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L Rosso

Publications and source records attributed to L Rosso.

28 records · Page 2Linked to original sources
PubMed1997

A descriptive model for the kinetics of a homogeneous fluorometric immunoassay.

A descriptive mathematical model was chosen to fit the antigen-antibody association kinetics of a new homogeneous immunometric assay for prolactin, involving time-resolved fluorescence detection (TRACE technology, Time Resolved Amplified Cryptate Emission). We paid special attention to the methodology and criteria applied, to yield a convenient and statistically valid model, designed to allow potential exploitation of kinetic information in the data processing of the assay. We compared specific parameterizations of an hyperbolic model, the Gompertz, and the monomolecular models on the basis of morphological considerations, a statistical analysis of fit, and an assessment of the parameters estimation quality, over a wide range of antigen concentrations. The monomolecular model gave the best fit, and the most precise and stable estimation of its parameters. The study of parameter properties confirmed this choice.

Antigens↗
PubMed1996

The particular behaviour of Listeria monocytogenes under sub-optimal conditions.

Listeria monocytogenes is a ubiquitous pathogenic microorganism which has been described as growing at temperatures of interest to food production and especially at low temperatures (-2 degrees to 8 degrees C) in storage process. However, the general relationship between the maximum specific growth rate, mumax and temperature has not often been studied for L. monocytogenes in the whole temperature range from minimal to maximal growth temperature. A global analysis of this relationship for temperatures between -2 degrees C and 42 degrees C was therefore done. The global shape of this relationship was that usually observed for microorganisms, especially in the neighbourhood of the optimal temperature, Topt. But a more detailed study showed the existence of a so-called "change temperature", occurring between 10 degrees and 15 degrees C, below which L. monocytogenes grows faster than one would expect. This implies that the minimal growth temperature of both studied strains of L. monocytogenes is lower than expected.

Cold Temperature↗
PubMed1995

Accuracy of microbial growth predictions with square root and polynomial models.

The results of growth predictions using square root and polynomial models published in 14 papers were studied. Errors on quantities of practical interest such as lag time, generation time or the time required to reach a given increase in number of cells, are analyzed. The distribution of these errors was examined with the perspective of the practical use of predictive models in food industry. Highly unsafe predictions and significant average errors were observed in some cases. A good knowledge of predictive models accuracy seems essential for their efficient and safe use, for example to predict the shelf life of a product. Yet, authors generally gave no pragmatic information on such things as the average relative error or the range of errors on predicted variables. Problems of robustness of models when tested in different conditions were noticed, which corroborates the necessity of a systematic validation of models on new data.

Bacteria↗
PubMed1995

The effect of incubation temperature and sodium chloride concentration on the growth kinetics of Vibrio anguillarum and Vibrio anguillarum-related organisms.

The effect of temperature and NaCl concentration on the growth kinetics of Vibrio anguillarum and V. anguillarum-related (VAR) strains was studied. For one wild VAR strain, NaCl concentration interfered with growth temperature parameters, in particular, with the maximum growth temperature but also with the optimum temperature (defined as the temperature at which mumax equals its maximal value muopt), and with muopt itself. For the same strain, optimal growth required the adding of NaCl to the medium to a final concentration of 1.5%. These results were not confirmed by tests on a V. anguillarum collection strain. When the NaCl concentration in the culture media was 1.5%, the optimum temperature for the nine strains studied ranged from 29.7 degrees C to 34 degrees C whereas the maximum temperature ranged between 35.3 degrees C and 38.5 degrees C. Hence, antibiotic susceptibility testing as well as biochemical identification might be carried out at 30 degrees C in the presence of 1.5% NaCl, which corresponded to a suboptimal growth.

Animals↗
PubMed1995

Convenient Model To Describe the Combined Effects of Temperature and pH on Microbial Growth.

A new model in which the maximum microbial specific growth rate ((mu)(infmax)) is described as a function of pH and temperature is presented. The seven parameters of this model are the three cardinal pH parameters (the pH below which no growth occurs, the pH above which no growth occurs, and the pH at which the (mu)(infmax) is optimal), the three cardinal temperature parameters (the temperature below which no growth occurs, the temperature above which no growth occurs, and the temperature at which the (mu)(infmax) is optimal), and the specific growth rate at the optimum temperature and optimum pH. The model is a combination of the cardinal temperature model with inflection and the cardinal pH model (CPM). The CPM was compared with the models of Wijtzes et al. and Zwietering et al. by using previously published data sets. The models were compared on the basis of the usual criteria (simplicity, biological significance and minimum number of parameters, applicability, quality of fit, minimum structural correlations, and ease of initial parameter estimation), and our results justified the choice of the CPM. Our combined model was constructed by using the hypothesis that the temperature and pH effects on the (mu)(infmax) are independent. An analysis of this new model with an Escherichia coli O157:H7 data set showed that there was a good correspondence between observed and calculated (mu)(infmax) values. The potential and convenience of the model are discussed.

Journal Article↗
PubMed1995

[Role of slime in the pathogenesis of pulmonary infections].

Microorganisms have proved to produce an amorphous substance that adheres to surfaces of several medical devices like intravenous catheters and endotracheal tubes. We investigated the presence of slime in endotracheal tubes in our Intensive Care Unit (ICU) in 12 patients. We found in this study no correlation between the strain of bacteria on the surface of endotracheal devices and those responsible for pneumonia.

Adult↗
PubMed1993

An unexpected correlation between cardinal temperatures of microbial growth highlighted by a new model.

A new model for the prediction of microbial-specific growth rate as a function of temperature is presented. The four parameters of this model are the three cardinal temperatures (Tmax, Tmin and Topt) and the specific growth rate at the optimum temperature (mu opt). A comparison with three other models was made on the basis of several criteria (simplicity and biological significance of parameters, applicability, quality of fit, minimum structural correlations and ease of determination of parameters). A detailed comparison of a 217-point data set, and an extensive comparison of 47 different data sets show that the new model is better than its competitors. The three cardinal temperatures were found to be independent of mu opt. A very strong and unexpected linear correlation between the cardinal temperatures was observed. The consequences of this biological result are discussed, even though causes remain unknown.

Bacteria↗
PubMedDate not supplied

Endoscopic ultrasonography for preoperative staging of gastric carcinoma.

BACKGROUND/AIMS: To assess the accuracy and limitation of endoscopic ultrasonography in preoperative staging of gastric cancer, we performed a prospective study on 99 patients. MATERIAL AND METHODS: Ninety-nine patients with gastric cancer had preoperative staging with endoscopic ultrasound (EUS) and CT. RESULTS: The depth of infiltration (T parameter) was correctly defined by EUS in 58/65 patients (89%). The lymph node involvement (N parameter) was correctly classified in 44/65 patients (68%), the sensitivity was 74% and the specificity was 54%. The most frequent cause of understaging T parameter was microscopic tumor invasion, whereas overstaging was due to peri-tumor inflammation. CONCLUSIONS: We believe that EUS is a reliable method, superior to all diagnostic tools, in the evaluation of locoregional extension of gastric cancer.

Endosonography↗