| 1. |
- Stenqvist, Björn, et al.
(författare)
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Membrane permeability based on mesh analysis
- 2023
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Ingår i: Journal of Colloid and Interface Science. - : Elsevier BV. - 0021-9797 .- 1095-7103. ; 633, s. 526-535
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Tidskriftsartikel (refereegranskat)abstract
- The main function of a membrane is to control the exchange of matter between the surrounding regions. As such, accurate modeling of membranes is important to properly describe their properties. In many cases in both biological systems and technical applications, the membranes are composite structures where transport properties may vary between the different sub-regions of the membrane. In this work we develop a method based on Mesh analysis that is asymptotically exact and can describe diffusion in composite membrane structures. We do this by first reformulating a generalized Fick's law to include the effects from activity coefficient, diffusion coefficient, and solubility using a single condensed param-eter. We then use the derived theory and Mesh analysis to, in essence, retrieve a finite element method approach. The calculated examples are based on a membrane structure that reassembles that of the brick and mortar structure of stratum corneum, the upper layer of our skin. Resulting concentration profiles from this procedure are then compared to experimental results for the distribution of different probes within intact stratum corneum, showing good agreement. Based on the derived approach we further investigate the impact from a gradient in the fluidity of the stratum corneum mortar lipids across the membrane, and find that it is substantial. We also show that anisotropic organisation of the lipid mortar can have large impact on the effective permeability compared to isotropic mortar lipids. Finally, we examine the effects of corneocyte swelling, and their lateral arrangement in the membrane on the overall membrane permeability.
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| 2. |
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| 3. |
- Domeika, Marius, et al.
(författare)
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Implementation of a national electronic reporting system in Lithuania
- 2009
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Ingår i: Euro surveillance. - 1560-7917. ; 14:13, s. 19165-
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Tidskriftsartikel (refereegranskat)abstract
- Electronic reporting systems improve the quality and timeliness of the surveillance of communicable diseases. The aim of this paper is to present the process of the implementation and introduction of an electronic reporting system for the surveillance of communicable diseases in Lithuania. The project which started in 2002 was performed in collaboration between Lithuania and Sweden and was facilitated by the parallel process of adapting the surveillance system to European Union (EU) standards. The Lotus-based software, SmittAdm, was acquired from the Department of Communicable Diseases Control and Prevention of Stockholm County in Sweden and adopted for Lithuania, resulting in the Lithuanian software, ULISAS. A major advantage of this program for Lithuania was the possibility to work offline. The project was initiated in the two largest counties in Lithuania where ULISAS had been installed and put in use by January 2005. The introduction was gradual, the national level was connected to the system during late 2005, and all remaining counties were included during 2006 and 2007. The reporting system remains to be evaluated concerning timeliness and completeness of the surveillance. Further development is needed, for example the inclusion of all physicians and laboratories and an alert system for outbreaks. The introduction of this case-based, timely electronic reporting system in Lithuania allows better reporting of data to the European Centre for Disease Prevention and Control (ECDC) and the World Health Organization (WHO) compared to the former reporting system with paper-based, aggregated data.
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| 4. |
- Hanstock, Helen, 1989-, et al.
(författare)
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Evaluation of physiological and nutritional risk factors for upper respiratory illness using a zero-inflated negative binomial model
- 2018
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Ingår i: Journal of Sports Sciences. - : Routledge. - 0264-0414 .- 1466-447X. ; , s. 44-45
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Konferensbidrag (refereegranskat)abstract
- Intensified training periods may increase incidence of upper respiratory illness (URI) in athletes (Meeusen et al., 2013,Medicine and Science in Sports and Exercise, 45(1), 186–205). Many physiological and nutritional risk factors have beenassociated with increased risk of URI (Bermon et al., 2017, Exercise Immunology Review, 23, 8–50), including reductionsin salivary IgA (sIgA), elevated cortisol, vitamin D insufficiency, iron deficiency and low energy availability (EA). However, few studies have explored the relative importance of each of thesehealth-related biomarkers in a multivariate model. Our aimwas therefore to investigate the relationship between multiplebiological risk factors for illness and incidence, duration andseverity of URIs that present during intensified training. 3815Twenty-five well-trained male cyclists and triathletes (age 30 ± 9 y, VO2peak 64 ± mL· kg−1· min−1) performed one ofthree different high-intensity interval training (HIT) programmes for three sessions per week over four weeks in November-December. The study received local ethical approval and participants provided written, informed consentto participate. Participants performed each HIT session at “isoeffort” intensity and sessions were matched for total accumulated work duration. Participants logged upper respiratorysymptoms (URS) daily using the Jackson Common Cold Scale; episodes of URI were identified retrospectively using the followinga priori criteria: weekly symptom score > 14 or selfreportedcommon cold for > 2 consecutive days (Jacksonet al., 1958, American Medical Association Archives of Internal Medicine, 101, 267–278). Before commencing the training period, VO2peak was determined using an incremental maximal cycling protocol and participants provided rested, fasted blood and saliva samples prior to the training period foranalysis of plasma 25(OH)D, ferritin, cortisol, testosterone and sIgA secretion rate. EA was calculated based on a 3-day registration of energy intake and expenditure relative to fat-free mass measured in a rested, fasted state using indirect calorimetry (Torstveit et al., 2018 February, International Journal of Sport Nutrition and Exercise Metabolism, 1–28). We used a zero-inflated negative binomial model to investigate the relationship between baseline VO2peak, health-related biomarkers and URI incidence/duration/global URS severity. Fourteen athletes(56%) reported an episode of URI during the four-week monitoring period. Higher sIgA was associated with reduced risk of URI (odds ratio = 0.90, 90% confidence interval (CI): [0.83,0.97]). Lower plasma cortisol (P = 0.02) and higher EA (P = 0.02) were associated with longer URI duration; holding cortisol constant, the incidence risk ratio (IRR) for a one-unit increase in EA was 1.04 (90% CI: [1.01, 1.07]). Participants with higher VO2peak reported higher total symptom scores during the intervention period (P = 0.03, IRR = 1.07, 90% CI: [1.01,1.13]). Several health-related biomarkers and physiological parameters may therefore be associated with risk and severityof URI, including sIgA, cortisol, EA and VO2peak.
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| 5. |
- Hanstock, Helen, 1989-, et al.
(författare)
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Influence of Immune and Nutritional Biomarkers on Illness Risk During Interval Training
- 2020
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Ingår i: International Journal of Sports Physiology and Performance. - : Human Kinetics. - 1555-0265 .- 1555-0273. ; 15:1, s. 60-67
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Tidskriftsartikel (refereegranskat)abstract
- Intensive training periods may negatively influence immune function, but the immunological consequences of specific high-intensity training (HIT) prescriptions are not well defined. Purpose: This study explored whether three different HIT prescriptions influence multiple health-related biomarkers and whether biomarker responses to HIT were associated with upper respiratory illness (URI) risk. Methods: Twenty-five male cyclists and triathleteswere randomised to three HIT groups and completed twelve HIT sessions over four weeks. Peak oxygen consumption (V̇O2peak) was determined using an incremental cycling protocol, while resting serum biomarkers (cortisol, testosterone, 25(OH)D and ferritin), salivary immunoglobulin-A (s-IgA) and energy availability (EA) were assessed before and after the training intervention. Participants self-reported upper respiratory symptoms during the interventionand episodes of URI were identified retrospectively. Results: Fourteen athletes reported URIs, but there were no differences in incidence, duration or severity between groups. Increased risk of URI was associated with higher s-IgA secretion rates (odds ratio=0.90, 90% CI:0.83-0.97). Lower pre-intervention cortisol and higher EA predicted a 4% increase in URI duration. Participants with higher V̇O2peak reported higher total symptom scores (incidence rate ratio=1.07, 90% CI:1.01-1.13). Conclusions: Although multiple biomarkers wereweakly associated with risk of URI, the direction of associations between s-IgA, cortisol, EA and URI risk were inverse to previous observations and physiological rationale. There was a cluster of URIs within the first week of the training intervention, but no samples were collected at this time-point. Future studies should incorporate more frequent sample time-points, especially around the onset of new training regimes, and include athletes with suspected or known nutritional deficiencies.
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| 6. |
- Hanstock, Helen, 1989-, et al.
(författare)
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Influence of interval duration on immunological responses to 4-weeks’ high-intensity interval training
- 2018
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Ingår i: Journal of Sports Sciences. - : Routledge. - 0264-0414 .- 1466-447X. ; , s. 1-94
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Konferensbidrag (refereegranskat)abstract
- High-intensity interval training (HIT) encompasses a wide range of training prescriptions where up to nine variables can be manipulated (Buchheit and Laursen, 2013, Sports Medicine, 43(5), 313–338). Four weeks of HIT with longer intervals and accumulated work durations (AWD) has been shown to elicit greater improvements in peak oxygen consumption (V O 2peak ) despite more modest physiological, hormonal and perceptual responses (Sylta et al., 2017, Medicine & Science in Sports & Exercise, 49(6), 1137–1146). However, immunological responses to different HIT pre- scriptions have rarely been investigated. The purpose of this study was to compare the cumulative effects of a four-week HIT intervention, performed either as short or long intervals with the same AWD, on V O 2peak , the immunological biomarker salivary secretory IgA (s-IgA) and upper respiratory illness (URI) incidence. In addition, we explored the influence of HIT on serum cortisol, testosterone, 25(OH)D and ferritin as biomarkers related to immune competence. Following local ethics committee approval, twenty-five well-trained male cyclists and triath- letes provided written consent to take part and were randomised to one of three HIT groups (Long Intervals [LI]: 4 × 8min; Short Intervals 1 [SI1]: 4×[12 × 40/20s]; Short Intervals 2 [SI2]: 4×[8 ×40/20s]). Participants per- formed three cycling HIT sessions per week for four weeks at maximal session effort (“isoeffort”) intensity, supplemented with ad libitumlow-intensity training. Participants recorded upper respiratory symptoms (URS) daily using the Jackson Common Cold Scale; episodes of URI were identified retrospectively. V O 2peak as well as rested saliva and blood biomarkers were analysed before and after the training period. Fourteen of twenty-five participants reported an episode of URI (LI: 4/8, SI1: 4/8, SI2: 6/9) but there were no differences in URI incidence, severity or duration between groups. Following the train- ing intervention, we observed a moderate increase in V O 2peak across the cohort (mean± SD: 4.75 ± 0.42 to 4.86 ± 0.43 L· min−1 ,Cohen’s d= 0.65, 90% confidence intervals: [0.16, 1.13]) but the change in V O 2peak was not different between groups. Serum cortisol displayed a moderate increase (367 ± 98 to 415 ± 108 nmol· L −1 ,d=0.60 [0.12, 1.08]) and 25(OH)D a large decrease (79.2 ± 17.1 to 70.4 ± 17.6 nmol· L −1 ,d= -0.87 [−1.36,−0.37]) from pre- to post-training, but there were no differences in the magnitude of the responses between groups. Four weeks’HIT did not influence s-IgA secretion rate, serum testosterone or ferritin. We conclude that four weeks’ AWD-matched HIT performed as short- or long-intervals at isoeffort intensity does not differentially influence ill- ness incidence, immunological responses to training nor other immune-related biomarkers. This observation can be viewed as a positive finding for training planning, since it could allow coaches some flexibility in constructing AWD-matched isoeffort HIT sessions to achieve performance goals, without concern about detrimental effects on athletes’ immune status.
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| 7. |
- Lindgren, Sophie, 1971, et al.
(författare)
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Effectiveness and side effects of closed and open suctioning: an experimental evaluation.
- 2004
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Ingår i: Intensive care medicine. - : Springer Science and Business Media LLC. - 0342-4642 .- 1432-1238. ; 30:8, s. 1630-7
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To compare the effectiveness of closed system suctioning (CSS) and open system suctioning (OSS) and the side effects on gas exchange and haemodynamics, during pressure-controlled ventilation (PCV) or continuous positive airway pressure (CPAP). DESIGN: Bench test and porcine lung injury model. PARTICIPANTS: Twelve bronchoalveolar saline-lavaged pigs. SETTING: Research laboratory in a university hospital. INTERVENTIONS: In a mechanical lung, the efficacy of OSS and CSS with 12 and 14 Fr catheters were compared during volume-control ventilation, PCV, CPAP 0 or 10 cmH(2)O by weighing the suction system before and after aspirating gel in a transparent trachea. Side effects were evaluated in the animals with the same ventilator settings during suctioning of 5, 10 or 20 s duration. MEASUREMENTS AND RESULTS: Suctioning with 12 and 14 Fr catheters was significantly more efficient with OSS (1.9+/-0.1, 2.8+/-0.9 g) and with CSS during CPAP 0 cmH(2)O (1.8+/-0.2, 4.2+/-0.5 g) as compared to CSS during PCV (0.2+/-0.2, 0.8+/-0.3 g) or CPAP 10 cmH(2)O (0.0+/-0.1, 0.7+/-0.4 g), p<0.01 (means +/- SD). OSS and CSS at CPAP 0 cmH(2)O resulted in a marked decrease in SpO(2), mixed venous oxygen saturation and tracheal pressure, p<0.001, but the side effects were considerably fewer during CSS with PCV and CPAP 10 cmH(2)O, p<0.05. CONCLUSIONS: Irrespective of catheter size, OSS and CSS during CPAP 0 cmH(2)O were markedly more effective than CSS during PCV and CPAP 10 cmH(2)O but had worse side effects. However, the side effects lasted less than 5 min in this animal model. Suctioning should be performed effectively when absolutely indicated and the side effects handled adequately.
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| 8. |
- Lundy, Bronwen, et al.
(författare)
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Screening for Low Energy Availability in Male Athletes : Attempted Validation of LEAM-Q
- 2022
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Ingår i: Nutrients. - : MDPI. - 2072-6643. ; 14:9
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Tidskriftsartikel (refereegranskat)abstract
- A questionnaire-based screening tool for male athletes at risk of low energy availability (LEA) could facilitate both research and clinical practice. The present options rely on proxies for LEA such screening tools for disordered eating, exercise dependence, or those validated in female athlete populations. in which the female-specific sections are excluded. To overcome these limitations and support progress in understanding LEA in males, centres in Australia, Norway, Denmark, and Sweden collaborated to develop a screening tool (LEAM-Q) based on clinical investigations of elite and sub-elite male athletes from multiple countries and ethnicities, and a variety of endurance and weight-sensitive sports. A bank of questions was developed from previously validated questionnaires and expert opinion on various clinical markers of LEA in athletic or eating disorder populations, dizziness, thermoregulation, gastrointestinal symptoms, injury, illness, wellbeing, recovery, sleep and sex drive. The validation process covered reliability, content validity, a multivariate analysis of associations between variable responses and clinical markers, and Receiver Operating Characteristics (ROC) curve analysis of variables, with the inclusion threshold being set at 60% sensitivity. Comparison of the scores of the retained questionnaire variables between subjects classified as cases or controls based on clinical markers of LEA revealed an internal consistency and reliability of 0.71. Scores for sleep and thermoregulation were not associated with any clinical marker and were excluded from any further analysis. Of the remaining variables, dizziness, illness, fatigue, and sex drive had sufficient sensitivity to be retained in the questionnaire, but only low sex drive was able to distinguish between LEA cases and controls and was associated with perturbations in key clinical markers and questionnaire responses. In summary, in this large and international cohort, low sex drive was the most effective self-reported symptom in identifying male athletes requiring further clinical assessment for LEA.
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| 9. |
- Sparr, Emma, et al.
(författare)
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The stratum corneum barrier - From molecular scale to macroscopic properties
- 2023
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Ingår i: Current Opinion in Colloid & Interface Science. - : Elsevier. - 1359-0294 .- 1879-0399. ; 67
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Forskningsöversikt (refereegranskat)abstract
- The upper layer of our skin, the stratum corneum (SC), is a versatile material that combines mechanical strength with efficient barrier function. In this paper, we discuss these macroscopic properties of SC in relation to recent findings on molecular responses and structural diversity in SC protein and lipids. We put particular focus on the intermediate (colloidal) length scale and how the different SC substructures are organized with respect to each other, including effects of nonequilibrium conditions in the skin with respect to the gradients in water and other components.
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| 10. |
- Stenberg, S., et al.
(författare)
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An Exact Ewald Summation Method in Theory and Practice
- 2020
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Ingår i: The Journal of Physical Chemistry Part A: Molecules, Spectroscopy, Kinetics, Environment and General Theory. - : American Chemical Society (ACS). - 1520-5215. ; 124:19, s. 3943-3946
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Tidskriftsartikel (refereegranskat)abstract
- We present the widespread Ewald summation method in a new light by utilizing a truncated Gaussian screening charge distribution. This choice entails an exact formalism, also as particle mesh Ewald, which in practice is not always the case when using a Gaussian screening function. The presented approach reduces the number of dependent parameters compared to a Gaussian and, for an infinite reciprocal space cutoff, makes the screening charge distribution width truly arbitrary. As such, this arbitrary variable becomes an ideal tool for computational optimization while maintaining accuracy, which is in contrast to when a Gaussian is used.
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