Modelling the effect of a heat shock and germinant concentration on spore germination of a wild strain of Bacillus cereus

The effect of different concentrations of L-alanine on the germination kinetics of a strain of Bacillus cereus isolated from liquid egg after heat shock during sporulation was studied. Germination at 30 degrees C and was followed by spectrophotometry. The higher the concentration of L-alanine within the range 100-1 mM the faster was the germination obtained. On the other hand, the application of a heat shock had an effect on the germination producing a diminution on the germination kinetic rates. The Weibull distribution function, a model that has been used for describing inactivation kinetics , was used for modelling germination experimental data. Results indicated that the Weibull distribution function model produced a good description of experimental data.

Quality and Safety Aspects of PEF Application in Milk and Milk Products

The articles published to date on the possibilities of applying the new PEF technology to milk and milk products are summarized in a review that presents them in chronological order and grouped on the basis of the factor studied (microorganism, enzyme, quality parameter, or shelf-life). An accompanying table shows details of the equipment and process corresponding to each article in chronological order.

Variation of the spore population of a natural source strain of Bacillus cereus in the presence of inosine

The heat resistance of a wild strain of Bacillus cereus spores isolated from liquid egg was characterized, and the effect of the nutritional germinant inosine on the spore population was then studied, considering different factors such as germination temperature, inosine concentration, and age of spore culture. The heat resistance clearly indicates that these spores can survive mild heat treatments such as those used for cooked refrigerated food of extended durability or liquid egg, posing safety problems for these foods with temperature abuse. The germination study indicates that temperature, spore age, and the interaction between the two were the factors affecting the level of spores remaining after the germination process. No significant differences were found for the three inosine concentrations used in the study (1, 5, and 10 mM). The highest reduction in the spore concentration was reached at 30 degrees C after 120 min, although the reduction in the spore counts at germination temperatures of 4 and 8 degrees C was also considerable.

[Gastrointestinal bleeding after endoscopic treatment of polypoid hamartoma (adenoma of Brunner's glands)]

The incidence of polypoidal tumors in the duodenum is scarce and Brunner's gland tumors represent 11% of these proliferations. Brunner's gland polypoid hamartoma or adenoma is a highly infrequent benign polypoid proliferation of Brunner's glands that is usually asymptomatic, although gastrointestinal bleeding or intestinal obstruction may sometimes occur. We present the case of a woman with an incidental diagnosis of duodenal polypoid hamartoma. The lesion was resected with polypectomy loop and at 48 h, the patient presented gastrointestinal bleeding as a complication. We describe the endoscopic treatment of the lesion and this complication.

Pectin methyl esterase and natural microflora of fresh mixed orange and carrot juice treated with pulsed electric fields

The effects of pulsed electric fields (PEFs) on pectin methyl esterase (PME), molds and yeast, and total flora in fresh (nonpasteurized) mixed orange and carrot juice were studied. The PEF effect was more extensive when juices with high levels of initial PME activity were subjected to treatment and when PEF treatment (at 25 kV/cm for 340 micros) was combined with a moderate temperature (63 degrees C), with the maximum level of PME inactivation being 81.4%. These conditions produced 3.7 decimal reductions in molds and yeast and 2.4 decimal reductions in total flora. Experimental inactivation data for PME, molds and yeast, and total flora were fitted to Bigelow, Hülsheger, and Weibull inactivation models by nonlinear regression. The best fit (lowest mean square error) was obtained with the Weibull model.

Weibull distribution function based on an empirical mathematical model for inactivation of Escherichia coli by pulsed electric fields

The pulsed electric field inactivation kinetics of Escherichia coli suspended in orange juices with three different concentrations of carrot juice (0, 20, and 60%) was studied. Electric field strengths ranged from 25 to 40 kV/cm, and treatment times ranged from 40 to 340 micros. Experimental data were fitted to Bigelow, Hülsheger, and Weibull distribution functions, and the Weibull function provided the best fit (with the lowest mean square error). The dependency of each model's kinetic constant on electric field strength and carrot juice concentration was studied. A secondary model was developed to describe the relationship of Weibull parameters a and n to electric field strength and carrot juice concentration. An empirical mathematical model based on the Weibull distribution function, relating the natural logarithm of the survival fraction to treatment time, electric field strength, and carrot juice concentration, was developed. Parameters were estimated by a nonlinear regression. The results of this study indicate that the error rate for the model's predictions was 6.5% and that the model was suitable for describing E. coli inactivation.

Kinetic model for the inactivation of Lactobacillus plantarum by pulsed electric fields

The kinetics of Lactobacillus plantarum inactivation by pulsed electric fields (PEF) was studied in two different growth stages (exponential and stationary), but in the same reference medium (0.6% peptone water). Electric field intensity and treatment time varied from 20 to 28 kV/cm and 30 to 240 micros, respectively. The experimental data showed that cells in the exponential growth stage were more sensitive to PEF treatment than those in the stationary stage. The inactivation data were adjusted to the Bigelow and Hülsheger models and the Weibull frequency distribution function, and constants were calculated for both growth stages in each model. The models were tested and their accuracy was assessed by using the Accuracy Factor. According to this parameter, the Weibull frequency distribution function gave better fittings for the inactivation by PEF than Bigelow or Hülsheger models. On the other hand, the Bigelow model gave a good accuracy factor and is simpler.

Use of polarography as a quality-control method for determining diacetyl in citrus and vegetable juices, yoghurt and butter

The determination of diacetyl permits the detection of microbial growth in the processing of citrus fruit before the appearance of other organoleptic, chemical or microbiological changes. It also makes it possible to detect a break in the cold chain during distribution and sale. The study proposed a polarographic method for the determination of diacetyl that allowed routine analysis with the aim of detecting possible contamination in the citrus juice manufacturing chain (orange and orange-carrot). The analytical performance of the method in terms of a linearity from 0 to 960 microg ml(-1), a recovery of 97 to 98%, a precision of 3.2 to 4.8%, and a sensitivity of 0.2 ng ml(-1) for juices indicated the robustness of the method. The same method was also applied to butter and yoghurt with detection limits of and 0.4 ng g(-1).

Modeling the combined effect of pH and temperature on the heat resistance of Bacillus stearothermophilus spores heated in a multicomponent food extract

The combined effect of pH and temperature on the heat resistance of Bacillus stearothermophilus spores heated in an extract of complex food was studied. The results showed that, in general, reducing the pH reduced the heat resistance of the spores. Similarly, the value for the D parameter in the nonacidified extract was between 30 and 70% lower than the one obtained with double-distilled water. This result once again shows the importance of the substrate in inactivation studies of microorganisms. The experimental data were used to carry out a comparison of two predictive mathematical models of inactivation, one based on a multiparametric regression obtained in this study and the other obtained from the bibliography and based on a linear-Bigelow equation. Both models predict reasonably well, although the multiparametric model presented a slightly better accuracy factor (1.11) than the one obtained with the linear-Bigelow equation (1.13).

Circulating and mitogen-induced tumor necrosis factor (TNF) in malnourished children

Malnutrition in children is associated with an increased risk of infection and death. Multiple abnormalities in the inflammatory-immune response, including cytokine production, have been described in protein energy malnourished (PEM) children and could account for increased severity and frequency of infection. The aim of the present study was to determine whether there are abnormal basal tumor necrosis factor (TNF) serum concentrations in PEM children, to relate it with serum cortisol and plasma corticotrophin levels and to explore simultaneously the in vitro production of TNF by peripheral blood leukocytes (PBL). No differences were found in basal plasma corticotrophin and serum cortisol concentrations in malnourished as compared with normal, well-nourished control children. Basal TNF serum concentrations were significantly higher in malnourished children than in controls. Conversely, mitogen induced TNF production by PBL in vitro was significantly reduced in PEM children compared with controls. Abnormalities in circulating and mitogen-induced TNF production are present in malnourished children even in absence of elevated serum cortisol concentrations. These abnormalities potentially could modify inflammatory-immune responses to infectious stimuli in malnourished children.

Study of inactivation of Lactobacillus plantarum in orange-carrot juice by means of pulsed electric fields: comparison of inactivation kinetics models

The inactivation kinetics of Lactobacillus plantarum was studied in orange-carrot juice using high intensity pulsed electric fields. The results indicated that under the treatment conditions applied, 28.6, 32.0, and 35.8 kV/cm and treatment times ranging from 10.2 to 46.3 micros, the inactivation of L. plantarum obtained was up to 2.5 decimal reductions. Experimental and literature data were fitted to Bigelow, Hülsheger et al. and Peleg models and to Weibull frequency distribution function. Weibull was the one that best interpreted the data with accuracy factor values closer to 1.

Effect of acidification and oil on the thermal resistance of Bacillus stearothermophilus spores heated in food substrate

The effect of the addition of vinegar and/or oil to a food homogenate (tomato sauce, tuna and vegetables) on the thermal resistance of Bacillus stearothermophilus spores was studied. The results indicated that the food substrate without the addition of vinegar and oil and a pH value of 5.28 reduced the thermal resistance of B. stearothermophilus spores compared with that obtained in double-distilled water, (D121 = 1.41 and 3.08 min respectively). The addition of vinegar reduced the pH of the substrate (4.81) and consequently the D values were reduced (D121 = 1.28 min). The addition of soya oil and vinegar to substrate until a pH of 4.81, further reduced the thermal resistance of the spores, giving a D121 value of 0.93 min.

Immunodeficiency associated with anorexia nervosa is secondary and improves after refeeding

Several studies have addressed the question of starvation effects on immune function by means of changes in lymphocyte subsets, cytokine induction or lymphocyte activation. Anorexia nervosa (AN) patients are severely malnourished and contradictory results have been obtained regarding the accompanying immunodeficiency, including its assignation as a part of the primary nervous disorder. In the present work, an extensive immunological function examination was carried out on 40 AN patients who were compared with a control group of 14 healthy girls. The AN patients were also classified according to their nutritional status (by the Body Mass Index: BMI), this being critical for a better understanding of these secondary immunodeficiency bases. Moreover, another immune system study was performed on five patients after refeeding. Lymphocyte subsets and function, cytokine induction and peripheral blood concentrations, and innate as well as humoral immunity were evaluated. Deregulation in the cytokine network, owing to the interaction of the central nervous (CNS) and immune systems, seems to be the initial immune alteration in AN immunodeficiency but it has not been disproved that the immunodeficiency is a direct consequence of the original psychiatric perturbation. Spontaneous high levels of circulating interleukin-1beta (IL-1beta) and tumour necrosis factor-alpha (TNF-alpha) have been observed; this is probably one of the causes of the anomalies found in the T-cell subpopulations (mainly the naive CD4+CD45RA+ reduction and the cytotoxic CD8+ increase) and T-cell activation status (mainly the down-regulation of the CD2 and CD69 activation pathways). This finally leads to an impairment, not only in T-cell function but also in T-cell to B-cell co-operation. The AN specificity of these results is confirmed by the fact that these immune alterations improve after refeeding and when nutritional status becomes less critical, which also suggests that AN immunodeficiency is indeed secondary to malnutrition.

[Electromyographic diagnosis of 772 patients in the Móstoles Hospital]

INTRODUCTION AND OBJECTIVE

There are few references in the literature to demographic data of the disorders most frequently studied by electromyography. Our objective was to obtain a demographic description of the patients usually sent to us for electromyographic studies.

MATERIAL AND METHODS

Descriptive and analytical assessment was done of 914 electromyographic diagnoses seen in a sample of 722 patients sent to Mostoles Hospital, referral centre of Health District VIII of the Community of Madrid with an estimated population of 407,836 inhabitants, for conventional electroneurographic and electromyographic studies between May 1995 and February 1996. We recorded data regarding electromyographic diagnosis, localization, intensity, whether the study was for diagnostic purposes or follow-up, medical centre referring the patient, medical speciality sending the patient, clinical impression, age and sex.

RESULTS

The commonest pathology seen was carpal trapping of the median nerve, both in men and in women (three times more frequent in women). There was an estimated incidence of 136 cases per year per 100,000 women and 36 cases per year per 100,000 men (most frequent in patients aged 20-70, with a maximum frequency in those in their fifties). There was marked right sided predominance. The commonest pathology in men was polyneuropathy, with an estimated incidence of 80 cases per 100,000 men and 72 cases per 100,000 women. This was the commonest diagnosis in the patients aged over 70. Mononeuropathy of the legs was most commonly seen in men and in the first twenty years of life.