Reflections on the use of robust and least-squares non-linear regression to model challenge tests conducted in/on food products.

In this research, we question the straight-forward use of the classical sum of squared error criterion for identifying the typical parameters of a primary model (like growth rate mumax and lag time lambda) when applied to growth curves obtained in and on food products. Firstly, we base our reflections on 62 Listeria monocytogenes laboratory challenge tests collected in various environments (broth, crushed cold-smoked salmon, and surface of cold-smoked salmon slices). Whereas growth data in broth resulted in residual values consistent with a Gaussian distribution, growth data in the crushed product and even more on the surface of slices appeared different.

Uncertainty distribution associated with estimating a proportion in microbial risk assessment.

The uncertainty associated with estimates should be taken into account in quantitative risk assessment. Each input's uncertainty can be characterized through a probabilistic distribution for use under Monte Carlo simulations. In this study, the sampling uncertainty associated with estimating a low proportion on the basis of a small sample size was considered.

Putative physiological significance of vasopressin V1a receptor activation in rat pituicytes.

Physiological stimuli operative during, for example, dehydration or lactation, induce neurohypophysial astrocytes (pituicytes) to undergo reversible morphological changes, which in turn may modulate the release of vasopressin and oxytocin. To study the molecular mechanisms of this morphological plasticity, we used primary cultures of rat pituicytes. During stimulation with adenosine, pituicytes become stellate, which is characterized by a round, phase-bright soma and complex arborization, implying major cytoskeletal modifications.

Vasopressin-induced taurine efflux from rat pituicytes: a potential negative feedback for hormone secretion.

Previous work on the whole neurohypophysis has shown that hypotonic conditions increase release of taurine from neurohypophysial astrocytes (pituicytes). The present work confirms that taurine is present in cultured pituicytes, and that its specific release increases in response to a hypotonic shock. We next show that vasopressin (VP) and oxytocin (OT) also specifically release taurine from pituicytes.

Diagnosis of complete mainstem bronchus avulsion by 3-dimensional spiral CT scan of the chest.

Tracheobronchial injury (TBI) after blunt trauma of the chest is a rare life-threatening entity that can be successfully managed by surgery if there is an early diagnosis. A 18-year-old man was injured in a motocycle accident. Three consecutive flexible bronchoscopies risulted negative for tracheo-bronchial lesions.

Autocrine inhibitory influences of alpha-melanocyte-stimulating hormone in malignant pleural mesothelioma.

Malignant pleural mesothelioma is a highly aggressive tumor arising from the mesothelial cells that line the pleural cavities. This tumor is resistant to most conventional anticancer treatments and appears to be very sensitive to growth-promoting influences of cytokines and growth factors. Identification of natural inhibitory pathways that control growth should aid discovery of novel therapeutic approaches.

Correlation between perioperative blood transfusion and prognosis of patients subjected to surgery for stage I lung cancer.

Background: It has been reported, but not proven, that perioperative blood transfusions have a detrimental effect on the survival of patients undergoing surgery for lung cancer.

Study Design: and methods: A prospective study was carried out on the patients undergoing lobectomy for stage I lung cancer at our department from 1995 to 2000. The criteria for exclusion included previous cases of malignancy, autoimmune diseases, and any other relevant comorbidity.

Vasopressin and oxytocin reverse adenosine-induced pituicyte stellation via calcium-dependent activation of Cdc42.

In view of the potential impact of pituicyte morphology on neurohypophysial hormone secretion, we have studied the mechanisms involved in the shape changes induced by vasopressin (AVP) and oxytocin (OXT) in cultured rat pituicytes. Pituicytes induced to become stellate in the presence of 10 micro m adenosine revert to their nonstellate shape approximately 20 min after application of AVP or OXT. The IC50 for this effect is 0.

Role of (99m)tc-hexakis-2-methoxy-isobutylisonitrile in the diagnosis and staging of lung cancer.

Background: Preliminary studies have shown that (99m)Tc-hexakis-2-methoxyisobutylisonitrile (MIBI) is an interesting tracer for various tumors. The aim of this study was to determine the feasibility of using (99m)Tc-MIBI as a diagnostic and staging procedure for lung cancer.

Methods: We prospectively compared the results of biopsy with (99m)Tc-MIBI imaging in patients with potentially resectable lung lesions (stages IIIA or lower).

RhoA inhibition is a key step in pituicyte stellation induced by A(1)-type adenosine receptor activation.

Pituicyte stellation in vitro represents a useful model with which to study morphological changes that occur in vivo in these cells during times of high neurohypophysial hormone output. This model has helped us establish the hypothesis of a purinergic regulation of pituicyte morphological plasticity. We first show that ATP induces stellation in 37% of pituicytes, an effect that is secondary to the metabolism of ATP to adenosine.

Video-assisted sleeve lobectomy for mucoepidermoid carcinoma of the left lower lobar bronchus: a case report.

We report what we believe to be the first case of video-assisted sleeve lobectomy in an adolescent girl who had experienced recurrent episodes of lobar pneumonia and received a diagnosis of low-grade mucoepidermoid carcinoma of the left lower lobar bronchus.

Pulmonary lobectomy for lung cancer: a prospective study to compare patients with forced expiratory volume in 1 s more or less than 80% of predicted.

Objective: To compare post-operative course, lung function and survival of lung cancer patients with a forced expiratory volume in 1 s (FEV1) more or less than 80% of predicted submitted to lobectomy.

Methods: The data of patients undergoing lobectomy for non small cell carcinoma at the Thoracic Surgery Unit of the Ospedale Maggiore Policlinico of Milan, Italy, were prospectively collected. Inclusion criteria were a radical resectable tumor with size less than 2.

A cardinal model to describe the effect of water activity on the growth of moulds.

A simple model was proposed to describe the effect of water activity (Aw) on the radial growth rate of moulds. This model is deduced from the cardinal model family proposed by Rosso in 1995, which is only defined from cardinal values of environmental factors (minimum, optimum and maximum values), the growth rate observed at the optimal value of the environmental factors, and n, a shape parameter. For Aw, a simple form of cardinal model is proposed.

Biological variability and exposure assessment.

Predictive models are now commonly used for exposure assessment, with growth parameters defined for each microbial species. In this study, we tried to take into account microbial growth variability among strains of a single species. Bacillus cereus in pasteurized milk was chosen to illustrate the influence of the biological variability on the outcome of exposure assessment.

A model describing the effect of temperature history on lag time for Listeria monocytogenes.

A model was built to describe the influence of the temperature and the duration of pre-incubation on the lag time for regrowth of Listeria monocytogenes at low temperature. This model is consistent with the usual procedure used to calculate lag times of cultures growing under fluctuating temperatures. It also describes the effect of prolonged starvation conditions on the regrowth lag time and takes into account the influence of the physiological state of inocula in predictive models.

Significance of inoculum size in the lag time of Listeria monocytogenes.

The lag time of Listeria monocytogenes growing under suboptimal conditions (low nutrient concentrations, pH 6, and 6.5 degrees C) was extended when the inoculum was severely stressed by starvation and the inoculum size was very small. Predictive microbiology should deal with bacterial stress and stochastic approaches to improve its value for the agro-food industry.

Estimation of temperature dependent growth rate and lag time of Listeria monocytogenes by optical density measurements.

An automated turbidimetric system, Bioscreen C, was used to monitor growth of ten strains of Listeria monocytogenes at different temperatures. Several methods for estimation of maximum specific growth rate (mu(max)) and lag time (lag) from turbidimetric data were compared to values estimated from viable count data. By using a calibration factor, reliable estimations of mu(max) could be obtained from turbidimetric measurements.

A quantitative approach for studying the effect of heat treatment conditions on resistance and recovery of Bacillus cereus spores.

When a bacterial population undergoes an unfavourable transient increase in temperature, a death phase followed by a lag and growth phase are observed for the surviving and cultivable population. The lag phase is of great interest in regard to food safety, but for bacterial spores, very few studies have been carried out on the evolution of lag time versus heat treatment duration. The experiments monitored on spores of two strains of Bacillus cereus showed a biphasic evolution of the lag time for germination of stressed spores with increase in heat treatment duration, at 90 degrees C, 95 degrees C and 100 degrees C and for different recovery conditions in laboratory medium.

A model describing the relationship between regrowth lag time and mild temperature increase for Listeria monocytogenes.

In order to comply with the consumer demand for ready-to-eat and look 'fresh' products, mild heat treatment will be used more and more in the agrofood industry. Nonetheless there is no tool to define the most appropriate mild heat treatment. In order to build this tool, it is necessary to study and describe the response of a bacterial population to a mild increase in temperature, from the dynamic point of view.

Value and limits of endorectal ultrasonography for preoperative staging of rectal carcinoma.

In rectal cancer, the depth of tumor infiltration and metastatic involvement of lymph nodes are important prognostic factors. Endosonography of the rectum, combining the advantages of both endoscopy and sonography, provides information not available from other imaging diagnostic techniques. From January 1989 to December 1997, 85 patients affected by rectal carcinoma were submitted to preoperative evaluation with endorectal ultrasonography.

Buttressing staple lines with bovine pericardium in lung resection for bullous emphysema.

The utility of buttressing an endoscopic mechanical stapler with strips of bovine pericardium in resection of pulmonary bullous areas was evaluated by comparing the duration of air leakage in two randomized patient groups, one with and one without buttressing. The duration of air leakage was not related to bulla size in either group but showed a linear relation with the radiologic emphysema score in both groups (p < 0.001) and was shorter when the stapler had been fitted with bovine pericardium, but significantly reduced (p = 0.

Gastroesophageal reflux disease. Pathogenesis, symptoms and complications.

The onset of GERD depends on several factors leading to a prolonged exposition of the esophageal mucosa to inflammatory agents. Various mechanisms play a role in different patients, but generally, decreased LES tone and delayed esophageal clearance are the major causes. Although pyrosis and regurgitation are the most frequent complaints, the patient may have different symptoms or can be asymptomatic.

Model of the influence of time and mild temperature on Listeria monocytogenes nonlinear survival curves.

Heat treatment has long been regarded as one of the most widely used and most effective means of destroying pathogens in food. Up to now the linear relationship between the death rate and the temperature has been used when choosing the best heat treatment to apply. However, the information given by this linear relationship is no longer sufficient when nonlinear survival curves are observed.

A model describing the relationship between lag time and mild temperature increase duration.

When a bacterial population undergoes an unfavourable increase in temperature for a given duration, called stress duration, a death phase followed by a lag and a growth phase are observed. The lag phase is actually of great interest in regard to foodstuff safety in choosing a suitable protocol for the detection of microorganisms which have undergone a mild heat treatment. The extension of lag time with the severity of the increase in temperature has been highlighted by previous papers.