COVID-19 and renin-angiotensin system inhibition: role of angiotensin converting enzyme 2 (ACE2) - Is there any scientific evidence for controversy?

Renin-angiotensin system (RAS) blockers are extensively used worldwide to treat many cardiovascular disorders, where they are effective in reducing both mortality and morbidity. These drugs are known to induce an increased expression of angiotensin-converting enzyme 2 (ACE2). ACE2 acts as receptor for the novel SARS coronavirus-2 (SARS-CoV-2) which raising the important issue of possible detrimental effects that RAS blockers could exert on the natural history and pathogenesis of the coronavirus disease-19 (COVID-19) and associated excessive inflammation, myocarditis and cardiac arrhythmias. We review the current knowledge on the interaction between SARS-CoV-2 infection and RAS blockers and suggest a scientific rationale for continuing RAS blockers therapy in patients with COVID-19 infection.

Atomic force microscopy analysis of extracellular vesicles.

Extracellular vesicles (EVs) are small vesicles ensuring transport of molecules between cells and throughout the body. EVs contain cell type-specific signatures and have been proposed as biomarkers in a variety of diseases. Their small size (<1 µm) and biological and physical functions make them obvious candidates for therapeutic agents in immune therapy, vaccination, regenerative medicine and drug delivery. However, due to the complexity and heterogeneity of their origin and composition, the actual mechanism through which these vesicles exert their functions is still unknown and represents a great biomedical challenge. Moreover, because of their small dimensions, the quantification, size distribution and biophysical characterization of these particles are challenging and still subject to controversy. Here, we address the advantage of atomic force microscopy (AFM), for the characterization of isolated EVs. We review AFM imaging of EVs immobilized on different substrates (mica, glass) to identify the influence of isolation and deposition methods on the size distribution, morphology and mechanical properties of EVs.

Alteration of Notch signaling and functionality of adipose tissue derived mesenchymal stem cells in heart failure.

AIM: Circulating mesenchymal cells increase in heart failure (HF) patients and could be used therapeutically. Our aim was to investigate whether HF affects adipose tissue derived mesenchymal cell (adMSC) isolation, functional characteristics and Notch pathway. METHODS AND RESULTS: We compared 25 patients with different degrees of HF (11 NYHA classes I and II and 14 NYHA III and IV) with 10 age and gender matched controls. 100% adMSC cultures were obtained from controls, while only 72.7% and 35.7% from patients with mild or severe HF (p<0.0001). adMSC from HF patients showed higher markers of senescence (p16 positive cells: 14±2.3% in controls and 35.6±5.6% (p<0.05) and 69±14.7% (p<0.01) in mild or severe HF; γ-H2AX positive cells: 3.7±1.2%, 19.4±4.1% (p<0.05) and 23.7±3.4% (p<0.05) respectively), lower proliferation index (Ki67 positive cells: 21.5±4.9%, 13.2±2.8% and 13.7±3.2%, respectively), reduced pluripotency-associated genes (Oct4 positive cells: 86.7±4.9%, 55±12% (p<0.05) and 43.3±8.7% (p<0.05), respectively; NANOG positive cells: 89.8±3.7%, 39.6±14.4% (p<0.01) and 47±8.1%, respectively), and decreased differentiation markers (α-sarcomeric actin positive cells: 79.8±4.6%, 49±18.1% and 47±12.1% (p<0.05) and CD31-positive endothelial cells: 24.5±2.9%, 0.5±0.5% (p<0.001) and 2.3±2.3% (p<0.001), respectively). AdMSC from HF patients also showed reduced Notch transcriptional activity (lowered expression of Hey 1 and Hey 2 mRNAs). Stimulation with TNF-α of adMSC isolated from controls affected the transcription of several components of the Notch pathway (reduction of Notch 4 and Hes 1 mRNAs and increase of Notch 2 and Hey 1 mRNAs). CONCLUSIONS: In HF yield and functionality of adMSC are impaired and their Notch signaling is downregulated.

La curación de las heridas de gran superficie y la medicina regenerativa / Wound healing of large surface and regenerative medicine

La medicina regenerativa, con los conocimientos de la biología celular y molecular, llegó a las especialidades quirúrgicas y así a la atención del paciente. Se describen los fundamentos teóricos de un nuevo concepto de curación de las superficies cruentas. Se explica un nuevo procedimiento de curación de las heridas no infectadas a través del uso de un epitelio transitorio que al evitar la evaporación protege a las señales electromagnéticas de información entre célula y célula, así como la regeneración de un nuevo tejido mediante el uso de ADM. Se presentan cinco pacientes críticos, cuatro de ellos con indicación de amputación por la gravedad del traumatismo.

Regenerative medicine with knowledge of cell and molecular biology, reached the surgical specialities and thereby patient care. It describes the theoretical basis of a new concept of wound healing and a new procedure for healing of uninfected wounds through the use of a transitional epithelium to prevent evaporation that protects information of the electromagnetic signals between the cells, and regeneration of a new tissue using ADM. We present five critical patients, four of them with an indication of amputation due to the severity of the injury.

La curación de las heridas de gran superficie y la medicina regenerativa / Wound healing of large surface and regenerative medicine

La medicina regenerativa, con los conocimientos de la biología celular y molecular, llegó a las especialidades quirúrgicas y así a la atención del paciente. Se describen los fundamentos teóricos de un nuevo concepto de curación de las superficies cruentas. Se explica un nuevo procedimiento de curación de las heridas no infectadas a través del uso de un epitelio transitorio que al evitar la evaporación protege a las señales electromagnéticas de información entre célula y célula, así como la regeneración de un nuevo tejido mediante el uso de ADM. Se presentan cinco pacientes críticos, cuatro de ellos con indicación de amputación por la gravedad del traumatismo. (AU)

Regenerative medicine with knowledge of cell and molecular biology, reached the surgical specialities and thereby patient care. It describes the theoretical basis of a new concept of wound healing and a new procedure for healing of uninfected wounds through the use of a transitional epithelium to prevent evaporation that protects information of the electromagnetic signals between the cells, and regeneration of a new tissue using ADM. We present five critical patients, four of them with an indication of amputation due to the severity of the injury. (AU)

Stem cell senescence and regenerative paradigms.

The term "cellular senescence" denotes a cellular response to several stressors that results in irreversible growth arrest, alterations of the gene expression profile, epigenetic modifications, and an altered secretome, all of which eventually impair the reparative properties of primitive cells, adding a layer of complexity to the field of regenerative medicine. The purpose of this review is to illustrate how cellular senescence could affect tissue repair and to propose interventions that aim at interfering with it.

Comparison of clinical and pathological staging and long-term results of liver transplantation for hepatocellular carcinoma in a single transplant center.

Liver transplantation (OLT) is a treatment for hepatocellular carcinoma (HCC) superimposed on cirrhosis provided that the disease meets defined criteria. The aim of the study was to evaluate our experience with respect to clinical and pathological staging and long-term results. From 1996 to 2005, 50 patients underwent OLT for HCC including 43 men (86%) and seven women (14%) of median age 57 years (range 37 to 67). All patients fulfilled the Milan criteria. The HCC diagnosis was based on preoperative imaging and alpha-fetoprotein levels; no tumor biopsy was performed. Upon histological examination of the resected specimens, we discovered 6 (12%) incidentalomas and 8 (16%) cases of no HCC. Finally we had 42 "true" HCC. Twenty-six patients (52%) have been downstaged and 10 (20%) upstaged by preoperative imaging; 15% were pT1, 45% were pT2, 27% pT3, and 13% pT4a. Twenty-six percent of cases exceeded the Milan criteria. One patient (pT4a) with microvascular invasion died of pulmonary metastases at 14 months after transplantation. No HCC recurrences within the liver have been encountered at a median follow-up of 20 months (range 0 to 80 months). Overall the estimated 1-, 3-, and 5-year survival rates were 83%, 77%, and 72%, respectively. One-, 3-, and 5-year estimated survival rates were 87%, 75%, and 75% for pT1, and pT2, and 75%, 67%, and 67% for pT3 and pT4a, respectively (P = .99). Based on our experience OLT for HCC has long-term results comparable to those without HCC despite the presence of a significant number of cases exceeding the Milan criteria upon pathological staging.

De novo malignancies after kidney and liver transplantations: experience on 582 consecutive cases.

De novo malignancies after transplantation are a growing problem of solid organ transplant recipients, due to longer survival follow-up under chronic immunosuppression. The aim of this study was to analyze a population of 582 consecutive kidney (n = 382) and liver (n = 202) transplant recipients, who survived at least 12 months after transplantation, at a single transplant center for the development of de novo cancers. The incidence of de novo malignancies was 7% after both renal and liver transplantation. The median elapsed time from transplant to the diagnosis of de novo malignancy was 45 months (range 3 to 220) months for kidney and 37 months (range 12 to 101 months) for liver transplants. Skin cancers were the most common within renal recipients, while gastroenteric cancers were more frequently encountered in liver transplants. Oropharyngeal and upper digestive tract tumors were always associated with a history of chronic alcohol consumption in liver recipients. Liver transplant recipients treated for acute rejection had a worse cancer prognosis than patients without rejection 1- and 2-year survivals 83% and 63% versus 36% and 17% (P = .026). The estimated 1- and 2-year survival rates for all types of de novo malignancies were 79% and 66%, including 64% and 51% for solid organ tumors versus 89% and 89% for skin cancers and posttransplant lymphoproliferative disorder (PTLD) (P = .17) in renal transplants and 70% and 42%, including 57% and 28% for solid organ tumors versus 85% and 64% for skin cancers and PTLD (P = .43) in liver transplants respectively.

[Stem cells and regeneration of human myocardium].

A concept of impossibility of appearance of novel cardiomyocytes in the heart of adult men in exchange for those lost due to cardiovascular diseases had dominated medicine and biology for many long decades. However ability of human myocardium to regenerate was demonstrated during recent years in multiple studies. This dictated necessity to reconsider previously generally accepted concept. At present researchers and practicing physicians actively discuss possibility of the use of transplantation of bone marrow stem cells, proper cardiac stem cells, skeletal muscle myoblasts or precursors of endothelial cells in patients with myocardial infarction and heart failure in order to restore normal cardiac structure and function. Another potential method of restoration of the myocardium in patients with cardiovascular diseases is the use of cytokines which stimulate migration of stem cells into myocardium and their differentiation into cardiomyocytes.

Non-HDL cholesterol predicts coronary heart disease in primary prevention: findings from an Italian 40-69 year-old cohort in general practice.

OBJECTS: Non-HDL cholesterol is now recommended as an index of risk associated with combined dyslipidemia, and it has also been found useful in predicting coronary heart disease (CHD) risk in patients with diabetes. We studied the association between known CHD risk factors, enclosed non-HDL cholesterol, and a "high CHD risk condition", i.e. a "5-years CHD risk >15%" in general practice. METHODS: We studied 4,085 40-69 year-old diabetic (no. 489) and non-diabetic (no. 3,596) individuals from an opportunistic cohort. Cross-sectional descriptive statistics, and age- and gender-adjusted multiple logistic exponential betas have been calculated. RESULTS: About 12% of the participants had diabetes. Age- and gender-adjusted comparison showed that all the study variables were significantly worse in diabetic vs. non-diabetic individuals (except cigarette smoking, total blood cholesterol and the ratio of total to HDL cholesterol). They had a mean "5-year CHD-risk" significantly higher than non-diabetic individuals (18.8+/-11.9% vs 7.5+/-6.9%, P<0.01), and a four-fold prevalence of "5-years CHD risk >15%" (55.4% vs 11.1%, P<0.01). As to diabetic individuals, the study variables associated to a "high CHD risk condition" were cigarette smoking, systolic blood pressure, and non-HDL blood cholesterol levels. As to non-diabetic individuals cigarette smoking, systolic blood pressure, and HDL (inversely) and non-HDL blood cholesterol levels were associated to a "high CHD risk condition". CONCLUSIONS: Non-HDL cholesterol--and cigarette smoking and systolic blood pressure--strongly predicted a "high CHD risk condition" both in diabetic and non-diabetic individuals.

Breath-by-breath alveolar oxygen transfer at the onset of step exercise in humans: methodological implications.

The effects of using different algorithms to estimate the time constant of changes in oxygen uptake at the onset of square-wave 120 W cycloergometric exercise were evaluated in seven subjects. The volume of oxygen taken up at the alveoli (VO(2Ai)) was determined breath-by-breath (BB) from the volume of O(2) transferred at the mouth (VO(2mi)) minus the corresponding volume changes in O(2) stores in the alveoli: VO(2Ai)= VO(2mi)-[V(Ai-1)(FO(2Ai)- FO(2Ai-1))+ FO(2Ai) x Delta V(Ai)], where V(Ai-1) is the alveolar volume at the end of the previous breath, FO(2Ai) and FO(2Ai-1) are estimated from the fractions of end-tidal O(2) in the current and previous breaths, respectively, and Delta V(Ai) is the change in volume during breath i. These quantities can be measured BB, with the exception of V(Ai-1) which must be assumed. The respiratory cycle has been defined as the time elapsing between identical fractions of expiratory gas in two successive breaths. Using this approach, since FO(2Ai)= FO(2Ai-1), any assumption regarding V(Ai-1) becomes unnecessary. In the present study, VO(2Ai) was calculated firstly, by using this approach, and secondly by setting different V(Ai-1) values (from 0 to FRC+0.5 l, where FRC is the functional residual capacity). Values for alveolar O(2) flow (VO(2Ai)), as calculated from the quotient of VO(2Ai) divided by breath duration, were then fitted bi-exponentially. The time constant of the phase II kinetics of VO(2Ai) (tau(2)) was linearly related to V(Ai-1), increasing from 36.6 s (V(Ai-1)=0) to 46.8 s (V(Ai-1)=FRC+0.5 l) while tau(2) estimated using the first approach amounted to 34.3 s. We concluded that, firstly, the first approach allowed us to calculate O(2A) during transitions in step exercise; and secondly, when using methods wherein V(Ai-1) must be assumed, tau(2) depended on V(Ai-1).

Oxidative stress-mediated cardiac cell death is a major determinant of ventricular dysfunction and failure in dog dilated cardiomyopathy.

Cell death has been questioned as a mechanism of ventricular failure. In this report, we tested the hypothesis that apoptotic death of myocytes, endothelial cells, and fibroblasts is implicated in the development of the dilated myopathy induced by ventricular pacing. Accumulation of reactive oxygen products such as nitrotyrosine, potentiation of the oxidative stress response by p66(shc) expression, formation of p53 fragments, release of cytochrome c, and caspase activation were examined to establish whether these events were coupled with apoptotic cell death in the paced dog heart. Myocyte, endothelial cell, and fibroblast apoptosis was detected before indices of severe impairment of cardiac function became apparent. Cell death increased with the duration of pacing, and myocyte death exceeded endothelial cell and fibroblast death throughout. Nitrotyrosine formation and p66(shc) levels progressively increased with pacing and were associated with cell apoptosis. Similarly, p50 (DeltaN) fragments augmented paralleling the degree of cell death in the failing heart. Moreover, cytochrome c release and activation of caspase-9 and -3 increased from 1 to 4 weeks of pacing. In conclusion, cardiac cell death precedes ventricular decompensation and correlates with the time-dependent deterioration of function in this model. Oxidative stress may be critical for activation of apoptosis in the overloaded heart.

Evidence that human cardiac myocytes divide after myocardial infarction.

BACKGROUND: The scarring of the heart that results from myocardial infarction has been interpreted as evidence that the heart is composed of myocytes that are unable to divide. However, recent observations have provided evidence of proliferation of myocytes in the adult heart. Therefore, we studied the extent of mitosis among myocytes after myocardial infarction in humans. METHODS: Samples from the border of the infarct and from areas of the myocardium distant from the infarct were obtained from 13 patients who had died 4 to 12 days after infarction. Ten normal hearts were used as controls. Myocytes that had entered the cell cycle in preparation for cell division were measured by labeling of the nuclear antigen Ki-67, which is associated with cell division. The fraction of myocyte nuclei that were undergoing mitosis was determined, and the mitotic index (the ratio of the number of nuclei undergoing mitosis to the number not undergoing mitosis) was calculated. The presence of mitotic spindles, contractile rings, karyokinesis, and cytokinesis was also recorded. RESULTS: In the infarcted hearts, Ki-67 expression was detected in 4 percent of myocyte nuclei in the regions adjacent to the infarcts and in 1 percent of those in regions distant from the infarcts. The reentry of myocytes into the cell cycle resulted in mitotic indexes of 0.08 percent and 0.03 percent, respectively, in the zones adjacent to and distant from the infarcts. Events characteristic of cell division--the formation of the mitotic spindles, the formation of contractile rings, karyokinesis, and cytokinesis--were identified; these features demonstrated that there was myocyte proliferation after myocardial infarction. CONCLUSIONS: Our results challenge the dogma that the adult heart is a postmitotic organ and indicate that the regeneration of myocytes may be a critical component of the increase in muscle mass of the myocardium.

Primary non-Hodgkin lymphoma of the right colon: a retrospective clinical-pathological study.

The objective of this study was to analyze the results of surgical treatment of primary non-Hodgkin lymphomas of the right colon. Ten patients were operated on with curative intention. Dawson's criteria were used to characterize the colonic lymphoma as a primary lymphomas. In the staging of the tumor, the Ann Arbor classification for gastrointestinal lymphomas modified by Musshoff and Schmidt-Vollmer was used. The histological classification was made by using the International Working Formulation Group system. All patients were submitted to radical right colectomy and 6 of them received postoperative chemotherapy. The overall average survival was 39.2 months. Four of the patients are still alive, without active disease, with an average survival of 85.2 months. Six patients died due to relapse in the abdomen, with an average survival of 8.2 months. These results suggest that it is advantageous to patient survival to have them submitted for resection of their lesions at an initial stage of the disease (IE and IIE1). Chemotherapy must be used as a complementary treatment in locally advanced lesions, in an attempt to control the residual microscopic disease.

Clinical correlation between diabetic and non diabetic patients with myocardial infarction.

We have studied 130 patients with diabetes mellitus and 455 patients without. All the patients were consecutively admitted to our Coronary Care Unit with their first myocardial infarction. We have observed a higher incidence of heart failure, in-hospital mortality, atrial fibrillation, conduction abnormalities, and post-infarction angina among diabetics. Nevertheless, diabetic patients do not show evidence of larger infarcts than those without diabetes. In our patients the higher mortality among diabetics is related to an increased occurrence of left ventricular failure. Moreover, post-infarction ischemic episodes are more common compared with non diabetics. Since infarcts in diabetics do not seem to be more extensive than in non diabetics, we suggest, in accordance with others, that the poorer outcome among diabetic patients with AMI could be related to an underlying cardiac dysfunction of diabetics in addition to coronary artery diseases.

T-lymphoblastic lymphomas expressing the non-disulfide-linked form of the T-cell receptor gamma/delta: characterization with monoclonal antibodies and genotypic analysis.

Three cases of T-lymphoblastic lymphomas (T-LL) expressing the T cell antigen receptor gamma delta (TCR gamma delta) are reported. All of them were CD3+/beta F1-/TCR delta 1+. Moreover, neoplastic cells reacted with the delta TCS1 monoclonal antibody (MoAb) which binds to the non-disulfide-linked form of the TCR gamma delta, but not with the BB3 MoAb which recognizes the disulfide-linked form of the TCR gamma delta. All cases showed a stage II cortical phenotype, eg, TdT+/CD1+/CD3+/CD5+/CD7+; two of them coexpressed CD4/CD8, while the other was CD4+/CD8-. Two cases were positive for CALLA and CD25. Immunogenotypic analysis showed evidence of T beta and C gamma 2 gene rearrangements in all three cases and immunoglobulin (Ig) gene rearrangements in two cases. Two patients presented with an anterior mediastinal mass and the third with a solitary inguinal lymphadenopathy. We suggest that these cases of TCR gamma delta+ T-LL may be derived from the small population (approximately 0.5%) of CD3+ cortical thymocytes which, in the normal human thymus, express the delta TCS1-reactive, non-disulfide-linked form of the TCR gamma delta.

[Intra-sinus echo: demonstration using direct intracavitary recording of the sinus potential]. / Echo intrasinusal: démonstration par enregistrement direct du potentiel sinusal par voie endocavitaire.

The authors searched for intra-sinusal echos during electrophysiological investigation of 53 patients (41 men, 12 women, average age: 61 +/- 12 years). Cycles of sinus echos were recorded in 8 patients (15 per cent). The period during which sinus echos could be recorded was 125 ms (average 40.6 +/- 34 ms). Indirect assessment of sinus node function in patients with sinus echos was normal (corrected sinus node recovery time, estimated atrio-sino atrial conduction times using Narula's technique). A valid and reproducible direct recording of the sinus node potential was only possible in one patient. In this case the echo cycles were provoked by stimulation periods of between 440 and 320 ms (echo zone of 120 ms). All the echos obtained were preceded by a sinus node potential with a different duration and morphology to that observed during basal sinus cycles (respective sino-atrial conduction times 105 and 115 ms). In this patient we were also able to induce sinus echos after a single extrastimulus during the spontaneous rhythm. the echo zone was 130 ms and with a shorter coupling interval (310 ms) two successive sinus echos were recorded. The demonstration of intrasinusal echos by direct recording of the sinus node potential supports the experimental data of Allessie and Bonke on isolated right atrial tissues of the rabbit. Improvements in the technique of endocavitary direct recording of the sinus node potential in man should complete this data by showing the possibility of sinoatrial tachycardias due to reentry.