Expanding the diversity of mycobacteriophages: insights into genome architecture and evolution

Mycobacteriophages are viruses that infect mycobacterial hosts such as Mycobacterium smegmatis and Mycobacterium tuberculosis. All mycobacteriophages characterized to date are dsDNA tailed phages, and have either siphoviral or myoviral morphotypes. However, their genetic diversity is considerable, and although sixty-two genomes have been sequenced and comparatively analyzed, these likely represent only a small portion of the diversity of the mycobacteriophage population at large. Here we report the isolation, sequencing and comparative genomic analysis of 18 new mycobacteriophages isolated from geographically distinct locations within the United States. Although no clear correlation between location and genome type can be discerned, these genomes expand our knowledge of mycobacteriophage diversity and enhance our understanding of the roles of mobile elements in viral evolution. Expansion of the number of mycobacteriophages grouped within Cluster A provides insights into the basis of immune specificity in these temperate phages, and we also describe a novel example of apparent immunity theft. The isolation and genomic analysis of bacteriophages by freshman college students provides an example of an authentic research experience for novice scientists.

Fluctuating dementia and rhinorrhoea

Images

Focal retrograde amnesia following closed head injury: a case study and theoretical account

In this paper we present data from a closed head injury patient who presents a striking example of what Kapur (Cortex 29, 217-234, 1993) has termed " focal retrograde amnesia". The patient, D.H., is unable to recollect any autobiographical incidents from the pre-morbid period, although he is able to provide personal and public information from this period. The data are discussed in relation to other reported instances of focal retrograde amnesia and a preliminary theoretical account is offered.

Coma arousal procedure: a therapeutic intervention in the treatment of head injury

This study reports on the efficacy of a 'coma arousal procedure'. This procedure involved a programme of vigorous sensory stimulation administered to comatose patients by relatives using Comakits. An experimental group of 12 severely head-injured patients received the coma arousal procedure while a matched control group did not. Total duration of coma and weekly Glasgow Coma Scale Scores were recorded for the two groups. Results indicate that the total duration of coma was significantly shorter and that coma lightened more rapidly for the experimental group.

Visuospatial working memory in Parkinson's disease

Visuospatial impairment is frequently reported in Parkinson's disease but the psychological mechanisms which subserve the impaired abilities and the way in which breakdown of the mechanisms leads to performance deficits have not been precisely delineated. This paper reports experimental investigations designed to test the hypothesis that the locus of the impairment is the visuospatial subsystem of working memory. Subjects were a group of sixteen patients with Parkinson's disease of mild to moderate severity and a matched control group. They performed complex visuospatial and verbal memory tasks. The Parkinsonian group were significantly slower than the control group when performing the visuospatial task. They were not significantly slower and made no more errors than the control group on the verbal task. The findings are compatible with the hypothesis that the visuospatial subsystem of working memory is impaired in Parkinson's disease. It is demonstrated that the impairment is not the result of a reduction in the capacity of this subsystem but is due to difficulty in utilising information stored in the subsystem to perform complex visuospatial tasks.

Aspects of the relationship between cognitive theories and therapies of depression

Cognitive theories of depression are examined with respect to the relationship between cognition and affect, the assumption that cognitions are accessible and open to modification, and the adequacy of cognitive accounts of the onset and maintenance of depression. The role of social and familial factors in maintaining depression and the extent to which negative cognitions may be based on accurate perceptions of the social milieu are considered. The relationship between cognitive therapy for depression and cognitive theories of depression is noted.

Residual ability to use grapheme-phoneme conversion rules in phonological dyslexia

A case of acquired phonological dyslexia is described (P.M.). The patient was encouraged to read nonwords by analogy with real words, i.e., by changing phonemes in real words to produce pronounceable nonwords. P.M. was able to perform this task suggesting that he retained some ability to use grapheme-phoneme conversion rules. On the basis of P.M.'s performance an additional connection in Morton's logogen model is postulated.