Velocity measurement accuracy in optical microhemodynamics: experiment and simulation

Micro particle image velocimetry (μPIV) is a common method to assess flow behavior in blood microvessels in vitro as well as in vivo. The use of red blood cells (RBCs) as tracer particles, as generally considered in vivo, creates a large depth of correlation (DOC), even as large as the vessel itself, which decreases the accuracy of the method. The limitations of μPIV for blood flow measurements based on RBC tracking still have to be evaluated. In this study, in vitro and in silico models were used to understand the effect of the DOC on blood flow measurements using μPIV RBC tracer particles. We therefore employed a μPIV technique to assess blood flow in a 15?μm radius glass tube with a high-speed CMOS camera. The tube was perfused with a sample of 40% hematocrit blood. The flow measured by a cross-correlating speckle tracking technique was compared to the flow rate of the pump. In addition, a three-dimensional mechanical RBC-flow model was used to simulate optical moving speckle at 20% and 40% hematocrits, in 15 and 20?μm radius circular tubes, at different focus planes, flow rates and for various velocity profile shapes. The velocity profiles extracted from the simulated pictures were compared with good agreement with the corresponding velocity profiles implemented in the mechanical model. The flow rates from both the in vitro flow phantom and the mathematical model were accurately measured with less than 10% errors. Simulation results demonstrated that the hematocrit (paired t tests, p = 0.5) and the tube radius (p = 0.1) do not influence the precision of the measured flow rate, whereas the shape of the velocity profile (p < 0.001) and the location of the focus plane (p < 0.001) do, as indicated by measured errors ranging from 3% to 97%. In conclusion, the use of RBCs as tracer particles makes a large DOC and affects the image processing required to estimate the flow velocities. We found that the current μPIV method is acceptable to estimate the flow rate on the condition that the measurement takes place at the equatorial plane of the vessel. Otherwise, it is not an appropriate method to estimate the shape of the velocity profile.     

Dental diseases and loss of teeth in a group of Finnish alcoholics: a radiological study

A total of 85 Finnish alcohol-dependent subjects and 53 controls were studied with panoramic radiography. The aim was to study the possible associations between prolonged alcohol consumption and dental health. The mean number of teeth, caries lesions, endodontic treatments, periapical lesions, marginal bone loss, and periodontal infrabony pockets was studied. The subjects met the diagnostic criteria of alcohol dependence as set out in DSM-IV and ICD-10. The control group comprised social drinking volunteers with an AUDIT score &#104 8. For the final results the subjects were divided into groups on the basis of sex and age. The social backgrounds of the subjects were similar, except for employment and smoking. The results show significantly fewer teeth and more caries in the alcoholic group. There was a tendency for the alcoholics <45 years of age to have more endodontically treated teeth than the controls, but no difference in the number of periapical lesions in endodontically treated teeth was found. Horizontal bone loss and the presence of calculus were more frequent in alcoholic men than in alcoholic women. Significantly more horizontal bone loss was observed in the group of alcoholic nonsmokers than in nonalcoholic nonsmokers. In the nonsmoking groups alcoholics had significantly more periodontal destruction than the nonsmoking controls. We conclude that radiological dental health among individuals dependent on alcohol is weakened by more caries, more horizontal bone loss, and more numerous vertical infrabony pockets than social drinkers.     

Quality of Life in Rural and Urban Adults 65 Years and Older: Findings From the National Health and Nutrition Examination Survey

Purpose: The proportion of people over 65 years of age is higher in rural areas than in urban areas, and their numbers are expected to increase in the next decade. This study used Andersen's behavioral model to examine quality of life (QOL) in a nationally representative sample of community‐dwelling adults 65 years and older according to geographic location. Specifically, associations between 3 dimensions of QOL (health‐related QOL [HQOL], social functioning, and emotional well‐being) and needs and health behaviors were examined. Methods: The 2005‐2006 National Health and Nutrition Examination survey was linked with the 2007 Area Resources File via the National Center for Health Statistics’ remote access system. Frequencies and distribution patterns were assessed according to rural, adjacent, and urban locations. Findings: Older adults reported high levels of QOL; however, rural older adults had lower social functioning than their urban counterparts. Older blacks and Hispanics had lower scores than whites on 2 dimensions of QOL. Associations between QOL and needs and health behaviors varied. Although activities of daily living were associated with all 3 dimensions, others were associated with 1 or 2 dimensions. Conclusions: The lower scores on social functioning in rural areas suggest that rural older adults may be socially isolated. Older rural adults may need interventions to maintain physical and mental health, strengthen social relationships and support, and increase their participation in the community to promote QOL. In addition, older blacks and Hispanics seem more vulnerable than whites and may need more assistance.     

Towards a solution for performance related confounds: frontal, striatal and parietal activation during a continuous spatiotemporal working memory manipulation task

Working memory plays a role in various forms of psychopathology. However, working memory consists of multiple theoretical components that may be differently taxed by various specific types of task, and brain activation differences between patients and healthy controls may result from differences in task performance. This makes it difficult to interpret such results in terms of disease-related dysfunctions in affected regions or networks. The aim of the current study was to determine the brain activation related to the updating of spatiotemporal content of working memory, in such a way that performance-related confounds in future clinical studies would be minimized. Nineteen healthy volunteers performed a task involving a continuous updating process during fMRI measurement. A frontostriatal network including medial and lateral prefrontal cortex, inferior frontal cortex, premotor cortex, supplementary motor cortex, thalamus and putamen was found to be related to the updating process. The results constrain the set of brain regions plausibly related to the specific updating component of working memory. Further, the task design may be of use in future studies of pathological conditions such as schizophrenia due to the minimization of potential confounds.