Detecting impaired language processing in patients with mild cognitive impairment using around-the-ear cEEgrid electrodes.

Mild cognitive impairment (MCI) is the term used to identify those individuals with subjective and objective cognitive decline but with preserved activities of daily living and an absence of dementia. Although MCI can impact functioning in different cognitive domains, most notably episodic memory, relatively little is known about the comprehension of language in MCI. In this study, we used around-the-ear electrodes (cEEGrids) to identify impairments during language comprehension in patients with MCI. In a group of 23 patients with MCI and 23 age-matched controls, language comprehension was tested in a two-word phrase paradigm. We examined the oscillatory changes following word onset as a function of lexico-semantic single-word retrieval (e.g., swrfeq vs. swift) and multiword binding processes (e.g., horse preceded by swift vs. preceded by swrfeq). Electrophysiological signatures (as measured by the cEEGrids) were significantly different between patients with MCI and controls. In controls, lexical retrieval was associated with a rebound in the alpha/beta range, and binding was associated with a post-word alpha/beta suppression. In contrast, both the single-word retrieval and multiword binding signatures were absent in the MCI group. The signatures observed using cEEGrids in controls were comparable with those signatures obtained with a full-cap EEG setup. Importantly, our findings suggest that patients with MCI have impaired electrophysiological signatures for comprehending single words and multiword phrases. Moreover, cEEGrid setups provide a noninvasive and sensitive clinical tool for detecting early impairments in language comprehension in MCI.

Higher physical fitness levels are associated with less language decline in healthy ageing.

Healthy ageing is associated with decline in cognitive abilities such as language. Aerobic fitness has been shown to ameliorate decline in some cognitive domains, but the potential benefits for language have not been examined. In a cross-sectional sample, we investigated the relationship between aerobic fitness and tip-of-the-tongue states. These are among the most frequent cognitive failures in healthy older adults and occur when a speaker knows a word but is unable to produce it. We found that healthy older adults indeed experience more tip-of-the-tongue states than young adults. Importantly, higher aerobic fitness levels decrease the probability of experiencing tip-of-the-tongue states in healthy older adults. Fitness-related differences in word finding abilities are observed over and above effects of age. This is the first demonstration of a link between aerobic fitness and language functioning in healthy older adults.

Histidine acts as a co-germinant with glycine and taurocholate for Clostridium difficile spores.

AIMS: It is well established that the bile salt sodium taurocholate acts as a germinant for Clostridium difficile spores and the amino acid glycine acts as a co-germinant. The aim of this study was to determine whether any other amino acids act as co-germinants. METHODS AND RESULTS: Clostridium difficile spore suspensions were exposed to different germinant solutions comprising taurocholate, glycine and an additional amino acid for 1 h before heating shocking (to kill germinating cells) or chilling on ice. Samples were then re-germinated and cultured to recover remaining viable cells. Only five amino acids out of the 19 common amino acids tested (valine, aspartic acid, arginine, histidine and serine) demonstrated co-germination activity with taurocholate and glycine. Of these, only histidine produced high levels of germination (97·9-99·9%) consistently in four strains of Cl. difficile spores. Some variation in the level of germination produced was observed between different PCR ribotypes, and the optimum concentration of amino acids with taurocholate for the germination of Cl. difficile NCTC 11204 spores was 10-100 mmol l-1. CONCLUSIONS: Histidine was found to be a co-germinant for Cl. difficile spores when combined with glycine and taurocholate.

Scope of lexical access in spoken sentence production: implications for the conceptual-syntactic interface.

Building on P. H. Allum and L. Wheeldon (2007), the authors conducted 5 experiments to investigate the scope of lexical access during spoken sentence production in Japanese and English. Speakers described pairs of pictured objects, and on critical trials, 1 object was previewed. In Japanese, sentence onset is speeded by the preview of each of the 2 pictures used to elicit a sentence initial coordinated noun phrase (Experiment 1). When the same displays are used to elicit an alternative Japanese listing structure, onset latencies are speeded only by the preview of the first picture to be named (Experiment 2). The findings of Experiment 1 were therefore not the result of stimulus design. Experiment 3 replicated the findings of Experiment 1 in English. Experiments 4 and 5 tested a subject phrase consisting of a noun phrase modified by a prepositional phrase in English and Japanese. In both languages, only preview of the first picture to be named speeds responses, irrespective of whether it occurs in the head phrase (English) or not (Japanese). These results suggest that prior to utterance onset, only access to the nouns for the first phrase to be produced is required, even if this is not the head phrase. The implications for speech production models are discussed.

Antimicrobial efficacy of copper surfaces against spores and vegetative cells of Clostridium difficile: the germination theory.

OBJECTIVES: Persistent contamination of surfaces by spores of Clostridium difficile is a major factor influencing the spread of C. difficile-associated diarrhoea (CDAD) in the clinical setting. In recent years, the antimicrobial efficacy of metal surfaces has been investigated against microorganisms including methicillin-resistant Staphylococcus aureus. This study compared the survival of C. difficile on stainless steel, a metal contact surface widely used in hospitals, and copper surfaces. METHODS: Antimicrobial efficacy was assessed using a carrier test method against dormant spores, germinating spores and vegetative cells of C. difficile (NCTC 11204 and ribotype 027) over a 3 h period in the presence and absence of organic matter. RESULTS: Copper metal eliminated all vegetative cells of C. difficile within 30 min, compared with stainless steel which demonstrated no antimicrobial activity (P < 0.05). Copper significantly reduced the viability of spores of C. difficile exposed to the germinant (sodium taurocholate) in aerobic conditions within 60 min (P < 0.05) while achieving a >or=2.5 log reduction (99.8% reduction) at 3 h. Organic material did not reduce the antimicrobial efficacy of the copper surface (P > 0.05). CONCLUSIONS: The use of copper surfaces within the clinical environment and application of a germination solution in infection control procedures may offer a novel way forward in eliminating C. difficile from contaminated surfaces and reducing CDAD.

Sporicidal activity of two disinfectants against Clostridium difficile spores.

The sporicidal activity of an odour-free peracetic acid-based disinfectant (Wofasteril) and a widely-used dichloroisocyanurate preparation (Chlor-clean) was assessed against spores of the hyper-virulent strain of Clostridium difficile (ribotype 027), in the presence and absence of organic matter. In environmentally clean conditions, dichloroisocyanurate achieved a >3 log10 reduction in 3 minutes, but a minimum contact time of 9 minutes was required to reduce the viable spore load to below detection levels. Peracetic acid achieved a >3 log10 reduction in 30 minutes and was overall significantly less effective (P<0.05). However, in the presence of organic matter - which reflects the true clinical environment - there was no significant difference between the sporicidal activity of dichloroisocyanurate and peracetic acid over a 60-minute period (P=0.188). Given the greater occupational health hazards generally associated with chlorine-releasing agents, odour-free peracetic acid-based disinfectants may offer a suitable alternative for environmental disinfection.

Physical and chemical factors influencing the germination of Clostridium difficile spores.

AIMS: To investigate the influence of chemical and physical factors on the rate and extent of germination of Clostridium difficile spores. METHODS AND RESULTS: Germination of C. difficile spores following exposure to chemical and physical germinants was measured by loss of either heat or ethanol resistance. Sodium taurocholate and chenodeoxycholate initiated germination together with thioglycollate medium at concentrations of 0.1-100 mmol l(-1) and 10-100 mmol l(-1) respectively. Glycine (0.2% w/v) was a co-factor required for germination with sodium taurocholate. There was no significant difference in the rate of germination of C. difficile spores in aerobic and anaerobic conditions (P > 0.05) however, the initial rate of germination was significantly increased at 37 degrees C compared to 20 degrees C (P < 0.05). The optimum pH range for germination was 6.5-7.5, with a decreased rate and extent of germination occurring at pH 5.5 and 8.5. CONCLUSIONS: This study demonstrates that sodium taurocholate and chenodeoxycholate initiate germination of C. difficile spores and is concentration dependant. Temperature and pH influence the rate and extent of germination. SIGNIFICANCE AND IMPACT OF THE STUDY: This manuscript enhances the knowledge of the factors influencing the germination of C. difficile spores. This may be applied to the development of potential novel strategies for the prevention of C. difficile infection.

Syntactic priming in spoken sentence production - an online study.

Six experiments investigate syntactic priming online via a picture description task in which participants produce target sentences whose initial phrase is syntactically similar or dissimilar to that of the prime sentence produced on the previous trial. In the first experiment it is shown that a syntactically related prime sentence speeds onset latencies to a subsequent target sentence by approximately 50 ms relative to a syntactically unrelated prime sentence. In the second experiment, the cost of the process of lemma access is factored out via a picture previewing technique but a priming effect is still obtained demonstrating that the effect is not a product of the priming of lemma access processes. In Experiment 3, the related and unrelated prime trials feature the same picture display but the 50 ms facilitation effect is still observed indicating that the effect does not result from the priming of visual perception of the picture movements. This is further strengthened in Experiment 4 which uses written prime sentences rather than a picture description task on the prime trial and still obtains a facilitation effect. In Experiment 5, the effect disappears when the participants are instructed to name the movements but not the objects depicted in the array and this is interpreted as evidence against the view that the effect results from the conceptualization of the events depicted by the array. In the final experiment, the scope of the syntactic persistence effect is investigated by priming sentences with initial phrases of varying syntactic complexity. Significant priming is only observed for an initial phrase featuring two nouns - a finding consistent with the view that the syntactic persistence effect applies only to the generation of the first phrase of an utterance prior to speech onset. The implications of these results are analyzed in the final discussion section.

High level processing scope in spoken sentence production.

Five experiments investigate the scope of conceptual and grammatical encoding during spoken sentence production. An online picture description task is employed in which participants generate a variety of sentences in response to an array of moving pictured objects. Experiment 1, demonstrates longer onset latencies for single clause sentences beginning with a complex phrase (e.g. The dog and the kite move above the house) than for matched single clause sentences beginning with a simple phrase (e.g. The dog moves above the kite and the house). This finding suggests that more time is dedicated to the processing of the first phrase of an utterance than the remainder prior to speech onset. Experiments 2 and 3, compare the production of single and double clause sentences. The main effect of Experiment 1 is replicated. However, the data also suggest that some time is dedicated to the processing of elements within the second clause prior to speech onset. In Experiment 4, when participants are allowed to preview pictures prior to movement and timer onset the effect of initial phrase complexity is significantly reduced indicating that the latency effects observed previously primarily reflect lemma access. Finally, Experiment 5 demonstrates that this reduction is greater for nouns within the first phrase than for nouns beyond it. We conclude from these experiments that, prior to speech onset, lemma access is completed for the first phrase of an utterance and that high level processing is initiated but not completed for the remainder of a sentence beyond the first phrase.

Do speakers have access to a mental syllabary?

The first, theoretical part of this paper sketches a framework for phonological encoding in which the speaker successively generates phonological syllables in connected speech. The final stage of this process, phonetic encoding, consists of accessing articulatory gestural scores for each of these syllables in a "mental syllabary". The second, experimental part studies various predictions derived from this theory. The main finding is a syllable frequency effect: words ending in a high-frequent syllable are named faster than words ending in a low-frequent syllable. As predicted, this syllable frequency effect is independent of and additive to the effect of word frequency on naming latency. The effect, moreover, is not due to the complexity of the word-final syllable. In the General Discussion, the syllabary model is further elaborated with respect to phonological underspecification and activation spreading. Alternative accounts of the empirical findings in terms of core syllables and demisyllables are considered.

The locus of repetition priming of spoken word production.

Naming of a pictured object is substantially facilitated when the name has recently been produced in response to a definition or read aloud. The first experiment shows this to be so when over one hundred trials have intervened, and when the subjects can name the pictures quickly and accurately in the absence of priming. The locus of the effect must be in lexicalization processes subsequent to picture identification and is unlikely to be mediated by recovery of an episodic trace. Two further experiments show that prior production of a homophone of the object's name is not an effective prime, (although slower responses are somewhat facilitated when the homophones are spelled the same). Hence the facilitation observed for repeated production of the same word cannot be associated with the repetition of the phonological form per se. We conclude that the facilitation must be associated with retrieval of the semantic specification or the process of mapping of that specification to its associated phonological representation.