| 1. |
- Ademuyiwa, Adesoji O., et al.
(författare)
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Determinants of morbidity and mortality following emergency abdominal surgery in children in low-income and middle-income countries
- 2016
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Ingår i: BMJ Global Health. - : BMJ Publishing Group Ltd. - 2059-7908. ; 1:4
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Tidskriftsartikel (refereegranskat)abstract
- Background: Child health is a key priority on the global health agenda, yet the provision of essential and emergency surgery in children is patchy in resource-poor regions. This study was aimed to determine the mortality risk for emergency abdominal paediatric surgery in low-income countries globally.Methods: Multicentre, international, prospective, cohort study. Self-selected surgical units performing emergency abdominal surgery submitted prespecified data for consecutive children aged <16 years during a 2-week period between July and December 2014. The United Nation's Human Development Index (HDI) was used to stratify countries. The main outcome measure was 30-day postoperative mortality, analysed by multilevel logistic regression.Results: This study included 1409 patients from 253 centres in 43 countries; 282 children were under 2 years of age. Among them, 265 (18.8%) were from low-HDI, 450 (31.9%) from middle-HDI and 694 (49.3%) from high-HDI countries. The most common operations performed were appendectomy, small bowel resection, pyloromyotomy and correction of intussusception. After adjustment for patient and hospital risk factors, child mortality at 30 days was significantly higher in low-HDI (adjusted OR 7.14 (95% CI 2.52 to 20.23), p<0.001) and middle-HDI (4.42 (1.44 to 13.56), p=0.009) countries compared with high-HDI countries, translating to 40 excess deaths per 1000 procedures performed.Conclusions: Adjusted mortality in children following emergency abdominal surgery may be as high as 7 times greater in low-HDI and middle-HDI countries compared with high-HDI countries. Effective provision of emergency essential surgery should be a key priority for global child health agendas.
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| 2. |
- Bravo, L, et al.
(författare)
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- 2021
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swepub:Mat__t
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| 3. |
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| 4. |
- Thomas, HS, et al.
(författare)
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- 2019
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swepub:Mat__t
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| 5. |
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| 6. |
- Tabiri, S, et al.
(författare)
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- 2021
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swepub:Mat__t
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| 7. |
- Abbara, Aula, et al.
(författare)
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Weaponizing water as an instrument of war in Syria: Impact on diarrhoeal disease in Idlib and Aleppo governorates, 2011–2019
- 2021
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Ingår i: International Journal of Infectious Diseases. - : Elsevier. - 1201-9712 .- 1878-3511. ; 108, s. 202-208
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: Investigate the weaponization of water during the Syrian conflict and the correlation of attacks on water, sanitation, and hygiene (WASH) infrastructure in Idlib and Aleppo governorates with trends in waterborne diseases reported by Early Warning and Response surveillance systems.Methods: We reviewed literature and databases to obtain information on attacks on WASH in Aleppo and Idlib governorates between 2011 and 2019. We plotted weekly trends in waterborne diseases from two surveillance systems operational in Aleppo and Idlib governorates between 2015 and early 2020.Results: The literature review noted several attacks on water and related infrastructure in both governorates, suggesting that WASH infrastructure was weaponized by state and non-state actors. Most interference with WASH in the Aleppo governorate occurred before 2019 and in the Idlib governorate in the summer of 2020. Other acute diarrhea represented >90% of cases of diarrhea; children under 5 years contributed 50% of cases. There was substantial evidence (p < 0.001) of an overall upward trend in cases of diarrheal disease.Conclusions: Though no direct correlation can be drawn between the weaponization of WASH and the burden of waterborne infections due to multiple confounders, this research introduces important concepts on attacks on WASH and their potential impacts on waterborne diseases.
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| 8. |
- Aboelazayem, Omar, et al.
(författare)
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Biodiesel production from high acid value waste cooking oil using supercritical methanol: Esterification kinetics of free fatty acids
- 2017
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Konferensbidrag (refereegranskat)abstract
- In this study, low quality waste cooking oil with high total acid value, has been used for biodiesel production. The main factors affecting the reaction has been analysed using Response Surface Methodology (RSM). A quadratic model representing the interrelationships between reaction variables and free fatty acids (FFA) conversion has been developed. Analysis of variance (ANOVA) has been used for checking the significance of the predicted model. Numerical optimisation concluded the optimum conditions for maximum conversion of FFA at methanol to oil (M:O) molar ratio, temperature, pressure and time of 35:1, 260oC, 110 bar and 16 minutes, respectively for 98% conversion. The predicted optimum conditions have been validated experimentally resulting in 97.7% conversion of FFA with 0.3% relative error. Kinetic and thermodynamic data of the esterification reaction has been studied resulting in pseudo first order reaction with reaction rate constant (k) of 0.00103 s-1, activation energy of 34.5 kJ/mol and Arrhenius constant of 1.26 s-1. Finally, a kinetic reaction has been simulated resulting in 97% conversion of FFA with 0.716% relative error from the experimental results.
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| 9. |
- Aboelazayem, Omar, et al.
(författare)
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Biodiesel Production from High Acid Value Waste Cooking Oil Using Supercritical Methanol: Esterification Kinetics of Free Fatty Acids
- 2017
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Ingår i: European Biomass Conference and Exhibition Proceedings, 25thEUBCE, June 2017. - 2282-5819. - 9788889407172 ; , s. 1381-1387
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Konferensbidrag (refereegranskat)abstract
- In this study, low quality waste cooking oil (WCO) with high total acid value has been used for biodiesel production. The main factors affecting the reaction have been analysed using Response Surface Methodology (RSM). A quadratic model representing the interrelationships between reaction variables and free fatty acids (FFA) conversion has been developed. Analysis of variance (ANOVA) has been used to evaluate the significance of the predicted model. Numerical optimisation predicted the optimum conditions for maximum conversion of FFA at methanol to oil (M:O) molar ratio, temperature, pressure and time of 35:1, 260 °C, 110 bar and 16 min, respectively for 98 % conversion. The predicted optimum conditions have been validated experimentally resulting in 97.7 % conversion of FFA with 0.3 % relative error. Kinetic and thermodynamic data of the esterification reaction has been studied resulting in pseudo first-order reaction with reaction rate constant of 0.00103 s-1, activation energy of 34.5 kJ/mol and Arrhenius constant of 1.26 s-1. Finally, a kinetic reactor has been simulated resulting in 97 % conversion of FFA with 0.716 % relative error from the experimental results.
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| 10. |
- Abuohashish, Hatem, et al.
(författare)
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Angiotensin(1-7) attenuates tooth movement and regulates alveolar bone response during orthodontic force application in experimental animal model.
- 2023
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Ingår i: Progress in orthodontics. - 2196-1042. ; 24:1
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Tidskriftsartikel (refereegranskat)abstract
- Renin-angiotensin system and its ACE2/Ang(1-7)/Mas receptor axis regulates skeletal response to multiple physiological and pathological conditions. Recent research suggested a vital role of Ang(1-7) in regulating alveolar bone metabolism and remodeling. In this context, this study evaluated the effects of the Ang(1-7)/Mas receptor axis on orthodontic tooth movement (OTM) and the alveolar bone response to mechanical load.A coil spring was placed between the right maxillary first molar and the anterior tooth of Wistar rats to apply bidirectional mechanical force. Ang(1-7) with or without a specific Mas receptor antagonist (A779) was infused using subcutaneous osmotic pumps (200 and 400 ng/kg/min: respectively). Animals were killed after 5 and 14 days from the OTM procedure after the clinical evaluation of tooth movement and mobility. Morphometric analysis of alveolar bone structure was conducted using micro-CT and the histological picture was evaluated after H&E staining. Moreover, collagen fiber distribution was assessed using Picro-Sirius red stain. In addition, bone samples were collected from the pressure and tension sites around the anterior tooth for gene expression analysis.Ang(1-7) infusion suppressed the tooth movement and mobility after 14 days of the orthodontic force application. Additionally, Ang(1-7) infusion preserved the morphometric and histological structure of the alveolar bone at pressure and tension sides. These effects were abolished by adding A779 infusion. Collagen fiber distribution was dysregulated mainly by the A779 Mas receptor blockage. Ang(1-7) affected the bone formation, remodeling- and vascularity-related genes in the pressure and tension sides, suggesting a prominent suppression of osteoclastogenesis. Ang(1-7) also improved osteoblasts-related genes on the tension side, whereas the osteoclasts-related genes were augmented by A779 on the pressure side.Collectively, the activation of Ang(1-7)/Mas receptor axis appears to hinder tooth movement and regulates alveolar bone remodeling in response to mechanical force.
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| 11. |
- Adisa, Adewale, et al.
(författare)
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A Prospective, Observational Cost Comparison of Laparoscopic and Open Appendicectomy in Three Tertiary Hospitals in Nigeria.
- 2023
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Ingår i: World journal of surgery. - 1432-2323. ; 47:12, s. 3042-3050
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Tidskriftsartikel (refereegranskat)abstract
- The clinical benefits of laparoscopic appendicectomy are well recognized over open appendicectomy. However, laparoscopic procedures are not frequently conducted in many low-and middle-income countries (LMICs) for several reasons, including perceived higher costs. The aim of this study was to assess the feasibility and cost of laparoscopic appendicectomy compared to open appendicectomy in Nigeria.A multicenter, prospective, cohort study among patients undergoing appendicectomy was conducted at three tertiary hospitals in Nigeria. Data were collected from October 2020 to February 2022 and analyses compared the average healthcare costs at 30 days after surgery. Quantile regression was conducted to identify variables that had an impact on the costs, reported in Nigerian Naira (Naira) and US dollars ($), with standard deviations (SD).This study included 105 patients, of which 39 had laparoscopic appendicectomy and 66 had open appendicectomy. The average healthcare cost of laparoscopic appendicectomy (147,562 Naira (SD: 97,130) or $355 (SD: 234)) was higher than open appendicectomy (113,556 Naira (SD: 88,559) or $273 (SD: 213)). The average time for return to work was shorter with laparoscopic than open appendicectomy (mean: 8 days vs. 14 days). At the average daily income of $5.06, laparoscopic appendicectomy was associated with 9778 Naira or $24 cost savings in return to work. Further, 5.1% of laparoscopic appendicectomy patients had surgical site infections compared to 22.7% for open appendicectomy. Regression analysis results showed that laparoscopic appendicectomy was associated with $14 higher costs than open appendicectomy, albeit non-significant (p = 0.53).Despite selection bias in this real-world study, laparoscopic appendicectomy was associated with a slightly higher overall cost, a lower societal cost, a lower infection rate, and a faster return to work, compared to open appendicectomy. It is technically and financially feasible, and its provision in Nigeria should be expanded.
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| 12. |
- Ahmed, Sirwan Khalid, et al.
(författare)
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Knowledge, Attitude and Worry in the Kurdistan Region of Iraq during the Mpox (Monkeypox) Outbreak in 2022 : An Online Cross-Sectional Study
- 2023
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Ingår i: Vaccines. - : MDPI AG. - 2076-393X. ; 11:3
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Tidskriftsartikel (refereegranskat)abstract
- The rapid spread of monkeypox (mpox) has been declared as a public health emergency of international concern (PHEIC). The present study aimed to assess the knowledge, attitude, and worry levels of the general population in the Kurdistan region of Iraq regarding the ongoing mpox multi-country outbreak. An online cross-sectional survey was conducted between 27–30 July 2022, using a convenience sampling method. The questionnaire was adapted from previous studies addressing the same topic. The independent Student’s t-test, one-way ANOVA, and logistic regression were used to assess possible factors associated with knowledge, attitude, and worry toward mpox. A total of 510 respondents were included in the final analysis. The participants showed a moderate level of mpox knowledge, a neutral attitude towards mpox, and a relatively moderate worry level. The logistic regression analysis showed that age, gender, marital status, religion, level of education, and place of residence were associated with mpox knowledge; however, the significant variables in the multivariate regression analysis were gender, religion, level of education, and residential area. Gender and residential area were associated with attitudes toward mpox; however, the significant variables in the multivariate regression analysis were gender and residential areas. The worry toward mpox was influenced by gender, marital status, religion, and place of residence, yet the significant variables in the multivariate regression analysis were gender, religion, educational level, and residential area. In conclusion, the Kurdish population had moderate knowledge, a neutral attitude, and a moderate level of worry about mpox. Considering the continuous rapid rise in mpox cases in several countries, and its possible risk as pandemic amid the ongoing COVID-19 pandemic, proactive control measures, adequate disease prevention strategies, and preparedness plans need to be formulated and immediately implemented to tackle the appearance of fears among people, and to safeguard the mental health of the public.
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| 13. |
- Al Omari, Omar, et al.
(författare)
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Prevalence and predictors of loneliness among youth during the time of COVID-19 : A multinational study
- 2021
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Ingår i: Journal of the American Psychiatric Nurses Association. - 1078-3903 .- 1532-5725. ; , s. 1-11
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Given the restrictions associated with COVID-19, feelings of loneliness among youth may increase.AIMS: The aims of the current study were to assess the prevalence of loneliness among young people at the time of COVID-19 and to identify whether selected variables related to the pandemic predicted the level of loneliness.METHOD: A cross-sectional study using WhatsApp and Facebook social media platforms was conducted to survey 1,057 young people aged 15 to 24 years from six Middle Eastern countries. Participants completed survey items including demographic and COVID-19-related questions; the Depression, Anxiety and Stress Scale (DASS); the Satisfaction With Life Scale (SWLS); and the UCLA Loneliness Scale.RESULTS: The prevalence of experienced loneliness was 1 (0.1%), 625 (59.1%), 429 (40.6%), and 2 (0.2%), reflecting low, moderate, moderately high, and high experiences for loneliness, respectively. History of depression or anxiety, being dissatisfied with life, and having depression at the time of COVID-19 were significant predictors of loneliness among youth. The model was significant (F = 44.95, p < .05) and accounted for 29.8% of the variance in UCLA Loneliness Scale scores.CONCLUSIONS: We found that the high prevalence rate of loneliness during the COVID-19 pandemic was correlated with depression and impaired life satisfaction among Middle Eastern youth. Thus, special attention and interventional action plans need to be developed taking into consideration the youths' special situation during COVID-19.
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| 14. |
- Al Omari, Omar, et al.
(författare)
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Prevalence and predictors of loneliness among youth during the time of COVID-19 : A multinational study
- 2021
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Ingår i: Journal of the American Psychiatric Nurses Association. - : SAGE Publications Inc.. - 1078-3903 .- 1532-5725. ; , s. 10
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Given the restrictions associated with COVID-19, feelings of loneliness among youth may increase. AIMS: The aims of the current study were to assess the prevalence of loneliness among young people at the time of COVID-19 and to identify whether selected variables related to the pandemic predicted the level of loneliness. METHOD: A cross-sectional study using WhatsApp and Facebook social media platforms was conducted to survey 1,057 young people aged 15 to 24 years from six Middle Eastern countries. Participants completed survey items including demographic and COVID-19-related questions; the Depression, Anxiety and Stress Scale (DASS); the Satisfaction With Life Scale (SWLS); and the UCLA Loneliness Scale. RESULTS: The prevalence of experienced loneliness was 1 (0.1%), 625 (59.1%), 429 (40.6%), and 2 (0.2%), reflecting low, moderate, moderately high, and high experiences for loneliness, respectively. History of depression or anxiety, being dissatisfied with life, and having depression at the time of COVID-19 were significant predictors of loneliness among youth. The model was significant (F = 44.95, p <.05) and accounted for 29.8% of the variance in UCLA Loneliness Scale scores. CONCLUSIONS: We found that the high prevalence rate of loneliness during the COVID-19 pandemic was correlated with depression and impaired life satisfaction among Middle Eastern youth. Thus, special attention and interventional action plans need to be developed taking into consideration the youths’ special situation during COVID-19.
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| 15. |
- AlAgil, Jumana, et al.
(författare)
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Risk of postoperative bleeding after dental extraction in patients on antiplatelet therapy: systematic review and meta-analysis.
- 2023
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Ingår i: Oral surgery, oral medicine, oral pathology and oral radiology. - 2212-4411.
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Tidskriftsartikel (refereegranskat)abstract
- To determine the risk of bleeding after minor extraction in patients on different antiplatelet therapy (APT) regimens.A search was conducted using PubMed and Google Scholar. Thirty-five papers were included in the systematic review, of which 23 papers provided the requisite information for meta-analysis. Subgroups were created based on the controls, as follows: (1) no control, (2) healthy control, and (3) interrupted APT control. In a meta-analysis, the studies were further subdivided into immediate and delayed bleeding.No immediate or delayed bleeding risk was found in patients treated with aspirin vs healthy controls (relative risk [RR] = 1.26; P = .5 and RR = 2.17; P = .09, respectively). A higher immediate bleeding was recorded for patients on single nonaspirin APT vs those in the healthy population (RR = 3.72; P = .0009). A high risk of bleeding was recorded in patients receiving dual APT compared with healthy controls for immediate (RR = 10.3; P < .0001) and delayed (RR = 7.72; P = .001) bleeding. Dual APT continuation showed a higher risk of immediate bleeding (RR = 2.13) than interrupted APT, but the difference was insignificant (P = .07).Dental extraction can be performed safely in patients on aspirin monotherapy. In contrast, patients receiving dual APT should be considered at risk for immediate and continued bleeding.
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| 16. |
- Arora, Teresa, et al.
(författare)
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A systematic review and meta-analysis to assess the relationship between sleep duration/quality, mental toughness and resilience amongst healthy individuals
- 2022
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Ingår i: Sleep Medicine Reviews. - : Elsevier. - 1087-0792 .- 1532-2955. ; 62
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Forskningsöversikt (refereegranskat)abstract
- The majority of sleep research has focused on deleterious health outcomes, with little attention to positive sequels. A systematic review of the literature regarding sleep duration and/or sleep quality in relation to mental toughness and resilience amongst non-clinical, healthy populations was completed. Eight databases and selected sources for grey literature were searched from their inception to April 2021. A total of 1925 unique records (1898 from the database search and 27 from grey sources) were identified and screened against the pre-set inclusion and exclusion criteria. Of these, 68 studies were eligible and 63 were included in the meta-analysis. Pooled results indicated a weak, positive correlation between sleep duration and resilience (r = 0.11, p < 0.001), and sleep quality (r = 0.27, p < 0.001). The pooled correlation was slightly attenuated for prospective studies pertaining to sleep quality and resilience (r = 0.18, p < 0.001). We found evidence of high publication bias for studies that explored the relationship between sleep quality and resilience. Sleep and resilience are positively correlated but additional research is needed to verify the direct relationship through carefully designed, prospective studies that capture both subjective and objective sleep estimates. For a more comprehensive understanding, complementary reviews that explore the sleep-resilience association are needed for clinical populations, and those who have suffered extreme hardship.
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| 17. |
- Arora, Teresa, et al.
(författare)
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The prevalence of psychological consequences of COVID-19 : A systematic review and meta-analysis of observational studies
- 2022
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Ingår i: Journal of Health Psychology. - : Sage Publications. - 1359-1053 .- 1461-7277. ; 27:4, s. 805-824
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Forskningsöversikt (refereegranskat)abstract
- A systematic review and a meta-analysis were conducted to examine the overall prevalence of psychological health outcomes during COVID-19. Seven databases were systematically searched to include studies reporting on at least one psychological outcome. The pooled prevalence of primary psychological outcomes was 26% (95%CI: 21-32). Pooled prevalence for symptoms of PTSD was 33% (0-86), anxiety 28% (21-36), stress 27% (14-43), and depression 22% (13-33). The prevalence of psychological outcomes was similar in healthcare workers and in the general population (34% [24-44] and 33% [27-40] respectively). High prevalence figures support the importance of ensuring adequate provision of resources for mental health.
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| 18. |
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| 19. |
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| 20. |
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| 21. |
- Ballo, Ahmed, 1978, et al.
(författare)
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Osseointegration: Outlines of Cellular and Molecular Mechanisms
- 2012
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Ingår i: Implant Dentistry Research Guide: Basic, Translational and Clinical Research. Ed. Ahmed Ballo. - New York, USA : Nova Science Publishers. - 9781619425033 ; , s. 1-30
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Bokkapitel (refereegranskat)abstract
- The osseointegration process is typically characterized by the overlap of different stages, including the initial inflammatory response, initial bone formation, osseous anchorage and bone remodeling. Each stage is characterized by a specific set of cellular and molecular events. Advances in molecular biology and biochemistry, cell biology, developmental biology, wound-healing physiology, materials science and engineering, and novel laboratory techniques, have provided incentives and opportunities for renewed and ever-increasing interest in detailed studies of the mechanisms of osseointegration. The aim of this chapter is to illustrate the sequence of molecular interaction, cellular events and the general pattern of the osseointegration process performed following implant placement. Further, the influence of surface modification on cellular and molecular activity at the bone-implant interface is discussed on the basis of recent in vivo investigations.
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| 22. |
- Bayomie, Omar S., et al.
(författare)
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Exceeding Pinch limits by process configuration of an existing modern crude oil distillation unit – A case study from refining industry
- 2019
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Ingår i: Journal of Cleaner Production. - : Elsevier BV. - 0959-6526. ; 231, s. 1050-1058
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Tidskriftsartikel (refereegranskat)abstract
- Crude Distillation Unit (CDU) represents significant challenge for retrofitting and energy optimisation as the most energy intensive consumer in a conventional crude oil refinery. Pinch Technology and its based-methodologies are found primary keys for decades to energy savings in refining industries for a range of common economic-based and environmental objectives or applications. Typical benefits in energy savings are reported within 20–40% of original designs. However, such savings are limited and questioned when modern refiners are dealt with. The current paper addresses the revamping of a modern refinery exhibiting an existing high energy efficiency (≈93%). This implies the maximum potential energy savings would only be 7% at current process conditions. The present research proposes an algorithm that tackles energy recovery of modern refiners, enabling additional savings beyond the energy targets set by the existing process. The algorithm starts by process simulation and validation against real plant data, followed by a network optimisation, e.g. stream splitting, to reach the energy targets set by Pinch Analysis. The energy targets are then moved to another lower level by performing potential process modifications to reduce the energy consumption further. Results showed that the current modern refinery unit could reach its energy targets by stream splitting modifications with hot energy savings of 2.69 MW. Process modifications resulted in additional energy savings of 31.3% beyond the current level of the existing plant alongside less than a year of payback period for estimated capital investment. An environmental assessment is performed, and comparable reductions were obtained with respect to greenhouse gas, with reduction in CO2 emissions by 45.1%. The proposed retrofit methodology is applicable to minimising energy consumptions of refiners including modern units to achieve energy levels beyond energy targets by new process modifications.
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| 23. |
- Ben Amara, Heithem, 1984, et al.
(författare)
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Bone healing around biodegradable Magnesium implants: Differential response between interfacial and near-implant bone in vivo
- 2022
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Ingår i: 14th Symposium on Biodegradable Metals, Alicante, Spain 24-29 August 2022.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- INTRODUCTION: By virtue of their mechanical properties and of their degradation, magnesium (Mg)-based osteosynthesis systems are metallic implants that hold the fractured bones while eliminated in situ, thus offering the promise of reduced complications posed by permanent implants. A growing amount of research validated Mg-based implants for bone fixation by providing robust evidence in support of new bone deposition in contact with the interfacial degradation layer. Whereas Mg-degradation products are known to distribute in the implant environment, less attention has been paid to the bone response at distance from the implant interface. The present study investigated the structural, cellular, and molecular events taking place at the bone-Mg implant interface and at distance from it after in vivo implantation in an experimental rat model. METHODS: Following approval by the Local Ethical Committee at the University of Gothenburg (Dnr: 14790/2019), male Sprague-Dawley rats (n=56) were implanted with miniature screws manufactured from pure magnesium (99.99% - high purity; Mg) or from pure titanium (grade 4; Ti) (herein, serving as a control, enabling osseointegration in this model). In each animal, the metaphysis of the left and right tibiae was drilled prior to the insertion of Ti or Mg screws. After 3 and 28 days, animals were euthanized, and two types of samples were retrieved (Fig. 1): 1-Implants and peri-implant bone for quantitative polymerase chain reaction (qPCR) (n=8/group/time-point): were separately collected and allocated for molecular gene expression of the implant-adherent cells and of the cells in the peri-implant space. 2-Peri-implant bone with implants en bloc for paraffin or plastic embedding (n=6/group/time-point): enabling radiographical analyses using micro-computed tomography (micro-CT) and histomorphometrical measurements of the bone at the implant interface and at distance from it. Statistical comparisons were made between experimental groups at each time point and between time-points for each experimental group. (Kruskal-Wallis, Mann-Whitney and Wilcoxon signed-rank tests; p<0.05). RESULTS: While histological observations provided evidence of new bone formation at the vicinity of both Ti and Mg, the bone marrow at distance from the implant-interface featured morphological differences between groups (Fig. 2). At 3 days, the proportion of the interstitial and microvascular area was significantly higher at the expense of the area occupied by the hematopoietic cells in Mg- vs Ti-implanted metaphyses. At 28 days, bone marrow around Mg implants showed significantly higher adiposity in comparison to Ti implants. Yet, no differences in the trabecular bone micro-architecture were detected between biomaterials by micro-CT analysis at distance from the implant-interface. The RNA extracted from cells from the implant surface and from the peri-implant bone revealed good quality, allowing detailed molecular analysis. CONCLUSIONS: In comparison to non-degradable Ti controls, the degradation of Mg implants changes the composition of the peri-implant bone marrow, but yet without alteration of new bone formation at the implant interface. ACKNOWLEDGEMENTS: Mg rods were generously provided by the Helmholtz-Zentrum Hereon, Geesthacht, Germany. This project is part of the European Training Network within the framework of Horizon 2020 Marie Skłodowska-Curie Action No 811226.
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| 24. |
- Ben Amara, Heithem, 1984, et al.
(författare)
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Dissecting the sequential interaction between biodegradable magnesium implants and soft tissues in vivo
- 2022
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Ingår i: Materials Science and Engineering Congress, Dredsen, Germany, 27-29 September 2022.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Magnesium-based biomaterials are developed with the intention to enable tissue regeneration while being degraded under physiological conditions and eventually eliminated from the body. Once in contact with tissues, the biodegradability and the biocompatibility of magnesium implants (Mg) are governed by the direct interactions with their immediate milieu. The precise mechanisms through which the soft tissue micro-environment shapes the behaviour of Mg and the host-response remain elusive. Here, it is demonstrated that Mg degradation modulates the initial acute immune response and the subsequent fibrous encapsulation upon subcutaneous implantation in rats monitored at 1-, 3-, 6-, 14- and 28-days following surgery. In comparison to titanium implants (Ti), the initial profuse release of Mg degradation products activates pro-inflammatory pathways through increased recruitment of inflammatory cells to the soft tissue/implant interface and upregulation of pro-inflammatory genes, in parallel with a superior neo-angiogenesis and vascularization at Mg. After 6d, a shift in Mg degradation kinetics dissipates the initial pro-inflammatory response and facilitates the assembly of a comparatively thinner fibrous tissue capsule than around Ti. The reduction in the fibrous encapsulation around the Mg implant aligns with a superior expression of anti-fibrotic marker FOXO-1 at the tissue interface with Mg versus Ti. Mg induce an initial potent yet transient inflammatory response, which is associated with less adverse fibrous encapsulation after tissue healing. Tailoring Mg with controlled initial degradation appears to be crucial to enabling a successful coupling between inflammation and tissue repair during the early host response to Mg.
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| 25. |
- Ben Amara, Heithem, 1984, et al.
(författare)
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Immunomodulation by biodegradable Mg-implants promotes soft and hard tissues responses in vivo
- 2023
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Ingår i: Scandinavian Society of Biomaterials conference, 21–24 March 2023, Røros, Norway.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- INTRODUCTION: Magnesium (Mg)-based degradable implants are an attractive treatment solution for musculoskeletal injuries, avoiding second-stage surgical removal. In multiple clinical applications, the implant is in contact with both the bone and the overlying soft tissue. Although Mg implants are often presented to hold anti-inflammatory properties, less attention has been paid to the sequential response to these implants including initial immune response and subsequent tissue repair. The present study investigated the molecular, cellular, and structural events taking place at the Mg implant interface to soft tissue and bone after in vivo implantation in dedicated experimental rat models. METHODS: Male Sprague Dawley rats received disc-shaped implants in the dorsum subcutis or screw-shaped implants in the proximal tibial metaphysis. Implants were manufactured from pure magnesium (99.99% - high purity; Mg) or from pure titanium (grade 4; Ti) as control. Animals were euthanized after 1, 3, 6, 14, and 28 day of soft tissue implantation, and after 3 and 28 days of bone implantation. Two types of samples were collected: 1-Implants with the adherent cells (n=7-8/group/time-point). These were allocated for cell counting and /or gene expression analyses of implant-adherent cells. 2-Peri-implant tissue with implants (n = 8/group/time-point). These enabled histological and histomorphometric analyses of the fibrous capsule organization around implants inserted in soft tissues and of osseointegration parameters at the bone-implant interface. Statistical comparisons between experimental groups were run using Kruskal-Wallis, and Mann-Whitney tests (p<0.05). RESULTS: Cells adherent to the surface of the implants featured different gene regulation patterns between Mg and Ti groups (Fig. 1). Consistently in soft tissue and in bone, macrophage polarization markers indicated higher expression of proinflammatory macrophage gene inducible nitric oxide synthase (iNos) initially at Mg versus Ti (3 d in bone and 1-6 d in soft tissue). Afterward, gene expression of both macrophage subtypes markers (proinflammatory – iNos and prohealing – Mannose receptor c1; Mrc1) was comparable between implants, irrespective of their insertion site. Histomorphometry evidenced superior bone-implant contact (at 28 d in bone) and thinner fibrous capsule (at 6-28 d in soft tissue) for Mg versus Ti. CONCLUSIONS: In comparison to non-degradable Ti, both soft tissue and bone responses to biodegradable Mg featured an initial yet transient gene activation of the macrophage proinflammatory subtype. Such immunomodulation by Mg resulted in the reduction of fibrous encapsulation in soft tissue and in the promotion of bone formation at the bone-implant interface. ACKNOWLEDGEMENTS: Mg implants were generously provided by Helmholtz-Zentrum Hereon, Geesthacht, Germany. This project is part of the European Training Network within the framework of Horizon 2020 Marie Skłodowska-Curie Action No 811226.
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