Desulfonation of aliphatic sulfonates by Pseudomonas aeruginosa PAO

Pseudomonas aeruginosa PAO1 used a broad range of alkanesulfonic acids as sole sulfur source for growth, with molar growth yields of 2.2 to 2.9 kg protein per mol sulfur. 4-Phenylbutane-1-sulfonate was desulfonated in vivo to yield 4-pheny 1-1-butyric acid quantitatively as the sole product, suggesting that the desulfonation mechanism is the same as when alkanesulfonates serve as a carbon source for growth. This contrasts with aromatic sulfonate utilization in other organisms, where different desulfonation reactions are used to provide carbon and sulfur. Desulfonation of alkanesulfonates to provide sulfur was repressed by sulfate or thiocyanate, and derepressed in their absence. The alkanesulfonatase system is hence controlled as part of the sulfate starvation-induced stimulo

Riding the sulfur cycle - metabolism of sulfonates and sulfate esters in Gram-negative bacteria

Sulfonates and sulfate esters are widespread in nature, and make up over 95% of the sulfur content of most aerobic soils. Many microorganisms can use sulfonates and sulfate esters as a source of sulfur for growth, even when they are unable to metabolize the carbon skeleton of the compounds. In these organisms, expression of sulfatases and sulfonatases is repressed in the presence of sulfate, in a process mediated by the LysR-type regulator protein CysB, and the corresponding genes therefore constitute an extension of the cys regulon. Additional regulator proteins required for sulfonate desulfonation have been identified in Escherichia coli (the Cbl protein) and Pseudomonas putida (the AsfR protein). Desulfonation of aromatic and aliphatic sulfonates as sulfur sources by aerobic bacteria is oxygen-dependent, carried out by the α-ketoglutarate-dependent taurine dioxygenase, or by one of several FMNH2-dependent monooxygenases. Desulfurization of condensed thiophenes is also FMNH2-dependent, both in the rhodococci and in two Gram-negative species. Bacterial utilization of aromatic sulfate esters is catalyzed by arylsulfatases, most of which are related to human lysosomal sulfatases and contain an active-site formylglycine group that is generated post-translationally. Sulfate-regulated alkylsulfatases, by contrast, are less well characterized. Our increasing knowledge of the sulfur-regulated metabolism of organosulfur compounds suggests applications in practical fields such as biodesulfurization, bioremediation, and optimization of crop sulfur nutritio

Construction of improved plasmid vectors for promoter characterization in Pseudomonas aeruginosa and other Gram-negative bacteria

We report the construction of two broad host range promoter-probe plasmid vectors for rapid analysis of promoters in Gram-negative bacteria. The new vectors, pME4507 and pME4510, carry carbenicillin and gentamycin resistance genes, respectively, and are small sized (4 kb) with a flexible multiple cloning site to facilitate directional cloning of putative promoter elements. The vectors allow rapid plate-based screening for promoter activities, using β-galactosidase as the reporter enzyme. In the absence of an inserted promoter fragment, they display very low background activity, making them a useful tool for analysis of low expression level promoter

Post-hospital medical respite care and hospital readmission of homeless persons

Medical respite programs offer medical, nursing, and other care as well as accommodation for homeless persons discharged from acute hospital stays. They represent a community-based adaptation of urban health systems to the specific needs of homeless persons. This article examines whether post-hospital discharge to a homeless medical respite program was associated with a reduced chance of 90-day readmission compared to other disposition options. Adjusting for imbalances in patient characteristics using propensity scores, respite patients were the only group that was significantly less likely to be readmitted within 90 days compared to those released to Own Care. Respite programs merit attention as a potentially efficacious service for homeless persons leaving the hospital

Vata-L: Visual-Analogue Test Assessing Anosognosia for Language Impairment

Lack of awareness (anosognosia) for one's own language impairments has rarely been investigated, despite hampering language rehabilitation. Assessment of anosognosia by means of self-report is particularly complex, as a patient's language difficulties may seriously prevent or bias the assessment. Other methods, such as measures of self-correction and error detection, have provided valuable information, although they are an indirect form of assessment of anosognosia and are not exempt from methodological criticisms. In this study we report on a new tool, the VATA-L (Visual-Analogue Test for Anosognosia for Language impairment), geared at assessing explicit anosognosia for aphasia. The VATA-L compares the patient's self-evaluation with caregivers’ evaluations of the patient's verbal communication abilities in a series of common situations. By means of non-verbal support and a system of check questions, this test minimizes some of the methodological limitations of existing diagnostic tools (e.g., structured interviews), enhancing reliability, and enabling assessment of patients with aphasia. Finally, normative data provided in the study allow a clearer interpretation of the patient's performance and facilitate assessment of anosognosia

Apraxia and motor dysfunction in corticobasal syndrome

Background: Corticobasal syndrome (CBS) is characterized by multifaceted motor system dysfunction and cognitive disturbance; distinctive clinical features include limb apraxia and visuospatial dysfunction. Transcranial magnetic stimulation (TMS) has been used to study motor system dysfunction in CBS, but the relationship of TMS parameters to clinical features has not been studied. The present study explored several hypotheses; firstly, that limb apraxia may be partly due to visuospatial impairment in CBS. Secondly, that motor system dysfunction can be demonstrated in CBS, using threshold-tracking TMS, and is linked to limb apraxia. Finally, that atrophy of the primary motor cortex, studied using voxel-based morphometry analysis (VBM), is associated with motor system dysfunction and limb apraxia in CBS.   Methods: Imitation of meaningful and meaningless hand gestures was graded to assess limb apraxia, while cognitive performance was assessed using the Addenbrooke's Cognitive Examination - Revised (ACE-R), with particular emphasis placed on the visuospatial subtask. Patients underwent TMS, to assess cortical function, and VBM.   Results: In total, 17 patients with CBS (7 male, 10 female; mean age 64.4+/2 6.6 years) were studied and compared to 17 matched control subjects. Of the CBS patients, 23.5% had a relatively inexcitable motor cortex, with evidence of cortical dysfunction in the remaining 76.5% patients. Reduced resting motor threshold, and visuospatial performance, correlated with limb apraxia. Patients with a resting motor threshold <50% performed significantly worse on the visuospatial sub-task of the ACE-R than other CBS patients. Cortical function correlated with atrophy of the primary and pre-motor cortices, and the thalamus, while apraxia correlated with atrophy of the pre-motor and parietal cortices.   Conclusions: Cortical dysfunction appears to underlie the core clinical features of CBS, and is associated with atrophy of the primary motor and pre-motor cortices, as well as the thalamus, while apraxia correlates with pre-motor and parietal atrophy

Anosognosia and self-correction of naming errors in aphasia

Background: There has been comparatively little research into anosognosia for aphasia (a lack of awareness of acquired language deficits). Direct assessments of metacognitive awareness tend to rely on high levels of verbal competence and are difficult for people with aphasia to complete. Therefore indirect measures of awareness have been considered, notably the person’s self-correction of his or her naming errors. Different mechanisms for self-correction based in comprehension or production skills have been proposed. In addition, in other areas of cognition, the relationships between direct and indirect measures and underlying forms of awareness have not been clearly established. Aims: The aims of this study were: a) to investigate the relationship between a direct and an indirect measure of awareness of aphasia, b) to examine the role of executive functioning in performance on both assessment types, and c) to examine the relationship between these measures and underlying language comprehension and production skills. Methods & Procedures: Forty-eight people with aphasia participated, drawn from rehabilitation hospital caseloads. Participants were assessed on a language battery, a non-verbal test of executive function, a direct measure of awareness (ratings of difficulties), and had self-correction behaviour examined in a 40-item naming test. Outcomes & Results: There was a trend relationship between performance on the direct and indirect measures. Both related to overall severity of language impairment, with more severely impaired people being less aware of their difficulties. The two measures, however, dissociated with respect to single-word production and comprehension scores: the direct measure related to production and not comprehension, while the indirect measure related to comprehension and not production. Executive functioning related only to the direct measure of metacognitive awareness. Within production scores, the rate of correction success rather than pre-correction naming rate was associated with metacognitive awareness. Conclusions: This study revealed different underlying bases, in language processes and executive function, for two measures of anosognosia for aphasia. When used to assess awareness of deficits, direct and indirect methods should not be regarded as equivalent