Leakage associated with intermediate restorative material and glass-ionomer cement retrograde fillings: a human and sheep teeth comparison with 2 different aging procedures.

OBJECTIVES: Leakage around retrograde fillings is an important cause of endodontic surgery. This in vitro study sought to compare the following: (1) methylene blue dye leakage linked to retrofillings in human and sheep teeth with the degree of dye penetration when intermediate restorative materials and Chemfil were used as retrofillings, (2) the apical microleakage in filled with that in unfilled root canals, and (3) 2 storage techniques, incubator-based and subcutaneous implantation in rats. STUDY DESIGN: Tested were 198 human and 196 sheep teeth that were retrofilled with intermediate restorative material or Chemfil, then stored in an incubator or subcutaneously in rats for 10, 20, and 30 days before immersion in methylene blue dye for 24 hours. Linear dye penetration was evaluated, and the results were statistically analyzed by means of analysis of variance. RESULTS: Leakage between sheep and human teeth was significantly different (P <.05). Chemfil had significantly less leakage than intermediate restorative material after storage in rat (P <.05) for up to 20 days, but not after 30 days. No differences were found between leakage of unfilled and filled human root canal teeth. CONCLUSIONS: The sheep incisor is a poor experimental model of the human tooth, and both aging procedures demonstrate extensive leakage of retrofilling materials after long-term storage.     

Dominant A1: angiographic and clinical correlations with anterior communicating artery aneurysms.

It has been observed but never proven that anomalies of the anterior communicating artery complex are associated with anterior communicating artery aneurysms (ACAA). Therefore, in an effort to understand the significance of haemodynamic factors in the genesis, as well as the clinical course of ACAA, we evaluated the correlation between certain angiographic patterns of flow in the anterior circulation and the clinical findings of 51 patients with ACAA compared with 50 matched controls. Four significant associations which have never been validated were identified: 1) a dominant A1 (filling both A2's) was found in 57% of ACAA patients versus 14% of controls (p less than 0.001). 2) Unilateral hypoplasia of the opposite A1 was present in 24% of ACAA patients versus 6% of controls (p = 0.01). 3) Exclusive filling of the ACAA from one A1 occurred in 78%. 4) No statistically significant relationship was found between the anatomic flow patterns studied and the patients clinical presentation including age, sex, or grade. We conclude that anterior communicating artery aneurysms are significantly related in a majority of patients with the presence of a dominant A1, probably as the result of enhanced haemodynamic stress caused by this anatomic abnormality in the circulation. However, this association is not constant, and a dominant pattern of flow did not correlate with the clinical course. This is probably a reflection of the differences between factors initiating aneurysm formation and those influencing its growth, as well as of the relative limitations of angiography when pathophysiological extrapolations are attempted.     

Brain tissue oxygenation in patients with cerebral occlusive disease and arteriovenous malformations

It is not clear if ventilation with oxygen increases brain tissue oxygen pressure (PO2) during ischaemia. We have measured brain tissue PO2, carbon dioxide pressure (PCO2) and pH during baseline anaesthesia and oxygen ventilation in non-ischaemic control patients (n = 9), patients with cerebral occlusive disease (n = 11) and patients with arteriovenous malformations (AVM, n = 12). The same anaesthetic treatment was given to all groups and anaesthesia was constant during the study. Arterial pressure, brain temperature and arterial blood-gas tensions were similar between groups. Under baseline conditions, brain tissue PO2 was mean 4.2 (SD 1.4) kPa in the controls and was 70% lower in patients with ischaemia and AVM. Patients with occlusive disease also had elevated tissue PCO2 and acidosis. During oxygen ventilation, PO2 increased to 7.5 (2.9) kPa in controls and this was 50% greater than the increase in the ischaemia and AVM patients. The results showed that baseline tissue oxygenation and increases in PO2 during hyperoxia were attenuated in patients with ischaemia or AVM.      

The nitric oxide pathway in pre-eclampsia: pathophysiological implications

Pre-eclampsia, one of the most significant health problems inhuman pregnancy, complicates 6-7% of all gestations and is theleading cause of fetal growth retardation, infant morbidityand mortality, premature birth and maternal death. Recent researchimplicates free radicals in the pathophysiology of pre-eclampsia.This review covers the biochemistry of nitric oxide (NO) andpossible interactions with other free radicals. Studies in therat show that pregnancy is associated with enhanced productionand responsiveness to NO in both reproductive tissues and bloodvessels. Rats infused with N^G-nitro-L-arginine methyl ester(L-NAME, a NO synthase inhibitor) have been used as an animalmodel of pre-eclampsia, and the effects of steroid hormoneson blood pressure in this model have been tested. Results suggestthat pre-eclampsia may be a state of NO deficiency. However,in humans there seem to be contradictions regarding the involvementof NO in maternal adaptation to pregnancy. It is suggested thatNO may be one of several systems that act in concert to maintaina symbiotic relationship between mother and fetus. However,the input of each system may be genetically determined.     

Studies of cervical ripening in pregnant rats: effects of various treatments

The exact mechanisms that regulate cervical softening or ripening during pregnancy are not completely understood. The aim of this study was to estimate the effects of various agents on cervical softening during pregnancy in rats. Cervical resistance was examined after treatment with nitric oxide (NO) donors and inhibitors and different hormonal agents. Cervical resistance was significantly reduced (P< 0.05) in rats treated with the NO donors: sodium nitroprusside, molsidomine and prostaglandin E(2). However, treatments with the NO synthase (NOS) inhibitors N(omega)-nitro-L-arginine methyl ester (L-NAME) and L-N(6)-1-iminoethyl-lysine (L-NIL), or the prostaglandin synthesis inhibitor, indomethacin, significantly increased resistance (P<0.05). The antiprogesterone, onapristone, reduced cervical resistance and its effects were only partially blocked by the progesterone agonist, promegestone. Relaxin reduced cervical resistance and NOS inhibitors partially blocked the effect of relaxin. These studies demonstrate that NO regulates cervical ripening. Relaxin also softens the cervix and may act by stimulating NO synthesis. Progesterone seems important in the control of cervical ripening, but its role appears complex. NO and prostaglandin pathways may independently control ripening by acting in parallel or synergistically.     

Does there exist an obesity paradox in COVID-19? Insights of the international HOPE-COVID-19-registry

BackgroundObesity has been described as a protective factor in cardiovascular and other diseases being expressed as ‘obesity paradox’. However, the impact of obesity on clinical outcomes including mortality in COVID-19 has been poorly systematically investigated until now. We aimed to compare clinical outcomes among COVID-19 patients divided into three groups according to the body mass index (BMI).MethodsWe retrospectively collected data up to May 31^st, 2020. 3635 patients were divided into three groups of BMI (<25 kg/m²; n = 1110, 25?30 kg/m²; n = 1464, and >30 kg/m²; n = 1061). Demographic, in-hospital complications, and predictors for mortality, respiratory insufficiency, and sepsis were analyzed.ResultsThe rate of respiratory insufficiency was more recorded in BMI 25?30 kg/m² as compared to BMI < 25 kg/m² (22.8% vs. 41.8%; p < 0.001), and in BMI > 30 kg/m² than BMI < 25 kg/m², respectively (22.8% vs. 35.4%; p < 0.001). Sepsis was more observed in BMI 25?30 kg/m² and BMI > 30 kg/m² as compared to BMI < 25 kg/m², respectively (25.1% vs. 42.5%; p = 0.02) and (25.1% vs. 32.5%; p = 0.006). The mortality rate was higher in BMI 25?30 kg/m² and BMI > 30 kg/m² as compared to BMI < 25 kg/m², respectively (27.2% vs. 39.2%; p = 0.31) (27.2% vs. 33.5%; p = 0.004). In the Cox multivariate analysis for mortality, BMI < 25 kg/m² and BMI > 30 kg/m² did not impact the mortality rate (HR 1.15, 95% CI: 0.889?1.508; p = 0.27) (HR 1.15, 95% CI: 0.893?1.479; p = 0.27). In multivariate logistic regression analyses for respiratory insufficiency and sepsis, BMI < 25 kg/m² is determined as an independent predictor for reduction of respiratory insufficiency (OR 0.73, 95% CI: 0.538?1.004; p = 0.05).ConclusionsHOPE COVID-19-Registry revealed no evidence of obesity paradox in patients with COVID-19. However, Obesity was associated with a higher rate of respiratory insufficiency and sepsis but was not determined as an independent predictor for a high mortality.     

The impact of non-pharmaceutical interventions on COVID-19 epidemic growth in the 37 OECD member states

We estimated the impact of a comprehensive set of non-pharmeceutical interventions on the COVID-19 epidemic growth rate across the 37 member states of the Organisation for Economic Co-operation and Development during the early phase of the COVID-19 pandemic and between October and December 2020. For this task, we conducted a data-driven, longitudinal analysis using a multilevel modelling approach with both maximum likelihood and Bayesian estimation. We found that during the early phase of the epidemic: implementing restrictions on gatherings of more than 100 people, between 11 and 100 people, and 10 people or less was associated with a respective average reduction of 2.58%, 2.78% and 2.81% in the daily growth rate in weekly confirmed cases; requiring closing for some sectors or for all but essential workplaces with an average reduction of 1.51% and 1.78%; requiring closing of some school levels or all school levels with an average reduction of 1.12% or 1.65%; recommending mask wearing with an average reduction of 0.45%, requiring mask wearing country-wide in specific public spaces or in specific geographical areas within the country with an average reduction of 0.44%, requiring mask-wearing country-wide in all public places or all public places where social distancing is not possible with an average reduction of 0.96%; and number of tests per thousand population with an average reduction of 0.02% per unit increase. Between October and December 2020 work closing requirements and testing policy were significant predictors of the epidemic growth rate. These findings provide evidence to support policy decision-making regarding which NPIs to implement to control the spread of the COVID-19 pandemic.

     

Multiphoton microscopy for pre-clinical evaluation of flow-diverter stents for treating aneurysms

BackgroundConventional histological analyses are the gold standard for the study of aneurysms and vascular pathologies in pre-clinical research. Over the past decade, in vivo and ex vivo imaging using multiphoton microscopy have emerged as powerful pre-clinical tools for detailed tissue analyses that can assess morphology, the extracellular matrix (ECM), cell density and vascularisation. Multiphoton microscopy allows for deeper tissue penetration with minor phototoxicity.ObjectiveThe present study aimed to demonstrate the current status of multimodality imaging, including multiphoton microscopy, for detailed analyses of neo-endothelialisation and ECM evolution after flow-diverter stent (FDS) treatment in an experimental rabbit model of aneurysms.MethodsMultiphoton microscopy tools for assessing autofluorescence and second harmonic generation (SHG) signals from biological tissues were used to evaluate the endovascular treatment of intracranial aneurysms in an animal model of aneurysms (pig, rabbit). Results from multiphoton microscopy were compared to those from standard histology, electronic and bright field microscopy.ConclusionsThe present study describes novel evaluation modes based on multiphoton microscopy for visualising tissue morphology (e.g., collagen, elastin, and cells) to qualify and quantify the extent of neo-intimal formation of covered arteries and device integration into the arterial wall using a rabbit model of intracranial aneurysms treated with FDS.