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At least 1,225 records · Page 68Linked to original sources
PubMed2000

Predictive models of the combined effects of curvaticin 13, NaCl and pH on the behaviour of Listeria monocytogenes ATCC 15313 in broth.

Thirty-three strains of Listeria monocytogenes belonging to different serotypes were tested for their sensitivity to curvaticin 13, an antilisterial bacteriocin produced by Lactobacillus curvatus SB13, using the well diffusion method in Institut Pasteur agar plates at 37 degrees C. No relationship between serotype and sensitivity was observed. The sensitivity of this species was strain-dependent and a large variation in tolerance to curvaticin 13 was observed. The combined effects of curvaticin 13 (0-160 AU ml-1), NaCl (0-6% w/v), pH values (5.0-8.2) and incubation time (0-24 h) were investigated on L. monocytogenes ATCC 15313 in trypcase soy-yeast extract broth at 22 degrees C. For this study, two Doehlert matrices were used in order to investigate the main effects of these factors and their different interactions. The results were analysed using the Response Surface Methodology. Curvaticin 13 had a major inhibitory effect and the response was NaCl concentration-, time- and pH-dependent. This inhibitory activity was the same at pH values between 6.6 and 8.2. Curvaticin 13 was bactericidic at acidic pH values, but the surviving cells resumed growth. For a short incubation time (12 h), the effectiveness of curvaticin 13 was maximal in the absence of NaCl. For longer incubation times (12-48 h), with high NaCl (6%) and curvaticin 13 concentrations (160 AU ml-1), the inhibition of L. monocytogenes was greater than that observed with NaCl or curvaticin 13 alone.

Bacteriocins↗
PubMed2001

Evaluation of a predictive model for implant surface topography effects on early osseointegration in the rat tibia model.

STATEMENT OF PROBLEM: Alterations in commercially pure titanium (cp Ti) implant surface topography can be made to increase bone formation or the interfacial shear strength of bone at the functioning implant. It is not known whether these 2 goals are congruent or mutually exclusive. PURPOSE: The aim of this study was to determine the effect of implant surface topography parameters of calculated biomechanical significance on the process of bone formation in a rat tibia model of osseointegration. MATERIAL AND METHODS: Implants (cp Ti grade IV) were machined and subsequently treated by grit blasting or grit blasting and 6.4 mol/L HCl. Measurements of surface roughness were made by atomic force microscopic analysis of similarly treated titanium disks. Cleaned and sterilized implants (12 machined, 12 with nonideal pit morphology, 12 with ideal pit morphology) were placed into the tibiae of 400-g male Wistar rats by using a series of drills, irrigation, and a self-tapping procedure. After 3 weeks, tibiae were harvested and processed and embedded in methyl methacrylate resin. Polished sections were examined by backscatter electron microscopy, and the percentage implant surface contacting bone was measured with the Scionics PC image analysis program. RESULTS. The implants possessing a proposed ideal pit morphology supported significantly greater bone formation at the implant surface (54% +/- 7% bone-to-implant contact [P<.003]) than the nonideal pit morphology (40% +/- 15%) or machined surfaces (34% +/- 6%). CONCLUSION: Implant surfaces with a proposed ideal pit morphology (which possess a calculated biomechanical significance) enhanced bone formation at early periods after placement in the rat tibia model.

Animals↗
PubMed2006

Developing a predictive model for vertigo using demographic and laboratory data: An evidence-based medicine approach.

CONCLUSION: The approach described in this paper may be helpful in establishing an early-warning, evidence-based mechanism for diagnosing vertigo, which can be utilized in medical education to reduce medical uncertainty. OBJECTIVE: To use an evidence-based medicine approach to evaluate the probability of having vertigo using laboratory and demographic data. MATERIAL AND METHODS: The study was conducted on 22 working days during July 2002. Targeted cases who visited a general hospital in southern Taiwan for routine physical examinations were asked to participate in the study and agreed to take additional tests during their visits. A total of 200 subjects were systematically and randomly selected from this data pool. We ran binary logistic regression on all these cases. RESULTS: The logistic regression model explained 71.3% of the variance in having vertigo or not. The equation for having vertigo was as follows: -21.855 + (1.132 x male gender) + (0.071 x age) + (-0.023 x systolic blood pressure) + (0.057 x diastolic blood pressure) + (0.048 x fasting glucose) + (0.051 x cholesterol) + (-0.005 x triglycerides) + (-0.361 x presence of cardiovascular diseases).

Adult↗
PubMedDate not supplied

Exposure to tetrachloroethylene via contaminated drinking water pipes in Massachusetts: a predictive model.

A computer model was developed to estimate exposure to tetrachloroethylene leaching from drinking-water pipes in Massachusetts between 1968 and 1979. The model was to be used for an epidemiologic study of cancer in five communities in Massachusetts. This model assigned a relative cumulative exposure score to each individual participant in the study, based on the geometry, size, age, and water flow through the water pipe that supplied a particular household and on the individual's duration of residence in that household. The results of modeling showed a wide range of exposure levels among the study participants. The epidemiologic study is described in the accompanying paper by Aschengrau et al.

Computer Simulation↗
PubMed2003

Enhanced desorption of phenanthrene from soils using hydroxypropyl-beta-cyclodextrin: experimental results and model predictions.

Objective of this study was to evaluate the effects of hydroxypropyl-beta-cyclodextrin (HPCD) on the removal of phenanthrene from solid phase. Batch tests for the phenanthrene distribution between aqueous and solid phase were conducted in the presence of HPCD. Column tests and numerical simulations were conducted to evaluate the roles of HPCD cavities and interaction rates between water, HPCD, and solid phase in the enhanced removal of phenanthrene. Experimental results showed that HPCD was effective in removing sorbed phenanthrene from subsurface environment, primarily due to its negligible sorption to the solid phase and the partitioning of phenanthrene into HPCD cavities. From the numerical simulations, it was found that rate-limited partitioning of phenanthrene into HPCD cavities was most influential factor in the enhanced elution of phenanthrene. Sorption and desorption rate of phenanthrene between aqueous and solid phase was very fast or near equilibrium state. Interaction rates of contaminant between water, HPCD, and solid phase could be affected by other factors such as soil types and organic matter contents. Results from this study implied that HPCD flushing could be effectively applied for the removal of hydrophobic organic pollutants existing in the soils as sorbed or NAPL state.

2-Hydroxypropyl-beta-cyclodextrin↗
PubMed2003

Total body protein: a new cellular level mass and distribution prediction model.

BACKGROUND: Protein is an important body component, and the presently accepted criterion method for estimating total body protein (TBPro) mass--in vivo neutron activation (IVNA) analysis--is unavailable to most investigators and is associated with moderate radiation exposure. OBJECTIVE: The objective was to derive a theoretical cellular level TBPro mass and distribution model formulated on measured total body potassium, total body water, and bone mineral and to evaluate the new model with the IVNA method as the criterion. DESIGN: The new model was developed on the basis of a combination of theoretical equations and empirically derived coefficients. TBPro mass estimates with the new model were evaluated in healthy women (n = 183) and men (n = 24) and in men with AIDS (n = 84). Total body nitrogen was measured by IVNA, total body potassium by whole-body (40)K counting, total body water by tritium dilution, and bone mineral by dual-energy X-ray absorptiometry. RESULTS: The group mean (+/- SD) TBPro mass estimates in healthy women and men and men with AIDS (8.2 +/- 0.9, 11.0 +/- 1.8, and 10.5 +/- 1.1 kg, respectively) with the new model were similar to IVNA criterion estimates (8.9 +/- 0.9, 11.1 +/- 1.6, and 10.9 +/- 1.2 kg, respectively). TBPro mass estimates with the new model correlated highly with the IVNA estimates in all subjects combined (r = 0.92, P < 0.001). The new model suggests that the composite TBPro mass within each group consists mainly of cellular protein (75-79%) and, to a lesser extent, protein in extracellular solids (19-23%) and extracellular fluid (approximately 2%). CONCLUSION: The new model provides a non-IVNA approach for estimating protein mass and distribution in vivo.

Absorptiometry, Photon↗
PubMed1997

An iterative algorithm for converting a class II MHC binding motif into a quantitative predictive model.

Biochemists and molecular biologists have suggested motifs for characterizing the binding of peptide fragments and class II major histocompatibility complex (MHC) molecules based on laboratory results and crystal structures. The iterative algorithm presented here converts a suggested motif into a quantitative data-based model. The database accessed consists of peptide fragments known to bind or not bind to class II MHC molecules of particular haplotypes. Stepwise discriminant analysis is utilized to increase or decrease motif coefficients until the resulting motif classifies all binders and non-binders correctly. Stepwise discriminant analysis is a standard multivariate statistical procedure and is available in comprehensive commercial statistical packages. Program 7M of BMDP Statistical Software was used in this study.

Algorithms↗
PubMed2006

A predictive model for identifying proteins by a single peptide match.

MOTIVATION: Tandem mass-spectrometry of trypsin digests, followed by database searching, is one of the most popular approaches in high-throughput proteomics studies. Peptides are considered identified if they pass certain scoring thresholds. To avoid false positive protein identification, > or = 2 unique peptides identified within a single protein are generally recommended. Still, in a typical high-throughput experiment, hundreds of proteins are identified only by a single peptide. We introduce here a method for distinguishing between true and false identifications among single-hit proteins. The approach is based on randomized database searching and usage of logistic regression models with cross-validation. This approach is implemented to analyze three bacterial samples enabling recovery 68-98% of the correct single-hit proteins with an error rate of < 2%. This results in a 22-65% increase in number of identified proteins. Identifying true single-hit proteins will lead to discovering many crucial regulators, biomarkers and other low abundance proteins. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

Algorithms↗
PubMed2000

Comparative pharmacodynamics of moxifloxacin and levofloxacin in an in vitro dynamic model: prediction of the equivalent AUC/MIC breakpoints and equiefficient doses.

To demonstrate the impact of the different pharmacokinetics of moxifloxacin and levofloxacin on their antimicrobial effects (AMEs), killing and regrowth kinetics of two clinical isolates of Staphylococcus aureus and one each of Escherichia coli and Klebsiella pneumoniae were studied. With each organism, a series of monoexponential pharmacokinetic profiles of single doses of moxifloxacin (T:1/2 = 12.1 h) and levofloxacin (T:(1/2) = 6.8 h) were simulated. The respective eight-fold ranges of the ratios of area under the concentration-time curve (AUC) to the MIC were 58-475 and 114-934. Species- and strain-independent linear relationships observed between the intensity of AME (I:(E)) and log AUC/MIC were not superimposed for moxifloxacin and levofloxacin (r(2) = 0.99 in both cases). The predicted AUC/MIC ratios for moxifloxacin and levofloxacin that might be equivalent to Schentag's AUC/MIC breakpoint for ciprofloxacin (125) were estimated at 80 and 130, respectively. The respective equivalent MIC breakpoints were 0.41 mg/L (for a 400 mg dose of moxifloxacin) and 0.35 mg/L (for a 500 mg dose of levofloxacin). Based on the I:(E)-log AUC/MIC relationships, equiefficient 24 h doses (D:(24)s) of moxifloxacin and levofloxacin were calculated for hypothetical strains of S. aureus, E. coli and K. pneumoniae with MICs equal to the respective MIC50s (weighted geometric means of reported values). To provide an 'acceptable' I:(E) = 200 (log cfu/mL)*h, the D:(24)s of moxifloxacin for all three organisms were much lower (150, 30 and 60 mg, respectively) than the clinically proposed 400 mg dose. Although the usual dose of levofloxacin (500 mg) would be in excess for E. coli and K. pneumoniae (D:(24) = 36 and 220 mg, respectively), it might be insufficient for S. aureus (the estimated D:(24) = 850 mg). Moreover, to provide the same effect as a 400 mg D:(24) of moxifloxacin against staphylococci, levofloxacin would have to be given in a 5000 mg D:(24), which is 10-fold higher than its clinically accepted dose. The described method of generalization of data obtained with specific organisms to other representatives of the same species might be useful to predict the AMEs of new quinolones.

Anti-Infective Agents↗
PubMed1994

Predictive modelling of the 3-D structure of interleukin-13.

Several atomic structures are now available for the family of helical cytokines, which includes growth hormone as well as many of the interleukins. Using structural information from five members of this family, two alternative models of interleukin (IL)-13 are proposed. IL-13 has biological properties similar to those of IL-4 and, like the other interleukins, is a potentially important pharmaceutical target. The model of IL-13 is discussed and compared with the known interleukin structures.

Amino Acid Sequence↗
PubMed1981

Outcome of intensive care. An application of a predictive model.

The development of a scoring system to estimate equivalency of illness between individuals has been undertaken. A model has been formulated to calculate probability of survival from each of 225 potential "conditions" apt to occur in patients admitted to intensive care areas. The presence or absence of each factor was noted on admission to a university hospital ICU. The relation between conditions noted in observations on a sample of patients, and survival allows assignment of a weight to each complication on the basis of which a "Condition Index Score" (CIS) or prognosis index can be objectively calculated. Potential uses of CIS are to: (1) establish objective criteria for admission to and discharge from intensive care, and for transfer to tertiary care centers; (2) compare quality of care (outcome vs. CIS) between different intensive care facilities; (3) serve as basis for multi-institutional studies concerning critically ill patients; (4) compare outcomes in groups of patients with equal CIS who are and are not treated in ICUs; and (5) establish appropriate numbers of critical care beds for any hospital or area by CIS criteria.

Critical Care↗
PubMed1983

Radon daughter plateout--II. Prediction model.

By a linear programming procedure, we have optimized the Jacobi room model to fit our data on the partitioning of radon daughters between air and wall surfaces (plateout), obtained at high radon concentrations in a small chamber. Subsequently, the optimized model yielded estimates that compared well with plateout data obtained at lower concentrations in a room-sized chamber. (The experimental work is described separately.) The major change made in the Jacobi model was to reduce the deposition velocity of free airborne radon daughters from 1 to 0.05 cm/sec. This value was obtained by using a fast algorithm to solve the linear programming to arrive at the "best fit". Lesser changes were made in other parameters.

Air↗