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At least 1,135 records · Page 63Linked to original sources
PubMed1995

Transurethral ultrasound-guided laser-induced prostatectomy: clinical outcome and data analysis.

OBJECTIVES: To analyze efficacy and side effects of the transurethral ultrasound-guided laser-induced prostatectomy (TULIP) procedure for the treatment of bladder outlet obstruction due to benign prostatic hyperplasia (BPH). Based on the results obtained so far, the influence of preoperative and intraoperative parameters on clinical outcome is analyzed. METHODS: Between May 1991 and March 1994, 89 men with symptomatic and obstructive BPH underwent a TULIP procedure and were followed after 3 and 6 weeks, and 3, 6, and 12 months postoperatively. RESULTS: On average, mean urinary peak flow increased from 7 to 15 mL/s, postvoidal residual urine decreased from 215 to 40 mL and symptoms (assessed by modified Boyarsky score) decreased from 17 to 5 at 12 months after TULIP: In about half of the patients peak flow increased to more than 20 mL/s on average, and approximately 85% of all men reported that their symptoms improved on average 80% during this time. Because of insufficient micturition, 7 patients subsequently underwent conventional transurethral resection of the prostate (TURP) and 1 had an open prostatectomy. Either partial or complete retrograde ejaculation was reported by 13 of 58 sexually active men. No blood transfusion was required and no post-transurethral resection syndrome occurred in any case. Analyses of preoperative and intraoperative parameters and clinical outcome with respect to prostate volume, urinary retention, type of BPH enlargement, sleeve size, and good and poor responders did not reveal any significant influence of any factor. There is, however, a trend toward a lower laser energy delivered in patients who failed or may be considered to be poor responders. CONCLUSIONS: In this unselected group of patients with BPH, who otherwise would have been TURP candidates, the TULIP procedure demonstrated the efficacy of this technique to relieve bladder outlet obstruction. Compared with TURP, the TULIP procedure proved to be advantageous in regard to less blood loss and rate of retrograde ejaculation. In addition, TULIP can be performed under analgesic sedation, which is especially advantageous in high-risk patients. Disadvantages, however, are that it takes a considerably longer time to obtain substantial improvements in subjective and objective symptoms and there are more irritative symptoms in the early postoperative phase.

Aged↗
PubMedDate not supplied

Ion selective microelectrodes: computer-controlled calibration, plotting, and data analysis.

Calibration of ion-selective microelectrodes involves delivering and measuring the potential of several different solutions both before and after intracellular measurement. A microprocessor-controlled system is described which completely automates that tedious process. The microcomputer controls the delivery of the calibration solutions and prints out the calibration value along with the solution number. A second program plots the calibration curve using a modified Nicholsky equation and a third program converts intracellular ion signals into ion concentration. Specific examples based on Ca-selective microelectrodes are shown.

Autoanalysis↗
PubMed1988

Quantitative immunocytochemistry using an image analyzer. I. Hardware evaluation, image processing, and data analysis.

In this review we describe how video-based image analysis systems are used to measure immunocytochemically labeled tissue. The general principles underlying hardware and software procedures are emphasized. First, the characteristics of image analyzers are described, including the densitometric measure, spatial resolution, gray scale resolution, dynamic range, and acquisition and processing speed. The errors produced by these instruments are described and methods for correcting or reducing the errors are discussed. Methods for evaluating image analyzers are also presented, including spatial resolution, photometric transfer function, short- and long-term temporal variability, and measurement error. The procedures used to measure immunocytochemically labeled cells and fibers are then described. Immunoreactive profiles are imaged and enhanced using an edge sharpening operator and then extracted using segmentation, a procedure which captures all labeled profiles above a threshold gray level. Binary operators, including erosion and dilation, are applied to separate objects and to remove artifacts. The software then automatically measures the geometry and optical density of the extracted profiles. The procedures are rapid and efficient methods for measuring simultaneously the position, geometry, and labeling intensity of immunocytochemically labeled tissue, including cells, fibers, and whole fields. A companion paper describes non-biological standards we have developed to estimate antigen concentration from the optical density produced by antibody labeling (Nabors et al., 1988).

Animals↗
PubMed1989

BOOMER, a simulation and modeling program for pharmacokinetic and pharmacodynamic data analysis.

BOOMER is an improved version of an earlier non-linear regression program, MULTI-FORTE. Rather than the user writing a FORTRAN subroutine, models are defined by means of the parameters which make up the model. Models based on differential equations are specified by means of zero-order, first-order, or Michaelis-Menten-type rate constants. Doses (in units of mass) are translated into the usually observed concentration units by a reciprocal volume parameter. Integrated equation models are specified in terms of baseline terms, exponential terms, or the emax function with slope term as described by the Hill equation. Time points can be specified as parameters to specify dose times, infusion start/stop times, or lag times. With careful selection of parameters quite complex models can be specified. The user has a choice of differential equation solvers and fitting algorithms.

Computer Simulation↗
PubMed1984

Thermodynamical model for insertion and aggregate binding of caffeine to the homopolymer poly(riboadenylate) and model choice by data analysis.

This paper describes the model used to estimate the parameters of caffeine-poly(riboadenylate) (poly(A)) interactions from corresponding 1H-NMR measurements. The model of insertion and aggregate binding describes the non-cooperative insertion of a molecule C into an interspace between two monomers of a homopolymer in competition with aggregate binding. It contains two binding constants, K1 for insertion and K2 for the interaction of monomeric A units of the polymer with C molecules in bound aggregates, and two cooperativity parameters, Kcc for stacking of C molecules within aggregates and tau which is thought to be due to conformational adaptation of the polymer to those bound aggregates which cover more than one A unit. In contrast to other models, the size of a binding site (within the aggregates) is less than one monomeric unit, with n denoting the maximum number of C molecules per A unit in bound aggregates. The model is developed for general n by means of the method of sequence-generating functions. For n = 2 and n = 3, the correctness of the model treatment was checked by the matrix method. The model is applicable to the binding of aggregates to homopolymers, which are flexible enough to fit their structure to the aggregates.

Journal Article↗
PubMedDate not supplied

Non-linear kinetics of ethanol elimination in man: medico-legal applications of the terminal concentration-time data analysis.

Research regarding parameters suitable for reporting on the activity of enzymatic systems responsible for ethanol metabolism is of obvious interest in medico-legal practice. Blood ethanol concentration-time curves, following oral administration of ethanol, have been developed for ethylic and non-ethylic subjects. This study has confirmed the non-linear kinetics of ethanol elimination; however, existing non-linear models appear to be inadequate for usual medico-legal practice, because of their complexity. We observed three phases during the elimination of ethanol. The first order terminal phase is characterized by its half-life. This parameter seems adequate as a basis for determining the activity of enzyme systems responsible for the metabolism of ethanol.

Adult↗
PubMed1990

A simplified competition data analysis for radioligand specific activity determination.

Non-linear regression and two-step linear fit methods were developed to determine the actual specific activity of 125I-ovine prolactin by radioreceptor self-displacement analysis. The experimental results obtained by the different methods are superposable. The non-linear regression method is considered to be the most adequate procedure to calculate the specific activity, but if its software is not available, the other described methods are also suitable.

Animals↗
PubMed1991

Data analysis and sample size issues in evaluations of community-based health promotion and disease prevention programs: a mixed-model analysis of variance approach.

The growing interest in community-based approaches to health promotion and disease prevention (HP/DP) has been accompanied by a growing need to evaluate the effectiveness of such programs. Special issues that arise in these evaluation studies include (1) entire communities are assigned to intervention and control groups, (2) only a small number of communities can usually be studied, (3) the time course of changes in behavior and other outcomes is often of interest, and (4) surveys to measure such changes over time can be conducted with either repeated cross-sectional samples or with longitudinal samples. This paper shows how these issues can be addressed under a mixed-model analysis of variance approach. This approach serves to unify several ideas in the literature on evaluation of community studies, including use of time-series regression and the question of whether the individual or the community should be the unit of analysis. We also describe how the method can be used to estimate sample size requirements, statistical power, or minimum detectable program effect.

Analysis of Variance↗
PubMed1992

Lifetime data analysis of disease and aging by the Weibull probability distribution.

We applied the Weibull distribution to the life-table and age-patterns of diseases in Japan. The life-table follows a composite Weibull distribution composed of initial failure and two stage wear-out failure periods. The extension of lifespan during the past century is manifested as increases in the scale parameters in all three periods and the shape parameters in the wear-out periods with female predominancy. The shape parameters of diseases show time-independent sex-dependent specific values. When consistent changes are observed, such as increases in the shape parameters of tuberculosis and pneumonia, legitimate causes such as prevention and repair at the societal and medical level are present. Cancer and arteriosclerosis share a common range of shape parameters suggesting analogous underlying biological processes. An analysis of the epidemiology of human aging and disease by the Weibull distribution discloses intrinsic properties of man as a biological organization as well as a societal presence.

Adolescent↗
PubMed2006

Software studies for germanium detectors data analysis.

Efficiency calibrations of multiple high-purity germanium (HPGe) detectors are being maintained at the National Institute of Standards and Technology (NIST). Four generally available software packages for HPGe detector gamma-ray spectrum analysis, including the one currently used at NIST, were tested on spectra collected from two HPGe detectors at different source-to-detector distances and using point sources and ampoules as calibration geometries. The resulting efficiency curves were inter-compared.

Algorithms↗
PubMed2004

Test-retest repeatability of muscle sympathetic nerve activity: influence of data analysis and head-up tilt.

Total integrated muscle sympathetic nerve activity (MSNA) is composed of bursts that vary in both frequency and amplitude. Various quantifiable indices are currently used to characterize MSNA and its reflex-mediated responses. However, a comprehensive and systematic analysis on the test-retest repeatability of these measures has not been conducted. Therefore, the purpose of this study was to compare the consistency of supine and passive head-up tilt-mediated sympathetic nerve activity using different descriptors of MSNA and a statistical paradigm that included Model II ordinary least products (OLP) regression, Bland-Altman method of differences, and analysis of variance. MSNA (microneurography), stroke volume (SV, Doppler), and arterial blood pressure (ABP, Finapres) were measured during repeated supine and 60 degrees head-up tilt (HUT) conditions separated by a minimum of 3 weeks. MSNA was quantified using; burst frequency (and incidence), burst amplitudes (and total integrated activity) normalized to the largest absolute amplitude within each posture, and calculated percent changes (from supine) in absolute burst amplitude and total integrated activity. Most indices of MSNA showed excellent test-retest repeatability during both postures with neither fixed nor proportional bias. However, MSNA expressed as burst incidence demonstrated both fixed and proportional bias in the supine position, but not during HUT. In addition, HUT-induced percent changes in absolute burst amplitude and total activity displayed a fixed bias with greater increases during the second test (P<0.05). The hemodynamic variables associated with the reflex responses were quite similar between tests (i.e., no bias). It was concluded that, with the exception of burst incidence, the majority of MSNA indices provided reliable markers of sympathetic activity on repeated tests. However, care must be taken when using percent changes in MSNA that incorporate absolute amplitudes.

Adult↗
PubMed2005

Gene expression microarray studies in polygenic psychiatric disorders: applications and data analysis.

Gene expression microarrays have become a mainstream technology that can provide valuable insight into psychiatric disorders. Gene expression studies in post mortem brain samples of schizophrenia and bipolar disorder have the potential to yield novel clues about the pathophysiology of these complex trait disorders. In the present review, a short introduction of the genetic and molecular background of schizophrenia and bipolar disorder is followed by a discussion of the basic concept and limits of gene expression microarray technology, and the complexities surrounding the analysis of thousands of gene transcripts. Although this review is intended for use in most platforms, it has a particular focus on the commercially available Affymetrix system. Various computer programs and their principal features are discussed, and it is shown how these programs can be applied to reveal a biological context of microarray findings. I will demonstrate how the programs can help to judge the results rather than focus on their statistical principles. The strength of gene array experiments is their emphasis on broad, biological themes, rather than on specific genes, and proper biostatistical approaches are important to ensure reproducibility of the findings. All results should be verified by independent means. This review is intended to help brain researchers who want to apply gene expression microarray technology to conceptualize research strategies and sample analysis.

Biomedical Research↗