An "in vitro" analysis of murine thymocyte-stromal cell interactions

This thesis is directed towards two separate but closely related goals; one involves the biology of precursor cells in T-cell development and the second involves the use of retroviral constructs for the establishment of thymic stromal cell lines and its application for studying differentiation of T-cells in vitro. Using the mouse foetal thymic organ culture system, a quantitative assay was devised in which the relative abundance of T-cell progenitors among different populations was estimated by seeding decreasing numbers of precursors into alymphoid thymic rudiments. This limiting dilution approach combined with serial transfer of successfully recolonised precursor cells in organ culture, provided evidence that certain populations seeding the thymus have the potential for extensive cell divisions (up to 10- 12 weeks). Stromal cells from adult and foetal sources were transformed by a temperature sensitive (ts) mutant of SV40 and Ela 12S in order to study interactions between the developing thymocytes and specific elements of the microenvironment. Eighty four cell lines were generated and have been shown to contain properties related to their counterparts in vivo. The thermolabile transforming agent (large T) allowed inactivation of the immortalising gene when the cells were switched to the nonpermissive temperature. Properties like the expression of MHC antigens and the ability to bind thymocytes could be induced by growing ts-derived clones at the nonpermissive temperature, which suggests that although cell proliferation had ceased, the cells were still metabolically active and had reverted to a more 'normal' non-transformed phenotype allowing certain molecules to be expressed at the cell surface. Close interaction of the developing thymocytes with the stroma is essential for the development of functionally mature T-cells. Using a rosette assay unfractionated adult thymocytes were found to bind unstimulated Ela-derived clones resembling epithelial cells (15.5 and 15.18) and also to several other established clones after temperature switching and/or IFNγ treatment. In co-culture with a multipotent bone-marrow derived stem cell clone (A4) it was shown that both proliferation and differentiation into certain myeloid lineages were supported. Furthermore, in co-culture with CD4'CD8' thymocytes, with and without interleukin-7, the growth of this subset could be sustained for ~20 days. In addition, phenotypic changes of thymocytes in these cultures suggest that some of these lines may have the potential to induce differentiation of early precursors. These findings indicate that established cell lines could be useful tools for studying maturation of T-cells in vitro and furthermore, to investigate distinct events in T-cell ontogeny governed by different stromal cell types

Development and validation of a new clinical decision support tool to optimize screening for retinopathy of prematurity

Background/Aims Prematurely born infants undergo costly, stressful eye examinations to uncover the small fraction with retinopathy of prematurity (ROP) that needs treatment to prevent blindness. The aim was to develop a prediction tool (DIGIROP-Screen) with 100% sensitivity and high specificity to safely reduce screening of those infants not needing treatment. DIGIROP-Screen was compared with four other ROP models based on longitudinal weights. Methods Data, including infants born at 24–30 weeks of gestational age (GA), for DIGIROP-Screen development (DevGroup, N=6991) originate from the Swedish National Registry for ROP. Three international cohorts comprised the external validation groups (ValGroups, N=1241). Multivariable logistic regressions, over postnatal ages (PNAs) 6–14 weeks, were validated. Predictors were birth characteristics, status and age at first diagnosed ROP and essential interactions. Results ROP treatment was required in 287 (4.1%)/6991 infants in DevGroup and 49 (3.9%)/1241 in ValGroups. To allow 100% sensitivity in DevGroup, specificity at birth was 53.1% and cumulatively 60.5% at PNA 8 weeks. Applying the same cut-offs in ValGroups, specificities were similar (46.3% and 53.5%). One infant with severe malformations in ValGroups was incorrectly classified as not needing screening. For all other infants, at PNA 6–14 weeks, sensitivity was 100%. In other published models, sensitivity ranged from 88.5% to 100% and specificity ranged from 9.6% to 45.2%. Conclusions DIGIROP-Screen, a clinical decision support tool using readily available birth and ROP screening data for infants born GA 24–30 weeks, in the European and North American populations tested can safely identify infants not needing ROP screening. DIGIROP-Screen had equal or higher sensitivity and specificity compared with other models. DIGIROP-Screen should be tested in any new cohort for validation and if not validated it can be modified using the same statistical approaches applied to a specific clinical setting

Nurses' and patients' communication in smoking cessation at nurse-led COPD clinics in primary health care

Background: Smokers with chronic obstructive pulmonary disease (COPD) have high nicotine dependence making it difficult to quit smoking. Motivational interviewing (MI) is a method that is used in stimulating motivation and behavioral changes. Objective: To describe smoking cessation communication between patients and registered nurses trained in MI in COPD nurse-led clinics in Swedish primary health care. Methods: A prospective observational study with structured quantitative content analyses of the communication between six nurses with basic education in MI and 13 patients in non-smoking consultations. Results: Only to a small extent did nurses’ evoke patients’ reasons for change, stimulate collaboration, and support patients’ autonomy. Nurses provided information, asked closed questions, and made simple reflections. Patients’ communication was mainly neutral and focusing on reasons for and against smoking. It was uncommon for patients to be committed and take steps toward smoking cessation. Conclusion: The nurses did not adhere to the principles of MI in smoking cessation, and the patients focused to a limited extent on how to quit smoking. Practice implications: To make patients more active, the nurses need more education and continuous training in motivational communication

Long-term follow-up of functioning after spinal surgery in patients with Rett syndrome

In a prospective study, 23 consecutive girls with Rett syndrome and neuromuscular scoliosis were evaluated for functioning at a long-term follow-up. The patients had mostly improved, which was confirmed by their parents. Rett syndrome is associated with neuromuscular scoliosis and has a typically long C-shaped thoracolumbar kyphoscoliosis. Prospective long-term follow-up studies related to these patients total situation are sparse. Most studies focus on the Cobb angle of the scoliosis, whereas parents are mainly concerned about the girls continued functioning. Twenty-three patients with Rett syndrome and neuromuscular scoliosis were evaluated preoperatively from 1993 to 2002. At follow-up, 19 patients remained in the study. Three patients died (not due to surgery), and one patient could not participate because it was too far to travel. Mean follow-up time was 74 months (range 49-99 months). The assessments comprised the sitting balance, seating supports in wheelchair, weight distribution, time used for rest, care given, and angle of scoliosis. Follow-up questionnaires and two-open-ended questions about the positive and negative effects of surgery were sent to parents. Sitting balance, number of seating supports in wheelchair, weight distribution, time used for rest, and the Cobb angle had all improved after surgery. The parents assessed improvement in seating position, daily activities, time used for rest, and cosmetic appearance. We can conclude that the stabilized spine resulted in sufficient strength to keep the body upright with the possibility of looking around at the surroundings more easily. The girls got better seating position with less need for seating adaptations in the wheelchair and with reduced time needed for resting during the day. Finally we can conclude that the indication for surgery is to get a better posture which lead to less risk of pressure sores, and that un upright position lead to better possibility to easily breath with fewer episodes of pneumonia and a better general health as result. The evidence of positive surgical effects for girls with Rett syndrome is of great importance in indication for surgery in the decision-making process.The original publication is available at www.springerlink.com: Eva-Lena Larsson, Stig Aaro, Peter Ahlinder, Helena Normelli, Hans Tropp and Birgitta Öberg, Long-term follow-up of functioning after spinal surgery in patients with Rett syndrome, 2009, EUROPEAN SPINE JOURNAL, (18), 4, 506-511. http://dx.doi.org/10.1007/s00586-008-0876-6 Copyright: Springer Science Business Media http://www.springerlink.com/</p

Retrospective evaluation of ophthalmological and neurological outcomes for infants born before 24 weeks gestational age in a Swedish cohort

Objectives To retrospectively evaluate ophthalmological and neurological outcomes in a Swedish cohort of infants born before 24 weeks gestational age (GA) and explore risk factors for visual impairment. Setting Eye and paediatric clinics in Sweden. Participants Infants screened for retinopathy of prematurity (ROP) (n=399), born before 24 weeks GA, 2007-2018. Cases were excluded if ophthalmological follow-up records could not be traced. Primary and secondary outcome measures Primary outcomes were ophthalmological, including visual acuity (VA), refractive error, strabismus, nystagmus and cerebral visual impairment (CVI). Secondary outcomes comprised neonatal and neurological morbidities. Data were retrospectively retrieved from medical records. Results The 355 assessed children had a median GA of 23 weeks and 2 days and a median birth weight of 565 g. At the last available ophthalmological examination, the median age was 4.8 years (range 0.5-13.2 years). Nystagmus was recorded in 21.1%, strabismus in 34.8%, and 51.0% wore spectacles. Seventy-three of 333 (21.9%) were visually impaired, defined as being referred to a low vision clinic and/or having a VA less than 20/60 at 3.5 years of age or older. ROP treatment was a significant risk factor for visual impairment (OR 2.244, p=0.003). Visually impaired children, compared with children without visual impairment, more often had neurological deficits such as intellectual disability 63.8% versus 33.3% (p&lt;0.001), epilepsy 21.1% versus 7.5% (p=0.001) and autism spectrum disorders 32.8% versus 20.9% (p=0.043). Nine of the 355 children had been diagnosed with CVI. Conclusions Children born before 24 weeks GA frequently had visual impairment in association with neurological deficits. CVI was rarely diagnosed. A multidisciplinary approach for the evaluation and habilitation of these vulnerable infants is warranted. National follow-up guidelines need to be developed and implemented

High rate and large intercentre variability in retreatment of retinopathy of prematurity in infants born &lt; 24 gestational weeks

Objective Prematurity is a major risk factor for retinopathy of prematurity (ROP). We aimed to elucidate ROP prevalence, treatment and retreatment in infants born before 24 gestational age (GA) weeks in a Swedish cohort. Methods and analysis Infants with completed ROP screening, born at &lt;24 GA weeks, 2007-2018 in Sweden were included. Data of GA, birth weight (BW), sex, neonatal morbidities, maximal ROP stage, aggressive posterior ROP (APROP), ROP treatments, treatment modality and treatment centre were retrieved. Results In total, 399 infants, with a mean GA of 23.2 weeks (range 21.9-23.9) and a mean BW of 567 g (range 340-874), were included. ROP was detected in 365 (91.5%) infants, 173 (43.4%) were treated for ROP and 68 of 173 (39.3%) were treated more than once. As the first treatment, 142 (82.0%) received laser and 29 (16.1%) received intravitreal injection of antivascular endothelial growth factor (anti-VEGF). Retreatment was performed after first laser in 46 of 142 (32.4%) and in 20 of 29 (69.0%) after first anti-VEGF treatment. Retreatment rate was not associated with GA, BW or sex but with APROP, treatment method (anti-VEGF) and treatment centre where the laser was performed (p&lt;0.001). Twenty eyes progressed to retinal detachment, and two infants developed unilateral endophthalmitis after anti-VEGF treatment. Conclusion Infants, born at &lt;24 weeks' GA, had high rates of treatment-warranting ROP and retreatments. Treatment centre highly influenced the retreatment rate after laser indicating that laser treatment could be improved in some settings

Validation of DIGIROP models and decision support tool for prediction of treatment for retinopathy of prematurity on a contemporary Swedish cohort

Background/Aims Retinopathy of prematurity (ROP) is currently diagnosed through repeated eye examinations to find the low percentage of infants that fulfil treatment criteria to reduce vision loss. A prediction model for severe ROP requiring treatment that might sensitively and specifically identify infants that develop severe ROP, DIGIROP-Birth, was developed using birth characteristics. DIGIROP-Screen additionally incorporates first signs of ROP in different models over time. The aim was to validate DIGIROP-Birth, DIGIROP-Screen and their decision support tool on a contemporary Swedish cohort. Methods Data were retrieved from the Swedish national registry for ROP (2018-2019) and two Swedish regions (2020), including 1082 infants born at gestational age (GA) 24 to &amp;lt;31 weeks. The predictors were GA at birth, sex, standardised birth weight and age at the first sign of ROP. The outcome was ROP treatment. Sensitivity, specificity and area under the receiver operating characteristic curve (AUC) with 95% CI were described. Results For DIGIROP-Birth, the AUC was 0.93 (95% CI 0.90 to 0.95); for DIGIROP-Screen, it ranged between 0.93 and 0.97. The specificity was 49.9% (95% CI 46.7 to 53.0) and the sensitivity was 96.5% (95% CI 87.9 to 99.6) for the tool applied at birth. For DIGIROP-Screen, the cumulative specificity ranged between 50.0% and 78.7%. One infant with Beckwith-Wiedemann syndrome who fulfilled criteria for ROP treatment and had no missed/incomplete examinations was incorrectly flagged as not needing screening. Conclusions DIGIROP-Birth and DIGIROP-Screen showed high predictive ability in a contemporary Swedish cohort. At birth, 50% of the infants born at 24 to &amp;lt;31 weeks of gestation were predicted to have low risk of severe ROP and could potentially be released from ROP screening examinations. All routinely screened treated infants, excluding those screened for clinical indications of severe illness, were correctly flagged as needing ROP screening.Funding Agencies|Swedish Medical Research CouncilSwedish Medical Research Council (SMRC)European Commission [2016-01131]; Gothenburg Medical Society and Government grants under the ALF agreement [ALFGBG-717971]; De Blindas Vanner; National Eye InstituteUnited States Department of Health &amp; Human ServicesNational Institutes of Health (NIH) - USANIH National Eye Institute (NEI) [EY017017, EY030904]; National Institute of HealthUnited States Department of Health &amp; Human ServicesNational Institutes of Health (NIH) - USA [1U54HD090255]</p

Oxygen targets and 6-month outcome after out of hospital cardiac arrest: a pre-planned sub-analysis of the targeted hypothermia versus targeted normothermia after Out-of-Hospital Cardiac Arrest (TTM2) trial

International audienceAbstract Background Optimal oxygen targets in patients resuscitated after cardiac arrest are uncertain. The primary aim of this study was to describe the values of partial pressure of oxygen values (PaO 2 ) and the episodes of hypoxemia and hyperoxemia occurring within the first 72 h of mechanical ventilation in out of hospital cardiac arrest (OHCA) patients. The secondary aim was to evaluate the association of PaO 2 with patients’ outcome. Methods Preplanned secondary analysis of the targeted hypothermia versus targeted normothermia after OHCA (TTM2) trial. Arterial blood gases values were collected from randomization every 4 h for the first 32 h, and then, every 8 h until day 3. Hypoxemia was defined as PaO 2  300 mmHg. Mortality and poor neurological outcome (defined according to modified Rankin scale) were collected at 6 months. Results 1418 patients were included in the analysis. The mean age was 64 ± 14 years, and 292 patients (20.6%) were female. 24.9% of patients had at least one episode of hypoxemia, and 7.6% of patients had at least one episode of severe hyperoxemia. Both hypoxemia and hyperoxemia were independently associated with 6-month mortality, but not with poor neurological outcome. The best cutoff point associated with 6-month mortality for hypoxemia was 69 mmHg (Risk Ratio, RR = 1.009, 95% CI 0.93–1.09), and for hyperoxemia was 195 mmHg (RR = 1.006, 95% CI 0.95–1.06). The time exposure, i.e., the area under the curve (PaO 2 -AUC), for hyperoxemia was significantly associated with mortality ( p = 0.003). Conclusions In OHCA patients, both hypoxemia and hyperoxemia are associated with 6-months mortality, with an effect mediated by the timing exposure to high values of oxygen. Precise titration of oxygen levels should be considered in this group of patients. Trial registration : clinicaltrials.gov NCT02908308 , Registered September 20, 2016

Ventilatory settings in the initial 72 h and their association with outcome in out-of-hospital cardiac arrest patients: a preplanned secondary analysis of the targeted hypothermia versus targeted normothermia after out-of-hospital cardiac arrest (TTM2) trial

International audienc