Unexpected better outcome in a liver transplant recipient with COVID-19: a beneficial effect of tacrolimus? / Evolución clínica en un receptor de trasplante de hígado con la COVID-19: ¿Un efecto benéfico del tacrolimus?

Coronavirus disease 2019 (COVID-19) is a serious respiratory illness caused by SARS-CoV-2. There is controversy about whether their immunosuppressive status is a risk factor or a protective factor for developing severe disease. We report herein the clinical outcome of three family members that had COVID-19 infection, presenting with and without different risk factors that have been described in more severe disease. Paradoxically, the patient with more risks of developing a severe disease, a 64-year-old woman, 2-years liver transplant recipient under treatment with tacrolimus, presented a similar outcome compared to the two other members of the family. She showed shorter hospitalization time, similar clinical outcome with fewer oxygen needs. The present clinical observation raises the question about the possible beneficial effect of tacrolimus in patients with COVID-19. Indeed, tacrolimus (FK-506) have an inhibitory effect on human coronaviruses by: 1) an antiviral effect by binding to the FK-506-binding proteins (FKBP) with a subsequent inhibition of their peptidyl-prolyl cis/trans isomerase (PPIase) activity, which seems to be important for the coronavirus life cycle; and 2) regulating the immune response by the inhibition of the activity of the nuclear factor of activated T-cells (NFAT) required for immunosuppression. The present observation states that liver recipients' patients with COVID-19 may not have worse outcomes when compared with other patients that have COVID-19 risk factors and puts in evidence the two mechanisms related to tacrolimus.

[Natriuretic peptides in heart failure]. / Peptidi natriuretici come guida alla prognosi e terapia nello scompenso cardiaco.

The recent discovery of cardiac endocrine function, together with the development of accurate and feasible assay methods for cardiac natriuretic hormone evaluation, i.e. for B-type natriuretic peptide (BNP) and inactive peptide NT-proBNP have confirmed their pathophysiological and clinical significance for cardiovascular disease assessment. Concerning heart failure, their value is for diagnostic screening in selected/unselected populations, for differential diagnosis of dyspnea and for prognostic stratification, and as a guide for follow-up and treatment of patients. Recent Italian recommendations pointed out that BNP/NT-proBNP has a role in ruling-out the diagnosis of heart failure in patients with dubious signs/symptoms: plasma BNP/NT-proBNP concentrations help in the clinical evaluation of chronic heart failure patients when risk stratification is needed, whereas the routine BNP/NT-proBNP assay is still not recommended to guide therapeutic decision-making.

Slow breathing reduces chemoreflex response to hypoxia and hypercapnia, and increases baroreflex sensitivity.

OBJECTIVE: To investigate whether breathing more slowly modifies the sensitivity of the chemoreflex and baroreflex. DESIGN SETTING: University of Pavia, IRCCS Policlinico S. Matteo. PARTICIPANTS: Fifteen healthy individuals. INTERVENTIONS: Progressive isocapnic hypoxia and progressive hyperoxic hypercapnia were measured during spontaneous breathing and during a breathing rate fixed at 6 and 15 breaths per minute (b.p.m.). MAIN OUTCOME MEASURES: Variations in chemo- and baroreflex sensitivity (by monitoring ventilation, oxygen saturation, end-tidal carbon dioxide, R-R interval and blood pressure) induced by different breathing rates. RESULTS: Breathing at 6 b.p.m. depressed (P < 0.01) both hypoxic and hypercapnic chemoreflex responses, compared with spontaneous or 15 b.p.m. controlled breathing. Hypoxic and hypercapnic responses during spontaneous breathing correlated with baseline spontaneous breathing rate (r = -0.52 and r = +0.51, respectively; P = 0.05). Baroreflex sensitivity was greater (P < 0.05) during slow breathing at baseline and remained greater at end rebreathing. CONCLUSIONS: Slow breathing reduces the chemoreflex response to both hypoxia and hypercapnia. Enhanced baroreflex sensitivity might be one factor inhibiting the chemoreflex during slow breathing. A slowing breathing rate may be of benefit in conditions such as chronic heart failure that are associated with inappropriate chemoreflex activation.

Modulatory effects of respiration.

Respiration is a powerful modulator of heart rate variability, and of baro- and chemoreflex sensitivity. Abnormal respiratory modulation of heart rate is often an early sign of autonomic dysfunction in a number of diseases. In addition, increase in venous return due to respiration may help in maintaining blood pressure during standing in critical situations. This review examines the possibility that manipulation of breathing pattern may provide beneficial effects in terms not only of ventilatory efficiency, but also of cardiovascular and respiratory control in physiologic and pathologic conditions, such as chronic heart failure. This opens a new area of future research in the better management of patients with cardiovascular autonomic dysfunction.

[Functions and changes of chemoreflex in physiological and pathological conditions]. / Funzioni e modificazioni del chemoriflesso in condizioni fisiologiche e patologiche.

Chemoreceptors are known to respond to changes in composition of the gases in the inspired air by changing pulmonary ventilation. Whereas, less known it is the role that they play in many both physiologic and pathologic conditions. In this review we do not only consider the anatomic and physiologic chemoreceptor features but also we analyse the relationship between chemoreflex and baroreflex in the cardiovascular control, their role in the pathogenesis of essential hypertension and in the increase of blood pressure in subjects affected by obstructive sleep apnea, their implication in the genesis of dyspnea in chronic heart failure and their role in pulmonary disease. In this review we also analyse the chemoreflex changes with relation to physiologic situations such as aging, obesity, exercise, training and high altitude. Three methods are described for the study of the chemoreflex function, but more attention is paid to the new rebreathing technic. The aim of this paper is to underline the interactions between chemoreceptors and cardiovascular system and to analyse their functional changes in both physiologic and pathologic conditions.

Yoga and chemoreflex response to hypoxia and hypercapnia.

We tested whether chemoreflex sensitivity could be affected by the practice of yoga, and whether this is specifically because of a slow breathing rate obtained during yoga or as a general consequence of yoga. We found that slow breathing rate per se substantially reduced chemoreflex sensitivity, but long-term yoga practice was responsible for a generalised reduction in chemoreflex.