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Biomedical subjects

T Jakobsen

Publications and source records attributed to T Jakobsen.

6 recordsLinked to original sources
PubMed2005

Use of optical scatter sensors for measurement of visibility.

A study on the measurement of visibility by the use of light scattering has been carried out. The basis for the research was the optical forward-scatter sensor, Mira visibility sensor, developed and produced by Aanderaa Instruments. The focus of the study was on how to measure correct visibility at different weather situations (e.g. fog, rain, haze and snow) and how a sensor can provide information on the type of particles/drops which are causing reduced visibility. Optical scatter measurement of airborne dust was also investigated. The work includes theoretical calculations and experimental work. The correlations between scatter measurements and both visibility and the concentration of airborne dust are studied. A short introduction to the subject of visibility measurement is also included.

Air Pollutants↗
PubMed2004

The ADP ribosyltransferase domain of Pseudomonas aeruginosa ExoT contributes to its biological activities.

ExoT is a type III secreted effector protein found in almost all strains of Pseudomonas aeruginosa and is required for full virulence in an animal model of acute pneumonia. It is comprised of an N-terminal domain with GTPase activating protein (GAP) activity towards Rho family GTPases and a C-terminal ADP ribosyltransferase (ADPRT) domain with minimal activity towards a synthetic substrate in vitro. Consistent with its activity as a Rho family GTPase, ExoT has been shown to inhibit P. aeruginosa internalization into epithelial cells and macrophages, disrupt the actin cytoskeleton through a Rho-dependent pathway, and inhibit wound repair in a scrape model of injured epithelium. We have previously shown that mutation of the invariant arginine of the GAP domain to lysine (R149K) results in complete loss of GAP activity in vitro but only partially inhibits ExoT anti-internalization and cell rounding activity. We have constructed in-frame deletions and point mutations within the ADPRT domain in order to test whether this domain might account for the residual activity observed in ExoT GAP mutants. Deletion of a majority of the ADPRT domain (residues 234 to 438) or point mutations of the ADPRT catalytic site (residues 383 to 385) led to distinct changes in host cell morphology and substantially reduced the ability of ExoT to inhibit in vitro epithelial wound healing over a 24-h period. In contrast, only subtle effects on the efficiency of ExoT-induced bacterial internalization were observed in the ADPRT mutant forms. Expression of each domain individually in Saccharomyces cerevisiae was toxic, whereas expression of each of the catalytically inactive mutant domains was not. Collectively, these data demonstrate that the ADPRT domain of ExoT is active in vivo and contributes to the pathogenesis of P. aeruginosa infections.

ADP Ribose Transferases↗
PubMed2001

[Therapeutic changes beyond the symptoms - effects of inpatient treatment according to the Heidelberg Structural Change Scale].

The question is discussed how changes concerning the patient's ability to recognize and obtain insight into dysfunctional relationship patterns, life-determining conflicts, and structural vulnerability as well as the readiness to take on the responsibility for the negative effects caused by these may be conceptualized. A model has been developed based on Operationalized Psychodynamic Diagnosis (OPD) in which individual problem areas for each patient may be chosen from a list of foci. Changes in these foci are evaluated using the Heidelberg Structural Change Scale which is presented and discussed in detail. This concept is applied to a sample of patients who had been treated in an in-patient setting. It is demonstrated that this method of measuring changes can be used reliably. Furthermore, the changes registered with the structural change scale correlate on an absolute level quite high to the global assessment of outcome through the therapeutic team; this correlation is even higher than the correlation between symptomatic changes and the global assessments. How this concept may be applied in planning, evaluating, and ensuring the quality of psychotherapy is presented in conclusion.

Adaptation, Psychological↗
PubMed2000

Enhanced cleavage of RNA mediated by an interaction between substrates and the arginine-rich domain of E. coli ribonuclease E.

Endonucleolytic cutting by the essential Escherichia coli ribonuclease RNaseE has a central role in both the processing and decay of RNA. Previously, it has been shown that an oligoribonucleotide corresponding in sequence to the single-stranded region at the 5' end of RNAI, the antisense regulator of ColE1-type plasmid replication, is efficiently cut by RNaseE. Combined with the knowledge that alteration of the structure of stem-loops within complex RNaseE substrates can either increase or decrease the rate of cleavage, this result has led to the notion that stem-loops do not serve as essential recognition motifs for RNaseE, but can affect the rate of cleavage indirectly by, for example, determining the single-strandedness of the site or its accessibility. We report here, however, that not all oligoribonucleotides corresponding to RNaseE-cleaved segments of complex substrates are sufficient to direct efficient RNaseE cleavage. We provide evidence using 9 S RNA, a precursor of 5 S rRNA, that binding of structured regions by the arginine-rich RNA- binding domain (ARRBD) of RNaseE can be required for efficient cleavage. Binding by the ARRBD appears to counteract the inhibitory effects of sub-optimal cleavage site sequence and overall substrate conformation. Furthermore, combined with the results from recent analyses of E. coli mutants in which the ARRBD of RNase E is deleted, our findings suggest that substrate binding by RNaseE is essential for the normal rapid decay of E. coli mRNA. The simplest interpretation of our results is that the ARRBD recruits RNaseE to structured RNAs, thereby increasing the localised concentration of the N-terminal catalytic domain, which in turn leads to an increase in the rate of cleavage.

Amino Acid Motifs↗