Diversity of Lactobacillus reuteri Strains in Converting Glycerol into 3-Hydroxypropionic Acid.

The present study aims at comparing the performances of three Lactobacillus reuteri strains (DSM 20016, DSM 17938, and ATCC 53608) in producing 3-hydroxypropionic acid (3-HP) from glycerol and at exploring inhibition phenomena during this bioconversion. Differences were highlighted between the three strains in terms of 3-HP production yield, kinetics of substrate consumption, and metabolite production. With a maximal productivity in non-optimal conditions (free pH) around 2 g.L(-1).h(-1) of 3-HP and 4 g.L(-1).h(-1) of 3-hydroxypropionaldehyde (3-HPA) depending on the strain, this study confirmed the potential of L. reuteri for the biotechnological production of 3-HP. Moreover, the molar ratios of 3-HP to 1,3-propanediol (1,3-PDO) obtained for the three strains (comprised between 1.25 and 1.65) showed systematically a higher 3-HP production. From these results, the DSM 17938 strain appeared to be the most promising strain. The impact of glycerol bioconversion on the bacteria's physiological state (a decrease of around 40 % in DSM 17938 cells showing an enzymatic activity after 3 h) and survival (total loss of cultivability after 2 or 3 h depending on the strains) was revealed and discussed. The effect of each metabolite on L. reuteri DSM 17938 was further investigated, displaying a drastic inhibition caused by 3-HPA, while 3-HP induced lower impact and only at acidic pH.

Effects of Proteus vulgaris growth on the establishment of a cheese microbial community and on the production of volatile aroma compounds in a model cheese.

AIMS: To investigate the impact of Proteus vulgaris growth on a multispecies ecosystem and on volatile aroma compound production during cheese ripening. METHODS AND RESULTS: The microbial community dynamics and the production of volatile aroma compounds of a nine-species cheese ecosystem were compared with or without the presence of P. vulgaris in the initial inoculum. Proteus vulgaris was able to colonize the cheese surface and it was one of the dominant species, representing 37% of total isolates at the end of ripening with counts of 9.2 log(10) CFU g(-1). In the presence of P. vulgaris, counts of Arthrobacter arilaitensis, Brevibacterium aurantiacum and Hafnia alvei significantly decreased. Proteus vulgaris influenced the production of total volatile aroma compounds with branched-chain aldehydes and their corresponding alcohols being most abundant. CONCLUSIONS: Proteus vulgaris was able to successfully implant itself in a complex cheese ecosystem and significantly contributed to the organoleptic properties of cheese during ripening. This bacterium also interacted negatively with other bacteria in the ecosystem studied. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first time that the impact of a Gram-negative bacterium on cheese microbial ecology and functionality has been described.

Are hallucinations and extrapyramidal signs associated with a steeper cognitive decline in degenerative dementia patients?

The aim of this study was to verify if visual hallucinations and extrapyramidal signs are associated with a high speed of cognitive decline in degenerative dementia patients with amnesic onset. The analysis of 1082 consecutive patients showed that hallucinations, but not extrapyramidal signs, were associated with a faster cognitive decline. However, patients with hallucinations were also more severe at the time of examination with the Milan Overall Dementia Assessment (MODA). One interpretation is that hallucinations are the marker of a distinct process of nervous degeneration that specifically causes a steeper cognitive decline from onset. Another interpretation is that the speed of cognitive decline is set along a continuum, and the incidence of hallucinations is simply proportional to the level of cognitive decline. The statistical analysis of our data was consistent with the latter interpretation, in that we were able to quantify the probability of presenting visual hallucinations on the basis of the overall severity of cognitive decline.

The case of lost Wilma: a clinical report of Capgras delusion.

This detailed clinical report of a typical Capgras delusion (CD) in a demented patient is presented in order to foster future descriptions in neurological cases. In the framework of a recently developed model of familiar person processing, it is suggested that CD might be due to a dysfunction at the level of Person Identity Nodes. Prefrontal impairment is held to represent a critical factor leading to a failure of belief evaluation.

Comparison of volatile sulphur compound production by cheese-ripening yeasts from methionine and methionine-cysteine mixtures.

Production of volatile sulphur compounds (VSC) was assessed in culture media supplemented with L-methionine or L-methionine/L-cysteine mixtures, using five cheese-ripening yeasts: Debaryomyces hansenii DH47(8), Kluyveromyces lactis KL640, Geotrichum candidum GC77, Yarrowia lipolytica YL200 and Saccharomyces cerevisiae SC45(3). All five yeasts produced VSC with L-methionine or L-methionine/L-cysteine, but different VSC profiles were found. GC77 and YL200 produced dimethyldisulphide and trace levels of dimethyltrisulphide while DH47(8), KL640 and SC45(3) produced mainly methionol and low levels of methional. S-methylthioacetate was produced by all the yeasts but at different concentrations. DH47(8), KL640 and SC45(3) also produced other minor VSC including 3-methylthiopropyl acetate, ethyl-3-methylthiopropanoate, a thiophenone, and an oxathiane. However, VSC production diminished in a strain-dependent behaviour when L-cysteine was supplemented, even at a low concentration (0.2 g l(-1)). This effect was due mainly to a significant decrease in L-methionine consumption in all the yeasts except YL200. Hydrogen sulphide produced by L-cysteine catabolism did not seem to contribute to VSC generation at the acid pH of yeast cultures. The significance of such results in the cheese-ripening context is discussed.

"What do you know about Ho Chi Minh?" Italian norms of proper name comprehension.

Ninety-eight healthy participants were examined with a new test of Famous Name Comprehension which, in the framework of a serial model of person processing, sequentially assessed Name Recognition (i.e., the ability to classify items as familiar or unfamiliar) and Person Identification (i.e., the ability to provide biographical knowledge of recognised items). Names were presented in a written format. A perfectly equivalent face version of the test allowed a comparison of familiarity and identification of people from name and from face input. Furthermore, the effect of the "age" of the items, i.e. the time elapsed from the presumed first exposure to the stimulus to the time of testing, was also investigated. Normative data are provided. Education was the only significant variable for recognition, while education, age and gender turned out to be significant for identification. Recognition was significantly better with name than with face input, while on identification names and faces did not differ significantly. "Oldest" items were both recognised and identified significantly worse than recent ones. The results of face-name comparison are interpreted in terms of the different opportunities to be exposed to names and faces, the relevance of visuoperceptual attributes linked to faces and the evidence of shared knowledge from different inputs. The relative advantage of recent celebrities supports the semantic characterisation of knowledge of famous people.

"Whose face is this?": Italian norms of naming celebrities.

Naming celebrities from visual input (i.e., face presentation) was examined in 98 healthy participants. Normative data are provided both for a 12-and a 63-item test. The first one is a brief screening tool, while the latter is to be administered whenever a pathological performance turns out in the former. Age adversely affected both performances. In both tests the most frequent errors were no responses, followed by semantic errors. The study makes explicit reference to current serial models of familiar person processing and naming. Findings allow to complement previously reported testing procedures, with the specific aim of qualifying proper name anomia by identifying the cognitive locus of lesion.

Temporal gradients for media-mediated memory: Italian norms.

Temporal gradient (TG), i.e., differential recall of recent and old memories, is a well known feature of amnesia. A recent study provided evidence of a classical TG for media-mediated events in elderly healthy people, showing that they recall remote events significantly better than recent ones, while a reverse TG, i.e., better recall of more recent events, was demonstrated in younger normal subjects. In the present study we present normative data which, using the same test, allow evaluation of TG in single cases and their qualification as classical or reverse. The normative procedure was also applied to a small sample of subjects with probable Alzheimer's disease or mild cognitive impairment. Norms for TG may be helpful not only to assess healthy people's performance, but also to judge any apparent TG in pathological subjects.

Who is who: Italian norms for visual recognition and identification of celebrities.

Age-, education- and sex-adjusted norms are provided for two new neuropsychological tests, namely (i) Face Recognition (guess of familiarity) and (ii) Person Identification (biographical contextualisation). Sixty-three pictures of celebrities and 63 of unknown people were selected following two interwoven criteria(1): the realm of their celebrity (i.e., entertainment, culture and politics) and the period of celebrity acquisition (i.e., pre-war, post-war and contemporary). Both media- and education-dependent knowledge of celebrity were considered. Ninety-eight unpaid healthy participants aged between 50 and 93 years and with at least 8 years of formal education took part in this study. Reference is made to serial models of familiar face/persons processing. Recognition is held to tackle the activity of Personal Identity Nodes (PINs) and identification of the Exemplar Semantics Archives. Given the seriality of the reference model, the Identification Test is embedded in the Recognition test. This entailed that only previously recognised faces were employed to achieve norms for identification.

An iterative sensory procedure to select odor-active associations in complex consortia of microorganisms: application to the construction of a cheese model.

The aim of this study was to develop and validate an iterative procedure based on odor assessment to select odor-active associations of microorganisms from a starting association of 82 strains (G1), which were chosen to be representative of Livarot cheese biodiversity. A 3-step dichotomous procedure was applied to reduce the starting association G1. At each step, 3 methods were used to evaluate the odor proximity between mother (n strains) and daughter (n/2 strains) associations: a direct assessment of odor dissimilarity using an original bidimensional scale system and 2 indirect methods based on comparisons of odor profile or hedonic scores. Odor dissimilarity ratings and odor profile gave reliable and sometimes complementary criteria to select G3 and G4 at the first iteration, G31 and G42 at the second iteration, and G312 and G421 at the final iteration. Principal component analysis of odor profile data permitted the interpretation at least in part, of the 2D multidimensional scaling representation of the similarity data. The second part of the study was dedicated to 1) validating the choice of the dichotomous procedure made at each iteration, and 2) evaluating together the magnitude of odor differences that may exist between G1 and its subsequent simplified associations. The strategy consisted of assessing odor similarity between the 13 cheese models by comparing the contents of their odor-active compounds. By using a purge-and-trap gas chromatography-olfactory/mass spectrometry device, 50 potent odorants were identified in models G312, G421, and in a typical Protected Denomination of Origin Livarot cheese. Their contributions to the odor profile of both selected model cheeses are discussed. These compounds were quantified by purge and trap-gas chromatography-mass spectrometry in the 13 products and the normalized data matrix was transformed to a between-product distance matrix. This instrumental assessment of odor similarities allowed validation of the choice of G312 as the best 10-strain ecosystem.

Cognitive deterioration in Alzheimer's disease: is the early course predictive of the later stages?

This study investigated the predictive value of the early progression rate of Alzheimer's disease on that of the later stages. We retrospectively evaluated 91 patients affected by possible Alzheimer's disease; the patients had been examined twice with the Milan overall dementia assessment (MODA) scale at an interval of 12 months (53 patients) or 24 months (38 patients). At the first assessment, speed of progression was calculated for each patient dividing the MODA difference from the normality threshold by the time elapsed from the cognitive decline onset. The second assessment of speed of progression was calculated dividing the difference between the two MODA scores by the time elapsed from the first examination. Patients with a slow progression rate in the early stage were unlikely to show a subsequent fast progression rate, and vice versa for patients with a fast early progression. A tool is provided for predicting the speed of cognitive decline of patients from a single MODA assessment. We suggest that, in future clinical trials on Alzheimer's disease, a stratification of participants based on the early rate of cognitive deterioration may be considered.

"What do you remember about Chernobyl?" A new test of memory for media-mediated events.

We devised a new test for assessing remote memory for media-mediated events, i.e. events that are reported by and known through the media. The test consists of a verbal questionnaire covering famous events that occurred over a long period of time, from 1976 to 2000, specifically designed for use with the Italian population. A free recall procedure was adopted which makes use of progressive cues. The test can be easily updated for inclusion of future events. Normative and test-retest reliability data are presented. The test provides a new tool for assessing media-mediated memory whenever an extensive assessment of retrograde memory performance is required, both in normal people and in brain-damaged patients.

The color of Brevibacterium linens depends on the yeast used for cheese deacidification.

The color of smear cheeses (Muenster) is traditionally thought to be due to the bacterial flora, e.g., Brevibacterium linens. This study was carried out to evaluate indirect effects of yeast on the color of B. linens. A 60% cheese medium was desacidified with Debaryomyces hansenii or Kluyveromyces marxianus until pH 5.8 was reached. After inactivation of the yeast and addition of agar-NaCl, B. linens was inoculated on the medium surface and incubated at 12 degrees C from d 2 to 28. For each bacterial biofilm, color was evaluated by L*C*h(degrees) (brightness, chroma, hue angle) spectrocolorimetry. After d 14 (D. hansenii deacidification) and d 21 (K marxianus desacidification), the color level (as a function of all 3 factors) of B. linens biofilms became maximal and remained so until d 28. Debaryomyces hansenii 304 (LGMPA) was less efficient for deacidification than K. marxianus Laf5. However, color intensity (function of chroma only) was higher when D. hansenii was used. The yeast used had an effect on the composition of the cheese medium in relation to production and consumption of metabolites during deacidification. The results concerning color are discussed with respect to this cheese medium composition.

Comparison of volatile compounds produced in model cheese medium deacidified by Debaryomyces hansenii or Kluyveromyces marxianus.

The aroma of a deacidified cheese medium is the result of the overall perception of a large number of molecules belonging to different classes. The volatile compound composition of (60%) cheese medium (pH 5.8) deacidified by Debaryomyces hansenii (DCM(Dh)) was compared with the one deacidified by Kluyveromyces marxianus (DCM(Km)). It was determined by dynamic headspace extraction, followed by gas chromatography separation and quantification as well as by mass spectrometry identification. Whatever the media tested, a first class of volatile compounds can be represented by the ones not produced by any of the yeasts, but some of them are affected by K. marxianus or by D. hansenii. A second class of volatile compounds can be represented by the ones produced by K. marxianus, which were essentially esters. Their concentrations were generally higher than their thresholds, explaining the DCM(Km) global fruity odor. A third class can be represented by the ones generated by D. hansenii, which were essentially methyl ketones with fruity, floral (rose), moldy, cheesy, or wine odor plus 2-phenylethanol with a faded-rose odor. The impact of methyl ketones on the DCMDh global flavor was lower than the impact of 2-phenylethanol and even negligible. Therefore, the global faded-rose odor of D. hansenii DCM can be explained by a high concentration of 2-phenylethanol.

Assessment of the rind microbial diversity in a farmhouse-produced vs a pasteurized industrially produced soft red-smear cheese using both cultivation and rDNA-based methods.

AIMS: The diversity of the surface flora of two French red-smear soft cheeses was examined by cultivation-dependent and cultivation-independent methods to assess their composition and to evaluate the accuracy of both approaches. METHODS AND RESULTS: Culture-independent methods used involved 16S ribosomal DNA gene cloning and sequencing and single-strand conformation polymorphism analysis (SSCP). The culture-dependent method used involved direct culture and macroscopic observation, polymerase chain reaction of the 16S rRNA gene from DNA extracted from single colonies followed by complete sequencing of the gene. Only few species were recovered by both approaches either in the pasteurized and the farmer cheese. A large diversity of isolates or 16S rDNA sequences related to marine bacteria was identified at the surface of both cheeses. CONCLUSIONS: The results indicated that all three techniques were informative and complementary to allow a more accurate representativeness of the cheese surface biodiversity. SIGNIFICANCE AND IMPACT OF THE STUDY: Cultivation and molecular methods have to be combined in order to obtain an extended view of the bacterial populations of complex ecosystems.

Dual task effects of walking when talking in Alzheimer's disease.

Previous studies with Alzheimer Disease (AD) patients have suggested that speed and accuracy in walking can be dramatically affected by a simultaneous secondary cognitive task, such as holding a conversation. Two experiments examined the impact on AD patients and age matched elderly controls of cognitive demands while walking. In Experiment 1 walking for AD patients was more affected than it was for the normal elderly by a concurrent cognitive demand. Experiment 2 demonstrated that both groups were equally impaired under dual task conditions when the demands of the cognitive tasks were adjusted for individual levels of ability. We conclude that walking may draw on general executive resources, that walking relies more heavily on these executive resources in the elderly, and on a damaged executive system for AD patients.

Walking difficulties in patients with Alzheimer's disease might originate from gait apraxia.

OBJECTIVES: To investigate whether gait apraxia is a possible cause for some of the walking abnormalities shown by patients with Alzheimer's disease. METHODS: 60 patients with Alzheimer's disease, selected as being free from overt extrapyramidal impairment or other potential causes of walking deficits, were assessed with a new test evaluating aspects of walking and related movements. Norms for this test were collected from a sample of 182 healthy volunteers. RESULTS: 40% of the Alzheimer group performed below the cut off score on this test, and half performed poorly. Performance of the Alzheimer group in the walking skills test correlated highly with scores in a test assessing limb apraxia and with dementia severity. CONCLUSIONS: Gait apraxia may be the cause of walking disorders found in a subgroup of patients with Alzheimer's disease. Its detection is made easier by the use of a standardised test, but still relies heavily on the exclusion of other causes of walking deficits. It is a recognisable and independent form of apraxia.

How to calculate an MMSE score from a MODA score (and vice versa) in patients with Alzheimer's disease.

The aim of the present study was to provide a statistically sound way of reciprocally converting scores of the mini-mental state examination (MMSE) and the Milan overall dementia assessment (MODA). A consecutive series of 182 patients with "probable" Alzheimer's disease patients was examined with both tests. MODA and MMSE scores proved to be highly correlated. A formula for converting MODA and MMSE scores was generated.

Dual influence of the carbon source and L-methionine on the synthesis of sulphur compounds in the cheese-ripening yeast Geotrichum candidum.

The effect of the carbon source and l-methionine on the ability of Geotrichum candidum to produce volatile sulphur compounds (VSC) was studied. This yeast was cultivated in a synthetic medium supplemented with various carbon sources and l-methionine at different concentrations. Both glycerol and glucose significantly increased VSC production by G. candidum. Unlike the effect on the l-methionine- and 4-methylthio-2-oxobutyric acid-demethiolating activities, the supply of a carbon source had a dramatic effect on the activity of aminotransferase, a key enzyme in l-methionine catabolism. An increase in the initial concentration of l-methionine resulted in a rise in the production of sulphur compounds (VSC, 4-methylthio-2-oxobutyric acid) but had limited effect on l-methionine-catabolising enzyme activities. Evidence for the existence of a dual effect of the carbon source and l-methionine on VSC biosynthesis was obtained in this study.

How many camels are there in Italy? Cognitive estimates standardised on the Italian population.

OBJECTIVE: We provided the standardisation of a new Cognitive Estimation Task (CET). PARTICIPANTS: the test was administered to 175 healthy subjects. RESULTS: performance on the Cognitive Estimation Task (CET) is associated with gender (where women show poorer performance than men) and education (where more highly educated individuals show better performance compared to individuals with lower levels of education). However,CET performance is not associated with age. DISCUSSION: the lack of age effects on the CET may be explained by the task dependence on "crystallised intelligence", which is less affected by healthy adult ageing than "fluid intelligence".