Six for the price of one: From a single precursor, dehydroalanine, six distinct post‐translational modifications can be site‐selectively installed on histone proteins (see figure), including the ...first site‐selective phosphorylation and glycosylation of histones. Direct observation of histone deacetylase activity on a full‐length modified histone as well as its interactions with both chromatin reader and writer/eraser proteins are reported.
Cognitive aging researchers have long reported "paradoxical" age differences in prospective memory (PM), with age deficits in laboratory settings and age benefits (or no deficits) in real-world ...settings. We propose a theoretical account that explains this "age-PM-paradox" as a consequence of both methodological factors and developmental changes in cognitive abilities and personality traits. To test this account, young and older adults performed a series of naturalistic PM tasks in the lab and real world. Age-related PM deficits were observed in both lab-based tasks where demands were implemented using virtual reality and in-person role-playing. In contrast, older adults performed equal to or better than young adults on both real-world tasks, where demands were implemented in participants' daily lives. Consistent with our proposed account, an index of these "paradoxical" effects was partially predicted by age-related differences in working memory, vigilance, agreeableness, and neuroticism, whose predictive utility varied across task settings.
Prospective memory (PM), the ability to execute delayed intentions, has received increasing attention in neuropsychology and gerontology. Most of this research is motivated by the claim that PM is ...critical for maintaining functional independence; yet, there is a dearth of empirical evidence to back up the claims. Thus, the present study tested whether PM predicts functional independence in older adults using validated behavioral performance measures for both PM and functional independence.
Fifty-eight healthy older adults performed a computerized PM paradigm, the Virtual Week task, as well as a timed version of an instrumental activities of daily living (TIADL) task. Furthermore, we assessed vocabulary, processing speed, and self-reported prospective remembering.
TIADL scores correlated significantly with performance in the Virtual Week task, vocabulary, and processing speed. Hierarchical linear regressions revealed that vocabulary and Virtual Week performance were significant predictors for TIADL. However, self-reported PM scores did not predict everyday functioning.
The findings indicate that PM is an important cognitive ability for successful and independent everyday life beyond vocabulary. Moreover, the results show a substantial incremental contribution of intact PM performance for the prediction of everyday functioning by using objective PM measures. (JINS, 2018, 24, 640-645).
We examined the effects of retrieval practice for students who varied in working memory capacity as a function of the lag between study of material and its initial test, whether or not feedback was ...given after the test, and the retention interval of the final test. We sought to determine whether a blend of these conditions exists that maximises benefits from retrieval practice for lower and higher working memory capacity students. College students learned general knowledge facts and then restudied the facts or were tested on them (with or without feedback) at lags of 0-9 intervening items. Final cued recall performance was better for tested items than for restudied items after both 10 minutes and 2 days, particularly for longer study-test lags. Furthermore, on the 2-day delayed test the benefits from retrieval practice with feedback were significantly greater for students with lower working memory capacity than for students with higher working memory capacity (r = −.42). Retrieval practice may be an especially effective learning strategy for lower ability students.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Maternal mortality was the subject of the United Nations' fifth Millennium Development Goal which was to reduce the maternal mortality ratio by three quarters from 1990 to 2015. The Sustainable ...Development Goals (SDGs), target 3.1 requires participating countries to reduce their maternal mortality ratio to less than 70 deaths per 100,000 live births by 2030. Although much research has been conducted, knowing the spatial patterns and risk factors associated with maternal mortality in developing countries helps target scarce resources and intervention programmes to high risk areas for the greatest impact.
Data were analysed from a longitudinal open cohort of women aged 15 to 49 years, enrolled from 2006 to 2010. An inverse distance weighted method of interpolation was used to assess spatial patterns of maternal mortality. Cox proportional hazards regression analysis was used to identify risk factors associated with maternal mortality.
The overall maternal mortality rate for the 36 792 study participants for the five years was 0.79 per 1000 person years. The trend declined from 90.42 in 2006 to 57.42 in 2010. Marked geographical differences were observed in maternal mortality patterns. The main causes of maternal death were eclampsia (23%), haemorrhage (22%) and abortion-related complications (10%). There was a reduced risk of 82% (HR = 0.18, 95% CI:0.05-0.74) and 78% (HR = 0.22, 95% CI:0.05-0.92) for women aged 20-29 and 30-39 years, respectively, compared with those younger than 20 years. While being married had a protective effect of 94% (HR = 0.06, 95% CI: 0.01-0.51) compared with being single, women who were widowed had an increased risk of maternal death of 913% (HR = 9.13, 95% CI: 1.02-81.94). Women who belong to poorer, poor and least poor socioeconomic quintile had 84%, 71% and 72% reduction in risk of maternal mortality respectively compared to those in the poorest category (HR = 0.16, 95% CI: 0.06-0.42; HR = 0.29, 95% CI: 0.12-0.69; HR = 0.28, 95% CI: 0.10-0.80).
Maternal mortality has declined in rural southern Tanzania since 2006, with geographical differences in patterns of death. Eclampsia, haemorrhage and abortion-related complications are the three leading causes of maternal death in the region, with risk factors being younger than 20 years, being single or widowed, and having a low socioeconomic status.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Polycomb group (PcG) proteins function as chromatin-based transcriptional repressors that are essential for normal gene regulation during development. However, how these systems function to achieve ...transcriptional regulation remains very poorly understood. Here, we discover that the histone H2AK119 E3 ubiquitin ligase activity of Polycomb repressive complex 1 (PRC1) is defined by the composition of its catalytic subunits and is highly regulated by RYBP/YAF2-dependent stimulation. In mouse embryonic stem cells, RYBP plays a central role in shaping H2AK119 mono-ubiquitylation at PcG targets and underpins an activity-based communication between PRC1 and Polycomb repressive complex 2 (PRC2) which is required for normal histone H3 lysine 27 trimethylation (H3K27me3). Without normal histone modification-dependent communication between PRC1 and PRC2, repressive Polycomb chromatin domains can erode, rendering target genes susceptible to inappropriate gene expression signals. This suggests that activity-based communication and histone modification-dependent thresholds create a localized form of epigenetic memory required for normal PcG chromatin domain function in gene regulation.
Nϵ-Methylations of histone lysine residues play critical roles in cell biology by “marking” chromatin for transcriptional activation or repression. Lysine demethylases reverse Nϵ-methylation in a ...sequence- and methylation-selective manner. The determinants of sequence selectivity for histone demethylases have been unclear. The human JMJD2 (KDM4) H3K9 and H3K36 demethylases can be divided into members that act on both H3K9 and H3K36 and H3K9 alone. Kinetic, crystallographic, and mutagenetic studies in vitro and in cells on KDM4A–E reveal that selectivity is determined by multiple interactions within the catalytic domain but outside the active site. Structurally informed phylogenetic analyses reveal that KDM4A–C orthologues exist in all genome-sequenced vertebrates with earlier animals containing only a single KDM4 enzyme. KDM4D orthologues only exist in eutherians (placental mammals) where they are conserved, including proposed substrate sequence-determining residues. The results will be useful for the identification of inhibitors for specific histone demethylases.
Background: Lysine demethylases reverse Nϵ-methylation in a sequence- and methylation-selective manner.
Results: Enzyme-histone interactions away from the conserved oxygenase active site are important in determining sequence selectivity in the JMJD2 (KDM4) subfamily.
Conclusion: The catalytic JmjC domain determines sequence selectivity for at least some JmjC demethylases.
Significance: This work might be a basis for the development of selective inhibitors.
Prospective memory (PM) - the ability to remember and successfully execute our intentions and planned activities - is critical for functional independence and declines with age, yet few studies have ...attempted to train PM in older adults. We developed a PM training program using the Virtual Week computer game. Trained participants played the game in 12, 1-h sessions over 1 month. Measures of neuropsychological functions, lab-based PM, event-related potentials (ERPs) during performance on a lab-based PM task, instrumental activities of daily living, and real-world PM were assessed before and after training. Performance was compared to both no-contact and active (music training) control groups. PM on the Virtual Week game dramatically improved following training relative to controls, suggesting PM plasticity is preserved in older adults. Relative to control participants, training did not produce reliable transfer to laboratory-based tasks, but was associated with a reduction of an ERP component (sustained negativity over occipito-parietal cortex) associated with processing PM cues, indicative of more automatic PM retrieval. Most importantly, training produced far transfer to real-world outcomes including improvements in performance on real-world PM and activities of daily living. Real-world gains were not observed in either control group. Our findings demonstrate that short-term training with the Virtual Week game produces cognitive and neural plasticity that may result in real-world benefits to supporting functional independence in older adulthood.
Young adolescents and unmarried women in low and middle income countries face challenges in accessing family planning services. One factor likely to limit contraceptive use is the attitude and ...opinion of local stakeholders such as community leaders and health workers. Much of the existing evidence on this topic focuses on women who have already started childbearing. Using primary qualitative data, we explored individual, community and health provider's perceptions about using modern contraceptives to delay the first birth in a high fertility setting.
A descriptive qualitative study was conducted in Tandahimba district in southern Tanzania between December 2014 and March 2015. We conducted 8 focus group discussions with men and women and 25 in-depth interviews (18 with women, 4 with family planning service providers and 3 with district-level staff). Participants were purposively sampled. Data transcripts were managed and coded using Nvivo 11 software and we employed a thematic framework analysis.
Three main themes emerged about using modern contraceptives to delay first birth: (1) the social and biological status of the woman (2) the type of contraceptive and (3) non-alignment among national policies for adolescents. Use of modern contraceptives to delay first birth was widely acceptable for women who were students, young, unmarried and women in unstable marriage. But long-acting reversible methods such as implants and intrauterine devices were perceived as inappropriate methods for delaying first birth, partly because of fears around delayed return to fecundity, discontinuation once woman's marital status changes and permanently limiting future fertility. The support for use of modern contraceptives to delay a first pregnancy was not unanimous. A small number of participants from both rural and urban areas did not approve the use of contraceptive methods before the birth of a first baby at all, not even for students. There was lack of clarity and consistency on the definition of 'young' and that had direct implications for access, autonomy in decision-making, confidentiality and consent for young people.
Women who wish to delay their first birth face challenges related to restrictions by age and method imposed by stakeholders in accessing and provision of modern contraceptives. There is a need for a clearly communicated policy on minimum age and appropriate method choice for delayers of first birth.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Previous studies have reported and validated equations for calculating the lean angle required for a motorcycle and rider to traverse a curved path at a particular speed. In 2015, Carter, Rose, and ...Pentecost reported physical testing with motorcycles traversing curved paths on an oval track on a pre-marked range in a relatively level parking lot. Several trends emerged in this study. First, while theoretical lean angle equations prescribe a single lean angle for a given lateral acceleration, there was considerable scatter in the real-world lean angles employed by motorcyclists for any given lateral acceleration level. Second, the actual lean angle was nearly always greater than the theoretical lean angle.
This prior study was limited in that it only examined the motorcycle lean angle at the apex of the curves. The research reported here extends the previous study by examining the accuracy of the lean angle formulas throughout the curves. The degree to which these equations can be used to model the development of lean as the rider enters a curve is evaluated. The prior study was also limited in that it only examined maneuvers on an oval track in a flat parking lot. The current study examines the accuracy of the theoretical lean angle formulas on a mountainous highway with curves of varying radius and changing banking and slope. The real-world data presented in this study are also utilized in conjunction with the lean angle formula to examine the interplay between the geometry of a curve, the motorcycle speed, and the rider’s skill level.
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