Regular Time Intervals (regular + time_interval)

Distribution by Scientific Domains


Selected Abstracts


Dementia and depression among nursing home residents in Lebanon: a pilot study

INTERNATIONAL JOURNAL OF GERIATRIC PSYCHIATRY, Issue 4 2007
L. M. Chahine
Abstract Background The proportion of elderly in the Lebanese population is 7.1% and this is expected to increase to 10.2% by the year 2025. The nursing home (NH) population in Lebanon has not been studied. The aim of this study was to investigate the prevalence of dementia and depression among a portion of nursing home residents (NHR) in Lebanon and describe the characteristics of NHR afflicted with dementia and depression. Method Of 200 NHR from three NH in Lebanon, 117 were selected by random sampling. Data on demographics and medical history were collected. An Arabic version of the Mini-Mental Status Examination and Geriatric Depression Scale (GDS) were administered. Results Our final sample consisted of 102 NHR. Sixty-one (59.8%) had dementia of some kind. Seventeen (27.9%) had mild dementia, 14 (22.9%) had moderate dementia, and 30 (49.2%) had severe dementia. Forty-five (57.7%) of the NHR tested had depression as measured by a GDS score of more than 10. Conclusions Dementia and depression were present in more than half of the NHR in our sample. Our results have important implications, being the first to be collected in the Lebanese community. Screening NHR for dementia and depression on admission and at regular time intervals is a must. More studies targeting all aspects of the elderly population in Lebanon are needed. Copyright 2006 John Wiley & Sons, Ltd. [source]


Genetically Manipulated Human Skeletal Myoblast Cells for Cardiac Transplantation

JOURNAL OF CARDIAC SURGERY, Issue 6 2002
Kh H Haider
Aim: Considering the promise of skeletal myoblast cell transplantation to improve cardiac function in myocardial myopathies, we aim in the present study to investigate the potential of human skeletal myoblast cells (HSMC) as a carrier for therapeutic genes for the heart muscle. Methods: Skeletal muscle sample is obtained from rectus femoris of the donor and is processed in the tissue culture to generate HSMC by a patented process of Cell Therapy Inc. The HSMC are grown in large 225 mm2 tissue culture flasks coated with collagen for enhanced cell adherence, using patented Super Medium (Cell Therapy Inc., Singapore) containing 10% fetal calf serum, to 80% confluence. The HSMC are passaged at regular time intervals of 48-72 hours to prevent in vitro differentiation. The HSMC thus obtained are transduced three times with retroviral vector carrying Lac-Z reporter gene before transplantation. The Lac-Z transduced HSMC are harvested by trypsinization, washed and re-suspended in serum free Super Medium. Ischemic Porcine model is created by clamping ameroid ring around left circumflex coronary artery in Yorkshire swine, four weeks prior to cell transplantation. For cell transplantation, the animal is anaesthetized, ventilated and heart is exposed by left thoracotomy. Fifteen injections (0.25 ml each) containing 300 million cells are injected in to the left ventricle endocardially under direct vision. For control animal, only culture medium without cells is injected. The animal is euthanized at pre-determined time, heart is explanted and processed for histological examination. The cryosectioning of the tissue and subsequent staining for Lac-Z expression and Hematoxylin-Eosin staining is carried out by standard methods. Results: The skeletal muscle samples processed by the patented method of Cell Therapy yield 85-90% pure HSMC. The preliminary data shows that repeated transductions of myoblast cells with retrovirus carrying Lac-Z yield highly efficient 70-75% Lac-Z positive HSMC population (Figure 1). Dye exclusion test using Trypan blue reveals >95% cell viability at the time of injection. Gross sections of the cardiac tissue stained positive for Lac-Z expression (Figure 2). Histological examination showed the presence of grafted myoblast cells expressing Lac-Z gene in the cardiac tissue (Figure 3). Conclusion: In the light of our preliminary results, we conclude that HSMC may prove to be excellent carriers of transgene for cardiac muscle cells which otherwise are refractory to ordinary gene transfection methods. The use of HSMC mediated gene delivery to cardiac muscle is safer as compared to direct injection of viral vectors in to the heart muscle. Furthermore, the grafted myoblast cells will additionally serve to strengthen the weakened heart muscle. Figure 1.Human Skeletal myoblasts transduced with Lac-Z carrying retrovirus and stained with x-gal. Figure 2.Gross sections of heart muscle stained for Lac-Z expression. Figure 3.X-gal stained porcine heart muscle counter-stained with Eosin. The heart was explanted 6 weeks after transplantation of Lac-Z stained human myoblasts. The arrow shows Lac-Z expressing myoblast cells. [source]


Modified evolving window factor analysis for process monitoring

JOURNAL OF CHEMOMETRICS, Issue 9 2004
S. Kamaledin Setarehdan
Abstract Reaction process monitoring and control are usually involved with direct measurement or indirect model-based prediction of concentration profiles of the constituents of interest in a chemical reaction at regular time intervals. These approaches are expensive, time-consuming and sometimes impossible. On the other hand, application of so-called ,calibration-free' techniques such as EFA and EWFA to spectral data usually provides important information regarding the structural variations in the chemical system without identification of the chemical components responsible for the variations. In this paper a novel spectral data pre-processing algorithm is presented which helps EWFA to extract the concentration trends of the components of interest within the reaction. The proposed algorithm uses the pure spectrum of the component of interest to develop a so-called ,weighting filter' which is applied to the input spectral information before EWFA. The algorithm was applied to a real Raman spectral data set obtained from a pre-treatment distillation column used for removing unwanted heavy/cyclic hydrocarbons from naphtha in an oil company. Comparison of the concentration trends resulting from the proposed algorithm with those obtained using conventional PLS1 models shows that the new calibration-free and on-line algorithm outperforms the calibration models obtained by difficult and expensive laboratory work. Copyright 2005 John Wiley & Sons, Ltd. [source]


Analysis of video images from a gas,liquid transfer experiment: a comparison of PCA and PARAFAC for multivariate image analysis

JOURNAL OF CHEMOMETRICS, Issue 7 2003
Stephen P. Gurden
Abstract The use of chemical imaging is a developing area which has potential benefits for chemical systems where spatial distribution is important. Examples include processes in which homogeneity is critical, such as polymerizations, pharmaceutical powder blending and surface catalysis, and dynamic processes such as the study of diffusion rates or the transport of environmental pollutants. Whilst single images can be used to determine chemical distribution patterns at a given point in time, dynamic processes can be studied using a sequence of images measured at regular time intervals, i.e. a movie. Multivariate modeling of image data can help to provide insight into the important chemical factors present. However, many issues of how best to apply these models remain unclear, especially when the data arrays involved have four or five different dimensions (height, width, wavelength, time, experiment number, etc.). In this paper we describe the analysis of video images recorded during an experiment to investigate the uptake of CO2 across a free air,water interface. The use of PCA and PARAFAC for the analysis of both single images and movies is described and some differences and similarities are highlighted. Some other image transformation techniques, such as chemical mapping and histograms, are found to be useful both for pretreatment of the raw data and for dimensionality reduction of the data arrays prior to further modeling. Copyright 2003 John Wiley & Sons, Ltd. [source]


Opioid Receptor Subtypes Involved in the Regulation of Prolactin Secretion During Pregnancy and Lactation

JOURNAL OF NEUROENDOCRINOLOGY, Issue 3 2003
Z. B. Andrews
Abstract Afferent endogenous opioid neuronal systems facilitate prolactin secretion in a number of physiological conditions including pregnancy and lactation, by decreasing tuberoinfundibular dopamine (TIDA) inhibitory tone. The aim of this study was to investigate the opioid receptor subtypes involved in regulating TIDA neuronal activity and therefore facilitating prolactin secretion during early pregnancy, late pregnancy and lactation in rats. Selective opioid receptor antagonists nor-binaltorphimine (, -receptor antagonist, 15 g/5 l), beta funaltrexamine (, -receptor antagonist, 5 g/5 l) and naltrindole (, -receptor antagonist, 5 g/5 l) or saline were administered intracerebroventricularly (i.c.v.) on day 8 of pregnancy during a nocturnal prolactin surge, on day 21 of pregnancy during the ante partum prolactin surge or on day 7 of lactation before the onset of a suckling stimulus. Serial blood samples were collected at regular time intervals, via chronic indwelling jugular cannulae, before and after drug administration and plasma prolactin was determined by radioimmunoassay. TIDA neuronal activity was measured using the 3,4-dihydroxyphenylacetic acid (DOPAC) : dopamine ratio in the median eminence 2 h 30 min after i.c.v. drug injection. In each experimental condition, plasma prolactin was significantly inhibited by both , - and , -receptor antagonists, whereas the , -receptor antagonist had no effect compared to saline-injected controls. Similarly, nor-binaltorphimine and beta funaltrexamine significantly increased the median eminence DOPAC : dopamine ratio during early and late pregnancy, and lactation whereas naltrindole had no effect compared to saline-injected controls. These data suggest that TIDA neuronal activity, and subsequent prolactin secretion, is regulated by endogenous opioid peptides acting at both , - and , -opioid receptors during prolactin surges of early pregnancy, late pregnancy and lactation. [source]


Photodegradation study of a new activator of the cystic fibrosis chloride channel, the 6-hydroxy-10-chlorobenzo[c]quinolizinium chloride (MPB-07)

JOURNAL OF PHARMACEUTICAL SCIENCES, Issue 2 2002
Jean-Christophe Olivier
Abstract The photodegradation of 6-hydroxy-10-chlorobenzo[c]quinolizinium chloride (MPB-07), a new activator of the transmembrane conductance regulator chloride channel, was studied in aqueous solutions exposed to artificial daylight (2300 Lux intensity). Various conditions of pH, concentration, and temperature were used. MPB-07 concentration was determined at regular time intervals by reversed-phase HPLC. MPB-07 stability was also studied at pH 7.4 in the dark. Results showed that in all the conditions tested MPB-07 underwent rapid photodegradation, apparently following first-order kinetics. Rate constants were dependent on the initial MPB-07 concentration, temperature, and pH. At pH 7.4, and for concentrations from 1 to 125 ,M, half-lives ranged from 0.681,,0.047 to 4.54,,0.28 h. The Arrhenius plot was linear and activation energy was calculated to be 20.7 kJ,,mol,1. Analysis by chemical ionization-mass spectrometry showed that the chlorine atom of the MPB-07 molecule might be replaced by an OH group during the photodegradation process. In the dark, MPB-07 in solutions at pH 7.4 was found to be stable over a 6-week period. In conclusion, MPB-07 is a highly photolabile molecule that should be carefully protected from light when used. 2002 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 91:324,330, 2002 [source]


A segmentation-based approach for temporal analysis of software version repositories,

JOURNAL OF SOFTWARE MAINTENANCE AND EVOLUTION: RESEARCH AND PRACTICE, Issue 3 2008
Harvey Siy
Abstract Time series segmentation is a promising approach to discover temporal patterns from time-stamped numeric data. A novel approach to apply time series segmentation to discern temporal information from software version repositories is proposed. Data from such repositories, both numeric and non-numeric, are represented as item-set time series data. A dynamic programming algorithm for optimal segmentation is presented. The algorithm automatically produces a compacted item-set time series that can be analyzed to identify temporal patterns. The effectiveness of the approach is illustrated by analyzing version control repositories of several open-source projects to identify time-varying patterns of developer activity. The experimental results show that the segmentation algorithm produces segments that capture meaningful information and is superior to the information content obtained by arbitrarily segmenting software history into regular time intervals. Copyright 2008 John Wiley & Sons, Ltd. [source]


Statistical methods for regular monitoring data

JOURNAL OF THE ROYAL STATISTICAL SOCIETY: SERIES B (STATISTICAL METHODOLOGY), Issue 5 2005
Michael L. Stein
Summary., Meteorological and environmental data that are collected at regular time intervals on a fixed monitoring network can be usefully studied combining ideas from multiple time series and spatial statistics, particularly when there are little or no missing data. This work investigates methods for modelling such data and ways of approximating the associated likelihood functions. Models for processes on the sphere crossed with time are emphasized, especially models that are not fully symmetric in space,time. Two approaches to obtaining such models are described. The first is to consider a rotated version of fully symmetric models for which we have explicit expressions for the covariance function. The second is based on a representation of space,time covariance functions that is spectral in just the time domain and is shown to lead to natural partially nonparametric asymmetric models on the sphere crossed with time. Various models are applied to a data set of daily winds at 11 sites in Ireland over 18 years. Spectral and space,time domain diagnostic procedures are used to assess the quality of the fits. The spectral-in-time modelling approach is shown to yield a good fit to many properties of the data and can be applied in a routine fashion relative to finding elaborate parametric models that describe the space,time dependences of the data about as well. [source]