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PubMedDate not supplied

US of the peritoneum.

Familiarity with the pathophysiology of peritoneal disease is the basis of successful ultrasound (US) study of the peritoneum. The pouch of Douglas, diaphragmatic surfaces, the paracolic gutters, and the regions of the mesentery and omentum should receive careful scrutiny in the patient at risk for a peritoneal disease process. An optimal US technique requires assessment of the entire peritoneum with a transducer selected to reflect the depth of the region of interest. US may demonstrate minute quantities of free intraperitoneal fluid and is therefore capable of providing sensitive quantitative information about ascites. Qualitative information may also be inferred, as blood, pus, and neoplastic cells demonstrate correlation with particulate ascites on gray-scale US scans. Peritoneal nodules, plaques, and thickening may be detected on the visceral or parietal peritoneal surfaces, especially when high-frequency probes are used. Transvaginal study in women increases the sensitivity of US for detection of peritoneal disease. In women who have unexplained sepsis or are at risk for carcinomatosis, transvaginal scanning should routinely be added to the regular abdominal and pelvic studies regardless of the findings of those studies. Peritoneal carcinomatosis, primary peritoneal neoplasms, pseudomyxoma peritonei, and peritonitis have characteristic appearances at US.

Diagnosis, Differential↗

PubMed1998

Demonstration of nonlinear components in heart rate variability of healthy persons.

We present a systematic approach for detecting nonlinear components in heart rate variability (HRV). The analysis is based on twenty-three 48-h Holter recordings in healthy persons during sinus rhythm. Although many segments of 1,024 R-R intervals are stationary, only few stationary segments of 8,192-32,768 R-R intervals can be found using a test of Isliker and Kurths (Int. J. Bifurcation Chaos 3:1573-1579, 1993.). By comparing the correlation integrals from these segments and corresponding surrogate data sets, we reject the null hypothesis that these time series are realization of linear processes. On the basis of a test statistic exploring the differences of consecutive R-R intervals, we reject the hypothesis that the R-R intervals represent a static transformation of a linear process using optimized surrogate data. Furthermore, time irreversibility of the heartbeat data is demonstrated. We interpret these results as a strong evidence for nonlinear components in HRV. Thus R-R intervals from healthy persons contain more information than can be extracted by linear analysis in the time and frequency domain.

Adult↗

PubMed2004

[Confirmatory factor analysis. Its role on the validation of health related questionnaires].

Researchers who use questionnaires in the health sciences tacitly base themselves (often inadvertently) in Classical Test Theory, the suppositions of which are unrealistic and frequently violated, leading to defective evaluation of the reliability and validity of the instrument.The present article emphasizes the need for precise definition of essential terms of measurement (reliability and validity) by clarifying the deficiencies that traditional methodology incurs in their use. The limitations of evaluation of reliability through Chronbach's alpha and laxity in quantitative evaluation of validity through exploratory factor analysis are described. As an alternative, a sequential and integrated approach to validity and reliability within the framework of confirmatory factor analysis models is proposed. These models provide the appropriate statistical framework to evaluate the validity and reliability of each item, instead of carrying out overall evaluations only. The confirmatory approach guides researchers to optimize the process of designing or adapting a questionnaire, freeing them from the largely unfounded ritual laid down by classical methodology.

Factor Analysis, Statistical↗

PubMed2005

Novel fusion protein approach for efficient high-throughput screening of small molecule-mediating protein-protein interactions in cells and living animals.

Networks of protein interactions execute many different intracellular pathways. Small molecules either synthesized within the cell or obtained from the external environment mediate many of these protein-protein interactions. The study of these small molecule-mediated protein-protein interactions is important in understanding abnormal signal transduction pathways in a variety of disorders, as well as in optimizing the process of drug development and validation. In this study, we evaluated the rapamycin-mediated interaction of the human proteins FK506-binding protein (FKBP12) rapamycin-binding domain (FRB) and FKBP12 by constructing a fusion of these proteins with a split-Renilla luciferase or a split enhanced green fluorescent protein (split-EGFP) such that complementation of the reporter fragments occurs in the presence of rapamycin. Different linker peptides in the fusion protein were evaluated for the efficient maintenance of complemented reporter activity. This system was studied in both cell culture and xenografts in living animals. We found that peptide linkers with two or four EAAAR repeat showed higher protein-protein interaction-mediated signal with lower background signal compared with having no linker or linkers with amino acid sequences GGGGSGGGGS, ACGSLSCGSF, and ACGSLSCGSFACGSLSCGSF. A 9 +/- 2-fold increase in signal intensity both in cell culture and in living mice was seen compared with a system that expresses both reporter fragments and the interacting proteins separately. In this fusion system, rapamycin induced heterodimerization of the FRB and FKBP12 moieties occurred rapidly even at very lower concentrations (0.00001 nmol/L) of rapamycin. For a similar fusion system employing split-EGFP, flow cytometry analysis showed significant level of rapamycin-induced complementation.

Amino Acid Sequence↗

PubMed2003

The bacterial cytoskeleton and its putative role in membrane vesicle formation observed in a Gram-positive bacterium producing starch-degrading enzymes.

Bacteria may possess various kinds of cytoskeleton. In general, bacterial cytoskeletons may play a role in the control and preservation of the cell shape. Such functions become especially evident when the bacteria do not possess a true wall and are nevertheless elongated (e.g. Mycoplasma spp.) or under extreme cultivation conditions whereby loss of the entire bacterial cell wall takes place. Bacterial cytoskeletons may control and preserve the cell shape only if a number of preconditions are fulfilled. They should be present not only transiently, but permanently, they should be located as a lining close to the inner face of the cytoplasmic membrane, enclosing the entire cytoplasm, and they should comprise structural elements (fibrils) crossing the inner volume of the cell in order to provide the necessary stability for the lining. Complete loss of the cell wall layers had earlier been observed to occur during extensive production of bacterial starch-degrading enzymes in an optimized fermentation process by a Gram-positive bacterium. Even under these conditions, the cells had maintained their elongated shape and full viability. Which of the various kinds of bacterial cytoskeleton might have been responsible for shape preservation? Only one of them, the primary or basic cytoskeleton turns out to fulfil the necessary preconditions listed above. Its structural features now provided a first insight into a possible mechanism of formation of membrane blebs and vesicles as observed in the Gram-positive eubacterium Thermoanaerobacterium thermosulfurogenes EM1, and the putative role of the cytoskeletal web in this process.

Bacterial Proteins↗

PubMed1994

Effects of cocaine on P3B in cocaine abusers.

Little is known about the effects of cocaine on cognitive tasks. Event-related potentials (ERP) were recorded in 7 cocaine abusers during the performance of the auditory oddball task before and after the intravenous injections of saline and cocaine (60-80 mg). The P3B and slow wave components of the ERP were significantly larger 60-210 min after the cocaine than after the placebo injection. The results suggest that cocaine abusers have difficulty in maintaining optimal stimulus processing during extended testing. Cocaine blocks this decrement in stimulus processing.

Adult↗

PubMed1998

Modular subdivisions of dolphin insular cortex: does evolutionary history repeat itself?

The structural organization of the insular cortex in the bottlenose dolphin was investigated by examining Nissl- and myelin-stained tissue that was sectioned coronally and tangentially. An uneven distribution of cell clusters that coincided with myelin-light zones was observed in layer II. When the present observations were compared to descriptions of modules in other animals, we found that the range of module size is restricted, while the size of the brain, particularly the neocortex, varies dramatically. Indeed, despite the tremendous expansion of the cetacean neocortex, the size of the modules in the insular cortex is similar to that described for small-brained mammals like the mouse, suggesting that module size is evolutionarily stable across species. Selection for optimal-size processing units, in terms of the lengths of connections within and between them, is a likely source of this stability.

Animals↗

PubMed2001

Artificial chemistries--a review.

This article reviews the growing body of scientific work in artificial chemistry. First, common motivations and fundamental concepts are introduced. Second, current research activities are discussed along three application dimensions: modeling, information processing, and optimization. Finally, common phenomena among the different systems are summarized. It is argued here that artificial chemistries are "the right stuff" for the study of prebiotic and biochemical evolution, and they provide a productive framework for questions regarding the origin and evolution of organizations in general. Furthermore, artificial chemistries have a broad application range of practical problems, as shown in this review.

Chemistry↗

PubMed2004

Controlled release of plasmid DNA from biodegradable scaffolds fabricated using a thermally-induced phase-separation method.

Highly porous poly(D,L-lactic-co-glycolic acid) (PLGA) scaffolds were fabricated by a thermally-induced phase-separation (TIPS) method to deliver plasmid DNA in a controlled manner. A variety of TIPS parameters directly affecting pore structures and their interconnectivities of the scaffold, such as polymer concentration, solvent/non-solvent ratio, quenching methods and annealing time, were systematically examined to explore their effects on sustained release behaviors of plasmid DNA. Plasmid DNA was directly loaded into the inner pore region of the scaffold during the TIPS process. By optimizing the parameters, PLGA scaffolds releasing plasmid DNA over 21 days were successfully fabricated. DNA release profiles were mainly affected by the pore structures and their interconnectivities of the scaffolds. Plasmid DNA released from the scaffolds fully maintained its structural integrity and showed comparable transfection efficiency to native plasmid DNA. These biodegradable polymeric scaffolds capable of sustained DNA release can be potentially applied for various tissue engineering purposes requiring a combined gene delivery strategy.

Absorbable Implants↗

PubMed2006

Estimating nonlinear receptive fields from natural images.

The response of visual cells is a nonlinear function of their stimuli. In addition, an increasing amount of evidence shows that visual cells are optimized to process natural images. Hence, finding good nonlinear models to characterize visual cells using natural stimuli is important. The Volterra model is an appealing nonlinear model for visual cells. However, their large number of parameters and the limited size of physiological recordings have hindered its application. Recently, a substantiated hypothesis stating that the responses of each visual cell could depend on an especially low-dimensional subspace of the image space has been proposed. We use this low-dimensional subspace in the Volterra relevant-space technique to allow the estimation of high-order Volterra models. Most laboratories characterize the response of visual cells as a nonlinear function on the low-dimensional subspace. They estimate this nonlinear function using histograms and by fitting parametric functions to them. Here, we compare the Volterra model with these histogram-based techniques. We use simulated data from cortical simple cells as well as simulated and physiological data from cortical complex cells. Volterra models yield equal or superior predictive power in all conditions studied. Several methods have been proposed to estimate the low-dimensional subspace. In this article, we test projection pursuit regression (PPR), a nonlinear regression algorithm. We compare PPR with two popular models used in vision: spike-triggered average (STA) and spike-triggered covariance (STC). We observe that PPR has advantages over these alternative algorithms. Hence, we conclude that PPR is a viable algorithm to recover the relevant subspace from natural images and that the Volterra model, estimated through the Volterra relevant-space technique, is a compelling alternative to histogram-based techniques.

Algorithms↗

PubMed1983

The quality of maintenance therapy for end-stage renal disease. A review of social adjustment and rehabilitation.

Prior to 1972, ESRD patients selected for maintenance dialysis or renal transplantation were generally young, emotionally and socially well-adjusted, and physically healthy except for their renal disease. Following the enactment of Public Law 92-603 (1972), which extended Medicare coverage to virtually all ESRD patients, the criteria for the selection of patients were substantially liberalized. During the past decade, maintenance therapy has increasingly been provided for severely debilitated ESRD patients whose reported levels of rehabilitation have been less than desired. While the majority of the current ESRD patient population have not been restored to their premorbid levels of individual and social functioning, recent studies suggest this may be the result of initiating rehabilitation efforts too late in the disease process. For optimal social functioning to be achieved by ESRD patients, it is concluded that psychosocial intervention and support must be initiated at the time ESRD is diagnosed and be focused on the maintenance, rather than rehabilitation, of the patient's functioning.

Humans↗

PubMed2004

Inhibitory interneurons in the olfactory bulb: from development to function.

Identifying and defining the characteristic features of the inhibitory neurons in the nervous system has become essential for achieving a cellular understanding of complex brain activities. For this, the olfactory bulb is ideally suited because it is readily accessible, it is a laminated structure where local interneurons can be easily distinguished from projecting neurons, and, more important, GABAergic interneurons are continuously replaced. How the newly generated neurons integrate into a preexisting neural network and how basic network functions are maintained when a large percentage of neurons are subjected to continuous renewal are important questions that have recently received new insights. Here, it is seen that the production of bulbar interneurons is specifically adapted to experience-dependent regulation of adult neural networks. In particular, the authors report the degree of sensitivity of the bulbar neurogenesis to the activity level of sensory inputs and, in turn, how the adult neurogenesis adjusts the neural network functioning to optimize information processing. By maintaining a constitutive neurogenesis sensitive to environmental cues, this neuronal recruitment leads to improving sensory abilities. This review brings together recently described properties and emerging principles of interneuron functions that may convey, into bulbar neuronal networks, a degree of circuit adaptation unmatched by synaptic plasticity alone.

Animals↗

PubMed2003

Utilizing Geographic Information Systems in community assessment and nursing research.

Application of Geographic Information Systems (GIS) in health sciences is relatively new, but it appears to be expanding faster than any other areas of GIS application. Although health scientists have long been using geographic information conceptually, the current availability of user-friendly GIS tools has caused a rapid endorsement of GIS in community health research. Locations of disease incidence, surrounding environments, health care facilities, geographic boundaries of the communities, and other essential community infrastructures have always been essential components of epidemiological and health care studies. This article provides an example of the effective use of GIS in a community assessment project. The purpose of this project was to survey the households in Hinds County, Mississippi, to assess community health status and the under-utilization of health care services. Ultimately, the assessment will be used to positively influence health outcomes within defined geographic communities. Community assessment was accomplished using extensive face-to-face surveys coupled with GIS technology to optimize the process and to evaluate the results.

Community Health Nursing↗

PubMed1999

Screening for dementia with the memory impairment screen.

OBJECTIVES: To validate a sensitive and specific screening test for AD and other dementias, assess its reliability and discriminative validity, and present normative data for its use in various applied settings. BACKGROUND: To improve discrimination in screening for AD and dementia, we developed the Memory Impairment Screen (MIS), a 4-minute, four-item, delayed free- and cued-recall test of memory impairment. The MIS uses controlled learning to ensure attention, induce specific semantic processing, and optimize encoding specificity to improve detection of dementia. METHODS: Equivalent forms of the MIS were given at the beginning and end of the testing session to assess alternate forms reliability. Discriminative validity was assessed in a criterion sample of 483 aged individuals, 50 of whom had dementia according to Diagnostic and Statistical Manual of Mental Disorders (3rd ed., revised) criteria. RESULTS: The MIS had good alternate forms reliability, high construct validity for memory impairment, and good discriminative validity in terms of sensitivity, specificity, and positive predictive value. We present normative data for use in settings with different base rates (prevalences) of AD and dementia. CONCLUSION: The MIS provides efficient, reliable, and valid screening for AD and other dementias.

Aged↗

PubMed2006

The postnatal development of neocortical neurons and glial cells in the Göttingen minipig and the domestic pig brain.

The first mathematically unbiased estimates of neocortical cell numbers are presented from the developing pig brain, including a full description of tissue processing and optimal sampling for application of the stereological optical fractionator method in this species. The postnatal development of neocortical neurons and glial cells from the experimental Göttingen minipig was compared with the postnatal development of neocortical neurons in the domestic pig. A significant postnatal development was observed in the Göttingen minipig brain for both neuronal (28%; P=0.01) and glial cells (87%; P<0.01). A corresponding postnatal development of neurons was not detected in the domestic pig brain. The reason for this strain difference is not known. The mean total number of neocortical neurons is 324 million in the adult Göttingen minipig compared with 432 million in the domestic pig. The glial-to-neuron cell ratio is around 2.2 in the adult Göttingen minipig. Based on these results, the domestic pig seems to be a more suitable model for evaluating the effects of developmental insults on human brain growth and neuronal development than the Göttingen minipig.

Animals↗

PubMed2001

Leaching of Mn, Co, and Ni from manganese nodules using an anaerobic bioleaching method.

An anaerobic bioleaching of a manganese nodule by anaerobic Mn-reducing bacteria was evaluated for the leaching of metals, Mn, Co, and Ni. Insoluble Mn4+ in the nodule could be reduced to soluble Mn2+ by dissimilatory Mn-reducing bacteria that use a carbon source and Mn4+ as an electron donor and acceptor, respectively. As a result of the Mn reduction, Co and Ni could be leached from the loosed Mn matrix. Leaching experiments were carried out to optimize various process parameters, such as inoculation, pH, temperature, mineral salts, and particle size of the nodule used. The leaching efficiencies of Mn, Co, and Ni increased from 18, 7, and 10% to 77, 70, and 75%, respectively by the inoculation of the Mn-reducing enrichment culture broth. Metals could be efficiently recovered from the nodule in the ranges of pH from 5.0 to 6.5 and temperature from 30 to 45 degrees C by anaerobic bioleaching. External addition of mineral salts was not necessary for Mn, Co, and Ni leaching from the nodule. The optimum ratio of nodule to glucose was 0.1 (w/w). To obtain a leaching efficiency above 70%, the particle size of the nodules must be less than 0.6 mm.

Journal Article↗

PubMed2004

Heteroassociative multiple-target tracking by fringe-adjusted joint transform correlation.

A heteroassociative joint transform correlation (JTC) technique is proposed for recognizing and tracking multiple heteroassociative or dissimilar targets from gray-level image sequences by use of the concept of fringe-adjusted JTC and a multiple-target-detection algorithm. A fringe-adjusted JTC technique is used to ensure quantification of the similarities among several input images while it satisfies the equal-correlation-peak criterion. Tracking is accomplished by retrieval of the target motion information estimated from multiple consecutive image frames. An enhanced version of the fringe-adjusted filter is incorporated into the heteroassociative multiple-target-detection process to optimize the correlation performance. The feasibility of the proposed technique is tested by computer simulation with real infrared image data.

Journal Article↗

PubMed2005

Design and fabrication of diffractive optical elements by use of gray-scale photolithography.

Diffractive optical elements (DOEs) are key components in the miniaturization of optical systems because of their planarity and extreme thinness. We demonstrate the fabrication of DOEs by use of gray-scale photolithography with a high-energy-beam sensitive glass photomask. We obtained DOE lenses with continuous phase profiles as small as 800 microm in diameter and 5.9 microm in the outermost grating pitch by selecting a suitable optical density for each height level and optimizing the process variables. Microlenses patterned with eight levels and replicated by UV embossing with the polymer master mold showed a diffraction efficiency of 81.5%, which was sufficiently high for the devices to be used as optical pickups. The effects of deviations in diffraction efficiency between the DOE height and profile design were analyzed.

Journal Article↗