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PubMed1983

A study of cell electrophoresis as a means of purifying growth hormone secreting cells.

Growth hormone secreting cells of the rat anterior pituitary are heavily laden with granules of growth hormone and can be partially purified on the basis of their resulting high density. Two methods of preparative cell electrophoresis were investigated as methods of enhancing the purification of growth hormone producing cells: density gradient electrophoresis and continuous flow electrophoresis. Both methods provided a two- to four-fold enrichment in growth hormone production per cell relative to that achieved by previous methods. Measurements of electrophoretic mobilities by two analytical methods, microscopic electrophoresis and laser-tracking electrophoresis, revealed very little distinction between unpurified anterior pituitary cell suspensions and somatotroph-enriched cell suspensions. Predictions calculated on the basis of analytical electrophoretic data are consistent with the hypothesis that sedimentation plays a significant role in both types of preparative electrophoresis and the electrophoretic mobility of the growth hormone secreting subpopulation of cells remains unknown.

Animals↗
PubMed1986

Purification and characterization of B-protein from human serum.

B-Protein, present in the serum of individuals with cancer, has been purified to electrophoretic homogeneity. The purification procedure consisted of chromatography on Sephacryl S-200, Affi-Gel Blue, Con A--Sepharose 4B, wheat germ lectin--Sepharose and preparative polyacrylamide gel electrophoresis. The molecular weight of B-Protein is estimated to be 100 000 to 120 000. It is a glycoprotein which appears to be composed of two subunits, each with a molecular weight of approximately 52 000. Analytical polyacrylamide gel electrophoresis and analytical ultracentrifugation data indicate that purified B-Protein is homogeneous. Isoelectric focusing studies also show the purified B-Protein to be homogeneous in composition consisting of a single band of pI = 4.8. Amino acid analysis is consistent with this acidic isoelectric point. Other analyses indicate that B-Protein contains 7% carbohydrate and 7% lipid in the form of triglycerides.

Amino Acids↗
PubMed1975

Analysis of chemically reacting systems by sedimentation-diffusion equilibrium.

A novel procedure to evaluate equilibrium constants from sedimentation-diffusion equilibrium data of analytical ultracentrifuge runs is proposed. It is shown that, by comparison of a reacting mixture at chemical equilibrium with a non-reacting but equally composed one, the sum of the mean concentrations of the reaction products can immediately be taken from optical absorption or from interferometric measurements. In most but not in all cases the use of stacked double-sector centerpieces is required.

Binding Sites↗
PubMed1993

Online repositioning during treatment of the prostate: a study of potential limits and gains.

PURPOSE: With on-line portal imaging devices and image registration tools, the verification of radiation field position prior to each treatment becomes technically feasible. In this paper, we analyze the impact of pre-treatment verification and field position adjustment on target coverage and normal tissue sparing. METHODS AND MATERIALS: Port films were compared with corresponding simulation films to determine the magnitude of setup variations in patients treated for prostate cancer. From these data, an analytic function was determined between geometric coverage of the target and field margin size. A paradigm for on-line patient repositioning was employed to generate a new relationship between margin and target coverage. Margins were selected for the situations of normal treatment and on-line repositioning to ensure target coverage. Dose-volume histograms were generated for a typical prostate treatment using these margins. RESULTS: On-line repositioning, when setup errors exceed 1 cm, results in a 6 mm reduction in margin, suggesting that 10% of the volume of bladder and rectum may be spared of high dose. CONCLUSION: The use of on-line imaging and image registration to guide adjustment of patient setup may lead to a reduction in the volume of normal tissues irradiated, and possibly improve the probability of complication-free survival in future treatments.

Computer Simulation↗
PubMed1992

Modeling of toxicological effects of fire effluents: prediction of toxicity and evaluation of animal model.

Methodology for the prediction of the toxic effects of fire effluents has made considerable progress [1,2]. As emphasized by Hartzell [2] a limiting factor has often been the availability and quality of analytical input data. The Finney model [3] was used to predict the lethal potency and would appear to have utility as a tool in reducing the number of experimental animals used in material testing. However, pilot bioassay data are indispensable to validate the prediction and to categorize fire effluents into narcosis inducing, irritant or of causing unusual or unexpected toxicity. The comparison of predicted and actually observed carboxy-hemoglobin levels is considered to be a sensitive but indirect tool to assess whether major effects on respiration occurred. All laboratory combustion toxicity methods suffer from several types of limitations. However, they might be expected to be relatable to at least some stages of actual fires. Due to a lack of a clearly defined 'generation process'--if compared with conventional inhalation toxicity studies--the classification into broad categories of relative toxic potency seemed to be more appropriate than an absolute classification scheme.

Animals↗
PubMed1991

Chemometrics, why, what and where to next?

The advantages of the application of chemometrics in pharmaceutical and biomedical analysis are discussed. Some chemometric approaches are described and the requirement for validation emphasized. Finally, possible future developments of chemometrics are assessed.

Biometry↗
PubMed2004

Importance of product/reactant equilibration in the kinetics of the phosphoglucose isomerization reaction by differential stopped flow microcalorimetry.

The kinetics for the isomerization of fructose-6-phosphate to glucose-6-phosphate (F6P --> G6P) by baker's yeast phosphoglucose isomerase (PGI) with regard to k(cat) and K(m) were determined from analysis of differential stopped flow microcalorimeter measurements using the integrated form of the Michaelis-Menten rate equation. Values for K(m) (F6P --> G6P) that were determined at pH 8.0 and ionic strength 0.1M at 293.4, 298.4, 303.4, and 311.5K exhibited a linear dependence on the substrate concentration at each temperature because of the substrate-product equilibrium. The minimum values for K(m) ranged from 2.62+/-0.55 mM at 293.4K to 7.8+/-4.8mM at 311.5K and were the same as the minimum values for the reverse reaction (G6P --> F6P) at 293.4 K and 298.4 K. Minimum values for k(cat) increased with temperature, from 2.78+/-0.34s(-1) at 293.4K to 11.4+/-1.0s(-1) at 311.5K, and for the reverse reaction, G6P --> F6P, from 0.852+/-0.086 s(-1) at 293.4K to 1.46+/-0.06s(-1) at 298.4K. The enzyme efficiency at 311.5K is close to the collision rate for a diffusion-controlled process in solution. The [F6P]/[G6P] equilibrium constants were determined from comparison of the values of k(cat) in both directions and were 0.307+/-0.053 at 293.4K and 0.395+/-0.033 at 298.4K. The heats of reaction in the F6P --> G6P direction increased from -8.96+/-0.26 kJmol(-1) at 311.5K to -8.27+/-0.40 kJmol(-1) at 293.4K, a value in fair agreement with 7.01+/-0.32 kJmol(-1) in the opposite G6P --> F6P direction.

Calorimetry↗
PubMed2004

A mouse optical simulation environment (MOSE) to investigate bioluminescent phenomena in the living mouse with the Monte Carlo method.

RATIONALE AND OBJECTIVES: As an important part of bioluminescence tomography, which is a newly developed optical imaging modality, mouse optical simulation environment (MOSE) is developed to simulate bioluminescent phenomena in the living mouse and to predict bioluminescent signals detectable outside the mouse. This simulator is dedicated to small animal optical imaging based on bioluminescence. MATERIALS AND METHODS: With the parameters of biological tissues, bioluminescent sources, and charge coupled device (CCD) detectors, the 2-dimensional/3-dimensional MOSE simulates the whole process of the light propagation in 2-dimensional/3-dimensional biological tissues using the Monte Carlo method. Both the implementation details and the software architecture are described in this article. RESULTS: The software system is implemented in the Visual C++ programming language with the OpenGL techniques and has a user-friendly interface facilitating interactions relevant to bioluminescent imaging. The accuracy of the system is verified by comparing the MOSE results with independent data from analytic solutions and commercial software. CONCLUSION: As shown in our simulation and analysis, the MOSE is accurate, flexible, and efficient to simulate the photon propagation for bioluminescence tomography. With graduate refinements and enhancements, it is hoped that the MOSE will become a standard tool for bioluminescence tomography.

Computer Simulation↗
PubMed2026

Next-Generation Disease Profiling by Integrating Histopathology with Spatial Multi-Omics Data.

The field of pathology has experienced several transformative changes in recent years with the advent of digital pathology and spatial multi-omics. These technologies have enhanced every aspect of pathology practice, from streamlining daily workflows to generating high-fidelity multi-omics data that provide pathologists with novel tools to refine disease profiling and clinical diagnosis. Each layer of multimodal data (genomic, metabolomic, proteomic, or transcriptomic) has uncovered a distinct facet of disease pathologies, and combined with machine learning/artificial intelligence-based data analysis and pattern recognition models, has provided holistic understanding of regulatory mechanisms underpinning them. However, high-dimensional data have far exceeded the volume, scale, and complexity of immunostaining methods implemented by pathologists and, thus, have generated significant challenges related to deconvolution, interpretation, and clinical translation. Furthermore, these multimodal studies have predominantly relied on computational methods to process data and extract disease-relevant insights, thus raising questions around relevance or role of a pathologist in this new era of multi-omics. This review will provide a perspective on the evolving fields of molecular histopathology and spatial -omics, leveraging them to approach disease profiling, and redefining the role of a pathologist during this process.

Humans↗
PubMed2005

Cost-effectiveness of training unselected laypersons in cardiopulmonary resuscitation and defibrillation.

PURPOSE: The cost-effectiveness of cardiopulmonary resuscitation (CPR) and defibrillation training for laypersons unselected for risk of encountering cases of cardiac arrest is not known. We compared the costs and health benefits of alternative resuscitation training strategies for adults without professional first-responder duties who are at average risk of encountering cases of out-of-hospital cardiac arrest. METHODS: We constructed a cost-effectiveness analytic model. Data on cardiac arrest epidemiology and the effectiveness of CPR/defibrillation training were obtained from the medical literature. Instructional costs were determined from a survey of training programs. Downstream cardiac arrest survivor quality-adjusted life expectancy and long-term health care costs were derived from prior studies. We compared three strategies for training unselected laypersons: CPR/defibrillation training alone, training combined with home defibrillator purchase, and no training. The main outcome measures were total instructional costs for trainees combined with health care costs for additional cardiac arrest survivors, and quality-adjusted survival for additional patients resuscitated by trainees. RESULTS: CPR/defibrillation training yielded 2.7 quality-adjusted hours of life at a cost of 62 US dollars per trainee (202,400 US dollars per quality-adjusted life-year [QALY] gained). Training laypersons in CPR/defibrillation with subsequent defibrillator purchase cost 2,489,700 US dollars per QALY. In contrast, CPR/defibrillation training cost less than 75,000 US dollars per QALY if trainees lived with persons older than 75 years or with persons who had cardiac disease, or if total training costs were less than 10 US dollars. CONCLUSION: Training unselected laypersons in CPR/defibrillation is costly compared with other public health initiatives. Conversely, training laypersons selected by occupation, low training costs, or having high-risk household companions is substantially more efficient.

Adult↗
PubMedDate not supplied

Low-level measurements of tritium in water.

Using a liquid scintillation counter, an experimental procedure for measuring low-level activity concentrations of tritium in environmental water has been developed by our laboratory, using the electrolytic tritium enrichment. Additionally, some quality tests were applied in order to assure the goodness of the method. Well-known water samples collected in the Tagus River (West of Spain) and the Danube River (Bulgaria), both affected by nuclear plant releases, were analysed and results were compared to previous data. The analytical procedure was applied to drinking water samples from the public water supply of Seville and mineral waters from different springs in Spain in order to characterize its origin. Due to the very low levels of tritium in the analysed samples, some results were reported as lower than the minimum detectable activity concentration (MDA). However, the count rate of these measurements was over the background count rate of LS counter in all the cases. For that reason, an exhaustive discussion about the meaning of the MDA, using an experimental essay, was made in order to establish a rigorous criterion that leads to a reliable value in the case of low-level measurements.

Industrial Waste↗
PubMed2004

The monotopic membrane protein human oxidosqualene cyclase is active as monomer.

The monotopic integral membrane protein 2,3-oxidosqualene cyclase (OSC) catalyzes the formation of lanosterol the first sterol precursor of cholesterol in mammals. Therefore, it is an important target for the development of new hypocholesterolemic drugs. Here, we report the overexpression and purification of functional human OSC (hOSC) in Pichia pastoris. The obtained IC(50) for the reference inhibitor Ro 48-8071 is nearly identical for the recombinant hOSC compared to OSC from human liver microsomes. The correlation of analytical ultracentrifugation data and activity measurements showed the highest enzymatic activity for the monomeric hOSC indicating that this would be the natural form. Furthermore, these data helped us to identify the detergent for a successful crystallization of the protein. The availability of this active recombinant human membrane protein is a very important step on the way to a more detailed functional and structural characterization of OSCs.

Benzophenones↗
PubMed2004

Development of infrared optical sensor for selective detection of tyrosine in biological fluids.

In this paper, a new and simple evanescent wave type of infrared biosensor is described for the selective detection of tyrosine in biological fluids. This sensor is based on the formation of copper complexes between the sensing phase and tyrosine. To demonstrate that this principle was applicable to the selective detection of tyrosine, a proline-modified sensing phase was synthesized on the surface of the internal reflection elements. This sensing phase was saturated with copper ions to allow it to interact with tyrosine units in aqueous solution through the formation of stable proline-Cu2+-tyrosine complexes. Tyrosine exhibits a unique spectral feature in its absorption band at 1515 cm-1. This band significantly differs from those of other amino acids and provides a further method for the discrimination of tyrosine. By investigating the signals from 12 amino acids, only three amino acids, each containing a phenyl group, could be sensed selectively by this sensing phase. Based on the unique absorption of tyrosine located at 1515 cm-1, tyrosine can be selectively detected. To perform quantitative analyses of tyrosine using this sensing phase, a theoretical working equation was developed and correlated with the experimental data. The analytical results indicated that the developed equations do explain and predict the detection behaviors of the proposed sensing scheme. Using the optimal conditions, the regression coefficients for standard curves of tyrosine recorded in the region of concentrations below 600 microM were higher than 0.996 under either equilibrium or non-equilibrium conditions. Detection limit of tyrosine when using this method was ca. 3 microM.

Biosensing Techniques↗
PubMed2005

Numerical simulation of two-phase partition chromatography in microchannels for moderated log P measurements.

A finite element simulation has been used in order to study the partition chromatography process of one species between an aqueous mobile phase and an organic stationary phase located at the bottom of a rectangular microchannel. The transient model incorporates convection--diffusion of the species in the water phase coupled to the diffusion in the stationary organic phase by the way of the partition kinetics at the interface. The time evolution of the injected species concentration is analyzed versus the velocity of the mobile phase, the detecting position and the thickness of the stationary phase. The comparison of simulation results with both experimental data and analytical model confirm its validity. These simulations show that thin channels can be used to measure log P of molecules from their retention time. Finally, we have shown how the sample velocity can be optimized for a given geometry of the channel and diffusion coefficient of the species.

Calibration↗
PubMed2005

Optimization of the preparative separation of a chiral pharmaceutical intermediate by high performance liquid chromatography.

The prediction of optimal conditions of the preparative HPLC separation of the enantiomers of a pharmaceutical intermediate was accomplished by employing analytical chromatographic data, i.e. sample injections at low concentrations. Various temperatures and mobile phase conditions were studied. It was assumed that the sample loadability of the stationary phase is constant for a constant value of the separation factor and different mobile phase conditions and temperatures. Using this assumption, possible production rates can be compared for different method conditions. Overloading experiments were carried out to verify that the procedure employed is adequate. It was found that the optimization approach used, changing the mobile phase composition and temperature to achieve the shortest cycle time while keeping the separation factor constant, could be applied to improve the production rate of the separation.

Chromatography, High Pressure Liquid↗
PubMed2005

Some protein interaction data do not exhibit power law statistics.

It has been claimed that protein-protein interaction (PPI) networks are scale-free, and that identifying high-degree "hub" proteins reveals important features of PPI networks. In this paper, we evaluate the claims that PPI node degree sequences follow a power law, a necessary condition for networks to be scale-free. We provide two PPI network examples which clearly do not have power laws when analyzed correctly, and thus at least these PPI networks are not scale-free. We also show that these PPI networks do appear to have power laws according to methods that have become standard in the existing literature. We explain the source of this error using numerically generated data from analytic formulas, where there are no sampling or noise ambiguities.

Humans↗
PubMed2005

Radon exhalation from phosphogypsum building boards: symmetry constraints, impermeable boundary conditions and numerical simulation of a test case.

Comprehensive understanding of (222)Rn exhalation from phosphogypsum-bearing building material and its accumulation in indoor air is likely to rely on numerical simulation, particularly if transient effects, three-dimensional domains and convection are to be included and investigated. Yet, experimental data and analytical results are helpful (if not crucial) as far as validation is concerned. Having in mind computational code simplicity and in the light of a recent experimental and theoretical report on (222)Rn release from phosphogypsum boards for housing panels, this paper presents and discusses an alternative testing set-up and the corresponding boundary conditions, namely one side of the panel bounded by impermeable wall. Although this is a new facility to be tested, the resultant steady-state one-dimensional diffusion-dominant analytical solution is shown to match the counterpart deduced in the aforementioned previous report, despite it relaxes the constraint of symmetry about the phosphogypsum board centerline, which is inferred in that prior experimental scenario. In addition, numerical results are conducted for a diffusion-dominant two-dimensional time-varying test case concerning (222)Rn accumulation in a closed chamber having an exhaling phosphogypsum board tightly placed at one wall.

Calcium Sulfate↗
PubMed2006

A mathematical model for the proliferation of bacteria in the urinary bladder due to enlarged prostate.

Urinary retention due to enlargement of the prostate (prostate hypertrophy) leads to increased proliferation of bacteria in the bladder. This in turn increases the infection rate. The reason is that the enlarged prostate presses on the urine channel and tends to close it. Thus the out flux of the bladder consists of repeatedly small amounts of fluid during a day. A mathematical dynamic model with differential equations is developed for the proliferation of bacteria in the urinary bladder (vesica urinary). The model accounts for how this proliferation is associated with varying amounts of mass of urine within the bladder. Parameters are estimated from published data and analytical and numerical results are presented. The relationships between the proliferation of bacteria within the bladder and the type of urinal out flux from the bladder are examined. The proliferation is shown to depend on the amount of mass of urine and the out flux of urine from the bladder. In the normal situation the bladder is drained successfully which also drains the bacteria. In the abnormal situation the bladder drains only partly. Despite frequent urination, substantial urine mass in the bladder on the average allows bacteria to proliferate and increase in number through time. The simulations depend on the numerical values of the parameters which again depend on the prostate condition of each male adult under scrutiny. By determining the parameters for each male, the dynamic model can be used as a powerful tool by which the proliferation of bacteria in the bladder can be studied and controlled by different means. Three clinical advices are provided. First, try to achieve that the proliferation rate of bacteria in the bladder is as small as possible, e.g. through altering the pH or chemical composition within the bladder. Second, try to achieve that the out flux of urine from the bladder is substantial, through sufficient drinking. Third, try to achieve that the mass of urine in the bladder is as small as possible, through sufficient urination. The intrinsic parameters for each male can be used to pinpoint the actual out flux during a day necessary to keep the number of bacteria in the bladder low. Suggestions for how to test the model are briefly presented.

Bacteria↗