The Future of Education Utilizing an Artificial Intelligence Robot in the Centre for Independent Language Learning: Teacher Perceptions of the Robot as a Service

This book chapter provides an overview of Temi, an autonomous, video-oriented personal assistant robot which was deployed within the Centre for Independent Language Learning (CILL) at The Hong Kong Polytechnic University. The artificial intelligence robot was chosen principally because of its role as a Robot as a Service (RaaS). Such a service can deliver greater self-improvement and better learning strategies (e.g. Cohen, A. D. (2014). Strategies in learning and using a second language (2nd ed.). Routledge., Dörnyei et. al., 2015, Wenden, Learner strategies for learner autonomy, Prentice Hall, 1991, Yang, Frontiers in Psychology 12:600, 218–600, 218, 2021) as well as foster beneficial attitudes and skills towards the users' long-term language learning success. Through its cloud-based system, Temi offers users access to dynamic interactions and enhanced CILL services, during the COVID-19 pandemic. As a whole, it appears that the introduction of Temi has proven to be an effective strategy to augment learners' autonomy. It further allows administrators to rethink how CILL services are conducted during human resource shortages. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

ACE and ACE2 catalytic activity in the fecal content along the gut.

BACKGROUND: Angiotensin-converting enzyme (ACE) and ACE2 are two major enzymes of the renin-angiotensin-aldosterone system (RAAS), which control the formation/degradation of angiotensin (Ang) II and Ang1-7, regulating their opposite effects. We aimed at evaluating the catalytic activity of ACE and ACE2 in the intestinal content and corresponding intestinal tissue along the gut of Wistar Han rats. METHODS: Portions of the ileum, cecum, proximal colon, and distal colon, and the corresponding intestinal content were collected from Wistar Han rats. Enzyme activity was evaluated by fluorometric assays using different substrates: Hippuryl-His-Leu for ACE-C-domain, Z-Phe-His-Leu for ACE-N-domain, and Mca-APK(Dnp) for ACE2. ACE and ACE2 concentration was assessed by ELISA. Ratios concerning concentrations and activities were calculated to evaluate the balance of the RAAS. Statistical analysis was performed using Friedman test followed by Dunn's multiple comparisons test or Wilcoxon matched-pairs test whenever needed. KEY RESULTS: ACE and ACE2 are catalytically active in the intestinal content along the rat gut. The ACE N-domain shows higher activity than the C-domain both in the intestinal content and in the intestinal tissue. ACE and ACE2 are globally more active in the intestinal content than in the corresponding intestinal tissue. There was a distal-to-proximal prevalence of ACE2 over ACE in the intestinal tissue. CONCLUSIONS & INFERENCES: This work is the first to report the presence of catalytically active ACE and ACE2 in the rat intestinal content, supporting future research on the regulatory role of the intestinal RAAS on gut function and a putative link to the microbiome.

Angiotensin-converting enzyme 2 in dogs with Dirofilaria immitis.

BACKGROUND: Infection by the canine heartworm, Dirofilaria immitis, causes significant cardiopulmonary disease, with progression impacted by increasing parasite numbers and duration of infection. The renin-angiotensin-aldosterone system (RAAS) is an important mediator of cardiac and pulmonary disease. Angiotensin-converting enzyme 2 (ACE2) mitigates the maladaptive effects of angiotensin II by converting it to angiotensin (1-7). We hypothesized that circulating ACE2 activity would be altered in dogs with high heartworm infection intensities relative to dogs without heartworms. METHODS: Frozen serum samples (-80 °C) from 30 dogs euthanized at Florida shelters were analyzed for ACE2 activity using liquid chromatography-mass spectrometry/mass spectroscopy and a kinetics approach with and without an ACE2 inhibitor. A convenience sample of 15 dogs without heartworms (HW0) and 15 dogs with > 50 heartworms (HW>50) was included. Heartworm number and microfilariae presence were determined at necropsy. The effects of heartworm status, body weight, and sex on ACE2 were evaluated using regression analysis. Values of P < 0.05 were considered significant. RESULTS: All HW0 dogs were D. immitis microfilariae-negative and all HW>50 dogs were D. immitis microfilariae-positive with a median adult worm count of 74 (minimum = 63, maximum = 137). The ACE2 activity of HW>50 dogs (median = 28.2 ng/ml; minimum = 13.6, maximum = 76.2) was not different from HW0 dogs (median 31.9 ng/ml; minimum = 14.1, maximum = 139.1; P = 0.53). The ACE2 activity was higher in dogs with high body weight (median 34.2 ng/ml minimum = 14.1, maximum = 76.2) than in dogs with low weight (median 27.5 ng/ml; minimum = 16.4, maximum = 139.1; P = .044). CONCLUSIONS: Heartworm infection did not impact ACE2 activity in shelter dogs with or without heartworms, but heavier dogs had higher ACE2 activity compared to lighter dogs. Comprehensive RAAS evaluation and additional clinical information would aid in understanding how ACE2 activity relates to the entire cascade and clinical status in dogs with heartworm disease.

Is arrhythmicity of microvascular "flowmotion" responsible for COVID-19-related acute respiratory distress syndrome and might it be treated through an adequate Mg supplementation?

Since the report of an emergence of severe respiratory viral infections of unknown etiology in China in December 2019, termed COVID-19-associated acute respiratory distress syndrome (ARDS), a large number of cases and deaths have been documented worldwide, with the pandemic still spreading around the world. In most critical cases, the acute symptoms may be accompanied by uncontrolled inflammatory cytokine responses and by multiorgan failure. The clinical observation that in severely ill patients, COVID-19 was characterized by cytokine storm and endothelial dysfunction, leading to fast and fatal progression of the disease, has prompted many investigators to consider COVID-19 as a systemic disease that primarily injures the vascular endothelium. Aim of this brief review is not to refute or even question a quite possible role of the vascular endothelial dysfunction as a potential trigger for ARDS, but rather to highlight a more probable role for the main function of the smooth muscle cells in the microcirculation, called "vasomotion", which helps physiologically to ensure an optimized energy supply to the tissues. Alterations in the rhythms of this microcirculatory vaso motion might thus play a similar role as a trigger of the ARDS diagnosed in COVID-19 patients. Furthermore, since obesity, type 2 diabetes, arterial hypertension, decrease in immune response, cytokine storm, endothelial dysfunction, and arrhythmias, which are frequent in COVID-19 patients, have been reported to be associated with hypomagnesemia, an adequate treatment with magnesium supplementation could be beneficial for COVID-19 patients in some specific cases and should also be taken into consideration.

Effect of COVID-19 on Endocrine Glands Function.

A new hitherto unknown virus called severe acute respiratory syndrome coronavirus-2, SARS-CoV-2 for short, the causative agent of the disease COVID-19, has swept the world and become pandemic in its spread. Penetration of the virus into host cells is accomplished by attachment of the spike protein of the virus to its receptor, ACE-2, an enzyme of the renin angiotensin aldosterone system (RAAS), a zinc-dependent carboxypeptidase, which is expressed predominantly in the lung, heart, vascular endothelium, kidney, adipose tissue, thyroid, hypothalamus, pituitary, adrenal pancreas, ovary and testis. SARS-CoV-2 exerts its adverse effects on the function of all endocrine glands, either by direct (viral-toxic) or indirect (immune) mechanisms, with the strength of its action being modulated mainly by hormones of the pituitary-hypothalamic-adrenal axis and also involving the RAAS. This review discusses in detail the impact of SARS-CoV-2 on the endocrine system and possible future complications. The aim is to answer whether SARS-CoV-2 causes endocrine disease per se and whether an increase in the incidence of endocrine disease is expected after rechallenge with COVID-19.Copyright © 2022 Medical Information Center. All rights reserved.

Interactions between the renin–angiotensin–aldosterone system and COVID-19

Since 2019, a substantial body of evidence has partially linked the SARS-CoV-2 infection severity and poor prognosis to renin–angiotensin–aldosterone system (RAAS) activation. There are two aspects to the RAAS involvement with COVID-19 development. First, SARS-CoV-2 entry into the host cell is mainly mediated through ACE2 receptor, and second, SARS-CoV-2 infection is associated with increased angiotensin II levels. The leveraging of the detrimental ACE/ANG II/AT1R arm over the protective ACE2/ANG (1–7)/MAS of the RAAS system following COVID-19 emphasizes the importance of RAAS targeting drugs in modulating the poor cardiovascular prognosis of the disease. This chapter summarizes the most up-to-date conclusions around major drugs targeting the RAAS along with their potential role in COVID-19 treatment. © 2023 Elsevier Inc. All rights reserved.

Effect of renin angiotensin blockers on angiotensin converting enzyme 2 level in cardiovascular patients.

BACKGROUND: Renin-angiotensin-aldosterone system (RAAS) is hypothesized to be in the center of COVID pathophysiology as the angiotensin converting enzyme 2 (ACE2) represents the main entrance of the virus, thus there is a need to address the effect of chronic use of RAAS blockers, as in case of treatment of cardiovascular diseases, on the expression of ACE2. Accordingly, this study aimed to clarify the effect of ACE inhibitors (ACEIs) and angiotensin-receptor blockers (ARBs) on ACE2 and to assess the correlation between ACE2 and several anthropometric and clinic-pathological factors. METHODS: A total of 40 healthy controls and 60 Egyptian patients suffering from chronic cardiovascular diseases were enrolled in this study. Patients were divided into 40 patients treated with ACEIs and 20 patients treated with ARBs. Serum ACE2 levels were assessed by ELISA. RESULTS: Assessment of serum ACE2 level in different groups showed a significant difference between ACEIs and healthy groups and ACEIs and ARBs group, while there was no difference between ARBs and healthy. Multivariate analysis using ACE2 level as constant and age, female sex, ACEIs use and myocardial infarction (MI) showed that there was a significant effect of female sex and ACEIs use on ACE2 level with no effect of age, MI and diabetes. CONCLUSION: ACE2 levels varied between ACEIs and ARBs. It tends to be lower in ACEIs group and there is a strong positive association between ACE2 level and the female sex. This needs to be considered in Future studies to further understand the relationship between gender, sex hormones and ACE2 level. TRIAL REGISTRATION: Retrospectively registered ClinicalTrials.gov ID: NCT05418361 (June 2022).

Effect of COVID-19 on Endocrine Glands Function.

A new hitherto unknown virus called severe acute respiratory syndrome coronavirus-2, SARS-CoV-2 for short, the causative agent of the disease COVID-19, has swept the world and become pandemic in its spread. Penetration of the virus into host cells is accomplished by attachment of the spike protein of the virus to its receptor, ACE-2, an enzyme of the renin angiotensin aldosterone system (RAAS), a zinc-dependent carboxypeptidase, which is expressed predominantly in the lung, heart, vascular endothelium, kidney, adipose tissue, thyroid, hypothalamus, pituitary, adrenal pancreas, ovary and testis. SARS-CoV-2 exerts its adverse effects on the function of all endocrine glands, either by direct (viral-toxic) or indirect (immune) mechanisms, with the strength of its action being modulated mainly by hormones of the pituitary-hypothalamic-adrenal axis and also involving the RAAS. This review discusses in detail the impact of SARS-CoV-2 on the endocrine system and possible future complications. The aim is to answer whether SARS-CoV-2 causes endocrine disease per se and whether an increase in the incidence of endocrine disease is expected after rechallenge with COVID-19.Copyright © 2022 Medical Information Center. All rights reserved.

Effect of COVID-19 on Endocrine Glands Function.

A new hitherto unknown virus called severe acute respiratory syndrome coronavirus-2, SARS-CoV-2 for short, the causative agent of the disease COVID-19, has swept the world and become pandemic in its spread. Penetration of the virus into host cells is accomplished by attachment of the spike protein of the virus to its receptor, ACE-2, an enzyme of the renin angiotensin aldosterone system (RAAS), a zinc-dependent carboxypeptidase, which is expressed predominantly in the lung, heart, vascular endothelium, kidney, adipose tissue, thyroid, hypothalamus, pituitary, adrenal pancreas, ovary and testis. SARS-CoV-2 exerts its adverse effects on the function of all endocrine glands, either by direct (viral-toxic) or indirect (immune) mechanisms, with the strength of its action being modulated mainly by hormones of the pituitary-hypothalamic-adrenal axis and also involving the RAAS. This review discusses in detail the impact of SARS-CoV-2 on the endocrine system and possible future complications. The aim is to answer whether SARS-CoV-2 causes endocrine disease per se and whether an increase in the incidence of endocrine disease is expected after rechallenge with COVID-19.Copyright © 2022 Medical Information Center. All rights reserved.

Potassium reduction with sodium zirconium cyclosilicate in patients with heart failure.

AIMS: Several patients with heart failure and reduced ejection fraction (HFrEF) do not receive renin-angiotensin-aldosterone system (RAAS) inhibitors at the recommended dose or at all, frequently due to actual or feared hyperkalaemia. Sodium zirconium cyclosilicate (SZC) is an orally administered non-absorbed intestinal potassium binder proven to lower serum potassium concentrations. METHODS AND RESULTS: PRIORITIZE-HF was an international, multicentre, parallel-group, randomized, double-blind, placebo-controlled study to evaluate the benefits and risks of using SZC to intensify RAAS inhibitor therapy. Patients with symptomatic HFrEF were eligible and randomly assigned to receive SZC 5 g or placebo once daily for 12 weeks. Doses of study medication and RAAS inhibitors were titrated during the treatment period. The primary endpoint was the proportion of patients at 12 weeks in the following categories: (i) any RAAS inhibitor at less than target dose, and no MRA; (ii) any RAAS inhibitor at target dose and no MRA; (ii) MRA at less than target dose; and (iv) MRA at target dose. Due to challenges in participant management related to the COVID-19 pandemic, the study was prematurely terminated with 182 randomized patients. There was no statistically significant difference in the distribution of patients by RAAS inhibitor treatment categories at 3 months (P = 0.43). The proportion of patients at target MRA dose was numerically higher in the SZC group (56.4%) compared with the placebo group (47.0%). Overall, SZC was well tolerated. CONCLUSIONS: PRIORITIZE-HF was terminated prematurely due to COVID-19 and did not demonstrate a statistically significant increase in the intensity of RAAS inhibitor therapies with the potassium-reducing agent SZC compared with placebo.

Renin-Angiotensin-Aldosterone Inhibitors and COVID-19 Infection.

PURPOSE OF REVIEW: This review summarises the literature data and provides an overview of the role and impact of the use of renin-angiotensin-aldosterone system (RAAS) inhibitors in patients with coronavirus disease 2019 (COVID-19) infection. RECENT FINDINGS: The angiotensin-converting enzyme 2 (ACE2) has a key role in the regulation of the RAAS pathway, downregulating angiotensin II and attenuating inflammation, vasoconstriction and oxidative stress. Additionally, it plays an instrumental part in COVID-19 infection as it facilitates the cell entry of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and enables its replication. The use and role of RAAS inhibitors therefore during the COVID-19 pandemic have been intensively investigated. Although it was initially assumed that RAAS inhibitors may relate to worse clinical outcomes and severe disease, data from large studies and meta-analyses demonstrated that they do not have an adverse impact on clinical outcomes or prognosis. On the contrary, some experimental and retrospective observational cohort studies showed a potential protective mechanism, although this effect remains to be seen in large clinical trials.

Mechanical dependency of the SARS-CoV-2 virus and the renin-angiotensin-aldosterone (RAAS) axis: a possible new threat.

Pathogens in our environment can act as agents capable of inflicting severe human diseases. Among them, the SARS-CoV-2 virus has recently plagued the globe and paralyzed the functioning of ordinary human life. The virus enters the cell through the angiotensin-converting enzyme-2 (ACE-2) receptor, an integral part of the renin-angiotensin system (RAAS). Reports on hypertension and its relation to the modulation of the RAAS are generating interest in the scientific community. This short review focuses on the SARS-CoV-2 infection's direct and indirect effects on our body through modulation of the RAAS axis. A patient having severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) infection, which causes COVID-19 relates to hypertension as a pre-existing disease or develops it in a post-COVID scenario. Several studies on how SARS-CoV-2 modulates the RAAS axis indicate that it alters our body's physiological balance. This review seeks to establish a hypothesis on the mechanical dependency of SARS-CoV-2 and RAAS modulation in the human body. This study intends to impart ideas on drug development and designing by targeting the modulation of the RAAS axis to inactivate the pathogenicity of the SARS-CoV-2 virus. A systematic hypothesis can severely attenuate the pathogenicity of the dreadful viruses of the future.

The effect of renin-angiotensin-aldosterone system inhibitors in patients with hypertension and COVID-19: A meta-analysis of randomized controlled trials and propensity score-matched studies.

Background: High-quality evidence for whether the use of renin-angiotensin-aldosterone system (RAAS) inhibitors worsens clinical outcomes for patients with coronavirus disease 2019 (COVID-19) is lacking. The present study aimed to evaluate the effect of RAAS inhibitors on disease severity and mortality in patients with hypertension and COVID-19 using randomized controlled trials (RCTs) and propensity score-matched (PSM) studies. Methods: A literature search was conducted with PubMed, Embase, and Scopus databases from 31 December 2019 to 10 January 2022. We included RCTs and PSM studies comparing the risk of severe illness or mortality in patients with hypertension and COVID-19 treated or not treated with RAAS inhibitors. Individual trial data were combined to estimate the pooled odds ratio (OR) with a random-effects model. Results: A total of 17 studies (4 RCTs and 13 PSM studies) were included in the meta-analysis. The use of RAAS inhibitors was not associated with an increased risk of severe illness (OR=1.00, 95% confidence interval [CI]: 0.88-1.14, I2=28%) or mortality (OR=0.96, 95% CI: 0.83-1.11, I2=16%) for patients with hypertension and COVID-19. Furthermore, there was no significant difference in the severity of COVID-19 when patients continued or discontinued treatment with RAAS inhibitors (OR=1.01, 95% CI: 0.78-1.29, I2=0%). Conclusions: This study suggests that there was no association between treatment with RAAS inhibitors and worsened COVID-19 disease outcomes. Our findings support the current guidelines that RAAS inhibitors should be continued in the setting of the COVID-19 pandemic. However, the benefit of RAAS inhibitor medications for COVID-19 patients should be further validated with more RCTs.

RAAS inhibitors are associated with a better chance of surviving of inpatients with Covid-19 without a diagnosis of diabetes mellitus, compared with similar patients who did not require antihypertensive therapy or were treated with other antihypertensives.

Purpose: The effect of renin-angiotensin-aldosterone system (RAAS) inhibitors in combination with COVID-19 and diabetes mellitus (DM) remains unknown. We assessed the risk of death in COVID-19 inpatients based on the presence or absence of DM, arterial hypertension (AH) and the use of RAAS inhibitors or other antihypertensives. Methods: The results of treatment of all adult PCR-confirmed COVID-19 inpatients (n = 1097, women 63.9%) from 02/12/2020 to 07/01/2022 are presented. The presence of DM at the time of admission and the category of antihypertensive drugs during hospital stay were noted. Leaving the hospital due to recovery or death was considered as a treatment outcome. Multivariable logistic regression analysis was used to assess the risk of death. Patients with COVID-19 without AH were considered the reference group. Results: DM was known in 150 of 1,097 patients with COVID-19 (13.7%). Mortality among DM inpatients was higher: 20.0% vs. 12.4% respectively (p=0.014). Male gender, age, fasting plasma glucose (FPG) and antihypertensives were independently associated with the risk of dying in patients without DM. In DM group such independent association was confirmed for FPG and treatment of AH. We found a reduction in the risk of death for COVID-19 inpatients without DM, who received RAAS inhibitors compared with the corresponding risk of normotensive inpatients, who did not receive antihypertensives: OR 0.22 (95% CI 0.07-0.72) adjusted for age, gender and FPG. Conclusion: This result raises a question about the study of RAAS inhibitors effect in patients with Covid-19 without AH.

An umbrella review and meta-analysis of renin-angiotensin system drugs use and COVID-19 outcomes.

BACKGROUND: Despite the availability of extensive literature on the effect of angiotensin-converting enzyme inhibitors (ACEIs)/angiotensin-receptor blockers (ARBs) on COVID-19 outcomes, the evidence is still controversial. We aimed to provide a comprehensive assessment of the effect of ACEIs/ARBs on COVID-19-related outcomes by summarising the currently available evidence. METHODS: An umbrella review was conducted using Medline (OVID), Embase, Scopus, Cochrane library and medRxiv from inception to 1 February 2021. Systematic reviews with meta-analysis that evaluated the effect of ACEIs/ARBs on COVID-19-related clinical outcomes were eligible. Studies' quality was appraised using the AMSTAR 2 Critical Appraisal Tool. Data were analysed using the random-effects modelling including several subgroup analyses. Heterogenicity was assessed using I2 statistic. The study protocol was registered in PROSPERO (CRD42021233398) and reported using PRISMA guidelines. RESULTS: Overall, 47 reviews were eligible for inclusion. Out of the nine COVID-19 outcomes evaluated, there was significant associations between ACEIs/ARBs use and each of death (OR = 0.80, 95%CI = 0.75-0.86; I2  = 51.9%), death/ICU admission as composite outcome (OR = 0.86, 95%CI = 0.80-0.92; I2  = 43.9%), severe COVID-19 (OR = 0.86, 95%CI = 0.78-0.95; I2  = 68%) and hospitalisation (OR = 1.23, 95%CI = 1.04-1.46; I2  = 76.4%). The significant reduction in death/ICU admission, however, was higher among studies which presented adjusted measure of effects (OR = 0.63, 95%CI = 0.47-0.84) and were of moderate quality (OR = 0.74, 95%CI = 0.63-0.85). CONCLUSIONS: Collective evidence from observational studies indicate a good quality evidence on the significant association between ACEIs/ARBs use and reduction in death and death/ICU admission, but poor-quality evidence on both reducing severe COVID-19 and increasing hospitalisation. Our findings further support the current recommendations of not discontinuing ACEIs/ARBs therapy in patients with COVID-19.

A Closer Look at ACE2 Signaling Pathway and Processing during COVID-19 Infection: Identifying Possible Targets.

Since the identification of its role as the functional receptor for SARS-CoV in 2003 and for SARS-CoV-2 in 2020, ACE2 has been studied in depth to understand COVID-19 susceptibility and severity. ACE2 is a widely expressed protein, and it plays a major regulatory role in the renin-angiotensin-aldosterone System (RAAS). The key to understanding susceptibility and severity may be found in ACE2 variants. Some variants have been shown to affect binding affinity with SARS-CoV-2. In this review, we discuss the role of ACE2 in COVID-19 infection, highlighting the importance of ACE2 isoforms (soluble and membrane-bound) and explore how ACE2 variants may influence an individual's susceptibility to SARS-CoV-2 infection and disease outcome.

Unravelling the Mechanistic Role of ACE2 and TMPRSS2 in Hypertension: A Risk Factor for COVID-19.

BACKGROUND: This review explores the mechanistic action of angiotensin-converting enzyme- 2 (ACE2) and transmembrane protease serine 2 (TMPRSS2) in the renin-angiotensinaldosterone system (RAAS) that predisposes hypertensive patients to the adverse outcome of severe COVID-19. METHODS AND RESULTS: Entry of SARS-CoV-2 into the host cell via ACE2 disrupts the RAAS system, creating an imbalance between ACE and ACE2, with an increased inflammatory response, leading to hypertension (HTN), pulmonary vasoconstriction and acute respiratory distress. SARSCoV- 2 may also predispose infected individuals with existing HTN to a greater risk of severe COVID-19 complications. In the duality of COVID-19 and HTN, the imbalance of ACE and ACE2 results in an elevation of AngII and a decrease in Ang (1-7), a hyperinflammatory response and endothelial dysfunction. Endothelial dysfunction is the main factor predisposing hypertensive patients to severe COVID-19 and vice-versa. CONCLUSION: Despite the increase in ACE2 expression in hypertensive SARS-CoV-2 infected patients, ARBs/ACE inhibitors do not influence their severity and clinical outcomes, implicating continued usage. Future large-scale clinical trials are warranted to further elucidate the association between HTN and SARS-CoV-2 infection and the use of ARBs/ACEIs in SARS-CoV-2 hypertensive patients.

THE ROLE OF THE JANUS-FACED ACE2-PROTEIN AND ITS PRACTICAL IMPORTANCE

The renin-angiotensin-aldosteron system is of pivotal importance in maintaining the homeostasis of human organism, however its pathological overactivity plays a significant role in the development of hyperten - sion, hypertensive organ damages and heart failure. While maintaining and regulating the proper balance of the RAAS, one of the carboxipeptidase enzymes, namely the ACE2-protein has a crucial role. In addi tion, the cell membrane-linked ACE2 functions also as a receptor of the SARSCoV 2 virus allowing it to penetrate the cells and develop COVID-19 disease, which caused the worldwide pandemic in recent years. Based on these facts, ACE2 may be named properly as a "Janus-faced" protein. Using pharmaceutically its beneficial role in regulating RAAS activity, angiotensin receptor blockers e.g. olmesartan can provide effective blood pressure lower - ing and cardiovascular protection. © 2022 Literatura Medica Publishing House. All rights reserved.

The RAAS Axis and SARS-CoV-2: From Oral to Systemic Manifestations.

One of the essential regulators of arterial blood pressure, the renin-angiotensin-aldosterone system (RAAS) seems to be one of the most complex mechanisms in the human body. Since the discovery of its key components and their actions, new substances and functions are still being unraveled. The main pathway begins with the secretion of renin in the kidney and culminates with the synthesis of angiotensin II (Ang II)-a strong vasoconstrictor-thanks to the angiotensin-converting enzyme (ACE). Research conducted in 2000 identified another enzyme, named ACE2, that converts Ang II into Ang-(1-7), a heptapeptide with opposing effects to those of Ang II: vasodilation and anti-inflammatory properties. This particular enzyme became of paramount importance during the last two decades, as a result of the confrontation of the human race with life-threatening epidemics. Multiple studies have been performed in order to uncover the link between ACE2 and human coronaviruses, the results of which we systemized in order to create an overview of the pathogenic mechanism. Human coronaviruses, such as SARS-CoV and SARS-CoV-2, attach to ACE2 via their spike proteins (S), causing the destruction of the enzyme. Because ACE2 limits the production of Ang II (by converting it into Ang-(1-7)), its destruction leads to a dysregulated inflammatory response. The purpose of this review is to decipher the complex pathophysiological mechanisms underlying the multiorgan complications (oral, cardiac, pulmonary, systemic) that appear as a result of the interaction of the SARS CoV-2 virus with the angiotensin-converting enzyme type 2.