Integration of the hand in postural reactions to sustained sideways force at the pelvis

 In order to investigate the potential hand contribution to sideways balance, sideways pushes to the right, which subjects resisted using either the lower limbs (”hip only”) or the lower limbs assisted by the right upper limb (”hand and hip”), were delivered to the pelvis. Analysis of force and electromyogram recordings from the legs, arm and hand in the hand-and-hip condition showed a close co-ordination of upper and lower limbs in terms of mean latencies and amplitudes. However, trial to trial fluctuations of forces generated by the hand and leg did not correlate, suggesting parallel pathways under central co-ordinative control. Received: 6 August 1998 / Accepted: 11 December 1998     

Bifidobacterium animalis subsp. lactis BB-12 Protects against Antibiotic-Induced Functional and Compositional Changes in Human Fecal Microbiome

The administration of broad-spectrum antibiotics is often associated with antibiotic-associated diarrhea (AAD), and impacts gastrointestinal tract homeostasis, as evidenced by the following: (a) an overall reduction in both the numbers and diversity of the gut microbiota, and (b) decreased short-chain fatty acid (SCFA) production. Evidence in humans that probiotics may enhance the recovery of microbiota populations after antibiotic treatment is equivocal, and few studies have addressed if probiotics improve the recovery of microbial metabolic function. Our aim was to determine if Bifidobacterium animalis subsp. lactis BB-12 (BB-12)-containing yogurt could protect against antibiotic-induced fecal SCFA and microbiota composition disruptions. We conducted a randomized, allocation-concealed, controlled trial of amoxicillin/clavulanate administration (days 1–7), in conjunction with either BB-12-containing or control yogurt (days 1–14). We measured the fecal levels of SCFAs and bacterial composition at baseline and days 7, 14, 21, and 30. Forty-two participants were randomly assigned to the BB-12 group, and 20 participants to the control group. Antibiotic treatment suppressed the fecal acetate levels in both the control and probiotic groups. Following the cessation of antibiotics, the fecal acetate levels in the probiotic group increased over the remainder of the study and returned to the baseline levels on day 30 (−1.6% baseline), whereas, in the control group, the acetate levels remained suppressed. Further, antibiotic treatment reduced the Shannon diversity of the gut microbiota, for all the study participants at day 7. The magnitude of this change was larger and more sustained in the control group compared to the probiotic group, which is consistent with the hypothesis that BB-12 enhanced microbiota recovery. There were no significant baseline clinical differences between the two groups. Concurrent administration of amoxicillin/clavulanate and BB-12 yogurt, to healthy subjects, was associated with a significantly smaller decrease in the fecal SCFA levels and a more stable taxonomic profile of the microbiota over time than the control group.     

Inequality of opportunities in health in France: a first pass

This article analyses the role played by childhood circumstances, especially social and family background in explaining health status among older adults. We explore the hypothesis of an intergenerational transmission of health inequalities using the French part of SHARE. As the impact of both social background and parents' health on health status in adulthood represents circumstances independent of individual responsibility, this study allows us testing the existence in France of inequalities of opportunity in health related to family and social background. Empirically, our study relies on tests of stochastic dominance at first order and multivariate regressions, supplemented by a counterfactual analysis to evaluate the long‐lasting impact of childhood conditions on inequality in health. Allocating the best circumstances in both parents' socioeconomic status and parents' health reduces inequality in health by an impressive 57% using the Gini coefficient. The mother's social status has a direct effect on the health of her offspring. By contrast, the effect on descendant's health from their father's social status is indirect only, which goes through the descendant's social status as an adult. There is also a strong effect of the father vital status on health in adulthood, revealing a selection effect. Copyright © 2009 John Wiley & Sons, Ltd.     

Graph‐theoretical analysis of EEG functional connectivity during balance perturbation in traumatic brain injury: A pilot study

Traumatic brain injury (TBI) often results in balance impairment, increasing the risk of falls, and the chances of further injuries. However, the underlying neural mechanisms of postural control after TBI are not well understood. To this end, we conducted a pilot study to explore the neural mechanisms of unpredictable balance perturbations in 17 chronic TBI participants and 15 matched healthy controls (HC) using the EEG, MRI, and diffusion tensor imaging (DTI) data. As quantitative measures of the functional integration and segregation of the brain networks during the postural task, we computed the global graph‐theoretic network measures (global efficiency and modularity) of brain functional connectivity derived from source‐space EEG in different frequency bands. We observed that the TBI group showed a lower balance performance as measured by the center of pressure displacement during the task, and the Berg Balance Scale (BBS). They also showed reduced brain activation and connectivity during the balance task. Furthermore, the decrease in brain network segregation in alpha‐band from baseline to task was smaller in TBI than HC. The DTI findings revealed widespread structural damage. In terms of the neural correlates, we observed a distinct role played by different frequency bands: theta‐band modularity during the task was negatively correlated with the BBS in the TBI group; lower beta‐band network connectivity was associated with the reduction in white matter structural integrity. Our future studies will focus on how postural training will modulate the functional brain networks in TBI.     

Functional and effective brain connectivity for discrimination between Alzheimer’s patients and healthy individuals: A study on resting state EEG rhythms

Objective

This exploratory study provided a proof of concept of a new procedure using multivariate electroencephalographic (EEG) topographic markers of cortical connectivity to discriminate normal elderly (Nold) and Alzheimer’s disease (AD) individuals.

TMS-evoked long-lasting artefacts: A new adaptive algorithm for EEG signal correction

Objective

During EEG the discharge of TMS generates a long-lasting decay artefact (DA) that makes the analysis of TMS-evoked potentials (TEPs) difficult. Our aim was twofold: (1) to describe how the DA affects the recorded EEG and (2) to develop a new adaptive detrend algorithm (ADA) able to correct the DA.

Community-level analysis of risk of vector-borne disease

Ecological community structure is particularly important in vector-borne zoonotic diseases with complex life cycles. Qualitative community model analysis may provide a meaningful alternative to standard population-based models of vector-borne disease. We built on recent mathematical developments in qualitative community modeling coupled with conventional biomathematical models of vector-borne disease transmission, to provide a procedure to analyze risk. Using this procedure, we can hypothesize changes in risk of vector-borne disease from disturbances, such as control measures, habitat alteration, or global warming. We demonstrate the application of this procedure to an oak forest community to predict the risk of Lyme disease. Our predictions of Lyme disease risk in an oak forest community confirm reports of positive associations between deer abundance and risk of disease and are consistent with published observations.     

On the estimation of the binomial probability in multistage clinical trials

Due to the optional sampling effect in a sequential design, the maximum likelihood estimator (MLE) following sequential tests is generally biased. In a typical two-stage design employed in a phase II clinical trial in cancer drug screening, a fixed number of patients are enrolled initially. The trial may be terminated for lack of clinical efficacy of treatment if the observed number of treatment responses after the first stage is too small. Otherwise, an additional fixed number of patients are enrolled to accumulate additional information on efficacy as well as on safety. There have been numerous suggestions for design of such two-stage studies. Here we establish that under the two-stage design the sufficient statistic, i.e. stopping stage and the number of treatment responses, for the parameter of the binomial distribution is also complete. Then, based on the Rao-Blackwell theorem, we derive the uniformly minimum variance unbiased estimator (UMVUE) as the conditional expectation of an unbiased estimator, which in this case is simply the maximum likelihood estimator based only on the first stage data, given the complete sufficient statistic. Our results generalize to a multistage design. We will illustrate features of the UMVUE based on two-stage phase II clinical trial design examples and present results of numerical studies on the properties of the UMVUE in comparison to the usual MLE.     

Stochastic model for non-standard case-cohort design

Application of case-cohort design to multi-state disease progression in epidemiological studies has been barely addressed. To estimate multi-state disease natural history, we proposed non-homogeneous exponential regression stochastic model to accommodate the data requiring a non-standard case-cohort design. We allowed transition rates to vary with time by modelling the time of transitions between two states with Weibull distribution. The exponential regression model was used to assess the effect of patient-specific covariates on multi-state disease progressions. This method was successfully applied to two epidemiological applications. The first application was to elucidate the effect of betel quids, smoking and alcohol on three-state disease progression, from normal, through leukoplakia and finally to oral cancer. The second application was to extend the three-state to a five-state model to estimate transition rates from normal to diminutive adenoma to small adenoma to large adenoma and finally to invasive carcinoma of the colon and rectum. Finally, an index for assessing the treatment efficacy for pre-cancerous lesion was developed by comparing transition probabilities derived from the proposed model with the probabilities of malignant transformation after a medical regime.