The conserved carboxyl domain of MorC, an inner membrane protein of Aggregatibacter actinomycetemcomitans, is essential for membrane function.

Morphogenesis protein C (MorC) of Aggregatibacter actinomycetemcomitans is important for maintaining the membrane morphology and integrity of the cell envelope of this oral pathogen. The MorC sequence and operon organization were found to be conserved in Gammaproteobacteria, based on a bioinformatic analysis of 435 sequences from representative organisms. Functional conservation of MorC was investigated using an A. actinomycetemcomitans morC mutant as a model system to express MorC homologs from four phylogenetically diverse representatives of the Gammaproteobacteria: Haemophilus influenzae, Escherichia coli, Pseudomonas aeruginosa, and Moraxella catarrhalis. The A. actinomycetemcomitans strains expressing the homologous proteins were assessed for sensitivity to bile salts, leukotoxin secretion, autoaggregation and membrane morphology. MorC from the most closely related organism (H. influenzae) was functionally identical to MorC from A. actinomycetemcomitans. However, the genes from more distantly related organisms restored some but not all A. actinomycetemcomitans mutant phenotypes. In addition, deletion mutagenesis indicated that the most conserved portion of the protein, the C-terminus DUF490 domain, was necessary to maintain the integrity of the membrane. Deletion of the last 10 amino acids of this domain of the A. actinomycetemcomitans MorC protein was sufficient to disrupt membrane stability and leukotoxin secretion. The data suggest that the MorC sequence is functionally conserved across Gammaproteobacteria and the C-terminus of the protein is essential for maintaining membrane physiology.

The cell envelope proteome of Aggregatibacter actinomycetemcomitans.

The cell envelope of gram-negative bacteria serves a critical role in maintenance of cellular homeostasis, resistance to external stress, and host-pathogen interactions. Envelope protein composition is influenced by the physiological and environmental demands placed on the bacterium. In this study, we report a comprehensive compilation of cell envelope proteins from the periodontal and systemic pathogen Aggregatibacter actinomycetemcomitans VT1169, an afimbriated serotype b strain. The urea-extracted membrane proteins were identified by mass spectrometry-based shotgun proteomics. The membrane proteome, isolated from actively growing bacteria under normal laboratory conditions, included 648 proteins representing 27% of the predicted open reading frames in the genome. Bioinformatic analyses were used to annotate and predict the cellular location and function of the proteins. Surface adhesins, porins, lipoproteins, numerous influx and efflux pumps, multiple sugar, amino acid and iron transporters, and components of the type I, II and V secretion systems were identified. Periplasmic space and cytoplasmic proteins with chaperone function were also identified. A total of 107 proteins with unknown function were associated with the cell envelope. Orthologs of a subset of these uncharacterized proteins are present in other bacterial genomes, whereas others are found exclusively in A. actinomycetemcomitans. This knowledge will contribute to elucidating the role of cell envelope proteins in bacterial growth and survival in the oral cavity.

The value of the D-Dimer assay for predicting vein thrombosis in rehabilitation patients receiving prophylactic low molecular weight heparin doses.

PURPOSE: Early diagnosis and treatment of venous thrombosis biocontact="no" are essential in preventing pulmonary embolism (PE) and reducing the risk of recurrence. The objective was to assess the usefulness of the D-Dimer testing to rule out symptomatic VT in populations of patients receiving heparin in prophylactic doses. METHODS: One hundred and twenty-three rehabilitation patients with medium or high risk for VT were investigated. Patients were affected by acquired cerebral diseases (n=31), severe brain damage (n=32) or orthopaedic surgical sequelae for major joint replacement or multiple limb fractures (n=60). All patients were receiving prophylactic heparin doses. D-Dimer levels were assessed using Dimertest Latex Agglutination Assay in citrated plasma. Single blinded compression Doppler Ultrasound (DUS) examination was performed in conformity with international standards. RESULTS: In this specific setting, good sensitivity and specificity of the D-Dimer test was confirmed in patients with acquired cerebral diseases during rehabilitation, whereas false positive results were found in most patients who had undergone major joint replacement, until several weeks after surgery. CONCLUSIONS: In rehabilitation patients receiving prophylactic heparin doses, the D-Dimer test seems to confirm high sensitivity and high negative predictive value for VT and PE. Relevant clinical variables seem to reduce the usefulness of the D-Dimer test as a screening tool for VT, at least in orthopaedic patients with joint prosthesis.

Time interval of oral feeding recovery as a prognostic factor in severe traumatic brain injury.

PRIMARY OBJECTIVES: To assess the outcome of severe traumatic brain injury at least 1 year after trauma, in relation to some early clinical prognostic factors occurring during coma recovery. RESEARCH DESIGN: Retrospective study conducted at the post-coma unit of a rehabilitation hospital. METHODS AND PROCEDURES: A total of 43 patients were included. All of the patients sustained severe traumatic brain injury and prolonged coma, i.e. coma lasting at least 15 days. Outcome was assessed by means of Glasgow Coma Scale, Barthel Index and Mini Mental State 1 year after trauma, in relation to some early clinical prognostic factors occurring during coma recovery. MAIN OUTCOMES AND RESULTS: At the 1 year follow-up, a statistically significant correlation was found with both the Glasgow Outcome Scale and the Barthel Index for the time interval from brain injury to recovery of the following clinical variables: optical fixation, ability to obey commands, spontaneous motor activity and first safe oral feeding. Psychomotor agitation and bulimia were also favourable prognostic factors for the final outcome. CONCLUSIONS: In the present study, first safe oral feeding during coma recovery represents the clinical feature that better predicts the final outcome of patients with severe traumatic brain injury and prolonged coma.

The impact of treatment on survival roles of a person with a traumatic brain injury.

Over 250 survivors of brain injury were clinically evaluated and a long term care plan developed for each of them. 105 survivors were located and a follow-up questionnaire was administered at least two years later to the survivors and families to evaluate the predictions that were made regarding long-term needs. The study looked at the impact on eight survival roles as defined by WHO and attempted to determine the effectiveness of services, correlating various treatment modalities and services with changes, adjustments, accommodations, achievements, and future goals. Results showed that there is a correlation between some non-traditional therapies (Recreational and Cognitive) and for individuals' future goals in physical independence, mobility, community reintergration and self care. These future goals were not significant for occupational and physical therapies. Also, a less significant correlation was made between paid attendant care and level of outside activities.

An evaluation of nonresponse bias in peer, self, and teacher ratings of children's psychosocial adjustment.

The last decades have shown a rapid increase in nonresponse rates. For this reason it is important to study nonresponse and think about it critically. In this article we investigated whether nonresponse affected estimates of the levels of adjustment problems in children and the correlations between these outcomes. The nonresponse was caused by parents who refused permission to interview their children at school, parents who did not return a questionnaire, teachers who did not complete the questionnaire, and parents who refused to participate in an in-depth study, with nonresponse rates of 9%, 69%, 25%, and 46% respectively. The sample consisted of 1282 children aged 4 5 years and the dependent measures were peer-rated sociometric status, self-rated wellbeing at school, and teacher-rated behaviour problems. Despite considerable nonresponse in some conditions our results showed hardly any evidence for bias. This suggested that bias cannot simply be inferred from the amount of nonresponse and that standard rules such as "nonresponse rates higher than 50% are not acceptable" lack a scientific basis. Instead, we argue that to assess nonresponse bias the specific conditions and analyses of the study will need to be considered and special measures may be required.

Quality of life: an aspect of life care planning and long-term care.

Traumatic brain injury (TBI) has a devastating effect on all aspects of a person's life, which negatively impacts the individual's quality of life. Indeed, the individual is not the same person following TBI. However, through systematic life care planning and appropriate long-term care, this negative impact can be mitigated.

Bromate reduction by denitrifying bacteria.

In the presence of bromide, ozonation as applied in water treatment results in the formation of bromate, an ion with carcinogenic properties. The reduction of bromate by mixed bacterial populations as well as pure cultures was studied under laboratory conditions. Bromate was reduced to bromide by a mixed bacterial population with and without a preceding nitrate reduction step in an anaerobically incubated medium with ethanol as the energy and carbon source at 20 and 25 deg C. The predominating bacteria isolated from the batches showing bromate reduction were identified as Pseudomonas spp. Strains of Pseudomonas fluorescens reduced BrO(inf3)(sup-) to Br(sup-) but at a much lower rate than the mixed bacterial population did. Nitrate is a preferred electron acceptor for the bromate-reducing bacteria. Bromate reduction did not occur in the presence of NO(inf3)(sup-), and the rate of bromate reduction was at least 100 times lower than the rate of nitrate reduction. Bromate was completely converted to Br(sup-), indicating that intermediates, e.g., BrO(inf2)(sup-), did not accumulate during bromate reduction.

Metronidazole need not be combined with an aminoglycoside when used for prophylaxis in elective colorectal surgery.

A prospective randomized controlled study has compared prophylactic intravenous metronidazole alone with the combination of metronidazole and gentamicin in 100 patients having elective colorectal surgery. There was no significant difference in mortality, infection, dehiscence or postoperative stay between the antibiotic groups. Postoperative sepsis was almost entirely due to aerobic organisms but was associated with minimal morbidity. A significantly higher rate of anastomotic dehiscence and postoperative infection was seen where the quality of bowel preparation was judged to be poor.