Identification of dichloroacetic acid degrading Cupriavidus bacteria in a drinking water distribution network model

AIMS

Bacterial community structure and composition of a drinking water network were assessed to better understand this ecosystem in relation to haloacetic acid (HAA) degradation and to identify new bacterial species having HAA degradation capacities.

METHODS AND RESULTS

Biofilm samples were collected from a model system, simulating the end of the drinking water distribution network and supplied with different concentrations of dichloroacetic and trichloroacetic acids at different periods over the course of a year. The samples were analysed by culturing, denaturing gradient gel electrophoresis (DGGE) and sequencing. Pipe diameter and HAA ratios did not impact the bacterial community profiles, but the season had a clear influence. Based on DGGE profiles, it appeared that a particular biomass has developed during the summer compared with the other seasons. Among the bacteria isolated in this study, those from genus Cupriavidus were able to degrade dichloroacetic acid. Moreover, these bacteria degrade dichloroacetic acid at 18°C but not at 10°C.

CONCLUSIONS

The microbial diversity evolved throughout the experiment, but the bacterial community was distinct during the summer. Results obtained on the capacity of Cupriavidus to degrade DCAA only at 18°C but not at 10°C indicate that water temperature is a major element affecting DCAA degradation and confirming observations made regarding season influence on HAA degradation in the drinking water distribution network.

SIGNIFICANCE AND IMPACT OF THE STUDY

This is the first demonstration of the HAA biodegradation capacity of the genus Cupriavidus.

A child with mutism after bilateral thalamic infarction

The occurence of mutism after thalamic lesions has rarely been observed before adulthood. We report a 6.5-year-old girl who presented with sudden mutism with a decreased level of alertness. Her MRI revealed a T2-fluid attenuated inversion recovery hyperintensity in both thalami, which suggested bithalamic infarction in the territory of the thalamo-perforating arteries and, more specifically, the para-median territories. Mutism was followed by a deficit of speech initiation with slow and slurred speech. Her speech returned to normal at 3 months after the onset of symptoms. Thus mutism could be the equivalent of akinetic mutism limited to the speech sphere.

[Reduplication of an event after right caudate nucleus haemorrhage]

BACKGROUND

Environmental reduplication which is characterized by reduplication of places has been reported in right hemispheric lesions, particularly but not only in the right frontal region. However, spatial delirium may follow right sub-cortical lesions.

METHODS

We describe a 53 years-old man who had a reduplicative paramnesia for event alone after an intracerebral haematoma of the right caudate nucleus.

RESULTS

MRI Scan showed also an extension of the right caudate nucleus haemorrhage into the ventricular system. Regional cerebral blood flow studied with 99Tcm-HMPAO showed a decrease of perfusion in the right dorso-lateral frontal cortex. To our knowledge, we reported the first case of reduplicative paramnesia of event associated with a right caudate nucleus injury. Similar right frontal deactivation was observed in two cases of reduplicative paramnesia for place, one of them after an infarction of the retro-lenticular portion of the right internal capsulae, the other after a right thalamo-capsular haemorrhage.

CONCLUSION

We suggest that reduplicative paramnesia for event, like the previous cases reported of reduplicative paramnesia for place, may be linked to a subcortical lesion of the frontal lobe inducing a right functional frontal deactivation.

Réactivation automatique en mémoire sémantique de connaissances didactiques au cours du vieillissement normal et dans la maladie d’Alzheimer

INTRODUCTION

The goal of our work is to study the most consolidated items of semantic memory in normal subjects and in patients with Alzheimer's disease (AD).

PATIENTS AND METHOD

The first test is based on automatic recall of didactic knowledge. This test is made of 250 automatic verbal expressions exploring general knowledge. It as been validated according to age and cultural levels in 219 normal subjects (20-90 years old). Another simplified test called EVA including only 50 of the 250 previously chosen items was also used. The EVA scores found in a normal population have been classified by centilages according to age and cultural levels. The EVA was also tested in 20 patients with AD and the results compared with MMSE and "Pyramids and Palm Trees Test" (semantic memory testing).

RESULTS

The results reveal that the scores observed with the first test in a normal population with comparable cultural levels are correlated with age. EVA test scores found in control subjects show that the median value, for a same age group, is positively correlated with cultural levels. In patients with AD, scores for EVA test and MMSE are associated, the low results being linked to the severity of dementia. In addition, scores for EVA test and "Pyramids and Palm Trees Test" are also significantly correlated. Seven patients with mild dementia (MMSE>20) have abnormal scores for the "Pyramids and Palm Trees Test".

CONCLUSION

Our study confirms that changes linked to aging do not involve all aspects of cognition. The most consolidated items of semantic memory assessed by EVA test seem to resist at the beginning of AD but later decline similarly to the other items of semantic memory. Normal results for EVA tests do not imply that semantic memory is not affected in the early phases of AD. We propose this new test which assesses the semantic memory stock without involving an active process of recuperation. This test is not suitable for an early diagnosis of AD but could help to evaluate the severity of the disease during the evolution.

Troubles de la communication après régression d’une aphasie sous-corticale : disconnexion fronto-sous-corticale ?

INTRODUCTION

Pragmatic analysis of Language difficulties examines the pertinence and adaptation of the spoken Language which can be disturbed even when phonologic, syntactic and semantic functions, taken separately, appear normal. Disorders of pragmatic Language function remain poorly explored and the few published papers in adult neuropsychology have been devoted to patients with traumatic frontal lesions.

METHODS

In the present study we report the case of a patient admitted for right hemiplegia with "dissident" aphasia related to a capsulo-lenticular hematoma. Aphasic disorders progressively improved but with the occurrence of speech disorders which were assessed by pragmatic indices.

RESULTS

There was no difference between free and directed interview with the exception for the non-contingencies which were significantly more frequent in the directed interview. As compared with the spoken Language of a normal individual, highly significant differences were noted for incoherent lexical proximities, non-contingencies and markers of difficulty.

DISCUSSION

and conclusion. For some Authors, the pragmatic speech disorders observed in this patient during the directed interview are linked to abnormal executive functions, also noted in the patient. The difficulties to adjust to speech constraints of the interview context could be related to a fronto-subcortical disconnection resulting in this patient to the left capsulo-lenticular lesion.

[Aphasic hypergraphy in the course of a bilateral hemispheric glioblastoma]

A 68-year old patient, suffering from a left temporal and right frontal multifocal glioblastoma, initially presented Wernicke's aphasia with abnormal behavior. After a stereotaxic biopsy of his right frontal lesion, the patient developed an activity of ceaseless writing associated with mutism. This hypergraphic behavior was accompanied with a production of numerous aphasic paragraphics contrasting with the mutism. Such association could evoke the rise of a suppressive activity of the right hemisphere on graphic functions linguistically organized by the left hemisphere.

[The effects of normal aging on face naming and recognition of famous people: battery 75]

The difficulty to recall proper nouns is often something elderly people complain about. Thus, we tried to build and standardize a tool that could allow a quantified estimation of the naming and recognition abilities about famous people faces, specifying the part of gender, age and cultural level for each kind of test. The performances of 542 subjects divided in 3 age brackets and 3 academic knowledge levels were analysed. To carry out the test material, the artistic team of the Grevin Museum (Paris) was called upon. Their work offers a homogeneous way to shape famous people faces. One same person thus photographed 75 characters from different social categories with the same conditions of light, during only one day. The results of the study show that men perform better than women as concerns naming task, but that there's no difference between genders as concerns recognition task. Recognition performances are significantly better whatever the age, the gender and the cultural level may be. Generally, performances are all the more better since subjects are younger and have a higher cultural level. Our study then confirms the fact that normal aging goes hand in hand with rising difficulties to name faces. Moreover, results tend to show that recognition of faces remains better preserved and that the greater disability to recall a name is linked to difficulties in lexical accessing.

[Taste impairment in Alzheimer's disease]

We conducted a study of Alzheimer's disease focusing on taste impairment to determine at which step of gustatory information processing (discriminative or perceptive, gnosic or associative, gustatory-verbal) possible perturbations might be located. We used various foods found in a normal diet. Twenty patients and a matched control group participated in this study. The patients were divided into two subgroups according to disease severity (mild, moderate or severe). The study showed that patients with Alzheimer's disease exhibited an impairment at all three levels of gustatory information processing. Impairment of discriminative and gustatory-verbal stages was more obvious in the group of patients with severe Alzheimer's disease. Our study also showed that the gustatory deficiency can be described as an associative agnosia in the mild stage of Alzheimer's disease. This concept is in line with the notion of a dissociation between preservation of olfactory and gustatory thresholds and an alteration in odor identification in patients with mild stage Alzheimer's disease, suggesting that the alteration is central rather than peripheral. Our findings suggest that an alteration of the associative level of gustatory information processing can be found in Alzheimer's disease early stage.

[Visuoverbal disconnection (optical aphasia) for objects, pictures, colors and faces with abstractive alexia]

The case is reported of a patient who, after a left occipital infarction, presented a deficit in naming visually presented objects with neither aphasia, nor perturbation in the perceptive and associative processing of visual informations. This visuo-verbal disconnection was accompanied by disturbance of the semantic function when this was explored via the visual channel. In addition the patient showed an alexia which could be described as an abstraction defect. Finally, the patient showed a deficit in naming colors and faces, without evidence for agnosia. This observation argues in favor of maintaining a distinction between visual associative agnosia and optic aphasia. It also demonstrates that the naming deficit implies a deficit in extracting semantic values from visual informations such as objects or graphic symbols.