Individual risk factors for Mycoplasma hyopneumoniae infections in suckling pigs at the age of weaning.

BACKGROUND In recent years, the occurrence and the relevance of Mycoplasma hyopneumoniae infections in suckling pigs has been examined in several studies. Whereas most of these studies were focused on sole prevalence estimation within different age groups, follow-up of infected piglets or assessment of pathological findings, none of the studies included a detailed analysis of individual and environmental risk factors. Therefore, the aim of the present study was to investigate the frequency of M. hyopneumoniae infections in suckling pigs of endemically infected herds and to identify individual risk factors potentially influencing the infection status of suckling pigs at the age of weaning. RESULTS The animal level prevalence of M. hyopneumoniae infections in suckling pigs examined in three conventional pig breeding herds was 3.6% (41/1127) at the time of weaning. A prevalence of 1.2% was found in the same pigs at the end of their nursery period. In a multivariable Poisson regression model it was found that incidence rate ratios (IRR) for suckling pigs are significantly lower than 1 when teeth grinding was conducted (IRR: 0.10). Moreover, high temperatures in the piglet nest during the first two weeks of life (occasionally >40°C) were associated with a decrease of the probability of an infection (IRR: 0.23-0.40). Contrary, the application of PCV2 vaccines to piglets was associated with an increased infection risk (IRR: 9.72). CONCLUSIONS Since single infected piglets are supposed to act as initiators for the transmission of this pathogen in nursery and fattening pigs, the elimination of the risk factors described in this study should help to reduce the incidence rate of M. hyopneumoniae infections and thereby might contribute to a reduced probability of high prevalences in older pigs.

Herd specific risk factors for Mycoplasma hyopneumoniae infections in suckling pigs at the age of weaning.

BACKGROUND Mycoplasma hyopneumoniae is the etiologic agent of enzootic pneumonia mainly occurring in fattening pigs. It is assumed that horizontal transmission of the pathogen during nursery and growing phase starts with few suckling pigs vertically infected by the sow. The aim of the present study was the exploration of the herd prevalence of M. hyopneumoniae infections in suckling pigs followed by an investigation of various herd specific factors for their potential of influencing the occurrence of this pathogen at the age of weaning. RESULTS In this cross-sectional study, 125 breeding herds were examined by taking nasal swabs from 20 suckling pigs in each herd. In total, 3.9% (98/2500) of all nasal swabs were tested positive for M. hyopneumoniae by real-time PCR. Piglets tested positive originated from 46 different herds resulting in an overall herd prevalence of 36.8% (46/125) for M. hyopneumoniae infection in pigs at the age of weaning. While the herds were epidemiologically characterized, the risk for demonstration of M. hyopneumoniae was significantly increased, when the number of purchased gilts per year was more than 120 (OR: 5.8), and when the number of farrowing pens per compartment was higher than 16 (OR: 3.3). In herds with a planned and segregated production, where groups of sows entered previously emptied farrowing units, the risk for demonstration of M. hyopneumoniae in piglets was higher in herds with two or four weeks between batches than in herds with one or three weeks between batches (OR: 2.7). CONCLUSIONS In this cross-sectional study, several risk factors could be identified enhancing the probability of breeding herds to raise suckling pigs already infected with M. hyopneumoniae at the time of weaning. Interestingly, some factors (farrowing rhythm, gilt acclimatisation issues) were overlapping with those also influencing the seroprevalences among sows or the transmission of the pathogen between older age groups. Taking the multifactorial character of enzootic pneumonia into account, the results of this study substantiate that a comprehensive herd specific prevention programme is a prerequisite to reduce transmission of and disease caused by M. hyopneumoniae.

Visuospatial working memory in very preterm and term born children - Impact of age and performance

Working memory is crucial for meeting the challenges of daily life and performing academic tasks, such as reading or arithmetic. Very preterm born children are at risk of low working memory capacity. The aim of this study was to examine the visuospatial working memory network of school-aged preterm children and to determine the effect of age and performance on the neural working memory network. Working memory was assessed in 41 very preterm born children and 36 term born controls (aged 7–12 years) using functional magnetic resonance imaging (fMRI) and neuropsychological assessment. While preterm children and controls showed equal working memory performance, preterm children showed less involvement of the right middle frontal gyrus, but higher fMRI activation in superior frontal regions than controls. The younger and low-performing preterm children presented an atypical working memory network whereas the older high-performing preterm children recruited a working memory network similar to the controls. Results suggest that younger and low-performing preterm children show signs of less neural efficiency in frontal brain areas. With increasing age and performance, compensational mechanisms seem to occur, so that in preterm children, the typical visuospatial working memory network is established by the age of 12 years.

Personality and Memory in Old Age

We examined the impact of personality on episodic memory performance in a sample of 287 healthy adults aged 68-95 years. Extraversion and neuroticism were assessed with a standardized personality inventory. Episodic memory was assessed with an everyday task. Results from regression analyses controlling for the effects of age, gender, and education show that higher extraversion and lower neuroticism are associated with higher episodic memory performance. In addition, the strength of the correlations between neuroticism and episodic memory declined with increasing age in a male sub-sample, revealing an interaction between age and neuroticism.

Does Age Matter? Semantic Memory in Healthy Young and Elderly Adults

Background: Semantic memory processes have been well described in literature. However, the available findings are mostly based on relatively young subjects and concrete word material (e.g. tree). Comparatively little information exists about semantic memory for abstract words (e.g. mind) and possible age related changes in semantic retrieval. In this respect, we developed a paradigm that is useful to investigate the implicit (i.e. attentionindependent) access to concrete and abstract semantic memory. These processes were then compared between young and elderly healthy subjects. Methods: A well established tool for investigating semantic memory processes is the semantic priming paradigm, which consists both of semantically unrelated and related word pairs. In our behavioral task these noun-noun word pairs were further divided into concrete, abstract and matched pronounceable non-word conditions. With this premise, the young and elderly participants performed a lexical decision task: they were asked to press a choice of two buttons as an indication for whether the word pair contained a non-word or not. In order to minimize controlled (i.e. attention-dependent) retrieval strategies, a short stimulus onset asynchrony (SOA) of 150ms was set. Reaction time (RT) changes and accuracy to related and unrelated words (priming effect) in the abstract vs. concrete condition (concreteness effect) were the dependent variables of interest. Results and Discussion: Statistical analysis confirmed both a significant priming effect (i.e. shorter RTs in semantically related compared to unrelated words) and a concreteness effect (i.e. RT decrease for concrete compared to abstract words) in the young and elderly subjects. There was no age difference in accuracy. The only age effect was a commonly known general slowing in RT over all conditions. In conclusion, age is not a critical factor in the implicit access to abstract and concrete semantic memory.

Relations among fluid intelligence, sensory discrimination and working memory in middle to late childhood – A latent variable approach

Two factors that have been suggested as key in explaining individual differences in fluid intelligence are working memory and sensory discrimination ability. A latent variable approach was used to explore the relative contributions of these two variables to individual differences in fluid intelligence in middle to late childhood. A sample of 263 children aged 7–12 years was examined. Correlational analyses showed that general discrimination ability (GDA)and working memory (WM) were related to each other and to fluid intelligence. Structural equation modeling showed that within both younger and older age groups and the sample as a whole, the relation between GDA and fluid intelligence could be accounted for by WM. While WM was able to predict variance in fluid intelligence above and beyond GDA, GDA was not able to explain significant amounts of variance in fluid intelligence, either in the whole sample or within the younger or older age group. We concluded that compared to GDA, WM should be considered the better predictor of individual differences in fluid intelligence in childhood. WM and fluid intelligence, while not being separable in middle childhood, develop at different rates, becoming more separable with age.

Factors affecting cognitive outcome in early pediatric stroke

OBJECTIVE We examined cognitive performance in children after stroke to study the influence of age at stroke, seizures, lesion characteristics, neurologic impairment (NI), and functional outcome on cognitive outcome. METHODS This was a prospectively designed study conducted in 99 children who sustained an arterial ischemic stroke (AIS) between the age of 1 month and 16 years. All children underwent cognitive and neurologic follow-up examination sessions 2 years after the insult. Cognitive development was assessed with age-appropriate instruments. RESULTS Although mean cognitive performance was in the lower normative range, we found poorer results in subtests measuring visuoconstructive skills, short-term memory, and processing speed. Risk factors for negative cognitive outcome were young age at stroke, seizures, combined lesion location (cortical and subcortical), as well as marked NI. CONCLUSIONS We recommend that all children with a history of AIS undergo regularly scheduled neuropsychological assessment to ensure implementation of appropriate interventions and environmental adjustments as early as possible.

Risk factors for depressed mood amongst a community dwelling older age population in England: cross-sectional survey data from the PRO-AGE study.

BACKGROUND The Quality and Outcomes Framework in the United Kingdom (UK) National Health Service previously highlighted case finding of depression amongst patients with diabetes or coronary heart disease. However, depression in older people remains under-recognized. Comprehensive data for analyses of the association of depression in older age with other health and functional measures, and demographic factors from community populations within England, are lacking. METHODS Secondary analyses of cross-sectional baseline survey data from the England arm of a randomised controlled trial of health risk appraisal for older people in Europe; PRO-AGE study. Data from 1085 community-dwelling non-disabled people aged 65 years or more from three group practices in suburban London contributed to this study. Depressed mood was ascertained from the 5-item Mental Health Inventory Screening test. Exploratory multivariable logistic regression was used to identify the strongest associations of depressed mood with a previous diagnosis of a specified physical/mental health condition, health and functional measures, and demographic factors. RESULTS Depressed mood occurred in 14% (155/1085) of participants. A previous diagnoses of depression (OR 3.39; P < 0.001) and poor vision as determined from a Visual Function Questionnaire (OR 2.37; P = 0.001) were amongst the strongest factors associated with depressed mood that were independent of functional impairment, other co-morbidities, and demographic factors. A subgroup analyses on those without a previous diagnosis of depression also indicated that within this group, poor vision (OR 2.51; P = 0.002) was amongst the strongest independent factors associated with depressed mood. CONCLUSIONS Previous case-finding strategies in primary care focussed on heart disease and diabetes but health-related conditions other than coronary heart disease and diabetes are also associated with an increased risk for depression. Complex issues of multi-morbidity occur within aging populations. 'Risk' factors that appeared stronger than those, such as, diabetes and coronary heart disease that until recently prompted for screening in the UK due to the QOF, were identified, and independent of other morbidities associated with depressed mood. From the health and functional factors investigated, amongst the strongest factors associated with depressed mood was poor vision. Consideration to case finding for depressed mood among older people with visual impairment might be justified.

Internal and external effects on cognition: Evidence from memory training in very preterm-born children and cognition in patients with carotid artery stenosis before and after treatment

The present synopsis aims to integrate one study about memory training in very preterm-born children and two studies about cognition in patients with carotid artery stenosis before and after treatments. Preterm-born children are at increased risk of cognitive deficits and behavioural problems compared with peers born at term. This thesis determined whether memory training would improve cognitive functions in school-age very preterm-born children. Memory strategy training produced significant improvements in trained and non-trained cognitive functions; a core working memory training revealed significant effects on short-term memory and working memory tasks. Six months after training, children in both training groups showed better working memory performance than children in the waiting control group. This is evidence that memory training – an external influence on cognition – induces plastic changes in very preterm-born children. Patients with carotid artery stenosis are known to be at increased risk of cognitive impairment. We showed that patients with symptomatic or asymptomatic carotid artery stenosis were at higher risk for cognitive deficits than expected in a normative sample. This thesis seeks to link cognitive plasticity to internal factors like carotid stenosis. An external factor, which influences blood flow to the brain is the nature of the carotid artery stenosis treatment. Research on the effects of carotid artery stenosis treatment on cognition has produced inconsistent results. We found significant improvement in frontal lobe functions, visual memory and motor speed one year after treatment independent of the treatment type (best medical treatment, carotid artery stenting, carotid artery endarterectomy); providing evidence for ‘treatment-induced’ cognitive plasticity. Baseline performance was negatively associated with improvement in various cognitive functions after training in very preterm-born children and after treatment in patients with carotid artery stenosis. The present synopsis aims to integrate these findings into the current and relevant literature, and discuss consequences as well as methodological considerations resulting from the studies constituting the thesis at hand.

Impact of oral contraceptives on weight, body composition, and cardiovascular disease risk factors in women age 18--30 years participating in a 15-week exercise program

Objective. To assess differences in body weight, body composition, total cholesterol, blood pressure, and blood glucose between OC users and non-users age 18-30 y before and after a 15-week cardiovascular exercise program in Houston, TX from 2003 to 2007.^ Study Design. Secondary analysis of prospective data. ^ Study Subjects. 453 Non-Hispanic white (NHW), Hispanic, and African American (AA) women age 18-30 y with no previous live birth, a history of menstruating, no use of other hormonal contraceptives or medications, no menopause or hysterectomy, and no current pregnancies.^ Measurements. Demographic data, medication use, and menstrual history were assessed via self-administered questionnaires at baseline. Anthropometric and laboratory measures were taken at baseline and 15-weeks. ^ Data Analysis. Linear regression assessed the association between OC use and study variables at baseline, and the change in study variables from baseline to 15-weeks. Logistic regression assessed the association between OC use and CVD risk. Each analysis was also stratified by race/ethnicity. ^ Results. At baseline, OC users had higher total cholesterol (p<.0005) and were above cholesterol risk cut points for CVD (OR=4.3, 95% CI=2.4-7.7) compared to non-users. At baseline, OC use was also associated with higher diastolic blood pressure (p=.018) compared to non-users, primarily in non-Hispanic whites (p=.007). OC use was associated with lower blood glucose compared to non-users in Hispanics only (p=.008). OC use was associated with absolute change in diastolic blood pressure (p=.044) and total cholesterol (p=.003). There was evidence that OC use may affect individuals differently based on race/ethnicity for certain obesity and CVD risk factors.^ Conclusions. OC users and non-users responded similarly to a 15-week cardiovascular exercise program. Exceptions included a greater change in diastolic blood pressure and total cholesterol among NHW and Hispanic OC users compared to non-users after exercise intervention. At baseline, OC use was associated with diastolic blood pressure and was most strongly associated with increased levels of total cholesterol. OC users were at greater risk of having total cholesterol above CVD risk cut points than non-users.^

Age-Related Effects in Working Memory Recognition Modulated by Retroactive Interference

One of the main causes for age-related declines in working memory is a higher vulnerability to retroactive interference due to a reduced ability to suppress irrelevant information. However, the underlying neural correlates remain to be established. Magnetoencephalography was used to investigate differential neural patterns in young and older adults performing an interference-based memory task with two experimental conditions, interrupting and distracting, during successful recognition. Behaviorally, both types of retroactive interference significantly impaired accuracy at recognition more in older adults than in young adults with the latter exhibiting greater disruptions by interrupters. Magnetoencephalography revealed the presence of differential age-related neural patterns. Specifically, time-modulated activations in temporo-occipital and superior parietal regions were higher in young adults compared with older adults for the interrupting condition. These results suggest that age-related deficits in inhibitory mechanisms that increase vulnerability to retroactive interference may be associated with neural under-recruitments in a high-interference task.

Memory systems analyses of mnemonic disorders in aging and age-related diseases

The effects upon memory of normal aging and two age-related neurodegenerative diseases, Alzheimer disease (AD) and Parkinson disease, are analyzed in terms of memory systems, specific neural networks that mediate specific mnemonic processes. An occipital memory system mediating implicit visual-perceptual memory appears to be unaffected by aging or AD. A frontal system that may mediate implicit conceptual memory is affected by AD but not by normal aging. Another frontal system that mediates aspects of working and strategic memory is affected by Parkinson disease and, to a lesser extent, by aging. The aging effect appears to occur during all ages of the adult life-span. Finally, a medial-temporal system that mediates declarative memory is affected by the late onset of AD. Studies of intact and impaired memory in age-related diseases suggest that normal aging has markedly different effects upon different memory systems.

Long-term functional recovery from age-induced spatial memory impairments by nerve growth factor gene transfer to the rat basal forebrain.

Nerve growth factor (NGF) stimulates functional recovery from cognitive impairments associated with aging, either when administered as a purified protein or by means of gene transfer to the basal forebrain. Because gene transfer procedures need to be tested in long-term experimental paradigms to assess their in vivo efficiency, we have used ex vivo experimental gene therapy to provide local delivery of NGF to the aged rat brain over a period of 2.5 months by transplanting immortalized central nervous system-derived neural stem cells genetically engineered to secrete NGF. By grafting them at two independent locations in the basal forebrain, medial septum and nucleus basalis magnocellularis, we show that functional recovery as assessed in the Morris water maze can be achieved by neurotrophic stimulation of any of these cholinergic cell groups. Moreover, the cholinergic neurons in the grafted regions showed a hypertrophic response resulting in a reversal of the age-associated atrophy seen in the learning-impaired aged control rats. Long-term expression of the transgene lead to an increased NGF tissue content (as determined by NGF-ELISA) in the transplanted regions up to at least 10 weeks after grafting. We conclude that the gene transfer procedure used here is efficient to provide the brain with a long-lasting local supply of exogenous NGF, induces long-term functional recovery of cognitive functions, and that independent trophic stimulation of the medial septum or nucleus basalis magnocellularis has similar consequences at the behavioral level.