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| 2. |
- Alm, Kersti, et al.
(författare)
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Cells and holograms : holograms and digital holographic microscopy as a tool to study the morphology of living cells
- 2013
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Ingår i: Holography. - : INTECH. - 9789535111177 ; , s. 335-351
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- We present a method to study the morphology of living, dividing and dying cells using DHM. DHM is a non-invasive, non-destructive and non-phototoxic method which allows the user to perform both qualitative and quantitative measurements of living cells over time. We show here our results on cell division and cell death in single cells. The morphological analyses performed here show changes caused by cell death and cell division, and indicate the possibilities to discriminate between different types of cell death. Cells dying in an apoptosis-like manner display different cell area and cell thickness profiles over time compared to cells dying in a necrosis-like manner, although their volume profiles are very similar. Dividing cells show a characteristic dip in the volume profile, which makes them easily distinguishable. Also, several previous studies show the versatile abilities of DHM. Different cell types have been studied and the morphology has been used to determine cell functionality as well as changes in morphology related to the environment. Cell morphology parameters can be very useful when following the effects of different treatments, the process of differentiation as well as cell growth and cell death. Cell morphology studied by DHM can be useful in toxicology, stem cell and cancer research.
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| 3. |
- Alm, Kersti, et al.
(författare)
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Cells and polyamines do it cyclically
- 2009
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Ingår i: Essays in Biochemistry. - : Portland Press Ltd.. - 0071-1365 .- 1744-1358. ; 46, s. 63-76
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Tidskriftsartikel (refereegranskat)abstract
- Cell-cycle progression is a one-way journey where the cell grows in size to be able to divide into two equally sized daughter cells. The cell cycle is divided into distinct consecutive phases defined as G(1) (first gap), S (synthesis), G(2) (second gap) and M (mitosis). A non-proliferating cell, which has retained the ability to enter the cell cycle when it receives appropriate signals, is in G(0) phase, and cycling cells that do not receive proper signals leave the cell cycle from G(1) into G(0). One of the major events of the cell cycle is the duplication of DNA during S-phase. A group of molecules that are important for proper cell-cycle progression is the polyamines. Polyamine biosynthesis occurs cyclically during the cell cycle with peaks in activity in conjunction with the G(1)/S transition and at the end of S-phase and during G(2)-phase. The negative regulator of polyamine biosynthesis, antizyme, shows an inverse activity compared with the polyamine biosynthetic activity. The levels of the polyamines, putrescine, spermidine and spermine, double during the cell cycle and show a certain degree of cyclic variation in accordance with the biosynthetic activity. When cells in G(0)/G(1) -phase are seeded in the presence of compounds that prevent the cell-cycle-related increases in the polyamine pools, the S-phase of the first cell cycle is prolonged, whereas the other phases are initially unaffected. The results point to an important role for polyamines with regard to the ability of the cell to attain optimal rates of DNA replication.
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| 4. |
- Alm, Kersti, et al.
(författare)
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Digital holography and cell studies
- 2011
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Ingår i: Holography, Research and Technologies. - : DKV - Deutscher Kälte- und Klimatechnischer Verein. - 9789533072272 ; , s. 237-252
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Digital holography microscopy (DHM) has developed into a broad field, and one of all the interesting applications is to study cells without staining, labeling or in any other way affecting them. Both fixed and living, dying or dead cells can be studied. The first DHM images showing living cells were published in 2004 and 2005 (Carl et al. 2004, Marquet et al. 2005), making this field of research rather new. Digital holography makes it possible to easily measure cell properties that previously have been very difficult to study, such as cell thickness and volume (Marquet et al. 2005, Mölder et al. 2008). Two of the major advantages of DHM is the 3-D imaging possibility and measurements over time. Digital holography has ben used to study several types of cells, such as nerve cells, red blood cells, stem cells and cancer cells (Emery et al. 2007, Kemper et al. 2006, Langehanenberg et al. 2009) . It has also been applied for studies of cell proliferation, cell movement, sub-cellular structures and cell morphology (Kemper et al. 2009, Yu et al. 2009). Both 2-D and 3-D cell movement can be determined ( Langehanenberg et al. 2009). Even cell viability status can be determined using DHM. Interestingly, it is possible to study both single cells and entire populations simultaneously, allowing for very nuanced studies. Older, well known techniques often require some degree of cell disturbance such as the fluorescent antibody labeling required for fluorescense or confocal microscopy studies. In this paper we will present some of the studies made possible by DHM. We will compare DHM with previously used techniques and discuss the benefits and drawbacks of digital holography cell measurements.
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| 6. |
- Alm, Stina, et al.
(författare)
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Erythrocyte transfusions increased the risk of elevated serum ferritin in very low birth weight infants and were associated with altered longitudinal growth
- 2020
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Ingår i: Acta Paediatrica. - : John Wiley & Sons. - 0803-5253 .- 1651-2227. ; 109:7, s. 1354-1360
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Tidskriftsartikel (refereegranskat)abstract
- Aim: There has been a lack of population‐based longitudinal data on serum ferritin in very low birth weight (VLBW) infants during hospitalisation. Our aim was to fill this gap in the knowledge and investigate risk factors for elevated serum ferritin and associations between erythrocyte transfusions and longitudinal growth.Methods: We retrospectively reviewed longitudinal data on 126 VLBW infants treated at Umeå University Hospital, Sweden, between 2010‐2013.Results: The infants’ mean gestational age and birth weight were 26.9 weeks and 899 grams. Most (91%) received erythrocyte transfusions and the majority had multiple erythrocyte transfusions. There was a significant correlation between serum ferritin and the volume of transfusions. Almost two‐thirds had at least one serum ferritin measurement of more than 350 µg/L, indicating iron overload. In those with complete anthropometric data (n=78) there was no significant effect of serum ferritin concentrations in relation to longitudinal growth, but there was a positive association between the erythrocyte transfusion dose and longitudinal growth in VLBW infants born before 25 weeks.Conclusion: This is the first population‐based study to investigate longitudinal data on serum ferritin in VLBW infants during hospitalisation. The unexpected positive finding in the subgroup born at less than 25 weeks needs further research with a larger cohort.
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| 7. |
- Alm, Stina, et al.
(författare)
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Increased enteral lipid supplementation is not associated with weight gain in extremely preterm infants with sufficient energy intake
- 2024
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Ingår i: Journal of Pediatric Gastroenterology and Nutrition - JPGN. - : John Wiley & Sons. - 0277-2116 .- 1536-4801.
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: Practices for fortifying human milk vary among neonatal intensive care units (NICUs). It is unclear whether enteral energy intake above 140 kcal/kg/day with increased fat supplementation, leads to greater weight gain in breast milk fed extremely preterm infants (EPT).Methods: Anthropometric and nutritional data were collected from clinical records for Swedish EPT infants born between gestational weeks 26+0 and 27+6. Included infants were treated at NICU A (n=17) or NICU B (n=39). The primary outcome was change in standard deviation scores (ΔSDS) for weight between postmenstrual weeks 29+0 and 34+0.Results: At birth, the mean gestational age was 26.9 (±0.45 SD) weeks, and the mean birthweight was 969 (±107 SD) grams. Between postmenstrual weeks 29+0 and 33+6, the energy intake was significantly higher at NICU B: mean (SD) 149 (±14.9) vs 132 (±11.2) kcal/kg/day, p=<0.001. This was driven by a higher fat intake at NICU B: mean (SD) 7.97 (±1.05) vs 6.20 (±0.92) grams/kg/day, p=<0.001, which in turn was explained by more liberal use of lipid supplements at NICU B. No significant differences were found in ΔSDS for weight, length, or head circumference between the two NICUs.Conclusions: Despite considerable differences in energy intake due to the use of enteral lipid supplements, our study showed no differences in ΔSDS for weight, length, or head circumference. This may be due to limited fat absorption in infants already receiving adequate energy and fat, and poor absorption of fat from human donor milk.
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| 8. |
- Alm, Stina, 1992-
(författare)
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Nutrition, growth, and feeding problems in preterm infants
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background: Nutrition and growth in the preterm infant are fundamentally intertwined. Nutrition plays an important role in the care of the preterm infant, and especially so in the extremely preterm (EPT) infant. EPT infants have a high risk of malnutrition and poor growth, known to be associated with adverse outcomes. It is therefore important to study the nutrient intakes, factors affecting growth and other outcomes in this population of infants. Infants born preterm are at risk for developing iron overload due to erythrocyte transfusions. It is established that infants born preterm are at an increased risk of developing feeding difficulties in later childhood, but the underlying mechanisms remain unclear.Methods: Three cohorts of infants born preterm were studied in this thesis. In Paper I (macronutrient intakes), data from a cohort of EPT infants born at two Swedish hospitals between 2011 and 2021 were collected. Paper II (transfusion and iron overload) used data from a cohort of very low birth weight infants (WLBW; <1500 g) treated at Umeå University Hospital born between 2010 and 2013. Papers III (catch-up growth) and IV (feeding problems after discharge) used data from the national EXtremely PREterm infants in Sweden Study (EXPRESS) between 2004 and 2007. Data collection for the three study populations included parenteral and enteral nutritional intakes, all anthropometric measurements during the hospitalisation, results of laboratory analyses, perinatal data, and neonatal morbidity.Results: Paper I: Energy intakes between gestational weeks (GA) 29+0 and 33+6 were significantly different between the two studied hospitals. There were no differences regarding the intake of protein or carbohydrates, but intake of fat from lipid supplements was significantly higher at the hospital with higher energy intake, where a lower proportion of mother’s own milk was noted as well. There were no differences in growth between the two hospitals during the study period. Paper II: Almost all (91%) of the infants received erythrocyte transfusions, and a majority received multiple transfusions. Serum ferritin was significantly correlated with the total transfusion volume. Almost two thirds of the infants met criteria for iron overload. No effects on longitudinal growth could be found in relation to the erythrocyte transfusion dose. Paper III: Catch-up growth ≥1 SD was found in 67% of the EPT infants, with a mean increase of 1.9 standard deviation scores in z-weight during the catch-up growth. Infants that started a catch-up period had a higher enteral energy percentage from protein. Paper IV: Feeding problems diagnosed before 2 years of age and/or underweight at 2.5 years of age was found in 19% of the EPT infants in the cohort. The strongest risk factor for feeding problems was found to be longer duration of mechanical ventilation (≥10 d) during the neonatal period.Conclusions: There was no difference in growth between the two hospitals although the energy and fat intakes were significantly different, suggesting that the lipid supplements may have limited absorption in general and when given with donor milk in particular. Almost two-thirds of VLBW infants had serum ferritin levels indicating iron overload, however, no association to longitudinal growth could be shown. A majority of EPT infants showed a period of catch-up growth in weight during the initial hospital stay. Infants with catch-up received a higher energy proportion from enteral protein during the week of catch-up growth initiation. Moreover, post discharge feeding problems are common in EPT infants, and the strongest perinatal risk factor was treatment with mechanical ventilation.
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| 9. |
- Alm, Stina, et al.
(författare)
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Prevalence and risk factors for post discharge feeding problems in children born extremely preterm
- 2023
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Ingår i: Journal of Pediatric Gastroenterology and Nutrition - JPGN. - : Wolters Kluwer. - 0277-2116 .- 1536-4801. ; 76:4, s. 498-504
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: Preterm infants have a high risk of post discharge feeding problems, but there is a lack of population-based studies in infants born extremely preterm and little is known about underlying mechanisms.The objectives were to assess the incidence of post discharge feeding problems and underweight in a population-based cohort of infants born extremely preterm in Sweden (EXPRESS) and identify perinatal risk factors.Methods: Perinatal health data and prenatal/postnatal growth data was prospectively collected in the cohort. Data on clinical diagnoses related to feeding problems were obtained from the Swedish Patient Register, population prevalence data was also obtained. The main outcome was a composite of post discharge feeding problem diagnosis and/or underweight at 2.5 years of age.Results: In total, 66 children (19%) had post discharge feeding problems diagnosed before 2 years and/or underweight at 2.5 years of age. The risk of feeding problems when compared to the general population was significantly higher, with an odds ratio (OR) of 193 (95% CI 137.6-270.9). The strongest risk factors for feeding problems were the number of days on mechanical ventilation during the first eight postnatal weeks, OR of 1.59 (CI 95% 1.29-1.98), and the Clinical Risk Index for Babies-score, OR of 1.14 (CI 95% 1.03-1.26).Conclusions: Post discharge feeding problems and underweight are common in children born extremely preterm. The strongest perinatal risk factor for later feeding problems was early treatment with mechanical ventilation. Identifying infants at risk of post discharge feeding problems might be useful for targeting of nutritional support.
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| 10. |
- Blomberg, Stina, et al.
(författare)
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Expression of the markers BDCA-2 and BDCA-4 and production of interferon-alpha by plasmacytoid dendritic cells in systemic lupus erythematosus
- 2003
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Ingår i: Arthritis and Rheumatism. - : Wiley. - 0004-3591 .- 1529-0131. ; 48:9, s. 2524-32
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To study the expression of blood dendritic cell antigen 2 (BDCA-2) and BDCA-4 molecules by plasmacytoid dendritic cells (PDCs) in the blood of patients with systemic lupus erythematosus (SLE), and to study PDC production of interferon-alpha (IFN alpha) and its inhibition by anti-BDCA-2 and anti-BDCA-4 antibodies. METHODS: Peripheral blood mononuclear cells (PBMCs) from SLE patients (SLE PBMCs) and from healthy controls were induced to produce IFN alpha in vitro by SLE serum containing an endogenous IFN alpha-inducing factor (SLE-IIF) or by herpes simplex virus type 1 (HSV-1). The frequencies and numbers of BDCA-2-, BDCA-3-, and BDCA-4-expressing cells were analyzed by flow cytometry, and the effects of anti-BDCA-2 and anti-BDCA-4 monoclonal antibodies (mAb) on IFN alpha production were investigated. RESULTS: IFN alpha production by SLE PBMCs induced by SLE-IIF or HSV-1 was decreased compared with that of healthy control PBMCs (P = 0.002 and P = 0.0007, respectively). The proportions of BDCA-2- and BDCA-3-expressing cells in SLE PBMCs were reduced compared with those in PBMCs from healthy controls (P = 0.01 and P = 0.004, respectively). IFN alpha producers in culture, especially among SLE PBMCs, displayed reduced BDCA-2 expression and constituted only a minority of the BDCA-2-positive cells, at least in healthy control PBMCs (median 18%). IFN alpha production by both SLE and healthy control PBMCs stimulated by SLE-IIF or HSV-1 was markedly reduced by anti-BDCA-2 mAb (median 81-98% inhibition). Anti-BDCA-4 mAb only partially inhibited SLE-IIF-induced IFN alpha production. CONCLUSION: SLE patients had a reduced number of BDCA-2-expressing PDCs, also termed natural IFN alpha-producing cells, and their IFN alpha production could be inhibited by anti-BDCA-2/4 mAb. Such mAb may be a therapeutic option for inhibiting the ongoing IFN alpha production in SLE patients.
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