Differences in levels of secreted locus of enterocyte effacement proteins between human disease-associated and bovine Escherichia coli O157

Ongoing extensive epidemiological studies of verotoxin-carrying Escherichia coli O157 (stx(+) eae(+)) have shown this bacterial pathogen to be common in cattle herds in the United States and the United Kingdom. However, the incidence of disease in humans due to this pathogen is still very low. This study set out to investigate if there is a difference between strains isolated from human disease cases and those isolated from asymptomatic cattle which would account for the low disease incidence of such a ubiquitous organism. The work presented here has compared human disease strains from both sporadic and outbreak cases with a cross-section, as defined by pulsed-field gel electrophoresis, of E. coli O157 strains from cattle. Human (n = 22) and bovine (n = 31) strains were genotyped for carriage of the genes for Shiga-like toxin types 1, 2, and 2c; E. coli secreted protein genes espA, espB, and espP; the enterohemolysin gene; eae (intimin); ast (enteroaggregative E. coli stable toxin [EAST]); and genes for common E. coli adhesins. Strains were also phenotyped for hemolysin, EspP, Tir, and EspD expression as well as production of actin and cytoskeletal rearrangement associated with attaching and effacing (A/E) lesions on HeLa cells. The genotyping confirmed that there was little difference between the two groups, including carriage of stx(2) and stx(2c), which was similar in both sets. ast alleles were confirmed to all contain mutations that would prevent EAST expression. espP mutations were found only in cattle strains (5 of 30). Clear differences were observed in the expression of locus of enterocyte effacement (LEE)-encoded factors between strains and in different media. EspD, as an indicator of LEE4 (espA, -B, and -D) expression, and Tir levels in supernatants were measured. Virtually all strains from both sources could produce EspD in Luria-Bertani broth, although at very different levels. Standard trichloroacetic acid precipitation of secreted proteins from tissue culture medium produced detectable levels of EspD from the majority of strains of human origin (15 of 20) compared with only a few (4 of 20) bovine strains (P < 0.001), which is indicative of much higher levels of protein secretion from the human strains. Addition of bovine serum albumin carrier protein before precipitation and enhanced detection techniques confirmed that EspD could be detected after growth in tissue culture medium for all strains, but levels from strains of human origin were on average 90-fold higher than those from strains of bovine origin. In general, levels of secretion also correlated with ability to form A/E lesions on HeLa cells, with only the high-level protein secretors in tissue culture medium exhibiting a localized adherence phenotype. This research shows significant differences between human- and bovine-derived E. coli O157 (stx(+) eae(+)) strains and their production of certain LEE-encoded virulence factors. These data support the recent finding of Kim et al. (J. Kim, J. Nietfeldt, and A. K. Benson, Proc. Natl. Acad. Sci. USA 96:13288-13293, 1999) proposing different E. coli O157 lineages in cattle and humans and extend the differential to the regulation of virulence factors. Potentially only a subset of E. coli O157 isolates (stx(+) eae(+)) in cattle may be capable of causing severe disease in humans.

Regional nerve blocks. Part 4--Office blocks of the foot and ankle

This is the fourth in our series of regional nerve blocks. This month we examine regional nerve blocks of the foot and ankle.

Regional nerve blocks. Part 3--Regional nerve blocks of the hand

This is the third in our series of regional nerve blocks. This month specific blocks of the hand are reviewed. The anatomy of the region is revised and the indications for using these blocks is discussed and some pitfalls to be aware of are highlighted. Some practical tips are also provided.

Regional nerve blocks. Part 2--the face and scalp

This is the second article in our series on regional nerve blocks. This month the use of blocks for procedures on the scalp and face is discussed. The anatomy of these areas is reviewed and some tips to make these blocks easier are presented.

Regional nerve blocks. Part 1--An introduction

Sustained nerve trauma is unlikely in a block. Local anaesthetics need time to work--the bigger the nerve the longer they need. Always perform a nerve block on an awake patient. Very young children and the frail elderly are more susceptible to cardiac toxicity. When used appropriately adrenaline slows the uptake of local anaesthetic into plasma.

Action research in action: reflections on a project to introduce Clinical Practice Facilitators to an acute hospital setting

AIMS OF THE PAPER

The process and philosophical basis of action research are discussed in this article by reviewing the insights that were gained from a study designed to enhance the support available to junior nursing staff in an acute hospital setting.

RATIONALE

It has been well documented that newly qualified nurses require help to develop professional competencies. With this in mind, the role of Clinical Practice Facilitator was established within a National Health Service (NHS) Trust to enhance clinical skill acquisition and the professional development of newly registered nurses and health care assistants.

DESIGN

In order to facilitate the inception, development and subsequent evaluation of these new roles, an action research approach was adopted. Strategies used to encourage collaboration and flexibility during the project are also discussed.

RESULTS

The primary aims of the project were achieved and the authors suggest that the choice of action research was significant to the successful outcome. However, a number of issues arose which deserve more attention including the importance of the interpersonal skills of the action researcher and the value of action research to facilitate change which is relevant at both an individual and organizational level.

A randomised controlled trial to evaluate the effectiveness and cost-effectiveness of counselling patients with chronic depression

OBJECTIVES

To examine the effectiveness and cost-effectiveness of short-term counselling in general practice for patients with chronic depression or combined depression and anxiety, compared with general practitioner (GP) care alone.

DESIGN

A randomised controlled trial and economic evaluation with an initial assessment at randomisation and follow-ups at 6 and 12 months.

SETTING

Nine general practices that were well-established participants of the Derbyshire counselling in general practice scheme, and already had a counsellor in the practice team.

SUBJECTS

Patients were screened at GP practices, and asked to participate if they scored >/= 14 on the Beck Depression Inventory (BDI), had suffered depression or depression/anxiety for 6 months or more, were aged 18-70 and had no history of drug or alcohol abuse, psychoses or suicidal tendencies.

INTERVENTIONS

The experimental group received usual GP treatment and were also referred to an experienced, well-qualified counsellor attached to their general practice. Of the eight counsellors, two practiced cognitive behavioural therapy (CBT) and six had a psychodynamic approach. The controls were referred back to their GP for routine treatment. There were no restrictions regarding the treatment that could be used, except that GPs could not refer controls to practice counsellors.

OUTCOME MEASURES

The main outcome measure was the BDI. Others included the Brief Symptom Inventory, the Inventory of Interpersonal Problems and the Social Adjustment Scale. All tests were given at initial, 6- and 12-month assessments. Comprehensive costs were also estimated, and combined with changes in outcomes to examine between-group differences and whether counselling was more cost-effective than standard GP care.

RESULTS

The trial recruited 181 patients. There was an overall significant improvement in the actual scores over time but no difference between groups or between CBT and psychodynamic counselling approaches at either 6 or 12 months. However, fewer experimental group patients were still 'cases' on the BDI than controls. This difference was statistically significant at 12 months and neared significance at 6 months (using logistic regression with the initial score as a covariate). In addition, most patients were very positive about the counselling and considered it helpful. Visual inspection of the outcomes suggested that more patients with mild or moderate depression at study entry had improved and ceased to be cases, and that more of these patients had become 'non-cases' in the experimental than the control group. However, a multiple regression analysis indicated no significant interactions between group and initial severity of depression. This could be partly due to there being no difference in outcome between the experimental and control group patients who were initially severely depressed and few of these patients ceasing to be cases at follow-up. There were no significant differences in the mean total costs, aggregate costs of services, or any of the service-group costs, except for primary care, between the experimental and control groups over time. The cost-burden to GP practices was significantly higher in the experimental than the control group at 6 months.

CONCLUSIONS

Although patients were generally appreciative of the counselling received, there was only limited evidence of improved outcomes in those referred to counselling. Stricter referral criteria to exclude the severely depressed may have yielded more conclusive results. It is also difficult to estimate the effect of recruitment by screening rather than GP referral, which may limit the applicability of the results to routine clinical practice, and may have interfered with the normal working alliance established between the GP, patient and counsellor. A patient preference trial may, therefore, have been more appropriate. The results indicated that there were similar improvements for both CBT and psychodynamic counselling, but a

Clinical relevance of the primary findings of the MTA: success rates based on severity of ADHD and ODD symptoms at the end of treatment

OBJECTIVES

To develop a categorical outcome measure related to clinical decisions and to perform secondary analyses to supplement the primary analyses of the NIMH Collaborative Multisite Multimodal Treatment Study of Children With Attention-Deficit/Hyperactivity Disorder (MTA).

METHOD

End-of-treatment status was summarized by averaging the parent and teacher ratings of attention-deficit/hyperactivity disorder and oppositional defiant disorder symptoms on the Swanson, Nolan, and Pelham, version IV (SNAP-IV) scale, and low symptom-severity ("Just a Little") on this continuous measure was set as a clinical cutoff to form a categorical outcome measure reflecting successful treatment. Three orthogonal comparisons of the treatment groups (combined treatment [Comb], medication management [MedMgt], behavioral treatment [Beh], and community comparison [CC]) evaluated hypotheses about the MTA medication algorithm ("Comb + MedMgt versus Beh + CC"), multimodality superiority ("Comb versus MedMgt"), and psychosocial substitution ("Beh versus CC").

RESULTS

The summary of SNAP-IV ratings across sources and domains increased the precision of measurement by 30%. The secondary analyses of group differences in success rates (Comb = 68%; MedMgt = 56%; Beh = 34%; CC = 25%) confirmed the large effect of the MTA medication algorithm and a smaller effect of multimodality superiority, which was now statistically significant (p < .05). The psychosocial substitution effect remained negligible and nonsignificant.

CONCLUSION

These secondary analyses confirm the primary findings and clarify clinical decisions about the choice between multimodal and unimodal treatment with medication.

Is the clinical expression of late-life depression influenced by brain changes? MRI subcortical neuroanatomical correlates of depressive symptoms

BACKGROUND

"Vascular depression" has recently been proposed. It is characterized by magnetic resonance imaging (MRI) T2-weighted subcortical lesions, a late onset of first episode of depression, and reduced heritability; a cerebrovascular etiology is suggested. The validity of "vascular depression" might be strengthened if an association was found between the subcortical lesions used to define it and particular depressive symptoms.

METHODS

A blinded cross-sectional examination of DSM-III-R depressive symptoms (American Psychiatric Association, 1987) and MRI T2-weighted subcortical lesions in 44 patients with late-life depression.

RESULTS

Many associations were found; however, because of multiple comparisons, their significance is viewed with caution. The most robust finding was that psychomotor retardation was independently related to total white-matter score. The odds of showing psychomotor retardation was increased 1.9 times for every point increase in severity of white-matter change.

CONCLUSION

In late-life depression the clinical expression of the depression is influenced by the pattern of MRI T2-weighted subcortical lesions. This gives some validity to the concept of an MRI-defined "vascular" subtype of late-life depression and strengthens the argument for including neuroimaging in the classification of late-life depression.

Behavioral versus behavioral and pharmacological treatment in ADHD children attending a summer treatment program

As part of the behavioral treatment in the Multimodal Treatment Study of Children with ADHD (MTA9), children participated in an intensive summer treatment program (STP). This study examined the differences between 57 children in the combined treatment (Comb) group, who were medicated, and 60 children in the behavioral treatment (Beh) group, who were unmedicated throughout the STP. Comb children were significantly better than Beh on 5 measures: rule following, good sportsmanship, peer negative nominations, and STP teacher posttreatment ratings of inattention/overactivity. Groups did not differ on any of the other 30 measures, and responded similarly to the STP over time. Comparisons to normative data revealed that Comb children were more likely to fall within the normative range on 6 measures. The differences between these results and the main MTA results, in which Comb was always superior to Beh, are discussed in terms of the relative intensity of combined treatments. The implications for future studies of pharmacological and behavioral treatment for ADHD are discussed.

Dyslexia: a developmental language disorder

The acquisition of literacy in an alphabetic script such as English makes heavy demands on linguistic skills. The relation between spoken and written language however, is far from straightforward. This article reviews the research that suggests that phonological processing skills are crucial in the translation of symbols to sounds, and the development of rapid and automatic decoding skills. It examines research that indicates that children whose phonological processing skills are compromised in some way, are at-risk of experiencing difficulties in the acquisition of literacy; it supports the suggestion that dyslexia can be viewed as lying on the continuum of developmental language disorders. It goes on to relate theory to practice and discusses the responsibilities of health care professionals in relation to the early identification of dyslexia, and makes suggestions regarding intervention. In particular, it looks at the responsibilities of speech and language therapy services in the care and management of children with dyslexia.

Neural network analysis of oxygenation signals in infants during sleep

The use of artificial neural networks (ANNs) to interpret sleep monitoring signals is described. Recordings from ten infants with apparent life threatening episodes were assigned into training feedforward R-PROP networks. In order to separate good signal from artefact, 60 second time frames of SaO2 and TcPO2 signals were processed and the mean and standard deviation values were used as inputs to the networks. Intra-human errors were minimized using this method whilst inter-human errors remained significant. To decrease the latter, the number of hidden units was increased to eight. Sensitivity figures of the SaO2 network were 0.93 and 0.9 for the training and test sets respectively whilst the specificity figures were 0.7 and 0.65 respectively. For the TcPO2 signals the above figures were 0.92, 0.85, 0.77 and 0.61 respectively.

Investigation of Thin Aqueous Films on Silica Using a Modified Interferometric Technique

The thinning behavior of liquid films between free bubbles and silica is investigated using the interferometric technique. Stable films were obtained at higher salt concentrations compared to previous studies because of the improved cleaning procedure. In contrast to the captive bubble technique used in the past, the free bubble method employed more closely approximates such processes as flotation. The results obtained for aqueous films at low and high ionic strengths are in better agreement with theoretical predictions than those in previous studies. Copyright 2000 Academic Press.