lead to more meaningful measures of niche overlap between species. The impact of a population on its food web or ecosystem can depend on the degree of individual variation (via Jensen's inequality), and we suggest how the dimensionality of individual specialization could amplify this effect. Finally, we draw from concepts in quantitative genetics and the study of animal personalities to propose new hypotheses about the ecological and evolutionary basis of niche shifts in multiple dimensions. We illustrate key ideas using empirical data from sea otters, wetland frogs, and threespine stickleback, and discuss outstanding questions about the consequences of multidimensional niche variation. Setting variation among individuals in an explicitly multivariate framework has the potential to transform our understanding of a range of ecological and evolutionary processes.

Introduction to Symposium: The Developmental and Proximate Mechanisms Causing Individual Variation in Cooperative Behavior.

Nearly all animals interact with members of their own species at some point during their lives. These behavioral interactions range from courtship, mating, and parental care to the complex cooperative behavior among related or unrelated individuals in group-living species. A number of theoretical models have attempted to explain how cooperation can evolve through natural selection. Although tremendously influential in animal behavior research, these traditional models have largely ignored individual variation in cooperative behavior and its underlying developmental and proximate mechanisms. However, a set of emerging models suggest that the evolution of cooperation can be heavily influenced by the degree of individual variation in cooperative behavior, as well as the complexity of the underlying mechanisms. Yet, while theoreticians argue the importance of studying individual variation in cooperation and the mechanisms underlying it, empiricists have not focused upon these aspects. The main objectives of our symposium at the 2017 meeting of the Society for Integrative and Comparative Biology is to establish new research avenues to study variation in cooperative behavior using both proximate and ultimate explanations and to produce a road map to study the developmental and proximate mechanisms in generating individual variation in cooperative behavior. This symposium brought together empiricists and theoreticians investigating cooperative behavior in diverse taxa and across multiple levels of analysis. Here we briefly describe the rationale for this symposium and why we thought it was needed as well as provide a brief overview of the contributions.

Interactions between three phonological subsystems of young multilinguals: the influence of language status

ABSTRACTThis study examines the interactions between three vocalic subsystems of multilingual speakers and explores the role language status might play in explaining variability across them. Eight 14-year-olds raised in Germany, who had learnt English at school for 6 years and Polish for 1 year, participated in the study. They were divided into three groups: children of German parents, children with one Polish-speaking parent but with German as the main home language, and children with two Polish-speaking parents and Polish as their main home language. The young multilinguals read a word list and performed a delayed repetition task in all their languages, with both tasks containing tokens of /i, ɪ, u, ʊ, ϵ, æ/. The results show a great degree of individual variability in the production of the vowels in all three languages and point to language status as one factor shaping the phonological subsystems of these multilinguals. The findings are interpreted within the framework of the Dynamic Systems Theory.

Trajectories of health-related quality of life during the natural history of dementia: a six-wave longitudinal study.

The objective of this study was to explore profiles of quality of life (QoL) trajectories during the natural history of dementia and individual variations contributing to QoL trajectories. We conducted a longitudinal community-based study of 520 elderly people with mild cognitive impairment and 100 healthy people aged 60 years or over. We conducted six waves of assessment between October 2010 and May 2013 in Taiyuan, mainland China. Cognitively normal, mild cognitive impairment, global impairment, and Alzheimer's disease (AD) were defined as state 1, 2, 3, and 4, respectively. We assessed health-related QoL (HRQoL) via the Quality of Life-Alzheimer's Disease (QoL-AD) Chinese version. We used the latent growth curve model (LGCM) to investigate change in HRQoL over time. Latent growth curve model analysis revealed a mean initial QoL level of 29.865 with substantial variation and a significant mean slope for the whole sample. Multigroup LGCM showed substantial variations across individuals in initial QoL levels for each cognitive state transition group. For the slope factor, we found significant changes and variations for the transition from state 2 to 3 and from state 3 to 4. We estimated mean QoL levels over six assessments based on intercept, slope, and factor loadings for the whole sample and the three cognitive state transition groups. A decline in subjective QoL is not inevitable during the natural history of dementia in community settings, and there is a degree of individual variation in QoL. Future studies should investigate the factors associated with individual variations in QoL trajectories in AD.

What do patients with epilepsy tell us about language dynamics? A review of fMRI studies.

The objective of this review is to resume major neuroimaging findings on language organization and plasticity in patients with focal and refractory epilepsy, to discuss the effect of modulatory variables that should be considered alongside patterns of reorganization, and to propose possible models of language reorganization. The focal and refractory epilepsy provides a real opportunity to investigate various types of language reorganization in different conditions. The 'chronic' condition (induced by the epileptogenic zone or EZ) is associated with either recruitment of homologous regions of the opposite hemisphere or recruitment of intrahemispheric, nonlinguistic regions. In the 'acute' condition (neurosurgery and EZ resection), the initial interhemispheric shift (induced by the chronic EZ) could follow a reverse direction, back to the initial hemisphere. These different patterns depend on several modulatory factors and are associated with various levels of language performance. As a neuroimaging tool, functional magnetic resonance imaging enables the detailed investigation of both hemispheres simultaneously and allows for comparison with healthy controls, potentially creating a more comprehensive and more realistic picture of brain-language relations. Importantly, functional neuroimaging approaches demonstrate a good degree of concordance on a theoretical level, but also a considerable degree of individual variability, attesting to the clinical importance with these methods to establish, empirically, language localization in individual patients. Overall, the unique features of epilepsy, combined with ongoing advances in technology, promise further improvement in understanding of language substrate.

How do modelled gestures influence preschool children’s spontaneous gesture production?

Around the age of nine months, children start to communicate by using first words and gestures, during interactions with caregivers. The question remains as to how older preschool children utilise the gestures they observe into their own gestural representations of previously unseen objects. Two accounts of gesture production (the ‘gesture learning’, and ‘simulated representation’ accounts) offer different predictions for how preschool children use the gestures they observe when describing objects. To test these two competing accounts underlying gesture production, we showed 42 children (mean age: 45 months 14 days) four novel objects using speech only, or speech accompanied by either movement or physical feature gestures. Analyses revealed that (a) overall symbolic gesture production showed a high degree of individual variability, and (b) distinct observed gesture types influenced the children’s subsequent gesture use. Specifically, it was found that children preferred to match movement gestures in a subsequent communicative interaction including the same objects, but not physical feature gestures. We conclude that the observation of gestures (in particular gestures that depict movement) may act to change preschool children’s object representations, which in turn influences how they depict objects in space.

Osteometric study of the Rasquera White goat

An osteometric study was carried out on the skulls of 70 adult female goats belonging to the Rasquera White (Blanca de Rasquera) breed. A total of 38 linear measurements and 11 indices or ratios were analysed. This study provided a statistical insight into skull measurements (neuro- and viscerocranium) for this breed using the bivariate and principal components (PC) techniques. The first two PCs provide a good quantitative approach to their study. A selection of the most relevant measurements was established based on variation, allowing the number of variables to be reduced from 38 to 4. The breed exhibited a fairly low degree of individual variation, but no significant clustering was observed in any of the plots. Evaluation of all quantitative data may also be useful for comparison with other present-day and extinct goat breeds. It is recommended to use a uniform craniometric evaluation system for the assessment of all goat breeds.

Cognitive Ability is Associated with Altered Medial Frontal Cortical Circuits in the LgDel Mouse Model of 22q11.2DS

We established a relationship between cognitive deficits and cortical circuits in the LgDel model of 22q11 Deletion Syndrome (22q11DS)-a genetic syndrome with one of the most significant risks for schizophrenia and autism. In the LgDel mouse, optimal acquisition, execution, and reversal of a visually guided discrimination task, comparable to executive function tasks in primates including humans, are compromised; however, there is significant individual variation in degree of impairment. The task relies critically on the integrity of circuits in medial anterior frontal cortical regions. Accordingly, we analyzed neuronal changes that reflect previously defined 22q11DS-related alterations of cortical development in the medial anterior frontal cortex of the behaviorally characterized LgDel mice. Interneuron placement, synapse distribution, and projection neuron frequency are altered in this region. The magnitude of one of these changes, layer 2/3 projection neuron frequency, is a robust predictor of behavioral performance: it is substantially and selectively lower in animals with the most significant behavioral deficits. These results parallel correlations of volume reduction and altered connectivity in comparable cortical regions with diminished executive function in 22q11DS patients. Apparently, 22q11 deletion alters behaviorally relevant circuits in a distinct cortical region that are essential for cognitive function.

Trajectories of quality of life in early‐stage dementia: individual variations and predictors of change

Little evidence is available about how quality of life (QoL) changes as dementia progresses. We explored QoL trajectories over a 20-month period and examined what predicted change in QoL. Fifty-one individuals with a diagnosis of Alzheimer's, vascular or mixed dementia (people with dementia (PwD)) participating in the Memory Impairment and Dementia Awareness Study rated their QoL using the QoL-Alzheimer's Disease Scale at baseline and at 20-month follow-up. PwD also rated their mood and quality of relationship with the carer. In each case, the carer rated his or her level of stress and perceived quality of relationship with the PwD. There was no change in mean QoL score. Nearly one-third of PwD rated QoL more positively at 20-month follow-up and nearly one-third rated QoL more negatively. These changes could be regarded as reliable in one-quarter of the sample. Participants taking acetylcholinesterase-inhibiting medication at baseline were more likely to show a decline in QoL score. There were no other significant differences between those whose scores increased, decreased or stayed the same on any demographic or disease-related variables, or in mood or perceived quality of relationship with the carer. Whereas baseline QoL score was the strongest predictor of QoL at 20 months, the quality of relationship with the carer as perceived by the PwD was also independently a significant predictor. There is a degree of individual variation in QoL trajectories. Use of acetylcholinesterase-inhibiting medication appears linked to decline in QoL score, whereas positive relationships with carers play an important role in maintaining QoL in early-stage dementia.

Endostructural characterization of the H. heidelbergensis dental remains from the early Middle Pleistocene site of Tighenif, Algeria

The early Middle Pleistocene human fossil assemblage from Tighenif, Algeria, likely samples some among the earliest representatives of the Homo heidelbergensis morph. A previous study of three deciduous molars from this assemblage revealed an inner structural signature (crown tissue proportions and enamel thickness topography) roughly approximating the modern human figures. By using advanced techniques of microtomographic-based 3D virtual imaging and quantitative analysis, we significantly extend here the currently available record to 22 permanent teeth, mostly from the mandibular dentition, and provide the first detailed description of the structural condition characterizing this North African deme near the Lower-Middle Pleistocene boundary. Together with a certain degree of individual variation, the teeth of Tighenif exhibit a structural pattern combining primitive, derived, and unique features. The lower molars display a set of enamel-dentine junction nonmetric traits more frequently found in recent humans than in Neanderthals, but also a blend of Neanderthal- and modern-like characteristics in terms of structural conformation and crown tissue proportions. They also exhibit relatively large pulp cavities, with a rather high root bifurcation and well-separated pulp canals, a pattern more closely approximating the condition reported for Late Pleistocene Aterians.