| 1. |
- Eriksson, Jens, 1980-, et al.
(author)
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Difference in twitching motility between Neisseria meningitidis and Neisseria gonorrhoeae and its relation to pilus dynamics
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Other publication (other academic/artistic)abstract
- Type IV pili of pathogenic Neisseria, i. e. Neisseria gonorrhoeae and Neisseria meningitidis, are essential for initial attachment to host cells, induction of signal transduction cascades and disease development. A characteristic feature of type IV pili is their ability to retract, which generates forces that move bacteria over surfaces. However, the relation between bacterial motility and pilus dynamics remains poorly understood. In this work we analyzed bacterial motility and monitored movement of fluorescently labeled pili by live cell imaging. We found that movement of N. meningitidis occurred at higher speed and with a larger number of retracting pili than for N. gonorrhoeae. Analysis of time-lapse images suggested that N. gonorrhoeae most often moved using one retracting pilus, whereas N. meningitidis most often used four pili. There were no differences in the membrane distribution of PilT among strains. However, we found significantly higher levels of PilT in N. gonorrhoeae than in N. meningitidis. This produces a higher retraction probability, which could contribute to explaining the lower number of pili observed in N. gonorrhoeae. Finally, we propose a mechanism for how the speed of bacterial movement on a surface depends on the number of retracting pili.
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| 2. |
- Franzen, Oscar, et al.
(author)
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Draft genome sequencing of Giardia intestinalis assemblage B isolate GS : is human giardiasis caused by two different species?
- 2009
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In: PLoS Pathogens. - : Public Library of Science (PLoS). - 1553-7366 .- 1553-7374. ; 5:8, s. e1000560-
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Journal article (peer-reviewed)abstract
- Giardia intestinalis is a major cause of diarrheal disease worldwide and two major Giardia genotypes, assemblages A and B, infect humans. The genome of assemblage A parasite WB was recently sequenced, and the structurally compact 11.7 Mbp genome contains simplified basic cellular machineries and metabolism. We here performed 454 sequencing to 16 x coverage of the assemblage B isolate GS, the only Giardia isolate successfully used to experimentally infect animals and humans. The two genomes show 77% nucleotide and 78% amino-acid identity in protein coding regions. Comparative analysis identified 28 unique GS and 3 unique WB protein coding genes, and the variable surface protein (VSP) repertoires of the two isolates are completely different. The promoters of several enzymes involved in the synthesis of the cyst-wall lack binding sites for encystation-specific transcription factors in GS. Several synteny-breaks were detected and verified. The tetraploid GS genome shows higher levels of overall allelic sequence polymorphism (0.5 versus <0.01% in WB). The genomic differences between WB and GS may explain some of the observed biological and clinical differences between the two isolates, and it suggests that assemblage A and B Giardia can be two different species.
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| 3. |
- Lindberg, Terese, et al.
(author)
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A systematic review and meta-analysis of dressings used for wound healing : the efficiency of honey compared to silver on burns
- 2015
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In: Contemporary Nurse. - : Taylor & Francis. - 1037-6178 .- 1839-3535. ; 51:2-3, s. 121-134
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Journal article (peer-reviewed)abstract
- Background: Honey has the antibacterial effect of silver without the toxic effect of silver on the skin. Even so, silver is the dominant antibacterial dressing used in wound healing.Objectives: To evaluate the healing effects of honey dressings compared to silver dressings for acute or chronic wounds. Design: A systematic review with meta-analysis.Method: The search, conducted in seven databases, resulted in six randomised controlled trial studies from South Asia focusing on antibacterial properties and healing times of honey and silver.Result: Honey was more efficacious for wound healing than silver, as measured in the number of days needed for wounds to heal (pooled risk difference -20, 95% CI -0.29 to -0.11, p < .001). Honey turned out to have more antibacterial qualities than silver.Conclusion: All the included studies based on burns showed the unequivocal result that honey had an even more positive effect than silver on wound healing.
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| 4. |
- Lodin-Sundström, Angelica, et al.
(author)
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Blood boosting by spleen contraction during exercise at different altitudes.
- 2014
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Conference paper (peer-reviewed)abstract
- Spleen contraction with release of erythrocytes improves human performance in hypoxic situations. Hypoxia and exercise are known to separately trigger the response. We studied the response to exercise at different altitudes during a two week ascent to 4200m. Eleven healthy lowlanders (five women; mean±SD age 26±3 years) did a modified Harvard step test at 1370, 3700 and 4200m altitude after 10 min rest. Spleen volume was measured via ultrasonic imaging and capillary hemoglobin (Hb) with Hemocue before and after tests. Mean(±SD) baseline spleen volume at 1370m was 250(±9)ml, after exercise it had been reduced to 207(±10)ml (P<0.01). At 3700m, baseline spleen volume was 230(±9)ml, after exercise 173(±10)ml (P<0.01). At 4200m baseline was 211(±10)ml, after exercise 158(±13)ml (P<0.05). Baseline Hb increased by altitude from 137.8(±3.8)g/L at 1370m, to 141.2(±2.3)g/L at 3700m and 151.4(±2.3)g/L at 4200m (P<0.01). At all locations Hb had increased after exercise; at 1370m by 7.2%, at 3700m by 6.2% and at 4200m by 3.2%. This suggests the spleen was already somewhat contracted during rest at higher altitudes, which was reflected by the progressively higher baseline Hb. Exercise initiated spleen contraction of similar magnitude at all altitudes, and post exercise values were progressively smaller with altitude. Hb was also elevated at all exercise tests, but not directly reflecting the spleen volume reductions, possibly due to differences in peak times. This study suggests that baseline spleen volume is affected by altitude which elevates Hb and that contraction after exercise results in further Hb elevation.
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| 5. |
- Melberg, Atle, et al.
(author)
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A patient with two mitochondrial DNA mutations causing PEO and LHON.
- 2009
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In: European journal of medical genetics. - : Elsevier BV. - 1878-0849 .- 1769-7212. ; 52:1, s. 47-8
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Journal article (peer-reviewed)abstract
- We report a 22-year-old man with PEO and optic atrophy. PEO developed before the onset of optic atrophy. The patient showed mitochondrial myopathy with cytochrome c oxidase deficient fibers. In skeletal muscle the patient was homoplasmic for the mtDNA G11778A Leber hereditary optic neuropathy (LHON) mutation and heteroplasmic for the mtDNA 5 kb "common" deletion mutation. In blood only the homoplasmic LHON mutation was identified. The occurrence of two pathogenic mtDNA mutations is exceedingly rare. The clinical findings in this patient indicate that the combination of the two mtDNA mutations resulted in the expected combined phenotype since the mtDNA deletion mutation accounted for the PEO and the mtDNA G11778A point mutation for the optic atrophy.
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| 6. |
- Palm, Martin, et al.
(author)
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The Effect of Heavy Metals on Conjugation Efficiency of an F-Plasmid in Escherichia coli.
- 2022
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In: Antibiotics (Basel, Switzerland). - : MDPI AG. - 2079-6382. ; 11:8
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Journal article (peer-reviewed)abstract
- Conjugation, the process by which conjugative plasmids are transferred between bacteria, is regarded as a major contributor to the spread of antibiotic resistance, in both environmental and clinical settings. Heavy metals are known to co-select for antibiotic resistance, but the impact of the presence of these metals on conjugation itself is not clear. Here, we systematically investigate the impact that five heavy metals (arsenic, cadmium, copper, manganese, and zinc) have on the transfer of an IncF conjugative plasmid in Escherichia coli. Our results show that two of the metals, cadmium and manganese, have no significant impact, while arsenic and zinc both reduce conjugation efficiency by approximately 2-fold. Copper showed the largest impact, with an almost 100-fold decrease in conjugation efficiency. This was not mediated by any change in transcription from the major Py promoter responsible for transcription of the conjugation machinery genes. Further, we show that in order to have this severe impact on the transfer of the plasmid, copper sulfate needs to be present during the mating process, and we suggest explanations for this.
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| 7. |
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| 8. |
- Schagatay, Erika, 1961-, et al.
(author)
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Spleen contraction elevates hemoglobin concentration at high altitude during rest and exercise
- 2020
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In: European Journal of Applied Physiology. - : Springer Science and Business Media LLC. - 1439-6319 .- 1439-6327. ; 120, s. 2693-2704
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Journal article (peer-reviewed)abstract
- Purpose: Hypoxia and exercise are known to separately trigger spleen contraction, leading to release of stored erythrocytes. We studied spleen volume and hemoglobin concentration (Hb) during rest and exercise at three altitudes. Methods: Eleven healthy lowlanders did a 5-min modified Harvard step test at 1370, 3700 and 4200 m altitude. Spleen volume was measured via ultrasonic imaging and capillary Hb with Hemocue during rest and after the step test, and arterial oxygen saturation (SaO2), heart rate (HR), expiratory CO2 (ETCO2) and respiratory rate (RR) across the test. Results: Resting spleen volume was reduced with increasing altitude and further reduced with exercise at all altitudes. Mean (SE) baseline spleen volume at 1370 m was 252 (20) mL and after exercise, it was 199 (15) mL (P < 0.01). At 3700 m, baseline spleen volume was 231 (22) mL and after exercise 166 (12) mL (P < 0.05). At 4200 m baseline volume was 210 (23) mL and after exercise 172 (20) mL (P < 0.05). After 10 min, spleen volume increased to baseline at all altitudes (NS). Baseline Hb increased with altitude from 138.9 (6.1) g/L at 1370 m, to 141.2 (4.1) at 3700 m and 152.4 (4.0) at 4200 m (P < 0.01). At all altitudes Hb increased from baseline during exercise to 146.8 (5.7) g/L at 1370 m, 150.4 (3.8) g/L at 3700 m and 157.3 (3.8) g/L at 4200 m (all P < 0.05 from baseline). Hb had returned to baseline after 10 min rest at all altitudes (NS). The spleen-derived Hb elevation during exercise was smaller at 4200 m compared to 3700 m (P < 0.05). Cardiorespiratory variables were also affected by altitude during both rest and exercise. Conclusions: The spleen contracts and mobilizes stored red blood cells during rest at high altitude and contracts further during exercise, to increase oxygen delivery to tissues during acute hypoxia. The attenuated Hb response to exercise at the highest altitude is likely due to the greater recruitment of the spleen reserve during rest, and that maximal spleen contraction is reached with exercise.
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| 9. |
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- 2019
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Journal article (peer-reviewed)
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