159 research outputs found
EXPLORING LACTOBACILLUS PARACASEI PROBIOSIS AND METABOLIC POTENTIAL
No full textProbiotics have been used so far for the prevention and treatment of various medical conditions and to support general wellness: for this reason, they are currently the subject of significant microbiological and clinical research. In fact, a body of literature suggests that including probiotics in the diet can be a strategy to reduce host-related immune diseases and, in general, modulate the intestinal microbiota composition. Although the mechanisms of action of probiotics are still largely unknown, particularly at molecular level, it is well understood that they can act in different ways, through interaction with the other bacteria residing the same niche, as well as the host, at both local and systemic levels. The genus Lactobacillus, which has important industrial applications as fermented food starter and probiotic adjunct, is a taxonomically broad and heterogeneous group and includes the species Lactobacillus paracasei, which is generally associated with habitats rich in nutrients, such as dairy food and human ecosystems, like gut and vagina.
The main purpose of my PhD activity, concerned the study of two L. paracasei strains, named DG and LPC-S01, isolated from two different ecological niches (human gut and vagina, respectively). They are already available on the market, included in two products as food supplements, but their characterization is still incomplete, particularly for LPC-S01. In order to deepen the knowledge about these strains, the first part of the work focused on exploring L. paracasei DG and LPC-S01 essential characteristics to define potential probiotics, by using L. paracasei Shirota as reference strain. The comparative genomic analyses evidenced that strain LPC-S01, a bacterium isolated from human vagina, but plausibly having its origin in the gut, resulted having the genetic features of a niche-generalist member of its species. Similarly, strain DG exhibited the potential ability to adapt to a wide range of environmental conditions if compared with other strains of dairy origin. In vitro tests conventionally used to evidence probiotic properties revealed that strains LPC-S01 and DG possessed comparable ability to resist to gastro-intestinal transit, as evidenced by tolerance to bile, and to decrease NF-κB activation in Caco-2 cells, with respect to strain Shirota. Moreover, LPC-S01 displayed higher tolerance to gastric juice and higher capacity to adhere to Caco-2 epithelial cells (whereas Shirota showed inability to adhere on Caco-2-cells). The in vitro observations were confirmed by setting up a pilot intervention trial on healthy adult volunteers, that demonstrated that LPC-S01 and DG can transiently colonize the gastrointestinal tract of the host, persisting for at least 5 days after the end of a 7-days oral consumption (corresponding to an average of 7 evacuations).
Thanks to the comparative genomic analysis on L. paracasei strains DG and LPC-S01, we identified two gene clusters putatively coding for exopolysaccharides biosynthesis related enzymes. Exopolysaccharides (EPSs), apart from their industrial applications, are found to be associated with many physiological functions, although their mechanism of action has not been fully clarified yet. In collaboration with Prof. Andy Laws, University of Huddersfield (United Kingdom), the second part of the work focused on the identification of the potential EPSs matrix from both strains DG and LPC-S01, and their structural characterization. Nonetheless, in the experimental conditions tested so far, only DG resulted able to synthetize EPSs. After performing its purification, we characterized DG derived EPS repeating unit by NMR spectroscopy based approaches. DG EPS structure resulted peculiar and unique compared to those identified in other lactic acid bacteria, prompting us to investigate its immunomodulatory potential, by using it as stimulus on phagocytes. Interestingly, THP-1 macrophages were highly responsive to the EPS stimulus, particularly through the activation of COX-2 expression. Moreover, COX-2 expression was also subjected to an additive effect due to the combination of EPS with the pro-inflammatory stimulus of lipopolysaccharides (LPS). This results strongly suggest a role of DG and its secreted polysaccharidic molecule in triggering stimulatory immune responses together with the activation of protective mechanisms of the intestinal mucosa.
Starting by previous observations on other lactic acid bacteria, particularly on Lactococcus lactis, which demonstrated the ability to switch from fermentation to respiratory metabolism, and thanks to the identification of the operon cydABCD in L. paracasei, the third part of the work focused on evaluating if respiration was activated also in the strains under study. The respiratory metabolism, activated by the addition of heme and menaquinone, two essential co-factors not synthetized by the cell, typically results in two main advantages for the cell: increased biomass and long-term survival. Our preliminary data, however, indicated that only one of the two phenotypes occurred in L. paracasei, namely a very strong robustness achieved only upon addition of both heme and menaquinone, that resulted in the maintenance of viability for long periods of storage at 4° C (>200 days). The robustness phenotype was present also when the two co-factors were added during the storage time, and not during growth. This fact, along with (i) the detection of the added heme only outside the cells, (ii) the under regulation of cydA evaluated by gene expression analyses, and (iii) the decrease of ATP reservoir, suggested that the phenotype observed was not a consequence of a respiratory metabolism. Our data are instead more consistent with the presence of an external electron transfer, as already described for other intestinal bacteria. A deeper investigation is required to clarify the molecular basis of L. paracasei acquired resistance. However, our collected evidences, i.e. the robustness phenotype, can potentially be exploited in industrial applications to ameliorate the technological performances, but also in the niche colonized by the bacterium, where it can counteract environmental stresses and exert its probiotic potential by reducing and neutralizing damaging chemicals in the surrounding environment.
In conclusion, this PhD work evidenced the multiple properties of two strains belonging to L. paracasei species to colonize the human gut (and potentially the vagina) upon oral administration, and to interact with the host immune system. Moreover, L. paracasei possesses very interesting metabolic abilities that may be exploited both in in vivo conditions and in the industrial processes
When Innovation meets Tradition : the case of " Riso &Rane" Rural District in Lombardy Region
No full textLombardy, with 87.393 hectares of rice is one of the leader region for this production in Italy and in the European Union (EU) too. This area is characterized by a strong connection with tradition both in terms of agricultural landscape and food culture. Nevertheless, during the last decade, farmers faced increasing competitiveness issues, mostly related to EU subsidies losses, market prices and the technical constraints of the traditional rice supply chain: provider of technical means, farmers, brokers and rice mill. In this scenario, the “Riso e Rane” Rural District (R&RD) supports farmers in improving competitiveness through innovation. The aim of the paper is to investigate the innovation in the rice supply chain related to the specific action of R&RD, that accounts for 60 farms. Starting from the direct survey carried out on the district productive structures, we investigate the farms' degree of innovation related to the adoption of a new model of supply chain. The case study areas is characterized by rice that represents the most important culture with 2.773 hectares (more than 58% of the district Utilized Agricultural Area (UAA)). In 2012, R&RD won a regional project titled “Buono, Sano e Vicino” with the aim to help local rice farmers developing an alternative supply chain in which the district grow into the local actor to increase farmers bargaining power and promotes new market strategies. To make this the attention was focused on one of the most important variety of Italian rice: Carnaroli. The main results of the study showed that the project was able to innovate the traditional supply chain in all the four innovation areas according to OECD (2005): product, process, market and organization. In conclusion, our results suggest that the R&RD is able to respond to farmers necessities in term of market competitiveness and to improve the sustainability of local food system
Consumers’ preferences for a local food product: the case of a new Carnaroli rice product in Lombardy
No full textItaly, with a cultivated area of 218,000 ha, is a European leader of rice production. In particular Lombardy region accounts for 40% of total rice cultivation and the case study in object accounts for 3.2% of Lombardy total rice area (2773 ha). Starting from 2012, through a regional project titled Buono, Sano e Vicino (good, healthy and close), Riso e Rane rural district supported local rice farmers in developing innovation in rice production and promoting an alternative supply chain to increase farmers bargaining power and promote new market strategies. More specifically, the innovation introduced is a new biotech method for variety certification, named DNA controllato (DNA tested). In the first step of the project, the attention was focused on an Italian traditional variety of rice: Carnaroli rice. Thanks to a commercial agreement with one of the most important large retailers in Lombardy, the Riso e Rane rice is offered for sale both in the traditional and wholegrain version. In this context, this work aims to evaluate the determinants of consumer’s quality perception of this product, through a preference study of the commercial rice package. Preliminary results reveal that consumers perceive information about origin, local food-system and tradition more easily than DNA tested certification. In conclusion, this work contributes to evaluate the role of bio economy applications to the food sector and offers new insights for the debate about the relationships between tradition and innovation
Amount of mineralized tissue removed by root planing
No full textThe Author's aim was to determine the amount of mineralized tissues removed during root planing conducted by means of a curette, using a profilometer. Records were kept at time 0 and after 4 cycles of 5 strokes each. Mean values of final records show that the average of tissue removal, expressed in microns, was greater than the mean thickness of cementum in the instrumented areas
Evaluation of a hedonic scaling method for measuring the acceptability of school lunches by children
No full textFew studies concerning product testing by children have been published, and practically no such studies have been carried out in Italy. The aim of this work was to set up an evaluation card and a procedure to test grading of meals supplied to school refectories by the Municipality of Milan. Children from four second grade classes were selected from two different primary schools, which received meals from the same meal service. The aims of the study were explained to the children involved (88), 7 and 8-year-olds who were trained in the use of scaling. They then provided acceptability scores for a series of first courses, second courses, vegetables and fruits. While it was not difficult to obtain judgements on grading of meals, some problems were encountered in setting up a model that was useful for both a real time evaluation of meals and any changes in meal formulations. Results were processed by Analysis of Variance, and comparable grading assessments were obtained from the four grades. No significant differences were found in most formulations between the two schools
Diferencia en la reactividad de los fenil propenos frente a la 1-bromo-3,5,5-trimetil hidantoína en las condiciones de Ziegler, evidencia de la formación del radical hidantoinilo
No full textTesis (Dr. en Química Orgánica)--Universidad Nacional de Córdoba. Facultad de Ciencias Químicas, 1978.Fil.: Balzaretti, Vilma Teresa. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas; Argentina.El objeto del presente trabajo es realizar una revisi6n de la reacci6n de halogenación del 1-fenil propeno (1-EF) con 1-Brorno-3,5,5-.trimetu hidantona(1)de le cual se había aislado el correspondiente derivado en posicin al1ica ]romo-1-f'enil-propeno, pero el rendimiento del mismo era solo de un 22/o. Este era un resultado francamente anormal considerando que la reacci6n de halogcnaci6n en las mismas condiciones utilizando cornoalogenan- (u) (3 te la SNBr di un % del mismo y la realizada por Ziejler y col.' 'en una relación molar de 1/2 de halogenante/olefina brindaba un rendimiento en el crivado halogenado alilico del 75,52A. Cuando esta misma olefina como sustrato fue ensayada por O.Orio con 1,3-dibrorno-5,5-dimctil hidantofra no pudo separar los productos de reacci6n, salvo en al gi re s bcasiones en que obtuvo el compuesto ce adición de bromo a la unión doble. Con el fin de determinar en que se transformaban los sustratos EC realiz6 un estudio detallado de la misma y se prodedi6 a la identificación y valoración de los productos formados. Se estudiaron en les mismas condiciones el 2- y 3-fenil propeno (2- y 3-FP), los que hasta el presente no han sido ensayados con este halogenante, a fin de encontrar pautas que indiquen el posible mecanismo actuante.Fil.: Balzaretti, Vilma Teresa. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas; Argentina
Prevalenza delle glossiti, delle glossodinie e delle glossopirosi in 1077 soggetti: studio retrospettivo
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