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- Ågren, Johan
(författare)
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Water transport through perinatal skin : Barrier function and aquaporin water channels
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- While constituting a well functioning interface with the aqueous environment in utero, the skin offers a poor barrier after very preterm birth. As a result, transepidermal water loss (TEWL) is high, a fact which has important clinical consequences in these infants. To investigate the transport of water through perinatal skin and the potential role of aquaporin (AQP), a water channel protein, in this process, we determined TEWL in a group of extremely preterm infants, and in an experimental rat model we analyzed the expression and distribution of AQP in perinatal skin in relation to TEWL, skin surface hydration and water content. The effects of antenatal corticosteroids (ANS) and of restricted intake of fluids and nutrients on barrier characteristics of the perinatal skin and its AQP expression were also studied.In infants born at 24 and 25 weeks of gestation TEWL was very high in the first days after birth and decreased with increasing postnatal age. At a postnatal age of 4 weeks, TEWL was still twice as high as previously reported in infants born at a gestational age of 25-27 weeks and four times higher than in infants born at term. In the rat model, immunohistochemical analysis revealed that AQP1 and AQP3 are abundantly expressed in the skin. AQP1 was expressed exclusively in dermal capillaries and AQP3 in basal layers of the epidermis. AQP1 and AQP3 mRNA as assessed by semiquantitative RT-PCR was higher in fetal than in adult skin. As in infants, TEWL and skin surface hydration were inversely related to gestational age in the rat. In preterm rat pups exposed to ANS, TEWL and skin surface hydration were lower than in unexposed controls, and AQP3 expression was selectively induced by ANS. In term newborn rat pups, restriction of fluid and nutrient intake resulted in a higher skin water content and higher TEWL early after birth, while at an age of 7 days TEWL was lower in fasting rat pups than in controls, although skin water content was still higher.To conclude, TEWL is very high in extremely preterm infants early after birth and then decreases at a slower rate than previously reported for a group of slightly more mature infants. This is the first time that the distribution and gene expression of AQP1 and AQP3 have been demonstrated in perinatal skin. The localization and expression of AQP in the skin might indicate that these water channels are involved in the regulation of skin hydration and transepidermal water transport in the fetus and newborn infant.
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- Macrae, Duncan J, et al.
(författare)
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Inhaled nitric oxide therapy in neonates and children: reaching a European consensus.
- 2004
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Ingår i: Intensive care medicine. - : Springer Science and Business Media LLC. - 0342-4642 .- 1432-1238. ; 30:3, s. 372-80
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Tidskriftsartikel (refereegranskat)abstract
- Inhaled nitric oxide (iNO) was first used in neonatal practice in 1992 and has subsequently been used extensively in the management of neonates and children with cardiorespiratory failure. This paper assesses evidence for the use of iNO in this population as presented to a consensus meeting jointly organised by the European Society of Paediatric and Neonatal Intensive Care, the European Society of Paediatric Research and the European Society of Neonatology. Consensus Guidelines on the Use of iNO in Neonates and Children were produced following discussion of the evidence at the consensus meeting.
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- Rieger-Fackeldey, Esther, 1960-
(författare)
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Regulation of Breathing under Different Pulmonary Conditions
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The breathing pattern of preterm infants is immature and is associated with a variety of reflexes. In a patient on the ventilator these reflexes interfere with spontaneous breathing. A better understanding of the immature control of breathing could lead to further improvements in ventilatory techniques. This thesis concerns studies of pulmonary stretch receptor (PSR) and phrenic nerve activity as part of the regulation of breathing in an animal model.During assist/control ventilation with three different inspiratory pressure waveforms in animals with healthy lungs, squarewave pressure waveform strongly inhibits spontaneous inspiratory activity.During partial liquid ventilation (PLV) in animals with healthy lungs, all PSRs studied maintained their phasic character, with increased impulse frequency during inspiration. PSR activity was not higher during PLV than during gas ventilation (GV), indicating that there was no extensive stretching of the lung during PLV.During proportional assist ventilation (PAV) the applied airway pressure is servo-controlled proportionally to the ongoing breathing effort, thereby interacting with the activity of PSRs. Peak PSR activity was higher and occurred earlier during PAV than during CPAP. The regulation of breathing is maintained during PAV in surfactant-depleted animals before and early after surfactant instillation, with a higher ventilatory response and a lower breathing effort than during CPAP in both conditions.Both lung mechanics and gas exchange influence the regulation of breathing. Inhibition of inspiratory activity occurred at a lower arterial pH and a higher PaCO2 during PLV than during GV in animals with surfactant-depleted lungs, which might be related to recruitment of a larger number of pulmonary stretch receptors during PLV.In summary, selected aspects of the regulation of breathing were studied in an animal model with different ventilatory techniques under different lung conditions similar to those that can occur in infants.
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- Sindelar, Richard, et al.
(författare)
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Effects of the inspiratory pressure waveform during patient-triggered ventilation on pulmonary stretch receptor and phrenic nerve activity in cats
- 2001
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Ingår i: Critical Care Medicine. - 0090-3493 .- 1530-0293. ; 29:6, s. 1207-1214
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Tidskriftsartikel (refereegranskat)abstract
- Objective:To examine the effects of square wave, sinusoidal, and linear inspiratory pressure waveforms during pressure-controlled assist/control ventilation on the firing pattern of pulmonary stretch receptors and phrenic nerve activity.Design:Experimental, comparative study.Setting:Research laboratory at a university biomedical center.Subjects:Nine anesthetized, endotracheally intubated young cats (2.5–3.4 kg).Intervention:With interposed periods of continuous positive airway pressure (0.2 kPa), each cat was exposed to periods of assist/control ventilation with three different pressure waveforms, where the peak inspiratory pressure (0.74 ± 0.13 kPa), end-expiratory pressure (0.2 ± 0.02 kPa), and tidal volume (14.9 ± 5.22 mL/kg) were kept constant. Preset controlled ventilator rate was set below the rate of spontaneous breathing, and the mechanical inflation time equaled the inspiratory time during spontaneous breathing on continuous positive airway pressure.Measurements and Main Results:Respiratory rate and arterial blood gases did not change between the three pressure waveforms during assist/control ventilation. Peak pulmonary stretch receptor activity was lower and mean phrenic nerve activity higher during continuous positive airway pressure than during assist/control ventilation (p < .05). Peak inspiratory pulmonary stretch receptor activity was the same with all three pressure waveforms (82 ± 17 impulses·sec-1) but occurred earlier with square wave than with sinusoidal or linear pressure waveforms (p < .05). The total number of impulses in the phrenic nerve activity burst was smaller with square wave than with the other two pressure waveforms (0.21 ± 0.17 vs. 0.33 ± 0.27 and 0.42 ± 0.30 arbitrary units;p < .05), and the phrenic nerve activity burst duration was shorter with square wave (1.10 ± 0.45 vs. 1.54 ± 0.36 and 1.64 ± 0.25 secs;p < .05).Conclusion:Square wave pressure waveform during pressure-controlled assist/control ventilation strongly inhibits spontaneous inspiratory activity in cats. One mechanism for this inhibition is earlier and sustained peak pulmonary stretch receptor activity during inspiration. These findings show that differences in inspiratory pressure waveforms influence the spontaneous breathing effort during assist/control ventilation in cats.
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| 17. |
- Ågren, Johan, et al.
(författare)
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Transepidermal water loss in developing rats : Role of aquaporins in the immature skin
- 2003
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Ingår i: Pediatric Research. - 0031-3998 .- 1530-0447. ; 53:4, s. 558-565
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Tidskriftsartikel (refereegranskat)abstract
- In the extremely preterm infant, high transepidermal water loss (TEWL) can result in severe dehydration. TEWL has been attributed to the structural properties of the epidermis but might also be influenced by mechanisms that facilitate water transport. To investigate whether aquaporins (AQP) may be involved in the extreme losses of water through immature skin, we examined the presence and cellular distributions of AQP-1 and AQP-3 in embryonic and adult rat skin by immunohistochemistry. The expression of AQP mRNA in skin was analyzed with the use of semiquantitative reverse transcription-PCR. In rat pups of different embryonic (E) and postnatal (P) ages (days), TEWL and skin hydration were measured. AQP-1 was detected in dermal capillaries, and AQP-3 was abundant in basal epidermal layers. Both AQP displayed several times higher expression in embryonic than in adult skin. TEWL was highest at embryonic day 18 (E18) (133 +/- 18 g/m2h) and lower at E20 (25 +/- 1 g/m2h) and P4 (9 +/- 2 g/m2h). Skin hydration measured as skin electrical capacitance paralleled TEWL, being highest in fetal skin (794 +/- 15 pF at E18) and decreasing to 109 +/- 11 pF at E20 and to 0 +/- 0 pF at P4. We conclude that, as in infants, water loss through the skin of rats decreases markedly with maturation during the perinatal period. The expression and cellular localization of the AQP are such that they might influence skin hydration and water transport and contribute to the high losses of water through the immature skin.
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