| 1. |
- Nägga, Katarina, 1962-, et al.
(författare)
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Evaluation of factors of importance for clinical dementia diagnosis
- 2005
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Ingår i: Dementia and Geriatric Cognitive Disorders. - : S. Karger AG. - 1420-8008 .- 1421-9824. ; 19:5-6, s. 289-298
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Tidskriftsartikel (refereegranskat)abstract
- Diagnosing clinical dementia is based on an assessment of different variables, such as the patient’s medical history, known risk factors, and biochemical features. Partial least squares discriminant analysis was used to evaluate variables of importance for diagnosing dementia in a clinical dementia population. Polymorphism for genotypes of glutathione S-transferase (GST) and sulfotransferase 1A1, hypothetically of importance in dementia disorders, was also included in the analysis. The study population consisted of 73 patients with Alzheimer’s disease (AD), 14 with mixed dementia, 75 patients with vascular dementia, and 28 control cases. We found that several of the variables, such as the presence of ApoE4 allele, high cerebrospinal fluid levels of total tau protein, low levels of β-amyloid<sub>(1–42)</sub>, and a low score on the Mini-Mental State Examination, facilitated a discrimination between the diagnoses compared with the controls. The different diagnoses overlapped. There were indications that genotypes of GSTs contributed to a subgrouping within AD.
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| 2. |
- Dunstan, R. H., et al.
(författare)
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Diverse characteristics of the urinary excretion of amino acids in humans and the use of amino acid supplementation to reduce fatigue and sub-health in adults
- 2017
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Ingår i: Nutrition Journal. - : Springer Science and Business Media LLC. - 1475-2891. ; 16:19
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Tidskriftsartikel (refereegranskat)abstract
- Background: The excretion of amino acids in urine represents an important avenue for the loss of key nutrients. Some amino acids such as glycine and histidine are lost in higher abundance than others. These two amino acids perform important physiological functions and are required for the synthesis of key proteins such as haemoglobin and collagen. Methods: Stage 1 of this study involved healthy subjects(n = 151) who provided first of the morning urine samples and completed symptom questionnaires. Urine was analysed for amino acid composition by gas chromatography. Stage 2 involved a subset of the initial cohort (n = 37) who completed a 30 day trial of an amino acid supplement and subsequent symptom profile evaluation. Results: Analyses of urinary amino acid profiles revealed that three groups could be objectively defined from the 151 participants using k-means clustering. The amino acid profiles were significantly different between each of the clusters (Wilks' Lambda = 0.13, p < 0.0001). Cluster 1 had the highest loss of amino acids with histidine being the most abundant component. Cluster 2 had glycine present as the most abundant urinary amino acid and cluster 3 had equivalent abundances of glycine and histidine. Strong associations were observed between urinary proline concentrations and fatigue/pain scores (r =.56 to.83) for females in cluster 1, with several other differential sets of associations observed for the other clusters. Conclusions: Different phenotypic subsets exist in the population based on amino acid excretion characteristics found in urine. Provision of the supplement resulted in significant improvements in reported fatigue and sleep for 81% of the trial cohort with all females reporting improvements in fatigue.
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| 3. |
- Dunstan, R. H., et al.
(författare)
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Sex differences in amino acids lost via sweating could lead to differential susceptibilities to disturbances in nitrogen balance and collagen turnover
- 2017
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Ingår i: Amino Acids. - : Springer Science and Business Media LLC. - 0939-4451 .- 1438-2199. ; 49:8, s. 1337-1345
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Tidskriftsartikel (refereegranskat)abstract
- Fluid collected during sweating is enriched with amino acids derived from the skin's natural moisturising factors and has been termed "faux" sweat. Little is known about sex differences in sweat amino acid composition or whether faux sweat amino acid losses affect nitrogen balance. Faux sweat collected by healthy adults (n = 47) after exercise, and at rest by chronic fatigue patients, was analysed for amino acid composition. Healthy females had higher total amino acid concentrations in sweat (10.5 +/- 1.2 mM) compared with healthy males (6.9 +/- 0.9 mM). Females had higher levels of 13 amino acids in sweat including serine, alanine and glycine. Higher hydroxyproline and proline levels suggested greater collagen turnover in females. Modelling indicated that with conservative levels of exercise, amino acid losses in females via faux sweat were triple than those predicted for urine, whereas in males they were double. It was concluded that females were more susceptible to key amino acid loss during exercise and/or hot conditions. Females reporting chronic fatigue had higher levels of methionine in faux sweat than healthy females. Males reporting chronic fatigue had higher levels of numerous amino acids in faux sweat compared to healthy males. Higher amino acid loss in faux sweat associated with chronic fatigue could contribute to a hypometabolic state. Depending on activity levels, climatic conditions and gender, amino acid losses in sweat and skin leachate could influence daily protein turnover where periods of continuously high turnover could lead to a negative net nitrogen balance.
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| 4. |
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| 5. |
- Pinto, Rui Climaco, et al.
(författare)
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Advantages of orthogonal inspection in chemometrics
- 2012
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Ingår i: Journal of Chemometrics. - : Wiley. - 0886-9383 .- 1099-128X. ; 26:6, s. 231-235
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Tidskriftsartikel (refereegranskat)abstract
- The demand for chemometrics tools and concepts to study complex problems in modern biology and medicine has prompted chemometricians to shift their focus away from a traditional emphasis on model predictive capacity toward optimizing information exchange via model interpretation for biological validation. The interpretation of projection-based latent variable models is not straightforward because of its confounding of different systematic variations in the model components. Over the last 15?years, this has spurred the development of orthogonal-based methods that are capable of separating the correlated variation (to Y) from the noncorrelated (orthogonal to Y) variations in a single model. Here, we aim to provide a conceptual explanation of the advantages of orthogonal variation inspection in the context of Partial Least Squares (PLS) in multivariate classification and calibration. We propose that by inspecting the orthogonal variation, both model interpretation and information quality are improved by enhancement of the resulting level of knowledge. Although the predictive capacity of PLS using orthogonal methods may be identical to that of PLS alone, the combined result can be superior when it comes to the model interpretation. By discussing theory and examples, several new advantages revealed by inspection of orthogonal variation are highlighted. Copyright (c) 2012 John Wiley & Sons, Ltd.
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| 6. |
- Rüetschi, Ulla, 1962, et al.
(författare)
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Identification of CSF biomarkers for frontotemporal dementia using SELDI-TOF.
- 2005
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Ingår i: Experimental neurology. - : Elsevier BV. - 0014-4886. ; 196:2, s. 273-81
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Tidskriftsartikel (refereegranskat)abstract
- This investigation describes the discovery of novel possible cerebrospinal fluid (CSF) biomarkers for frontotemporal dementia (FTD) using surface-enhanced laser desorption/ionization time-of-flight (SELDI-TOF) mass spectrometry (MS). Sixteen clinically diagnosed FTD patients and 12 non-demented controls were included in the study. CSF was collected and analyzed for protein expression by SELDI-TOF MS. The samples were analyzed on four different array surfaces using two different energy-absorbing molecules as matrices. In total each sample was subjected to eight different surface/matrix conditions. About 2000 protein peaks (mass/charge ratios) were detected. Forty-two peaks were differentially expressed in FTD (P < 0.01). After exclusion of peaks with low signal-to-noise ratio and/or poor resolution and peaks representing differentially charged proteins, 10 peaks remained, five of which were increased and five decreased in FTD cases compared to controls. Using partial least square discriminant analysis (PLS-DA), the combination of these biomarkers discriminated FTD from non-demented controls with a sensitivity of 94%, a specificity of 83% and an accuracy of 89%. Five of the peaks were purified further and identified by tandem MS as a fragment of neurosecretory protein VGF, transthyretin, S-cysteinylated transthyretin, truncated cystatin C and a fragment of chromogranin B. With use of these potential biomarkers, FTD can be distinguished from control subjects with high accuracy in this pilot study.
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| 7. |
- Svelander, Cecilia, 1980, et al.
(författare)
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Postprandial lipid and insulin responses among healthy, overweight men to mixed meals served with baked herring, pickled herring or baked, minced beef
- 2015
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Ingår i: European Journal of Nutrition. - : Springer Science and Business Media LLC. - 1436-6207 .- 1436-6215. ; 54:6, s. 945-958
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: The aim was to compare postprandial lipid, insulin and vitamin D responses after consumption of three otherwise identical meals served either with baked herring, pickled herring or with baked, minced beef. METHODS: Seventeen healthy, overweight men (mean age 58 years, BMI 26.4-29.5 kg/m2) consumed standardized lunches together with baked herring, pickled herring or baked, minced beef on three occasions in a crossover design. Blood samples were taken just before and up to 7 h after the meal. The postprandial response was measured as serum concentrations of triglycerides (TG), total cholesterol and lipoproteins (LDL, HDL and VLDL), insulin, 25-OH vitamin D and plasma fatty acid composition. RESULTS: There was no difference in postprandial lipid responses between the two herring meals, whereas a slower TG clearance was observed after the baked, minced beef meal. The 150 g servings of baked and pickled herring provided 3.3 and 2.8 g of long-chain n-3 polyunsaturated fatty acids (LC n-3 PUFA), respectively, which was reflected in a substantial postprandial increase in plasma LC n-3 PUFA levels. The pickled herring contained 22 % sugar and consequently gave a higher insulin response compared with the other two meals. CONCLUSIONS: Both pickled and baked herring are good sources of LC n-3 PUFA in the diet, but the presence of sugar in pickled herring should be taken into consideration, especially if large amounts are consumed. The faster postprandial TG clearance after a meal with baked herring compared with baked beef supports previous studies on the beneficial effects of herring on cardiovascular health.
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| 8. |
- Alreshidi, M. M., et al.
(författare)
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Amino acids and proteomic acclimation of Staphylococcus aureus when incubated in a defined minimal medium supplemented with 5% sodium chloride
- 2019
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Ingår i: Microbiologyopen. - : Wiley. - 2045-8827. ; 8:6
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Tidskriftsartikel (refereegranskat)abstract
- Staphylococcus aureus is a versatile bacterium that can adapt to survive and grow in a wide range of salt concentrations. This study investigated whether the cells could mount a response to survive a challenge of 5% NaCl in a minimal incubation medium that would not support cell replication. Cells were grown in liquid culture, washed and then incubated for 90 min at 37 degrees C in a medium that contained only glycine and glucose as substrates in PBS plus trace elements. The control cells were compared with a treatment group which was incubated with an additional 5% NaCl. Significantly more glycine was taken up by the cells exposed to 5% NaCl compared with control cells, and both groups consumed 99% of the glucose supplied. The NaCl treated cells had significantly higher cytoplasmic levels of proline and glutamic acid as well as lower levels of alanine and methionine compared with the controls (p < 0.05). The levels of the two major cytoplasmic amino acids, aspartic acid and glycine, remained constant in control and treated cells. Proteomic analyses revealed that 10 proteins showed differential responses between the control and treatment groups. The reductions in proteins were primarily associated with processes of protein biosynthesis, pathogenicity, and cell adhesion. Since cell numbers remained constant during the incubation period in minimal medium, it was concluded that there was no cell division to support population growth. The results provided evidence that the cells in the minimal medium exposed to the NaCl treatment underwent in situ homeostatic changes to adjust to the new environmental conditions. It was proposed that this represented a phenotypic shift to form cells akin to small colony variants, with lower metabolic rates and lower levels of key proteins associated with pathogenicity.
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| 9. |
- Alreshidi, M. M., et al.
(författare)
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Changes in the Cytoplasmic Composition of Amino Acids and Proteins Observed in Staphylococcus aureus during Growth under Variable Growth Conditions Representative of the Human Wound Site
- 2016
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Ingår i: Plos One. - : Public Library of Science (PLoS). - 1932-6203. ; 11:7
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Tidskriftsartikel (refereegranskat)abstract
- Staphylococcus aureus is an opportunistic pathogen responsible for a high proportion of nosocomial infections. This study was conducted to assess the bacterial responses in the cytoplasmic composition of amino acids and ribosomal proteins under various environmental conditions designed to mimic those on the human skin or within a wound site: pH6-8, temperature 35-37 degrees C, and additional 0-5% NaCl. It was found that each set of environmental conditions elicited substantial adjustments in cytoplasmic levels of glutamic acid, aspartic acid, proline, alanine and glycine (P < 0.05). These alterations generated characteristic amino acid profiles assessed by principle component analysis (PCA). Substantial alterations in cytoplasmic amino acid and protein composition occurred during growth under conditions of higher salinity stress implemented via additional levels of NaCl in the growth medium. The cells responded to additional NaCl at pH 6 by reducing levels of ribosomal proteins, whereas at pH 8 there was an upregulation of ribosomal proteins compared with the reference control. The levels of two ribosomal proteins, L32 and S19, remained constant across all experimental conditions. The data supported the hypothesis that the bacterium was continually responding to the dynamic environment by modifying the proteome and optimising metabolic homeostasis.
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| 10. |
- Alreshidi, M. M., et al.
(författare)
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Metabolomic and proteomic responses of Staphylococcus aureus to prolonged cold stress
- 2015
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Ingår i: Journal of Proteomics. - : Elsevier BV. - 1874-3919. ; 121, s. 44-55
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Tidskriftsartikel (refereegranskat)abstract
- The high pathogenicity of Staphylococcus aureus is thought to be due to its extraordinary capacity to rapidly adapt to changes in environmental conditions. This study was carried out to investigate whether the cytoplasmic profiles of metabolites and proteins of Staphylococcus aureus were altered in response to prolonged exposure to cold stress. Metabolic profiling and proteomics were used to characterise alterations in cytoplasmic proteins and metabolites in cells from the mid-exponential phase of growth under ideal conditions at 37 degrees C and compared with equivalent cells exposed to prolonged cold stress for 2 weeks at 4 degrees C. Principle component analysis (PCA) of the metabolomic and proteomic data indicated that, at the mid-exponential phase of growth, prolonged cold stress conditions generated cells with different metabolite and protein profiles compared with those grown at 37 degrees C. Nine ribosomal proteins and citric acid were substantially elevated in the cytoplasmic fractions from the cells adapted to cold-stress but most amino acids showed a reduction in their concentration in cold-stressed samples. The data provided strong evidence supporting the hypothesis that specific changes in metabolic homeostasis and protein composition were critical to the adaptive processes required for survival under cold stress. Work in our laboratory has shown that prolonged exposure of Staphylococcus aureus to cold stress can result in the formation of small colony variants (SCVs) associated with significant alterations in the cell wall composition [8]. Further studies revealed that Staphylococcus aureus altered cell size and cell wall thickness in response to exposure to cold temperatures, alterations in pH and exposure to antibiotics [10]. The current study has utilised the prolonged exposure to cold stress as a model system to explore changes in the proteome and associated metabolic homeostasis following environmental challenges. The study provides an improved understanding of how Staphylococcus aureus adapts to the changing environment whilst in transition between human hosts. The results indicated an unexpected production of 9 ribosomal proteins and citric acid in response to cold stress suggesting specific survival roles for these proteins and citric acid as an adaptation mechanism for empowering survival under these conditions. Crown Copyright (C) 2015 Published by Elsevier B.V. All rights reserved.
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| 11. |
- Alreshidi, M. M., et al.
(författare)
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The Uptake and Release of Amino Acids by Staphylococcus aureus at Mid-Exponential and Stationary Phases and Their Corresponding Responses to Changes in Temperature, pH and Osmolality
- 2020
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Ingår i: Frontiers in Microbiology. - : Frontiers Media SA. - 1664-302X. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Staphylococcus aureus is an important pathogen that is associated with nosocomial infections, as well as food poisoning. This bacterium is resistant to antimicrobial agents and can survive in a wide range of environmental conditions. The aim of this study was to measure the uptake and release of amino acids by S. aureus at mid-exponential and stationary phases of growth following exposure to a combination of conditions including variations in temperature, pH and NaCl. Bacterial cells were grown up to mid-exponential and stationary phases in tryptic soy broth (TSB), where the supernatants were collected for analyses of amino acids to determine the uptake and release characteristics. The uptake/release of amino acids was estimated by subtracting the initial levels of the free amino acids in the media from those measured at mid-exponential and stationary phases of growth. When cells were grown at ideal conditions, the analyses revealed that significant uptake of amino acids had occurred by stationary phase compared with the mid-exponential phase. A substantial release of valine and tyrosine into the external media was observed by cells at stationary phase. At both phases, the uptake and release patterns were significantly different between cells grown under ideal control conditions, when compared with those grown under various combinations of sub-optimal environmental conditions. The analyses of the supernatants harvested from controls and treatment groups at exponential phase indicated that the total uptake of amino acids was reduced approximately five times by cells grown with addition of 2.5% NaCl or with pH6 at 35 degrees C, and 2-fold by cells grown at pH8 at 35 degrees C. However, the final quantities of amino acids taken up by cells grown to stationary phase did not significantly alter between control and treated samples. Valine was found to be the most abundant amino acid that was significantly released into the media at stationary phase by both control and treated samples. It was evident that diverse environmental conditions resulted in differential patterns of amino acid uptake and release during adaptation to designated conditions.
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| 12. |
- Crompton, M. J., et al.
(författare)
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Small changes in environmental parameters lead to alterations in antibiotic resistance, cell morphology and membrane fatty acid composition in Staphylococcus lugdunensis
- 2014
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Ingår i: PLoS ONE. - : Public Library of Science. - 1932-6203. ; 9:4
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Tidskriftsartikel (refereegranskat)abstract
- Staphylococcus lugdunensis has emerged as a major cause of community-acquired and nosocomial infections. This bacterium can rapidly adapt to changing environmental conditions to survive and capitalize on opportunities to colonize and infect through wound surfaces. It was proposed that S. lugdunensis would have underlying alterations in metabolic homeostasis to provide the necessary levels of adaptive protection. The aims of this project were to examine the impacts of subtle variations in environmental conditions on growth characteristics, cell size and membrane fatty acid composition in S. lugdunensis. Liquid broth cultures of S. lugdunensis were grown under varying combinations of pH (6-8), temperature (35-39°C) and osmotic pressure (0-5% sodium chloride w/w) to reflect potential ranges of conditions encountered during transition from skin surfaces to invasion of wound sites. The cells were harvested at the mid-exponential phase of growth and assessed for antibiotic minimal inhibitory concentration (MIC), generation time, formation of small colony variants, cell size (by scanning electron microscopy) and membrane fatty acid composition. Stress regimes with elevated NaCl concentrations resulted in significantly higher antibiotic resistance (MIC) and three of the combinations with 5% NaCl had increased generation times (P<0.05). It was found that all ten experimental growth regimes, including the control and centroid cultures, yielded significantly different profiles of plasma membrane fatty acid composition (P<0.0001). Alterations in cell size (P<0.01) were also observed under the range of conditions with the most substantial reduction occurring when cells were grown at 39°C, pH 8 (514±52 nm, mean ± Standard Deviation) compared with cells grown under control conditions at 37°C with pH 7 (702±76 nm, P<0.01). It was concluded that S. lugdunensis responded to slight changes in environmental conditions by altering plasma membrane fatty acid composition, growth rates and morphology to achieve optimal adaptations for survival in changing environments. © 2014 Crompton et al.
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| 13. |
- Dunstan, R H, et al.
(författare)
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Development of a complex amino acid supplement, Fatigue Reviva¿, for oral ingestion: initial evaluations of product concept and impact on symptoms of sub-health in a group of males
- 2013
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Ingår i: Nutrition Journal. - 1475-2891. ; 12:115
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Tidskriftsartikel (refereegranskat)abstract
- Abstract Background A new dietary supplement, Fatigue Reviva™, has been recently developed to address issues related to amino acid depletion following illness or in conditions of sub-health where altered amino acid homeostasis has been associated with fatigue. Complex formulations of amino acids present significant challenges due to solubility and taste constraints. This initial study sets out to provide an initial appraisal of product palatability and to gather pilot evidence for efficacy. Methods Males reporting symptoms of sub-health were recruited on the basis of being free from any significant medical or psychological condition. Each participant took an amino acid based dietary supplement (Fatigue Reviva™) daily for 30 days. Comparisons were then made between pre- and post-supplement general health symptoms and urinary amino acid profiles. Results Seventeen men took part in the study. Following amino acid supplementation the total Chalder fatigue score improved significantly (mean ± SEM, 12.5 ± 0.9 versus 10.0 ± 1.0, P<0.03). When asked whether they thought that the supplement had improved their health, 65% of participants responded positively. A subgroup of participants reported gastrointestinal symptoms which were attributed to the supplement and which were believed to result from the component fructooligosaccharide. Analysis of urinary amino acids revealed significant alterations in the relative abundances of a number of amino acids after supplementation including an increase in valine, isoleucine and glutamic acid and reduced levels of glutamine and ornithine. Discriminant function analysis of the urinary amino acid data revealed significant differences between the pre- and post-supplement urine excretion profiles. Conclusions The results indicated that Fatigue Reviva™ was palatable and that 65% of the study group reported that they felt the product had improved their health. The product could provide an effective tool for the management of unexplained fatigue and symptoms of sub-health. Further product development may yield additional options for those patients susceptible to fructooligosaccharide.
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| 14. |
- Dunstan, R. H., et al.
(författare)
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Sweat facilitated amino acid losses in male athletes during exercise at 32-34°C
- 2016
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 11:12
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Tidskriftsartikel (refereegranskat)abstract
- Sweat contains amino acids and electrolytes derived from plasma and athletes can lose 1-2L of sweat per hour during exercise. Sweat may also contain contributions of amino acids as well as urea, sodium and potassium from the natural moisturizing factors (NMF) produced in the stratum corneum. In preliminary experiments, one participant was tested on three separate occasions to compare sweat composition with surface water washings from the same area of skin to assess contributions from NMF. Two participants performed a 40 minute self-paced cycle session with sweat collected from cleansed skin at regular intervals to assess the contributions to the sweat load from NMF over the period of exercise. The main study investigated sweat amino acid composition collected from nineteen male athletes following standardised endurance exercise regimes at 32-34°C and 20-30% RH. Plasma was also collected from ten of the athletes to compare sweat and plasma composition of amino acids. The amino acid profiles of the skin washings were similar to the sweat, suggesting that the NMF could contribute certain amino acids into sweat. Since the sweat collected from athletes contained some amino acid contributions from the skin, this fluid was subsequently referred to as "faux" sweat. Samples taken over 40 minutes of exercise showed that these contributions diminished over time and were minimal at 35 minutes. In the main study, the faux sweat samples collected from the athletes with minimal NMF contributions, were characterised by relatively high levels of serine, histidine, ornithine, glycine and alanine compared with the corresponding levels measured in the plasma. Aspartic acid was detected in faux sweat but not in the plasma. Glutamine and proline were lower in the faux sweat than plasma in all the athletes. Three phenotypic groups of athletes were defined based on faux sweat volumes and composition profiles of amino acids with varying relative abundances of histidine, serine, glycine and ornithine. It was concluded that for some individuals, faux sweat resulting from exercise at 32-34°C and 20-30% RH posed a potentially significant source of amino acid loss. © 2016 Dunstan et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
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| 15. |
- Dunstan, R. H., et al.
(författare)
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Sweat facilitated losses of amino acids in Standardbred horses and the application of supplementation strategies to maintain condition during training
- 2015
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Ingår i: Comparative Exercise Physiology. - : Wageningen Academic Publishers. - 1755-2540 .- 1755-2559. ; 11:4, s. 201-212
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Tidskriftsartikel (refereegranskat)abstract
- Little is known about the amino acid composition of horse sweat, but significant fluid losses can occur during exercise with the potential to facilitate substantial nutrient losses. Sweat and plasma amino acid compositions for Standardbred horses were assessed to determine losses during a standardised training regime. Two cohorts of horses 2013 (n=5) and 2014 (n=6) were assessed to determine baseline levels of plasma and sweat amino acids. An amino acid supplement designed to counter losses in sweat during exercise was provided after morning exercise daily for 5 weeks (2013, n=5; 2014, n=4). After the supplementation period, blood and sweat samples were collected to assess amino acid composition changes. From baseline assessments of sweat in both cohorts, it was found that serine, glutamic acid, histidine and phenylalanine were present at up to 9 times the corresponding plasma concentrations and aspartic acid at 0-2.2 mu mol/l in plasma was measured at 154-262 mu mol/l in sweat. In contrast, glutamine, asparagine, methionine and cystine were conserved in the plasma by having lower concentrations in the sweat. The predominant plasma amino acids were glycine, glutamine, alanine, valine, serine, lysine and leucine. As the sweat amino acid profile did not simply reflect plasma composition, it was proposed that mechanisms exist to generate high concentrations of certain amino acids in sweat whilst selectively preventing the loss of others. The estimated amino acid load in 16 l of circulating plasma was 3.8-4.3 g and the calculated loss via sweat during high intensity exercise was 1.6-3.0 g. Following supplementation, total plasma amino acid levels from both cohorts increased from initial levels of 2,293 and 2,044 mu mol/l to post-supplementation levels of 2,674 and 2,663 mu mol/l respectively (P<0.05). It was concluded that the strategy of providing free amino acids immediately after exercise resulted in raising resting plasma amino acid levels.
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| 16. |
- Gao, C. X., et al.
(författare)
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Exploration of multiple Sortase A protein conformations in virtual screening
- 2016
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 6:20413
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Tidskriftsartikel (refereegranskat)abstract
- Methicillin resistant Staphylococcus aureus (MRSA) has become a major health concern which has brought about an urgent need for new therapeutic agents. As the S. aureus Sortase A (SrtA) enzyme contributes to the adherence of the bacteria to the host cells, inhibition thereof by small molecules could be employed as potential antivirulence agents, also towards resistant strains. Albeit several virtual docking SrtA campaigns have been reported, no strongly inhibitatory non-covalent binders have as yet emerged therefrom. In order to better understand the binding modes of small molecules, and the effect of different receptor structures employed in the screening, we herein report on an exploratory study employing 10 known binders and 500 decoys on 100 SrtA structures generated from regular or steered molecular dynamics simulations on four different SrtA crystal/NMR structures. The results suggest a correlation between the protein structural flexibility and the virtual screening performance, and confirm the noted immobilization of the beta 6/beta 7 loop upon substrate binding. The NMR structures reported appear to perform slightly better than the Xray-crystal structures, but the binding modes fluctuate tremendously, and it might be suspected that the catalytic site is not necessarily the preferred site of binding for some of the reported active compounds.
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| 17. |
- Gertow, J., et al.
(författare)
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Ceramides are associated with inflammatory processes in human mediastinal adipose tissue
- 2014
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Ingår i: NMCD. Nutrition Metabolism and Cardiovascular Diseases. - : Elsevier BV. - 0939-4753 .- 1590-3729. ; 24:2, s. 124-131
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Tidskriftsartikel (refereegranskat)abstract
- Background and Aim: Ceramides are poorly characterized in human adipose tissue. The aim of this study was to investigate concentrations of different ceramide species in human subcutaneous and visceral adipose tissue depots and to determine associations between ceramides and global gene expression profiles. Methods and Results: Concentrations of six ceramide species were determined in plasma and in subcutaneous and mediastinal adipose tissue from 10 overweight subjects (BMI 29.4±4.9kg/m2). In the adipose tissue biopsies gene expression arrays were performed and relationships between ceramides and gene expression analyzed. Immunostaining of the two adipose tissue depots was performed in an independent group of 10 patients. Mediastinal adipose tissue contained significantly higher concentrations (p<0.05) of all six ceramide species than the subcutaneous depot. Of the six ceramides in plasma, concentrations of only two (Cer d18:1/18:0 and Cer d18:1/22:0) correlated significantly (p<0.05) with the corresponding species in mediastinal adipose tissue, but there were no significant correlations between ceramides in plasma and subcutaneous adipose tissue. Multivariate analysis identified significant correlations between the total ceramide concentration and global gene expression within mediastinal, but not subcutaneous adipose tissue, according to cross-validation. Gene ontology analysis of genes related to ceramides in the mediastinal depot revealed that genes positively correlated with ceramides were associated mainly with immune and inflammatory categories, while genes negatively correlated with ceramides were associated mainly with lipid and carbohydrate metabolism. Conclusions: Ceramides in human mediastinal adipose tissue may be involved in inflammation and lipid and carbohydrate metabolism. © 2013 Elsevier B.V.
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| 18. |
- Gottfries, Johan, 1958
(författare)
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Effect of low temperature on growth and ultra-structure of Staphylococcus spp.
- 2012
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 7:1
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Tidskriftsartikel (refereegranskat)abstract
- The effect of temperature fluctuation is an important factor in bacterial growth especially for pathogens such as the staphylococci that have to remain viable during potentially harsh and prolonged transfer conditions between hosts. The aim of this study was to investigate the response of S. aureus, S. epidermidis, and S. lugdunensis when exposed to low temperature (4°C) for prolonged periods, and how this factor affected their subsequent growth, colony morphology, cellular ultra-structure, and amino acid composition in the non-cytoplasmic hydrolysate fraction. Clinical isolates were grown under optimal conditions and then subjected to 4°C conditions for a period of 8 wks. Cold-stressed and reference control samples were assessed under transmission electron microscopy (TEM) to identify potential ultra-structural changes. To determine changes in amino acid composition, cells were fractured to remove the lipid and cytoplasmic components and the remaining structural components were hydrolysed. Amino acid profiles for the hydrolysis fraction were then analysed for changes by using principal component analysis (PCA). Exposure of the three staphylococci to prolonged low temperature stress resulted in the formation of increasing proportions of small colony variant (SCV) phenotypes. TEM revealed that SCV cells had significantly thicker and more diffuse cell-walls than their corresponding WT samples for both S. aureus and S. epidermidis, but the changes were not significant for S. lugdunensis. Substantial species-specific alterations in the amino acid composition of the structural hydrolysate fraction were also observed in the cold-treated cells. The data indicated that the staphylococci responded over prolonged periods of cold-stress treatment by transforming into SCV populations. The observed ultra-structural and amino acid changes were proposed to represent response mechanisms for staphylococcal survival amidst hostile conditions, thus maintaining the viability of the species until favourable conditions arise again.
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| 19. |
- Gottfries, Johan, 1958
(författare)
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Modelling of Mouse Experimental Colitis by Global Property Screens: A Holistic Approach to Assess Drug Effects in Inflammatory Bowel Diseas
- 2012
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 7:1
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Tidskriftsartikel (refereegranskat)abstract
- Preclinical disease models play an important role in the establishment of new treatment paradigms, identification of biomarkers and assessment of drug efficacy and safety. However, the accuracy of these models in context of the human disease are sometimes questioned, e.g. due to trials failing to confirm efficacy in humans. We suggest that one reason behind this gap in predictability may relate to how the preclinical data is analyzed and interpreted. In the present paper, we introduce a holistic approach to analyze and illustrate data in context of one of the most commonly used colitis models, i.e. the mouse dextran sulphate sodium (DSS) colitis model. Diseased mice were followed over time along disease progression and by use of tool pharmacological compounds activating nuclear hormone receptors, respectively. A new multivariate statistics approach was applied including principal component analysis (PCA) with treatment prediction subsequent to establishing the principal component analysis model. Thus, several studies could be overlaid and compared to each other in a new, comprehensive and holistic way. This method, named mouse colitis global property screening, appears applicable not only to any animal modelling series of studies but also to human clinical studies. The prerequisites for the study set up and calculations are delineated and examples of new learnings from the global property screening will be presented.
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| 20. |
- Kjellqvist, S., et al.
(författare)
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Identification of Shared and Unique Serum Lipid Profiles in Diabetes Mellitus and Myocardial Infarction
- 2016
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Ingår i: Journal of the American Heart Association. - : Ovid Technologies (Wolters Kluwer Health). - 2047-9980. ; 5:12
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Tidskriftsartikel (refereegranskat)abstract
- Background-Diabetes mellitus (DM) and cardiovascular disease are associated with dyslipidemia, but the detailed lipid molecular pattern in both diseases remains unknown. Methods and Results-We used shotgun mass spectrometry to determine serum levels of 255 molecular lipids in 316 controls, 171 DM, and 99 myocardial infarction (MI) events from a cohort derived from the Malmo Diet and Cancer study. Orthogonal projections to latent structures analyses were conducted between the lipids and clinical parameters describing DM or MI. Fatty acid desaturases (FADS) and elongation of very long chain fatty acid protein 5 (ELOVL5) activities were estimated by calculating product to precursor ratios of polyunsaturated fatty acids in complex lipids. FADS genotypes encoding these desaturases were then tested for association with lipid levels and ratios. Differences in the levels of lipids belonging to the phosphatidylcholine and triacylglyceride (TAG) classes contributed the most to separating DM from controls. TAGs also played a dominating role in discriminating MI from controls. Levels of C18:2 fatty acids in complex lipids were lower both in DM and MI versus controls (DM, P=0.004; MI, P=6.0E-06) at least due to an acceleration in the metabolic flux from C18: 2 to C20:4 (eg, increased estimated ELOVL5: DM, P=0.02; MI, P=0.04, and combined elongase-desaturase activities: DM, P=3.0E-06; MI, P=2.0E-06). Minor allele carriers of FADS genotypes were associated with increased levels of C18: 2 (P <= 0.007) and lower desaturase activity (P <= 0.002). Conclusions-We demonstrate a possible relationship between decreased levels of C18: 2 in complex lipids and DM or MI. We thereby highlight the importance of molecular lipids in the pathogenesis of both diseases.
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| 21. |
- Kurtovic, Sanela, et al.
(författare)
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Diverging alternative splicing fingerprints in the transforming growth factor-β signaling pathway identified in thoracic aortic aneurysms.
- 2011
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Ingår i: Molecular medicine (Cambridge, Mass.). - : Springer Science and Business Media LLC. - 1528-3658 .- 1076-1551. ; 17:7-8, s. 665-75
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Tidskriftsartikel (refereegranskat)abstract
- Impaired regulation of the transforming growth factor-β (TGFβ) signaling pathway has been linked to thoracic aortic aneurysm (TAA). Previous work has indicated that differential splicing is a common phenomenon, potentially influencing the function of proteins. In the present study we investigated the occurrence of differential splicing in the TGFβ pathway associated with TAA in patients with bicuspid aortic valve (BAV) and tricuspid aortic valve (TAV). Affymetrix human exon arrays were applied to 81 intima/media tissue samples from dilated (n = 51) and nondilated (n = 30) aortas of TAV and BAV patients. To analyze the occurrence of alternative splicing in the TGFβ pathway, multivariate techniques, including principal component analysis and OPLS-DA (orthogonal partial least squares to latent structures discriminant analysis), were applied on all exons (n = 614) of the TGFβ pathway. The scores plot, based on the splice index of individual exons, showed separate clusters of patients with both dilated and nondilated aorta, thereby illustrating the potential importance of alternative splicing in TAA. In total, differential splicing was detected in 187 exons. Furthermore, the pattern of alternative splicing is clearly differs between TAV and BAV patients. Differential splicing was specific for BAV and TAV patients in 40 and 86 exons, respectively, and splicings of 61 exons were shared between the two phenotypes. The occurrence of differential splicing was demonstrated in selected genes by reverse transcription-polymerase chain reaction. In summary, alternative splicing is a common feature of TAA formation. Our results suggest that dilatation in TAV and BAV patients has different alternative splicing fingerprints in the TGFβ pathway.
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| 22. |
- Murphy, G. R., et al.
(författare)
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Alterations in amino acid metabolism during growth by Staphylococcus aureus following exposure to H2O2 - A multifactorial approach
- 2018
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Ingår i: Heliyon. - : Elsevier BV. - 2405-8440. ; 4:5
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Tidskriftsartikel (refereegranskat)abstract
- Temperature and pH are known to vary in a wound site due to the immune response and subsequent healing processes. This study used a multifactorial design to examine the cellular responses of Staphylococcus aureus to hydrogen peroxide (0-100 mM) when bacteria were grown in temperatures of 37 +/- 2 degrees C and pH 7 +/- 1, conditions potentially encountered in wound sites. A centroid sample was included in the design which represented the mid-point values of all three environmental parameters (37 degrees C, pH 7, 50 mM H2O2). Cytoplasmic extracts and corresponding medium supernatants were analysed for amino acid composition by gas chromatography. Exposures of S. aureus to H2O2 during the inoculation process resulted in extended lag phases lasting well after the peroxide had been neutralised by the bacterium's antioxidant systems, after which the bacteria eventually resumed growth at equivalent rates to the controls. Even though the subsequent growth rates appeared normal, the cells exhibited a variant metabolic regime at the mid-exponential phase of growth as a result of the initial exposure to peroxide. The alterations in metabolism were reflected by the differential amino acid profiles measured in the cytoplasmic extracts (P < 0.0001). The data indicated that the metabolic responses to H2O2 challenge were uniquely different depending on the variations of temperature and pH. The uptake patterns of amino acids from the media also altered depending on prevailing environmental conditions. From these results, it was proposed that a specific reproducible homeostasis could be induced under a specific set of defined environmental conditions. It was also evident that early toxic insults on the bacterial culture could have lasting impacts on cellular homeostasis after successive generations, even after the offending chemical had been removed and initial cell integrity restored. It was concluded that metabolic homeostasis would be continually adjusting and responding to changing environmental conditions to deploy defensive proteins as well as optimising processes for survival. The powerful ability to continually and rapidly adapt to the environment may represent the key feature supporting the virulence of S. aureus as an opportunistic pathogen invading the wound site.
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| 23. |
- Onyango, L. A., et al.
(författare)
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Phenotypic Variants of Staphylococci and Their Underlying Population Distributions Following Exposure to Stress
- 2013
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Ingår i: Plos One. - : Public Library of Science (PLoS). - 1932-6203. ; 8:10
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Tidskriftsartikel (refereegranskat)abstract
- This study investigated whether alterations in environmental conditions would induce the formation of small colony variant phenotypes (SCV) with associated changes in cell morphology and ultra-structure in S. aureus, s. epidermidis, and S. lugdunensis. Wild-type clinical isolates were exposed to low temperature (4 degrees C), antibiotic stress (penicillin G and vancomycin; 0-10,000 mu g mL(-1)), pH stress (pH 3-9) and osmotic challenge (NaCl concentrations of 0-20%). Changes in cell diameter, cell-wall thickness, and population distribution changes (n >= 300) were assessed via scanning and transmission electron microscopy (SEM and TEM), and compared to control populations. Our analyses found that prolonged exposure to all treatments resulted in the subsequent formation of SCV phenotypes. Observed SCVs manifested as minute colonies with reduced haemolysis and pigmentation (NaCl, pH and 4 degrees C treatments), or complete lack thereof (antibiotic treatments). SEM comparison analyses revealed significantly smaller cell sizes for SCV populations except in S. aureus and S. epidermidis 10% NaCl, and S. epidermidis 4 degrees C (p<0.05). Shifts in population distribution patterns were also observed with distinct sub-populations of smaller cells appearing for S. epidermidis, and S. lugdunensis. TEM analyses revealed significantly thicker cell-walls in all treatments and species except S. lugdunensis exposed to 4 degrees C. These findings suggest that staphylococci adapted to environmental stresses by altering their cell size and wall thickness which could represent the formation of altered phenotypes which facilitate survival under harsh conditions. The phenotypic response was governed by the type of prevailing environmental stress regime leading to appropriate alterations in ultra-structure and size, suggesting downstream changes in gene expression, the proteome, and metabolome.
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| 24. |
- Peilot, Birgitta, 1947, et al.
(författare)
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Evaluation of treatment with Cognitive therapy and a patient-centered approach in patients with chronic musculoskeletal pain and psychiatric co-morbidity – A pilot study
- 2019
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Ingår i: ECRONICON open access. ; 11:8, s. 612-629
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Tidskriftsartikel (refereegranskat)abstract
- Objective. The aim was to evaluate Cognitive therapy (CT) and a patient-centered-approach in a group of patients with chronic pain and psychiatric co-morbidity in relation to pain, dysfunction, anxiety, depression, burnout and health related quality of life (HRQoL). Design. Pilot study. Setting. Consulting psychiatry. Participants 30 consecutive patients with chronic pain, who had not responded to conventional pain treatment, were recruited during a period of 21 months. Interventions. All patients were offered treatment with cognitive therapy (CT). Twenty patients accepted treatment with CT and 13 patients, the therapy group, completed therapy. The no therapy group consisted of 7 patients who did not complete therapy and 10 patients who were only followed-up at monthly intervals. Main otutcome measures. Patient reported outcome measures (PROM) were administered at baseline and at follow-up after 8-11 months. PROM included Relationship Scales Questionnaire (RSQ ) for attachment pattern, Sense of coherence (SOC), Multidimensional Pain Inventory (MPI) for pain and dysfunction, Beck Anxiety Inventory (BAI), Beck Depression Inventory (BDI), Pines´scale for burnout and Short-Form 36 (SF-36). Statistical tests were conducted at a 5% significance level. Subgroup identification was accomplished by means of Multivariate data analysis (MVDA). Results. At the individualized follow-up the patients (n=25) reported significant improvement of Bodily Pain and Mental Health in Short-Form 36 ( SF-36), life control in MPI, depression, anxiety and SOC. There was a correlation between completed treatment with CT and improvement. Explorative modellings with MVDA suggested that patients with chronic pain and fearful attachment pattern had a better outcome than patients with preoccupied attachment pattern if they were treated with CT. Conclusion.. A patient-centered approach in combination with CT was beneficial for patients with chronic pain and psychiatric co-morbidity. MVDA indicated that the outcome of treatment may differ according to individual vulnerability and severity of burnout, depression and pain interference. Strengths and limitations of the study * This study is a small hypothesis generating pilot study and the results need to be followed up with larger randomized studies. *Patients who dropped out from therapy were followed in the no therapy group * The same therapist/physician (BP) treated the entire group. * In order to compensate for many variables and a limited number of observations explorative modellings with MVDA were performed.
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| 25. |
- Peilot, Birgitta, 1947, et al.
(författare)
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Vulnerability and Resilience in Patients with Chronic Pain in Occupational Healthcare : A Pilot Study with a Patient-Centered Approach.
- 2018
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Ingår i: Pain Research and Treatment. - : Hindawi Limited. - 2090-1542 .- 2090-1550. ; 2018
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: The aim of this pilot study was to describe vulnerability and resilience and possible subgroups in patients with chronic work related musculoskeletal pain in occupational healthcare. A second aim was to evaluate a patient-centered approach.Methods: This study was based on consecutive patients with chronic pain, seen by the same physician and sick-listed full or part time three months or longer. They were included during a period of three months. Patient reported outcome measures (PROM) were administered at baseline and at follow-up after 8 months. A patient-centered approach was applied where the patient's whole situation was taken into account.Results: A dominance of an insecure dismissing attachment pattern and a subnormal sense of coherence (SOC) was reported both at baseline and at follow-up. The patients (n=38) reported significant improvement of pain severity (p=0.01), pain interference (p=0.001), life control (p=0.01), affective distress (p=0.02), and dysfunction (p=0.001) on the multidimensional pain inventory (MPI) and fewer patients were sick-listed full time at follow-up (13 patients versus 21). By means of multivariate data analyses this change in MPI was confirmed and was also correlated with a significant increase in health related quality of life (HRQoL). Moreover subgroups with different outcome at follow-up were identified according to attachment pattern and subgroups on MPI.Conclusion: A patient-centered approach may be of value for patients with chronic pain in occupational healthcare, improving pain and dysfunction. Patients with chronic pain are a heterogeneous group where outcome of treatment might be influenced by individual resilience and/or vulnerability.
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| 26. |
- Peilot, Birgitta, 1947, et al.
(författare)
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Vulnerability, Resilience and Pain associated Symptoms in two Groups of Patients with Chronic Pain- a Pilot Study : Vulnerability factors in patients with chronic pain
- 2019
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Ingår i: ECRONICON open access. ; 11:11, s. 01-19
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Tidskriftsartikel (refereegranskat)abstract
- Objective. To compare pain and pain associated symptoms, vulnerability factors and factors of resilience in two groups with chronic pain. Design. An explorative and hypothesis generating pilot study. Setting. Consulting psychiatry and occupational health care Participants. 30 consecutive patients in consulting psychiatry with chronic pain, who had not responded to conventional pain treatment, and 42 consecutive patients with chronic pain in occupational health care. Interventions. All patients referred to consulting psychiatry were offered treatment with cognitive therapy (CT). The patients in occupational health care were offered patient-centered treatment and follow-up. Main otutcome measures. Patient reported outcome measures (PROM) were administered at baseline and at follow-up after 8-11 months. PROM included Relationship Scales Questionnaire (RSQ ) for attachment pattern, Sense of coherence (SOC), Multidimensional Pain Inventory (MPI) for pain and dysfunction, Beck Anxiety Inventory (BAI), Beck Depression Inventory (BDI), Pines´scale for burnout and Short-Form 36 (SF-36). Statistical tests were conducted at a 5% significance level. Subgroup identification was accomplished by means of Multivariate data analysis (MVDA). Results. Both patient groups had vulnerability factors in terms of insecure attachment (RSQ), a low SOC and dysfunctional subgroups according to MPI. The occupational health care group reported higher SOC (p=0.02) and less anxiety (p=0.002), depression (p=0.01) and burnout (p<0.001) than the psychiatry group. These findings were further interpreted by using multivariate analyses. Hereby an overlapping between the two patient groups was obtained, indicating that there were patients within the occupational health care group with higher vulnerability than expected. The results of this study also indicated that a strong SOC per se did not seem to protect against chronic pain but may have a positive impact on HRQoL and the ability to handle pain. Conclusion. The impact of vulnerability factors on pain management and rehabilitation in patients with chronic pain in primary care might be underestimated. Thus SOC as well as MPI and RSQ could be important tools for assessing vulnerability and resilience in chronic pain. The role of SOC as well as attachment pattern. in chronic pain could be an aim of further research Strengths and limitations of the study * This study is a small hypothesis generating pilot study and the results need to be validated in further studies of vulnerability and resilience in new groups of patients with chronic pain * In order to compensate for many variables and a limited number of observations explorative modellings with MVDA were performed. * The same therapist/physician (BP) treated both patient groups.
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| 27. |
- Uzelac, Ivana, et al.
(författare)
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A Structural Comparison Approach for Identifying Small Variations in Binding Sites of Homologous Proteins
- 2015
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Ingår i: Computational Molecular Bioscience. - : Scientific Research Publishing, Inc.. - 2165-3453 .- 2165-3445. ; 5:3, s. 45-55
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Tidskriftsartikel (refereegranskat)abstract
- A method for analyzing the protein site similarity was devised aiming at understanding selectivity of homologous proteins and guiding the design of new drugs. The method is based on calculating Cα distances between selected pocket residues and subsequent analysis by multivariate methods. Five closely related serine proteases, the coagulation factors II, VII, IX, X, and XI, were studied and their pocket similarity was illustrated by PCA clustering. OPLS-DA was then applied to identify the residues responsible for the variation. By combining these two multivariate methods, we could successfully cluster the different proteases according to class and identify the important residues responsible for the observed variation.
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| 28. |
- Wang, Hui, et al.
(författare)
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Identification of novel biomarkers in seasonal allergic rhinitis by combining proteomic, multivariate and pathway analysis
- 2011
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Ingår i: Plos ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 6:8
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Tidskriftsartikel (refereegranskat)abstract
- Abstract BACKGROUND: Glucocorticoids (GCs) play a key role in the treatment of seasonal allergic rhinitis (SAR). However, some patients show a low response to GC treatment. We hypothesized that proteins that correlated to discrimination between symptomatic high and low responders (HR and LR) to GC treatment might be regulated by GCs and therefore suitable as biomarkers for GC treatment. METHODOLOGY/PRINCIPAL FINDINGS: We identified 953 nasal fluid proteins in symptomatic HR and LR with a LC MS/MS based-quantitative proteomics analysis and performed multivariate analysis to identify a combination of proteins that best separated symptomatic HR and LR. Pathway analysis showed that those proteins were most enriched in the acute phase response pathway. We prioritized candidate biomarkers for GC treatment based on the multivariate and pathway analysis. Next, we tested if those candidate biomarkers differed before and after GC treatment in nasal fluids from 40 patients with SAR using ELISA. Several proteins including ORM (P<0.0001), APOH (P<0.0001), FGA (P<0.01), CTSD (P<0.05) and SERPINB3 (P<0.05) differed significantly before and after GC treatment. Particularly, ORM (P<0.01), FGA (P<0.05) and APOH (P<0.01) that belonged to the acute phase response pathway decreased significantly in HR but not LR before and after GC treatment. CONCLUSIONS/SIGNIFICANCE: We identified several novel biomarkers for GC treatment response in SAR with combined proteomics, multivariate and pathway analysis. The analytical principles may be generally applicable to identify biomarkers in clinical studies of complex diseases.
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| 29. |
- Wehrli, Patrick M., et al.
(författare)
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Discovery and development of substituted thiadiazoles as inhibitors of Staphylococcus aureus Sortase A
- 2019
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Ingår i: Bioorganic & Medicinal Chemistry. - : Elsevier BV. - 0968-0896. ; 27:19
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Tidskriftsartikel (refereegranskat)abstract
- High-throughput screening of small-molecule libraries has led to the identification of thiadiazoles as a new class of inhibitors against Staphylococcus aureus sortase A (SrtA). N-(5-((4-nitrobenzyl) thio)-1,3,4-thiadiazol-2-yl)nicotinamide (IC50= 3.8 mu M) was identified as a potent inhibitor of SrtA after synthetic modification of hit compounds. Additional ligands developed in this study displayed affinities in the low micromolar range without affecting bacterial growth in vitro. The study also suggest a new mode of action through covalent binding to the active site cysteine.
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| 30. |
- Wehrli, Patrick M., et al.
(författare)
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Exploring bacterial phenotypic diversity using factorial design and FTIR multivariate fingerprinting
- 2014
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Ingår i: Journal of Chemometrics. - : John Wiley and Sons Ltd. - 0886-9383. ; 28:8, s. 681-686
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Tidskriftsartikel (refereegranskat)abstract
- Transmission Fourier transform infrared (FTIR) spectra were obtained from cultures of Staphylococcus aureus that were grown under sets of various environmental conditions enclosing ranges of potential conditions in wound sites. The primary aim of this study was to determine whether bacterial phenotypic diversity could be characterized by FTIR spectroscopy analyses of cultures of S.aureus grown under variable sets of environmental conditions. Designing experiments with full factorial design has shown to be a powerful way to explore an expectedly large array of phenotypic diversity of S.aureus. Various combinations of environmental conditions caused the bacteria to adapt their phenotype, which was assessed via FTIR spectral fingerprinting. Transmission FTIR spectroscopy was found to be superior to other vibrational spectroscopy techniques for this purpose because of its high sensitivity, reproducibility, and rapidity of analysis. The sample preparation presented was fundamental for reproducible results. Different spectral preprocessing methods were compared in combination with scaling methods to obtain distinguishable phenotypes in principal component analysis (PCA) models. Spectral preprocessing with combined filters, including standard normal variate transformation, Savitzky-Golay smoothing, and use of the first derivative in a PCA model with unit variance scaling, gave the most optimal clustering for the data in this study. Spectra obtained from each treatment group were found to have a unique FTIR profile with good reproducibility, and thus PCA resulted in full separation between all groups on three principal components. In conclusion, transmission FTIR spectroscopy in conjunction with design of experiment, and multivariate analysis are powerful tools to investigate phenotypic diversity of S.aureus. © 2014 John Wiley & Sons, Ltd.
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| 31. |
- Wehrli, Patrick M., et al.
(författare)
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Investigating the Role of the Stringent Response in Lipid Modifications during the Stationary Phase in E. coli by Direct Analysis with Time-of-Flight-Secondary Ion Mass Spectrometry
- 2016
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Ingår i: Analytical Chemistry. - 0003-2700 .- 1520-6882. ; 88:17, s. 8680-8688
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Tidskriftsartikel (refereegranskat)abstract
- Escherichia coli is able to rapidly adjust the biophysical properties of its membrane phospholipids to adapt to environmental challenges including starvation stress. These membrane lipid modifications were investigated in glucose starved E. coli cultures and compared to a ΔrelAΔspoT (ppGpp0) mutant strain of E. coli, deficient in the stringent response, by means of time-of-flight-secondary ion mass spectrometry (TOF-SIMS). Recent advances in TOF-SIMS, through the implementation of gas cluster ion beams (GCIBs), now permit the analysis of higher mass species from native, underivatized, biological specimen, i.e., intact bacterial cells. Cultures in stationary phase were found to exhibit a radically different lipid composition as compared to cultures in the exponential growth phase. Wild-type E. coli reacted upon carbon starvation by lipid modifications including elongation, cyclopropanation, and increased cardiolipin formation. Observations are consistent with variants of cardiolipins (CL), phosphatidylglycerols (PG), phosphatidylethanolamines (PE), phosphatidic acids (PA), and fatty acids. Notably, despite having a proteomic profile and a gene expression profile somewhat similar to the wild-type during growth, the ppGpp0 mutant E. coli strain was found to exhibit modified phospholipids corresponding to unsaturated analogues of those found in the wild-type. We concluded that the ppGpp0 mutant reacts upon starvation stress by elongation and desaturation of fatty acyl chains, implying that only the last step of the lipid modification, the cyclopropanation, is under stringent control. These observations suggest alternative stress response mechanisms and illustrate the role of the RelA and SpoT enzymes in the biosynthetic pathway underlying these lipid modifications.
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| 32. |
- Wehrli, Patrick M., et al.
(författare)
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Maximising the potential for bacterial phenotyping using time‐of‐flight secondary ion mass spectrometry with multivariate analysis and Tandem Mass Spectrometry
- 2014
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Ingår i: Surface and Interface Analysis. - : Wiley. - 1096-9918 .- 0142-2421. ; 46:1, s. 173-176
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Tidskriftsartikel (refereegranskat)abstract
- The increasing trend towards bacteria becoming resistant to current antibiotic treatments is of great concern to the healthcare industry with severe potential consequences for society as a whole. In many cases, it is the interaction of the antibacterial agent with the targets within the bacterial envelope of the microorganism that is a critical factor. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) is uniquely capable of probing the chemistry in this region. This study aimed at optimising sample preparation and data pre-processing for bacterial analysis with ToF-SIMS and principal components analysis to study small chemical differences related to changes in bacterial phenotype that will help to find new antibiotics and understand how antibiotics are trafficked in the bacteria. ToF-SIMS analysis was performed using a J105 instrument equipped with a 40 kV C60+ ion source. Combination of positive and negative ion mode data enhanced the multivariate model quality regarding classification and aided chemical identification particularly when coupled with tandem mass spectrometry. Copyright © 2014 John Wiley & Sons, Ltd.
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| 33. |
- Wennerås, Christine, 1963, et al.
(författare)
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Distinct Inflammatory Mediator Patterns Characterize Infectious and Sterile Systemic Inflammation in Febrile Neutropenic Hematology Patients
- 2014
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Ingår i: Plos One. - : Public Library of Science (PLoS). - 1932-6203. ; 9:3
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Tidskriftsartikel (refereegranskat)abstract
- Background: Invasive infections and sterile tissue damage can both give rise to systemic inflammation with fever and production of inflammatory mediators. This makes it difficult to diagnose infections in patients who are already inflamed, e.g. due to cell and tissue damage. For example, fever in patients with hematological malignancies may depend on infection, lysis of malignant cells, and/or chemotherapy-induced mucosal damage. We hypothesized that it would be possible to distinguish patterns of inflammatory mediators characterizing infectious and non-infectious causes of inflammation, respectively. Analysis of a broad range of parameters using a multivariate method of pattern recognition was done for this purpose. Methods: In this prospective study, febrile (>38 degrees C) neutropenic patients (n = 42) with hematologic malignancies were classified as having or not having a microbiologically defined infection by an infectious disease specialist. In parallel, blood was analyzed for 116 biomarkers, and 23 clinical variables were recorded for each patient. Using O-PLS (orthogonal projection to latent structures), a model was constructed based on these 139 variables that could separate the infected from the non-infected patients. Non-discriminatory variables were discarded until a final model was reached. Finally, the capacity of this model to accurately classify a validation set of febrile neutropenic patients (n = 10) as infected or non-infected was tested. Results: A model that could segregate infected from non-infected patients was achieved based on discrete differences in the levels of 40 variables. These variables included acute phase proteins, cytokines, measures of coagulation, metabolism, organ stress and iron turn-over. The model correctly identified the infectious status of nine out of ten subsequently recruited febrile neutropenic hematology patients. Conclusions: It is possible to separate patients with infectious inflammation from those with sterile inflammation based on inflammatory mediator patterns. This strategy could be developed into a decision-making tool for diverse clinical applications.
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