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K Dodson

Publications and source records attributed to K Dodson.

17 recordsLinked to original sources
PubMed2000

Role of intestinal surfactant-like particles as a potential reservoir of uropathogenic Escherichia coli.

The binding of uropathogenic Escherichia coli is mediated at the tips of pili by the PapG adhesin, which recognizes the Galalpha(1-4)Gal disaccharide on the uroepithelial surface. These receptors have been identified unequivocally in the human and murine urinary tracts but not in intestinal epithelium, yet uropathogenic E. coli strains are commonly found in normal colonic microflora. The gastrointestinal tract from duodenum to rectum elaborates a phospholipid-rich membrane particle with surfactant-like properties. In these studies, we report that purified murine particles contain a receptor recognized by the class I PapG adhesin because: (1) PapD-PapG complexes and class I pili bound to surfactant-like particles in a solid-phase assay, whereas binding was not detected in microvillous membranes derived from the same tissues, (2) purified PapD-PapG complex bound to a glycolipid receptor detectable in lipid extracts from the particles, and (3) soluble Galalpha(1-4)Gal inhibited the adhesin by 72% from binding to surfactant-like particles. The Galalpha(1-4)Gal receptor present in the intestinal surfactant-like particle which overlies the intestinal mucosa could provide one means to establish an intestinal habitat for uropathogenic E. coli.

Adhesins, Escherichia coli↗
PubMed2000

The genome sequence of Drosophila melanogaster.

The fly Drosophila melanogaster is one of the most intensively studied organisms in biology and serves as a model system for the investigation of many developmental and cellular processes common to higher eukaryotes, including humans. We have determined the nucleotide sequence of nearly all of the approximately 120-megabase euchromatic portion of the Drosophila genome using a whole-genome shotgun sequencing strategy supported by extensive clone-based sequence and a high-quality bacterial artificial chromosome physical map. Efforts are under way to close the remaining gaps; however, the sequence is of sufficient accuracy and contiguity to be declared substantially complete and to support an initial analysis of genome structure and preliminary gene annotation and interpretation. The genome encodes approximately 13,600 genes, somewhat fewer than the smaller Caenorhabditis elegans genome, but with comparable functional diversity.

Animals↗
PubMed1999

Binding of pili from uropathogenic Escherichia coli to membranes secreted by human colonocytes and enterocytes.

PapG adhesins mediate the binding of uropathogenic Escherichia coli. Although receptors for these adhesins have not been demonstrated in intestinal epithelia, the colonic microflora includes strains of uropathogenic E. coli. We now report that surfactant-like particles secreted by the human intestine contain receptors for PapG adhesins and may provide an intestinal habitat for uropathogenic bacteria.

Adhesins, Escherichia coli↗
PubMed1999

Standardized visual evoked potentials for telematic electrodiagnosis from five laboratories in three European countries.

The pattern-reversal visual evoked potential (PR VEP) is an electrodiagnostic test which uses an alternating checkerboard pattern as the visual stimulus. To validate the performance of an automated testing system, the equipment was installed in five locations in three countries (the UK, Greece and Cyprus). PR VEPs require accurate control of stimulus size, luminance, contrast, timing, multichannel recordings and various modes of signal processing. Recordings were obtained from 70 subjects, 18-34 years old (seven male and seven female in each laboratory). The data were transmitted by telephone line to the central station in Bristol. Only in Bristol were the operators experienced. There were no significant differences between laboratories in latency or amplitude of the N70 and P100 components. There were no significant differences between eyes. There were significant differences between the sexes but this was related to head size. Decreased square size used in stimulation produced an increased latency in both components. The amplitude of the N70 component increased while that of the P100 decreased with reduced square size. The results confirmed the ability of the automated system to produce standardized PR VEP recordings comparable to those obtainable in advanced laboratories. The system performed well in different locations using inexperienced operators. The system is suitable for multicentre research studies and telemedicine.

Adolescent↗
PubMed1999

Evaluation of the first international teleconference in ophthalmology.

The First International Teleconference in Ophthalmology was held during March 1998 between five sites in the UK, USA, Greece and Malaysia. ISDN transmission at 128 kbit/s was used to reduce costs while maintaining the clarity of the presented material. Specialized lecture theatres were not available at all sites and conventional halls had to be adapted for videoconferencing. For this reason initial point-to-point testing was carried with Bristol to simplify problem solving. Thereafter, a multipoint bridge was used to connect all sites together. During the conference a number of individual presentations were given, all followed by extensive discussion periods. Special instructions were given beforehand on the production of slide material, with particular reference to font sizes and colour combinations. Full use was made of various presentation media, including slides, videos and live demonstrations. The conference was attended by over 500 delegates, all of whom were specialists in ophthalmology. The technology employed was ideal for teaching purposes. However, if used in a clinical field, it should be kept in mind that the choice of transmission rate makes certain features not easily apparent in images but they become clearer when pointed out by the presenter.

Computer Communication Networks↗
PubMed1998

Acquiring the transitive construction in English: the role of animacy and pronouns.

Twenty-four children between 2;5 and 3;1 were taught two nonce verbs. Each verb was used multiple times by an adult experimenter to refer to a highly transitive action involving a mostly animate agent (including the child herself) and a patient of varying animacy. One of the verbs was modelled in the Two-Participants condition in which the experimenter said: 'Look. Big Bird is dopping the boat'. The other verb was modelled in the No-Participant condition in which the experimenter named the Two-Participants but did not use them as arguments of the novel verb: 'Look what Big Bird is doing to the boat. It's called keefing'. It was found that whereas many children produced transitive sentences with the Two-Participants verb, only children close to 3;0 produced transitive sentences with the No-Participant verb. This age is somewhat younger than previous studies in which young children were asked to produce transitive sentences with two lexical nouns for the two animate participants. Also, re-analyses of previously published studies in which children learned novel verbs in sentence frames without arguments found that the few transitive sentences produced by children under 2;6 involved either I or me as subject. One hypothesis is thus that as young children in the third year of life begin to construct a more abstract and verb-general transitive construction, this construction initially contains only certain types of participants expressed in only certain kinds of linguistic forms.

Child Language↗
PubMed1997

Differential productivity in young children's use of nouns and verbs.

A fundamental question of child language acquisition is children's productivity with newly learned forms. The current study addressed this question experimentally with children just beginning to combine words. Ten children between 1;6 and 1;11 were taught four new words, two nouns and two verbs, over multiple sessions. All four words were modelled in minimal syntactic contexts. The experimenter gave children multiple opportunities to produce the words and made attempts to elicit morphological endings (plural for nouns, past tense for verbs). Overall, children combined the novel nouns productively with already known words much more often than they did the novel verbs-by many orders of magnitude. Several children also pluralized a newly learned noun, whereas none of them formed a past tense with a newly learned verb. A follow-up study using a slightly different methodology confirmed the finding of limited syntactic productivity with verbs. Hypotheses accounting for this asymmetry in the early use of nouns and verbs are discussed.

Child Language↗
PubMed1997

Comprehensive standardized ophthalmic telemedicine.

The Electrodiagnostic Neurophysiological Automated Analysis (ENAA) telematic system was developed in the EU EUREKA project. To validate the system 2500 electrodiagnostic tests were administered in a standardized manner during a three-year period. The tests were performed on 70 normal subjects and 500 patients in five laboratories in three European countries. The data were transmitted to the Bristol Telematic Electrodiagnostic Centre in the Bristol Eye Hospital. Data from normal subjects were not significantly different between laboratories. Data from patients were reported upon and the conclusions transmitted to the place of origin. The system provided the remote consultant with multimedia data, including medical images such as colour fundus photography and angiography, video and sound.

Humans↗
PubMed1995

Molecular dissection of PapD interaction with PapG reveals two chaperone-binding sites.

P pili are composite adhesive fibres that allow uropathogenic Escherichia coli to gain a foothold in the host by binding to receptors present on the uroepithelium via the adhesin PapG. The assembly of P pili requires a periplasmic chaperone, PapD, that has an immunoglobulin-like three-dimensional structure. PapD-subunit complex formation involves a conserved anchoring mechanism in the chaperone cleft and a 'molecular zippering' to the extreme C-terminus of pilus subunits. A chaperone-binding assay was developed using fusions of the C-terminus of PapG to maltose-binding protein (MBP/G fusions) to investigate whether chaperone-subunit complex formation requires additional interactions. PapD bound strongly to an MBP/G fusion containing the C-terminal 140 amino acids of PapG (MBP/G175-314) but only weakly to the MBP/G234-314 fusion containing 81 C-terminal residues, arguing that the region between residues 175-234 contains additional information that is required for strong PapD-PapG interactions. PapD was shown to interact with a PapG C-terminal truncate containing residues 1-198 but not a truncate containing residues 1-145, suggesting the presence of a second, independent PapD interactive site. Four peptides overlapping the second site region were tested for binding to PapD in vitro to further delineate this motif. Only one of the peptides synthesized was recognized by PapD. The MBP/G fusion containing both binding sites formed a tight complex with PapD in vivo and inhibited pilus assembly by preventing chaperone-subunit complex formation.

ATP-Binding Cassette Transporters↗
PubMed1993

Initiation of assembly and association of the structural elements of a bacterial pilus depend on two specialized tip proteins.

Uropathogenic Escherichia coli produce heteropolymeric surface fibers called P pili, which present an adhesin at their tip that specifically recognizes globoside receptors on the host uroepithelium. The initial attachment step is thought to be essential for pathogenesis. P pili are composite fibers consisting of a thin tip fibrillum joined end to end to a rigid helical rod. Here we show that the ordered assembly of these structures requires the activity of two proteins that are minor components of the tip fibrillum, PapF and PapK. PapF is required for the correct presentation of the adhesin at the distal end of the tip fibrillum. PapK regulates the length of the tip fibrillum and joins it to the pilus rod. We propose that these subunits function as adaptors, by providing complementary surfaces to different substructures of the pilus and promoting their proper associations. In addition, the conversion of chaperone-subunit complexes into pili depends on PapF and PapK since a papF- papK- double mutation abolishes piliation. We suggest that in addition to the adaptor functions of PapF and PapK, they are also required to initiate the formation of tip fibrillae and pilus rods.

Adhesins, Escherichia coli↗
PubMedDate not supplied

Young children's overgeneralizations with fixed transitivity verbs.

The present study examined English-speaking children's tendency to make argument structure overgeneralization errors (e.g., I disappeared it). Children were exposed to several English verbs of fixed transitivity (exclusively intransitive or exclusively transitive) and then asked questions that encouraged them to overgeneralize usage of the verbs. Seventy-two children (24 in each of three age groups: 3, 4/5, and 8 years of age) experienced four actions performed by puppets. Each action had two verbs of similar meaning associated with it in the context of the experimental action: one more familiar to young children and one less familiar. Children at all ages were more likely to overgeneralize usage of verbs that were less familiar to them, supporting the hypothesis that children's usage of verbs in particular construction types becomes entrenched over time. As children solidly learn the transitivity status of particular verbs, they become more reluctant to use those verbs in other argument structure constructions.

Child↗