Surveillance for severe acute respiratory infections in the 2019/2020 season in Tuscany, Italy

Background

Influenza is a major public health burden. In Italy there were 7.6 million symptomatic case of influenza in the 2019/2020 influenza season. In Italy, the influenza season lasts from October to April of the following year. We analysed influenza A and B viruses from hospitalized patients with Severe Acute Respiratory Infections (SARI) to carry out epidemiological and virological surveillance.

Methods

68 oropharyngeal swabs were taken from the patients with SARI at Le Scotte University Hospital in Siena and they were given a questionnaire to record their underlying disease and vaccination status. Total RNA was extracted from the swabs by means of the QIAamp Viral RNA Mini kit and RT-PCR was carried out. After, biodirectional DNA sequencing reactions were performed. All statistical analyses were performed by means of GraphPad Prism 6 software.

Results

The median age of subject was 82 years and 52.9% were female. The subjects showed fever (89.7%), fatigue (77%), headache (47%), cough (75%), sore throat (70.5%), breathlessness (63.2%).We found that 20.5% of 68 subject were positive (13% for A H3N2 and 7% for A H1N1). Out of the 68 subject, 25% received seasonal influenza vaccination (91.6% trivalent vaccine and 8.4% quadrivalent vaccine). The most common underlying disease found in the positive subjects were cardiovascular diseases (50%), renal diseases (50%), lung diseases (42.8%), diabetes (35.7%), cancer (35%).

Conclusions

Epidemiological and virological surveillance remains an essential tool for monitoring virus circulation and possible mismatches with seasonal vaccine strains, and providing information that can be used to improve the composition of influenza vaccines. Our data support the importance of seasonal vaccination in subjects with chronic diseases to reduce hospitalisation and mortality.

Key messages

Virological surveillance is important for determining the spread of influenza viruses. Seasonal vaccination is considered as the most effective way to prevent influenza and its complications.

Pleuroparenchymal fibroelastosis (PPFE) associated with giant cell arteritis: A coincidence or a novel phenotype?

Pleuroparenchymal fibroelastosis (PPFE) is a rare interstitial lung disease characterized by the fibrotic thickening of subpleural and parenchymal areas of the upper lobes. It may be both idiopathic or secondary to infections, interstitial lung diseases and/or drug exposure. Often PPFE patients report recurrent lower respiratory tract infections, suggesting that repeated inflammatory alterations induced by pulmonary infections may contribute to the development/progression of PPFE.

Here, we report for the first time the case of a patient affected by Giant cell Arteritis with histologically proven PPFE. The lung involvement in GCA is rare and interstitial lung diseases are usually reported as an uncommon clinical manifestation of GCA. Our patient is probably the first case presenting PPFE associated with GCA and we wonder if this is a real associative disease or a coincidence perhaps, secondary to drug effects.

Adenosine and chronic ischemia of the lower limbs

Adenosine is an endogenous nucleoside with multiple biological properties which plays a central role in the pathophysiology of tissue ischemia. Adenosine signals an imbalance between oxygen demand and supply, and it initiates responses to redress such a discrepancy. Besides its vasodilating properties, adenosine possesses anti-platelet and anti-neutrophil activities and provides cytoprotection. Adenosine is presumably the main mediator of the preconditioning phenomenon. During ischemia of the lower limbs, adenosine plays a physiological role by inducing vasodilatation and by preventing microcirculatory failure. Exercise training prolongs claudication distance possibly by inducing pulse increases of adenosine and consequently skeletal muscle preconditioning. Moreover, the adenosine increase which follows the administration of some drugs, such as buflomedil and propionylcarnitine, opens new perspectives in the management of leg ischemia. In fact, the concept arises of an ischemic (exercise-dependent) or pharmacologic preconditioning in the treatment of patients with claudication.

Development and preliminary validation of a diagnostic score for identifying patients affected with adult-onset autoinflammatory disorders

To date, the rate of detection of autoinflammatory gene mutations in patients suspected of having an autoinflammatory disorder is very low. However, most of these data refer to pediatric populations. The relative rarity and lack of information on adult-onset autoinflammatory diseases make it likely that mutations will be found in an even smaller percentage of cases. Our aim was to develop and validate a set of variables for predicting the risk that a given adult patient presenting with recurrent fever episodes carries mutations in the MEFV or TNFRSF1A genes, in order to increase the probability of obtaining positive results on genetic testing. One hundred and ten consecutive patients with a clinical history of periodic fever attacks were screened for mutations in the TNFRSF1A and the MEFV genes. The mean age at disease onset was 27.85 years. Detailed information about each patient?s family history, personal history, and clinical manifestations were retrospectively collected. A diagnostic score was constructed based on univariate and multivariate analysis in a randomly-selected dataset (training set; n=40). The score was validated on an independent set of the remaining patients (validation set; n=70). Age at onset (odds ratio 0.958, P =0.050), positive family history of recurrent fever episodes (OR 5.738, P = 0.006 ), thoracic pain (OR 7.390, P = 0.002), abdominal pain (OR 2.853, P = 0.038) and skin involvement (OR 8.241, P = 0.003) were independently correlated with a positive genetic test result. A diagnostic score was calculated using the linear combination of the estimated coefficients of the logistic model (cut off equal to 0.24) revealing high sensitivity (0.94), high specificity (0.94) and high accuracy (0.94). We have identified variables that appear to be strongly related to the probability of detecting gene mutations in MEF and TNFRSF1A in adults, thus improving the evaluation of patients with suspected autoinflammatory disorders.

Anti-Ro/SSA antibodies and cardiac arrhythmias in the adult: facts and hypotheses

It is well established that the passive trans-placental passage of anti-Ro/SSA antibodies from mother to foetus is associated with the risk to develop an uncommon syndrome named neonatal lupus (NLE), where the congenital heart block represents the most severe clinical feature. Recent evidence demonstrated that also adult heart, classically considered invulnerable to the anti-Ro/SSA antibodies, may represent a target of the arrhythmogenicity of these autoantibodies. In particular, the prolongation of the QTc interval appears the most frequent abnormality observed in adults with circulating anti-Ro/SSA antibodies, with some data suggesting an association with an increased risk of ventricular arrhythmias, also life threatening. Moreover, even though the association between anti-Ro/SSA antibodies and conduction disturbances is undoubtedly less evident in adults than in infants, from the accurate dissection of the literature data the possibility arises that sometimes also the adult cardiac conduction tissue may be affected by such antibodies. The exact arrhythmogenic mechanisms involved in foetus/newborns and adults, respectively, have not been completely clarified as yet. However, increasing evidence suggests that anti-Ro/SSA antibodies may trigger rhythm disturbances through an inhibiting cross-reaction with several cardiac ionic channels, particularly the calcium channels (L-type and T-type), but also the potassium channel hERG, whose different expression and involvement in the cardiac electrophysiology during lifespan might account for the occurrence of age-related differences.

Idiopathic recurrent pericarditis refractory to colchicine treatment can reveal tumor necrosis factor receptor-associated periodic syndrome

Recurrences develop in up to 20-50% of patients with acute pericarditis. Although different causes of recurrent pericarditis have been identified, the etiology remains obscure in most cases which are therefore labelled as idiopathic. Autoinflammatory syndromes include familial Mediterranean fever (FMF), due to mutations in the MEFV gene, and tumor necrosis factor receptor-associated periodic syndrome (TRAPS), due to mutations in the TNFRSF1A gene. Recurrent pericarditis is a common feature of both conditions, but it rarely occurs alone. Colchicine is the standard treatment for FMF, while patients with TRAPS do not respond to colchicine therapy, but are responsive to corticosteroids. Based on the proven efficacy of colchicine in preventing polyserositis in FMF, colchicine has been proposed for the treatment of recurrent pericarditis and is able to decrease the recurrence rate. Our aim was to investigate the possible involvement of TNFRSF1A mutations in a group of patients with idiopathic recurrent pericarditis who were refractory to colchicine treatment. Thirty consecutive patients (17 males, 13 females) diagnosed with idiopathic recurrent pericarditis, who were characterized by a poor response to colchicine treatment, were enrolled in the study. Mutations of the TNFRSF1A gene were searched for by amplifying, using polymerase chain reaction (PCR), genomic DNA, and direct sequencing. TNFRSF1A mutations were found in 4 of the 30 patients. None of these 4 patients had a family history of recurrent inflammatory syndromes or history of pericarditis. One of the 4 patients had a novel heterozygous deletion (DeltaY103-R104) and three patients carried a heterozygous low-penetrance R92Q mutation. Our data suggest that TRAPS should be kept in mind in the differential diagnosis of recurrent pericarditis, and mutation analysis of the TNFRSF1A gene should be considered, in addition to MEFV analysis, in patients of Mediterranean origin. A poor response to colchicine treatment and/or a steroid-dependence may be the clue to investigate TNFRSF1A mutations in patients with idiopathic recurrent pericarditis.

Zygomycosis in Italy: a survey of FIMUA-ECMM (Federazione Italiana di Micopatologia Umana ed Animale and European Confederation of Medical Mycology)

The aims of the study were to analyze the clinical and epidemiological characteristics and treatments for patients who developed zygomycosis enrolled in Italy during the European Confederation of Medical Mycology of medical mycology survey. This prospective multicenter study was performed between 2004 and 2007 at 49 italian Departments. 60 cases of zygomycosis were enrolled: the median age was 59.5 years (range 1-87), with a prevalence of males (70%). The majority of cases were immunocompromised patients (42 cases, 70%), mainly hematological malignancies (37). Among non-immunocompromised (18 cases, 30%), the main category was represented by patients with penetrating trauma (7/18, 39%). The most common sites of infection were sinus (35%) with/without CNS involvement, lung alone (25%), skin (20%), but in 11 cases (18%) dissemination was observed. According to EORTC criteria, the diagnosis of zygomycosis was proven in 46 patients (77%) and in most of them it was made in vivo (40/46 patients, 87%); in the remaining 14 cases (23%) the diagnosis was probable. 51 patients received antifungal therapy and in 30 of them surgical debridement was also performed. The most commonly used antifungal drug was liposomal amphotericin B (L-AmB), administered in 44 patients: 36 of these patients (82%) responded to therapy. Altogether an attributable mortality rate of 32% (19/60) was registered, which was reduced to 18% in patients treated with L-AmB (8/44). Zygomycosis is a rare and aggressive filamentous fungal infection, still associated with a high mortality rate. This study indicates an inversion of this trend, with a better prognosis and significantly lower mortality than that reported in the literature. It is possible that new extensive, aggressive diagnostic and therapeutic procedures, such as the use of L-AmB and surgery, have improved the prognosis of these patients.

Inhibitory effect of synthetic cannabinoids on cytokine production in rheumatoid fibroblast-like synoviocytes

OBJECTIVE

To verify whether synthetic cannabinoids (CP55,940 and WIN55,212-2) are able to exert an anti-inflammatory effect on rheumatoid fibroblast-like synoviocytes (FLS) by down-regulating cytokine production, and determine whether this effect could be mediated by CB1/CB2 cannabinoid receptors.

METHODS

Interleukin-6 (IL-6) and interleukin-8 (IL-8) were assayed in the supernatant from cultured FLS by ELISA method before and after 3 hours of incubation with CP55,940 (10 microM) and WIN55,212-2 (10 microM). Co-stimulation of cells with the cannabinoid receptor antagonists was performed to evaluate receptor involvement in cytokine modulation. All the experiments were conducted in basal conditions and after 1 hour pre-incubation with 0.1 ng/ml IL-1beta. FLS expression of CB1 and CB2 receptor was studied by Western Blot analyses.

RESULTS

Both CP55,940 and WIN55,212-2 induced a potent and significant reduction in IL-6 and IL-8 secretion from IL-1beta. stimulated FLS. Although FLS express CB1 and CB2 receptor, cannabinoid receptor antagonists did not significantly modify the inhibition of cytokines secretion induced by CP55,940 and WIN55,212-2.

CONCLUSIONS

In vitro, CP55,940 and WIN55,212-2 exert a potent anti-inflammatory effect on rheumatoid FLS via a non-CB1/CB2 receptor mediated mechanism.

Simvastatin inhibits cytokine production and nuclear factor-kB activation in interleukin 1beta-stimulated synoviocytes from rheumatoid arthritis patients

OBJECTIVES

Recent studies demonstrated in vivo the effectiveness of statins in reducing the inflammatory response in rheumatic diseases, and still more recently, simvastatin has been reported to inhibit in vitro IL-6 and IL-8 production by unstimulated fibroblast-like-synoviocytes (FLS) from rheumatoid arthritis (RA) patients. However, no data are available on the effect of statins on the production of these cytokines induced by IL-1, which plays a crucial role in joint inflammation in the course of active RA in vivo.

METHODS

In 12 RA patients, synovial tissue specimens were taken to obtain cultures of FLS. Cultures were incubated with IL-1 +/- simvastatin (5-50 micromol/l), and IL-6 and IL-8 production was evaluated (ELISA), also following the addition of mevalonate and its isoprenoid derivatives. Moreover, nuclear factor-kB (NF-kB) activation (immunocytochemistry and Western Blot analysis) were also evaluated.

RESULTS

Culture incubation with IL-1 produced a dramatic increase (up to 40-fold) in cytokine production with respect to unstimulated cells. Simvastatin significantly inhibited (about 20%) IL-6 and IL-8 production from IL-1-stimulated FLS. This effect was completely reverted by the concomitant incubation with mevalonate or geranylgeraniol (but not farnesol or squalene). Moreover, simvastatin produced a clear-cut inhibition of IL-1-induced NF-kB activation.

CONCLUSION

Simvastatin significantly inhibits the production of IL-6 and IL-8 also in IL-1-stimulated FLS, even though to a lesser extent than in unstimulated cells, via a HMG-CoA-reductase block with an interference in prenylation process and NF-kB activation. Our results further support the rationale for the use of statins in the treatment of rheumatoid synovitis.

Primary subcutaneous zygomycosis due to Rhizopus oryzae in a 71-year-old man with normal immune status

A case of primary subcutaneous zygomycosis due to Rhizopus oryzae is described in a 71-year-old man with normal immune status. Diagnosis was based on histological examination and culture of biopsy fragments from skin lesions. The patient recovered after itraconazole therapy (200 mg day(-1) for 60 days followed by 100 mg day(-1) for 45 days).

Homocysteine enhances cytokine production in cultured synoviocytes from rheumatoid arthritis patients

OBJECTIVE

Hyperhomocysteinemia is commonly observed in Rheumatoid Arthritis (RA) patients, thus putatively accounting in part for the high rate of cardiovascular events in these subjects. Homocysteine (Hcy) is known to exert a pro-inflammatory effect putatively contributing to the progression of atherosclerotic lesions by cytokine production from several vascular cell-types. In order to evaluate the possibility that Hcy may play a direct pro-inflammatory activity also in the joints of RA patients, we investigated: (i) the joint concentration of Hcy, and (ii) the effect of Hcy on cytokine production by unstimulated and IL-1beta-stimulated human RA cultured synoviocytes.

METHODS

In 5 RA and 5 controls subjects, Hcy was measured in the blood and knee synovial fluid, and specimens of synovial tissue were taken to obtain cell cultures. Cultures were incubated with Hcy (10-100 micromol/l) +/- IL-1beta, and IL-6 and IL-8 concentrations were evaluated in the supernatants (ELISA) together with the activation of nuclear factor-kB (NF-kB) (immunocytochemistry).

RESULTS

Hcy was present in synovial fluids, with a mean concentration significantly higher in RA patients than in controls (9.0 +/- 1.1 vs 5.9 +/- 1.2 micromol/l). Hcy enhanced IL-6 and IL-8 production in RA synoviocytes only (up to 35%). Moreover, Hcy produced a clear-cut activation of NF-kB in rheumatoid cells only.

CONCLUSION

Hcy enhances IL-1-dependent cytokine production by rheumatoid synoviocytes at a concentration measurable in RA joints in vivo. Thus, in RA patients, Hcy may not only represent an important risk factor for the progression of cardiovascular diseases, but it may also contribute to the joint damage.

Simvastatin reduces MMP-3 level in interleukin 1beta stimulated human chondrocyte culture

OBJECTIVES

Matrix metalloproteinases (MMPs) produced by chondrocytes play a role in the development of cartilage degradation in joint diseases. Moreover, inhibition of MMP secretion by macrophages accumulating in arteriosclerotic plaques would account for the plaque stabilising activity of statins in cardiovascular patients. Recently, simvastatin has been shown to inhibit both developing and established collagen induced arthritis in a murine model. We thus decided to investigate the effect of simvastatin on the production of MMP-3 from cultured interleukin (IL)1 stimulated human chondrocytes.

METHODS

Cells from human cartilage, obtained from eight subjects with osteoarthritis undergoing surgery for total hip prostheses, were cultured in the presence of different concentrations of simvastatin (5, 10, and 50 micromol/l) with and without IL1beta (5 ng/ml). MMP-3 level was measured in the culture medium after 48 h of incubation.

RESULTS

IL1beta stimulation of chondrocytes increased MMP-3 concentration in the cultures (from 0.69 (0.09) to 1.94 (0.12) ng/microg protein). Incubation with simvastatin was associated with a dose dependent reduction in MMP-3 increase, both in the presence (-15%, -17%, and -26% with 5, 10, and 50 micromol/l, respectively) and in the absence (-32% with 50 micromol/l) of IL1beta. The inhibiting effect of simvastatin was completely reversed by the addition of mevalonate (100 micromol/l) or farnesol (10 micromol/l).

CONCLUSIONS

Our data show that simvastatin, by blocking HMGCoA-reductase and interfering in the prenylation processes, is able to inhibit MMP-3 production from cultured human chondrocytes that have been either unstimulated or stimulated with IL1beta, thus suggesting a possible additional mechanism for statins in counteracting chronic joint disease related cartilage damage.

Blunted increase in plasma adenosine levels following dipyridamole stress in dilated cardiomyopathy patients

BACKGROUND

Heart failure is characterized by chronically increased adenosine levels, which are thought to express a protective anti-heart failure activation of the adenosinergic system. The aim of the study was to assess whether the activation of adenosinergic system in idiopathic dilated cardiomyopathy (IDC) can be mirrored by a blunted increase in plasma adenosine concentration following dipyridamole stress, which accumulates endogenous adenosine.

METHODS

Two groups were studied: IDC patients (n = 19, seven women, mean age 60 +/- 12 years) with angiographically confirmed normal coronary arteries and left ventricular ejection fraction <35%; and normal controls (n = 15, six women, mean age 68 +/- 5 years). Plasma adenosine was assessed by high-performance liquid chromatography methods in blood samples from peripheral vein at baseline and 12 min after dipyridamole infusion (0.84 mg kg-1 in 10 min).

RESULTS

At baseline, IDC patients showed higher plasma adenosine levels than controls (276 +/- 27 nM L-1 vs. 208 +/- 48 nM L-1, P < 0.001). Following dipyridamole, IDC patients showed lower plasma adenosine levels than controls (322 +/- 56 nM L-1 vs. 732 +/- 250 nM L-1, P < 0.001). The dipyridamole-induced percentage increase in plasma adenosine over baseline was 17% in IDC and 251% in controls (P < 0.001). By individual patient analysis, 18 IDC patients exceeded (over the upper limit) the 95% confidence limits for normal plasma adenosine levels at baseline, and all 19 exceeded (below the lower limit) the 95% confidence limits for postdipyridamole plasma adenosine levels found in normal subjects.

CONCLUSION

Patients with IDC have abnormally high baseline adenosine levels and--even more strikingly--blunted plasma adenosine increase following dipyridamole infusion. This is consistent with a chronic activation of the adenosinergic system present in IDC, which can be measured noninvasively in the clinical theatre.

ECP-treated lymphocytes of chronic graft-versus-host disease patients undergo apoptosis which involves both the Fas/FasL system and the Bcl-2 protein family

Chronic graft-versus-host disease (cGVHD) is a severe and frequent complication of allogenic bone marrow transplantation which is often treated with extracorporeal photochemotherapy (ECP) with a positive clinical outcome in patients resistant to conventional protocols. The mechanism of action of ECP has not been fully elucidated, although several authors have reported that it is able to induce apoptosis. Using samples obtained from ten cGVHD patients, we sought to determine whether lymphocytes treated with ECP underwent apoptosis and, above all, the mechanisms involved. Lymphocytes at four stages were isolated: immediately before ECP, from the last buffy coat collected, after UV irradiation prior to reinfusion, and the day after ECP. When cultured for 48 h, lymphocytes treated with ECP underwent accelerated apoptosis (tested as annexin V binding cells and as intracellular histone-associated DNA fragments) in comparison with lymphocytes from the other samples. This enhanced programmed cell death could not be prevented by IL-2. Immediately after isolation, there was no difference in Bcl-2 or bax expression among the four different samples, or in Fas and FasL mRNA. However, when cultured, lymphocytes treated with ECP showed a rapid downregulation of Bcl-2, an upregulation of bax with an increased bax/Bcl-2 ratio, a decrease in bcl-2 mRNA and an increase in Fas. No changes were detectable in lymphocytes from the other samples. IL-2 and TNF-alpha production was not significantly different among lymphocytes from the four samples. In conclusion, in patients affected by cGVHD, ECP induced apoptosis of lymphocytes with the involvement of both the Fas/FasL system and the Bcl-2 protein family.

Acute effects of glibenclamide on reactive hyperaemia in the lower limbs in humans

Three episodes of 1 min ischemia in the lower limbs in humans reduced the metabolic debt repayment (expressed as AUC of reactive hyperaemia) following more prolonged ischemia (666.6+/-86.6 vs 500.0+/-33.5 ml/100 ml). The administration of the ATP-dependent K(+) channel blocker glibenclamide was associated with a significant reduction in the AUC of reactive hyperaemia (666.6+/-86.6 vs 563.1+/-76.6 ml/100 ml), and with the removal of the protective effect produced by 3 episodes of 1 min ischemia (563.1+/-76.6 vs 551.8+/-71.3 ml/100 ml). Plasma level of glibenclamide reached the peak value of 1.295+/-0.15 micromol/l 2 h after drug administration, ranging around the 1 micromol/l concentration in the following 3 hours. Our findings produce indirect evidence that, similarly to the ischemic preconditioning of the heart, the protective effects towards ischemia of brief repeated episodes of sub-maximal occlusion in the peripheral circulation of the lower limbs in humans are mediated by ATP-dependent K(+) channels.

Enhanced apoptosis of peripheral blood mononuclear cells in cardiac transplanted patients undergoing chronic immunosuppressive treatment

Apoptosis plays a major role in tissue transplantation because intact T-cell-apoptosis pathways are required for the induction of tolerance to allografts. Moreover, immunosuppressive agents commonly used in clinical transplantation medicine promote lymphocyte apoptosis inhibiting the expression and production of cytokines involved in lymphocyte survival. The aim of our study was to evaluate peripheral blood mononuclear cells (PBMC) spontaneous apoptosis in patients undergoing chronic immunosuppressive treatment after cardiac transplantation. PBMC obtained from patients (n = 31) and controls matched for age and sex (n = 25) were cultured for 72 h and apoptosis was evaluated by quantification of fragmented DNA, staining with Hoechst 33258 dye and annexin V binding. We also investigated Fas expression and FasL mRNA expression as well as the ability of an IgM anti-Fas antibody to induce apoptosis. Finally, we evaluated IL2 production induced by PHA and the ability of IL2 to prevent apoptosis. In patients, PBMC underwent enhanced spontaneous apoptosis in comparison with controls. However, we could not find any difference between patients and normals as regards the expression of Fas and of FasL mRNA, even if the cross-linking of the Fas molecule induced apoptosis in PBMC from patients, whereas it failed to induce cell death in normals. We also found that IL2 production was significantly decreased in patients and that the addition of IL2 to the culture medium reduced PBMC spontaneous apoptosis. Our findings suggest that in cardiac transplanted patients PBMC undergo enhanced spontaneous apoptosis, which may contribute to prevent allograft rejection.

Effects of alprostadil on blood rheology and nucleoside metabolism in patients affected with lower limb chronic ischaemia

The acute (0.57 microg/kg i.v. in 2 hours) and long-term (0.57 microg/kg i.v. in 2 hours for 5 days over 4 weeks) effects of the PGE1 analogue alprostadil were studied in patients affected with intermittent claudication. Whole Blood Viscosity (WBV), Whole Blood Filterability (WBF), haematocrit (Htc) and fibrinogen plasma concentration, were studied together with P50, 2,3-diphosphoglycerate, and adenosine plasma levels. Moreover, in the long-term study, pain-free (PFWD) and maximal walking distance (MWD) were measured. Single alprostadil infusion induced an improvement in WBV, WBF, and oxygen transport, and an increase in adenosine plasma levels. Long-term alprostadil administration produced a decrease in WBV only, without significant changes in WBF, Htc, fibrinogen, P50, 2,3-diphosphoglycerate, also inducing a significant prolongation of PFWD and MWD. The possibility is suggested that pulse rises in adenosine plasma levels play a role in the effects of chronic alprostadil administration, maybe in a way similar to that observed in the phenomenon of ischaemic preconditioning,

Adenosine and chronic ischemia of the lower limbs

Adenosine is an endogenous nucleoside with multiple biological properties which plays a central role in the pathophysiology of tissue ischemia. Adenosine signals an imbalance between oxygen demand and supply, and it initiates responses to redress such a discrepancy. Besides its vasodilating properties, adenosine possesses anti-platelet and anti-neutrophil activities and provides cytoprotection. Adenosine is presumably the main mediator of the preconditioning phenomenon. During ischemia of the lower limbs, adenosine plays a physiological role by inducing vasodilatation and by preventing microcirculatory failure. Exercise training prolongs claudication distance possibly by inducing pulse increases of adenosine and consequently skeletal muscle preconditioning. Moreover, the adenosine increase which follows the administration of some drugs, such as buflomedil and propionylcarnitine, opens new perspectives in the management of leg ischemia. In fact, the concept arises of an ischemic (exercise-dependent) or pharmacologic preconditioning in the treatment of patients with claudication.

Effects of dipyridamole and adenosine on vasoactive peptides calcitonin gene-related peptide and atrial natriuretic peptide in humans: role of sympathetic activation

1. It has been observed that dipyridamole (DIP) administration produces equivalent cardiovascular effects at lower systemic adenosine (ADO) plasma concentrations than those obtained with exogenous ADO infusion. This observation led to the identification of DIP for additional 'ischaemia-inducing' mechanisms, possibly based on sympathetic activation. 2. In turn, exogenous ADO administration has proven to elicit a complex neurohumoral response, including an increase in the plasma concentration of catecholamines, associated with augmented levels of the vasoactive peptides calcitonin gene-related peptide (CGRP) and atrial natriuretic peptide (ANP). More particularly, increases in CGRP seem to be dependent on sympathetic activation, while changes in ANP do not. 3. In order to clarify some aspects of the activity of DIP on neurohumoral systems, the effects of administration of DIP and ADO on plasma levels of noradrenaline (NA), CGRP and ANP were studied in healthy volunteers. Haemodynamic parameters were also monitored. 4. Infusion of exogenous ADO produced plasma levels of ADO as high as 1893+/-386 nmol/L, together with a significant increase in plasma levels of CGRP, ANP and NA. Similarly, the infusion of DIP produced augmented plasma concentrations of the examined parameters, with a peak plasma ADO concentration of 470+/-49 nmol/L. 5. At a given ADO plasma concentration of 450+/-10 nmol/L, the increase in CGRP and NA levels with DIP infusion was significantly higher than that observed following the infusion of ADO, whereas the increase in the plasma concentration of ANP following DIP infusion was very similar to that seen following ADO infusion. 6. The physiological background of these findings is based on evidence that DIP displays a greater sympathoexcitatory activity than does exogenous ADO and only the increase in plasma CGRP seems to be mediated, although indirectly, by beta-adrenoceptor stimulation. The exact mechanism of DIP-dependent sympathetic activation remains to be elucidated.

Systemic adenosine increase during cold pressor test is dependent on sympathetic activation

1. Following local vasoconstriction-inducing stimuli, such as the cold pressor test (CPT), significant changes occur in haemodynamics, with a rise in arterial blood pressure and heart rate (HR) due to the activation of the sympathetic nervous system. Among the compensatory mechanisms to local ischaemia, the endogenous nucleoside adenosine (ADO) has been suggested to play a relevant role by contributing to sympathetic stimulation. The possibility was investigated that CPT-induced increases in plasma ADO levels were not only an expression of the increased production of ADO in the ischaemic area, but also a consequence of systemic sympathoexcitatory mechanisms, thus showing a bidirectional involvement of the mechanisms of ADO formation. 2. The CPT was performed in 15 volunteers and mean arterial blood pressure (MABP) and HR were evaluated, together with plasma levels of noradrenaline (NA) and ADO in the tested and contralateral arm. The 15 subjects were then divided into three groups of five that were treated with either 5 mg transdermal clonidine weekly, 100 mg atenolol daily or 600 mg aminophylline twice daily. After 1 week treatment, the same test was repeated in the respective groups. 3. The CPT induced a rise in MABP and HR and an increase in plasma levels of NA and ADO. Increases in ADO were more pronounced in the tested arm. Clonidine blunted the haemodynamic response and NA release, while increases in ADO increase were reduced to a greater extent in the contralateral arm rather than the tested arm. Atenolol only affected MABP and HR without any effect on NA and ADO levels. Theophylline did not show any effect on CPT-induced changes. 4. In conclusion, local vasoconstriction and ischaemia induced in one arm following CPT are associated with haemodynamic changes dependent on the activation of the sympathetic system. The observed increase in plasma levels of ADO seems to be, in part, a direct expression of local responses to ischaemia (pre-dominant in the tested arm), but also appears as the consequence of systemic sympathoexcitatory mechanisms. Such increases in ADO are not dependent on a beta 1-adrenoceptor-mediated mechanism. Finally, theophylline, at a therapeutic dose, has no effect on the response to CPT.

Carnitines increase plasma levels of adenosine and ATP in humans

In order to help to clarify the mode of action of carnitine derivatives, plasma levels of adenosine, ATP and inosine were evaluated following the infusion of 0.75, 0.50 and 0.25 mg/kg/min propionyl-L-carnitine (PLC) for 30 min in patients affected with peripheral arterial disease. Moreover, the effects of 0.75 mg/kg/min acetyl-L-carnitine (ALC) and L-carnitine (LC) were studied in the same conditions. Finally, the activity of 7.5 mg/kg/min PLC administered for 3 min was also evaluated. PLC and ALC produced a significant increase in plasma levels of adenosine and ATP, whereas LC induced less relevant changes. The administration of the compounds did not affect the adenosine/inosine ratio. Peak plasma levels of adenosine preceded in any case those of ATP. The possibility can be suggested that the pharmacological activity of PLC, ALC, and LC may be mediated, at least in part, by an interference with the endogenous purine system. Since these effects may be related to physiological mechanisms of tissue protection, new pharmacological perspectives for the compounds may arise.

[Usefulness of blood and plasma viscosity measurements in the evaluation of arteriopathic patients]

Blood viscosity represents the internal friction of the blood, in other terms, its resistance to be deformed and to flow under a tangential force. This function is conditioned by the intrinsic characteristics of blood and the geometry of the system in which flow occurs. Thus, any in vitro (or ex vivo) system of measurement of blood viscosity represents a relatively approximate evaluation of the ratio between intertial forces and viscous resistance. However, the possibility of measuring blood viscosity in a reproducible way provided the opportunity of identifying some clinical conditions associated with a worsening in rheologic parameters. Thus, "primary" and "secondary" hyperviscosity syndromes have been defined, on the basis of the pathogenetic responsibility of rheologic or hemodynamic factors, respectively. The possibility of performing in vitro measurement of blood viscosity provided the opportunity of planning several clinical pharmacology studies with theoretically active drugs. On such a basis, the rationale has arisen for a "rheologic therapy" of circulatory disturbances. Moreover, the evaluation of rheologic parameters is extremely useful since epidemiological studies have shown that viscosity may represent a marker and a prognostic factor for the progression of ischemic diseases as well as an independent risk factor, thus suggesting the opportunity of performing controlled clinical studies to evaluate the impact of hemorheological changes in the prevention of cardiovascular events.

Experimental model of short-time exercise-induced preconditioning in POAD patients

Regular physical exercise improves walking performance in patients affected with peripheral obliterative arterial disease (POAD). The mechanisms underlying the phenomenon are still controversial. In order to verify the hypothesis that physical conditioning of lower limbs on a treadmill and ischemic preconditioning of the heart could share some biological aspects, 14 POAD subjects underwent a training program on the treadmill consisting of five repeated submaximal exercises at five-minute and two-hour intervals preceding the maximal tolerance test. Moreover, a protocol with two daily submaximal walking exercises over one week was also performed. Pain-free and total walking distance were measured before and after they performed the program. Moreover, plasma levels of adenosine and adenosine triphosphate (ATP) were measured and polymorphonuclear (PMN) leukocyte activity was studied together with rheologic parameters. Pain-free distance was prolonged by 15.4% and 14.3%, and total distance was prolonged by 23.1% and 26.9%, in the exercises with five-minute and two-hour intervals, respectively. After one week of daily exercises, the onset of pain and the end of the test were delayed by 24% and 43.7%, respectively. An improvement in blood rheology and a reduced PMN reactivity were also observed with the three protocols, associated with an increase in plasma levels of adenosine and ATP. Similarly to ischemic preconditioning in the heart, the possibility is suggested that an adenosine-mediated mechanism may contribute to the development of physical conditioning in treadmill-trained POAD patients.

Pharmacological preconditioning of ischaemia

Five repeated submaximal treadmill exercises at 2 h intervals following a maximal test prolong walking distance and reduce haemorheological derangement in a second maximal test in patients affected with peripheral obliterative arterial disease (POAD). An increase in adenosine plasma levels is observed during maximal tests, thus suggesting the possibility of an ischaemic preconditioning of lower limbs. The intravenous infusion of 50-100-200 mg buflomedil, and the oral administration of 300-600-900 mg of the drug in POAD patients, also produce an increase in plasma levels of adenosine. Finally, 600 mg buflomedil orally at 12 h intervals produced pulse increase in adenosine plasma levels without any accumulation of the drug or adenosine for at least one week. The possibility of a pharmacological preconditioning of ischaemia is suggested.

Pharmacological preconditioning of ischemic heart disease by low-dose dipyridamole

Fourteen patients affected with coronary artery disease underwent two consecutive dipyridamole echocardiographic stress tests, in basal conditions and after repeated low doses of intravenous dipyridamole, following the observation that pulse increases in adenosine plasma levels due to repeated intravenous administration of dipyridamole mimic the mechanism of ischemic preconditioning. Echocardiographic, electrocardiographic, haemodynamic parameters, and adenosine plasma levels were measured. After the second test, six patients were completely negative, and in those eight still positive the onset of dyssynergy was delayed.

Pharmacokinetics and pharmacodynamics of neutrophil-associated ciprofloxacin in humans

OBJECTIVE

To study the possibility that the penetration of the antibiotic ciprofloxacin into polymorphonuclear leukocytes (PMN) may be associated with some changes in cell reactivity.

DESIGN

Superoxide anion and chemiluminescence generation induced by formyl-methionyl-leucyl-phenylalanine (fMLP) and platelet-activating factor (PAF) were studied ex vivo in 12 healthy volunteers (mean age, 53.15 +/- 16.3 years; mean body weight, 71.23 +/- 6.9 kg) at fixed intervals up to 72 hours from the administration of a single oral dose of 250 mg ciprofloxacin. Cytosolic free calcium levels ([Ca2+]i) in resting and stimulated cells were also evaluated. The dynamic parameters of the effects on PMNs were compared with the kinetic profile of the drug in plasma and in PMNs.

RESULTS

Superoxide generation induced by the stimulating agents increased significantly, reaching a peak after 12 hours (+116% [p < 0.001] for fMLP and +66% [p < 0.05] for PAF). Similarly, chemiluminescence production showed a threefold increase in the response to the stimulating agents 12 hours after drug administration (p < 0.001). The increase in [Ca2+]i in stimulated PMNs was significantly potentiated (p < 0.001). The mathematic analysis of the effects of ciprofloxacin showed that time to maximal activity was between 10.4 hours (PAF-dependent [Ca2+]i increase), and 15 hours (fMLP-induced superoxide anion and chemiluminescence production). The ratio of PMNs to plasma ciprofloxacin concentration increased progressively, from 0.5 at 30 minutes to 10.4 after 24 hours. In addition, time to maximal activity and half-life differed in PMNs and in plasma (4.66 versus 1.90 hours and 13.03 versus 7.28 hours, respectively).

CONCLUSIONS

Ciprofloxacin administration induced a long-lasting enhancement of PMN reactivity to fMLP and PAF. The levels of the drug in the cells were greater and more sustained in the time than those in plasma.

Increase in plasma levels of adenosine and adenine nucleotides after intravenous infusion of buflomedil in humans

To clarify the mode of action of the vasoactive agent buflomedil, we evaluated plasma levels of adenosine and adenine nucleotides after intravenous (i.v.) infusion in humans of 50, 100, and 200 mg of the drug in 20 min. Buflomedil induced an increase of the same order of magnitude in plasma levels of adenosine and adenine nucleotides. Maximal adenosine increase (84%) was observed at the end of the infusion period, whereas peak plasma levels of ATP and ADP (69 and 55%, respectively) and of AMP (61%) were detected 10 and 5 min after discontinuation of infusion, respectively. Although the exact mode of action of buflomedil at the molecular level remains unclear, some indirect findings suggest that the increase in adenosine may be due to enhanced release rather than to inhibition of cell uptake. Because such activity of buflomedil consists of enhancement of physiologic mechanisms of vasodilation and tissue protection occurring in the course of ischemic events, new pharmacologic perspectives for the drug may arise.

Inhibition of neutrophil function in vitro by nimesulide. Preliminary evidence of an adenosine-mediated mechanism

Nimesulide (CAS 51803-78-2) is a methane sulphoanilide derivative provided with specific anti-inflammatory activity. In human polymorphonuclear leucocytes (PMNs), the activity of nimesulide has been suggested to be based on the inhibition of the oxidative burst. However, the effect of the compound on PMNs function seems to be very complex. In order to give a major insight into the mechanism of action of nimesulide, the effect of the drug was studied in vitro on human PMNs functions, such as free radical generation and enzyme release, and on cytosolic free calcium levels, following the activation with specific stimuli. Moreover, the hypothesis that nimesulide could act by interfering with the adenosine cell receptor system was also evaluated. Nimesulide (1-50 mumol/l showed a dose-dependent inhibitory activity on superoxide anion and chemiluminescence production from PMNs stimulated with the oligopeptide fMLP, the ionophore A23187, and the phorbol ester PMA. Enzyme release was significantly reduced, when fMLP and A23187 represented the stimulating agents, while no effect at all was observed with PMA. Studies with the fluorescent calcium chelating dye FURA 2/AM showed that nimesulide was able to reduce free cytosolic calcium increase produced by fMLP and the ionophore ionomycin. The preincubation of cells with the specific adenosine receptor antagonist theophylline was able to significantly reverse the inhibitory activity of nimesulide, either on free radical production and enzyme release, and on free cytosolic calcium increase sustained by fMLP and the ionophores.(ABSTRACT TRUNCATED AT 250 WORDS)

Isradipine inhibits PMN leukocyte function. A possible interference with the adenosine system

The dihydropyridine derivative isradipine is able to inhibit PMN leukocyte function, such as enzyme release and free radical generation, following the activation with specific stimuli. Moreover, the drug prevents calcium influx into the cells as detected by the specific fluorescent dye FURA 2/acetoxymethylester. The specific adenosine receptor antagonist theophylline is able to partially remove the inhibiting activity, thus suggesting a possible interference of isradipine with the adenosine system. Such a cell-protecting activity adds further rationale to the employment of isradipine in those conditions, such as acute and chronic ischaemia and reperfusion damage, in which PMN leukocyte-dependent tissue injury represents a relevant pathogenetic mechanism.

Pharmacodynamics of salmon calcitonin in humans: new markers of pharmacological activity

In order to define the pharmacodynamic profile of salmon calcitonin (sCT) in humans, several markers of the biological activity of the drug have been studied, namely cAMP, adenosine and pO2 in venous blood, and the cytosolic free calcium level in circulating cells. Different dosages and routes of administration (1.5 IU.kg-1 and 0.75 IU kg-1 IM, and 1.5 IU.kg-1 via nasal spray) were compared. sCT caused an increase in cAMP, adenosine and pO2, and a decrease in cytosolic free calcium in neutrophils, lymphocytes and platelets. The peak times of all these parameters ranged between 109 and 182 min, and 101 and 168 min after IM and nasal spray administration respectively. There was greater variability in the values after IM than nasal spray of administration of sCT. It is concluded that adenosine and pO2 in venous blood, and cytosolic free calcium in circulating cells are valuable markers of the activity of sCT and that sCT decreases the cytosolic free calcium level in neutrophils, lymphocytes and platelets. Pharmacodynamic analysis of the biological effects of the drug is highly reliable and valuable in predicting its pharmacological profile. sCT administration via a nasal spray is able to produce significant biological effects, although they are less marked than after IM dosing.

Defibrotide inhibits Ca2+ dependent neutrophil activation: implications for its pharmacological activity in vascular disorders

Defibrotide (DEF) is a polydeoxyribonucleotide agent provided with profibrinolytic and antithrombotic properties. Moreover, an antiischemic, cardioprotective effect of the drug has recently been demonstrated in experimental animals. Increasing evidence exists of the important role played by neutrophils in the development of tissue damage during chronic and acute ischemia and in the early phases of reperfusion. In order to evaluate whether the overall cytoprotective effect of DEF could be based, at least in part, on a neutrophil-involving mechanism, the authors studied the in vitro effects of the drug on human neutrophil activation triggered by several specific stimuli. The drug dose-dependently (10-100 microM) inhibited enzyme release, superoxide anion generation, and chemiluminescence induced in neutrophils by the chemoattractant oligopeptide fMLP and by the divalent cation ionophores A23187 and ionomycin. The increase of extracellular calcium concentration from 0.5 to 2.0 mM antagonized the inhibitory effect of DEF. The use of the fluorescent probe Fura 2/AM led them to show that DEF is able to reduce the cytosolic free calcium increase following specific stimulation by affecting extracellular calcium entrance. Such a behavior resembles that of calcium-antagonistic drugs, thus suggesting that DEF works, at least in part, similarly to calcium entry blockers. Such an activity on cell calcium translocation could represent the underlying molecular mechanism of cytoprotection. Finally, the inhibitory action on neutrophil functions may play a role in tissue protection during ischemic injury.

Differential effect of adenosine on DNA synthesis in lymphoid and myeloid cell lines

In this report, the effects of adenosine on the promyelocytic cell line HL-60 and on T-lymphocytic clones are compared. According to previous reports, adenosine induces a dose-dependent inhibition of DNA synthesis in T-lymphocytes. Conversely, adenosine dose-dependently enhances DNA synthesis in HL-60 cells, as documented with [3H]thymidine uptake studies and flow cytometric cell-cycle analysis. Unlike its effect on lymphocytes, the adenosine effect on HL-60 cells does not seem to be mediated by receptor binding, but it appears to be correlated with an intracellular mechanism following active uptake. Despite the different effects exerted by adenosine on lymphocytes and myeloid cells, a purinergic pathway appears to be more generally involved in the regulation of some phases of cell growth.

Nitroprusside in vitro inhibits platelet aggregation and intracellular calcium translocation. Effect of haemoglobin

The biologically final active compound of nitrovasodilators is now supposed to be nitric oxide (NO), a labile substance identical to EDRF. The effects of nitroprusside on platelet functions were studied in vitro. Platelet aggregation induced by several stimuli (ADP, collagen, arachidonic acid and PAF) was inhibited by increasing concentrations of the drug (1-50 uM); interestingly, the potency of nitroprusside is higher when PAF is employed as stimulating agent in comparison with the other agonists (ED50 = 2 uM for ADP, 2.5 uM for A.A., 4.5 uM for collagen and 0.3 uM for PAF-induced aggregations). The concomitant addition of haemoglobin is able to reverse the inhibitory effect of nitroprusside, according to the view that haemoglobin possesses a high affinity for NO, thus antagonizing the effect of this compound. Nitroprusside was also able to inhibit intracellular calcium translocation, as studied with the Quin 2 technique, induced by PAF and arachidonic acid. Fron these observations the hypothesis may be suggested that nitroprusside inhibits platelet functions by mimicking the endogenous NO, and that the intracellular calcium metabolism is involved in the inhibitory activity of the drug.

Selective 1H-NMR relaxation investigations of membrane-bound drugs in vitro. 3. Calcium-entry blockers and adenosine

Selective proton relaxation rates (SPRR) were measured for selected protons of nimodipine or diltiazem in the presence of neutrophils, allowing detection of binding to the cell membrane. Fast exchange exchange of drug molecules between bound and free environments was shown to be the main factor determining the enhancement of SPRR, whereas viscosity effects could be neglected. The SPRR enhancement was almost completely cancelled out by the presence of adenosine as a cosolute in a dose-dependent fashion, leading to the suggestion that the endogenous mediator 'adenosine' affects binding of calcium-entry blockers to the neutrophil surface.

Adenosine blocks calcium entry in activated neutrophils and binds to flunarizine-sensitive calcium channels

Adenosine is able to prevent Ca+(+) influx into activated neutrophils as detected by the specific fluorescent indicator Quin 2. Such an effect is shown in a similar fashion by the calcium entry blocker flunarizine. The binding interaction between flunarizine and the neutrophil membrane as well as the flunarizine-adenosine antagonism are shown by the 1H-NMR technique, thus supporting evidence of a competition between the agents at the same or a nearby site on the cell membrane.

Adenosine system and cell calcium translocation: interference of calcium channel blockers

Adenosine is able to inhibit in vitro neutrophil functions induced by formyl-methionyl-leucyl-phenylalanine (FMLP) and A23187, but not phorbol 12-myristate 13-acetate (PMA). The inhibiting activity on A23187 is reversed by increasing extracellular Ca2++ concentration. The calcium entry blocker flunarizine shows an activity very similar to that of adenosine. Both adenosine and flunarizine prevent Ca++ influx into activated neutrophils as detected by the fluorescent Ca++ chelator Quin-2. Finally, flunarizine binds to the neutrophil membrane and adenosine competitively inhibits flunarizine binding as assessed by 1H-Nuclear Magnetic Resonance (1H-NMR) technique, thus indicating that the two agents share a common binding site on the cell membrane.

New in vivo model to assess venous endothelial cell functions. Effect of defibrotide

In the past few years there has been increasing interest in the role of the vascular endothelium as an active modulator of biological responses. Endothelial cells exert antithrombotic activity by the release of prostacyclin [23] and adenine nucleotides [16], the availability on the cell surface of heparin-like substances [3], and thrombomodulin-mediated activation of protein C [8]. In addition, endothelium is involved in the regulation of fibrinolysis by releasing soluble factors, such as tissue plasminogen activator (tPA; [10]) and plasminogen activator inhibitor (PAI; [22, 11]), as well as in the control of vascular responsiveness by the production of smooth muscle relaxing and contracting factors. Endothelial cells have also been shown to synthesize and to express procoagulant activities [18]. Many data on endothelial cell functions has been obtained from two experimental models, namely endothelial cell cultures and perfused segments of animal and human vessels. Both are subject to methodological criticism since they only represent in part in vivo conditions, and the necessary experimental manipulations and laboratory procedures greatly modify the naturally occurring cellular functions. In order to overcome such difficulties as far as possible, a new in vivo model has been employed to provide easily assessable and reliable data on the properties of endothelial cells in man. A venous segment was isolated functionally by cannulating a dorsal vein in the hand and a cubital vein in the same arm. Changes observed ex vivo in blood from the cubital vein following infusion into the hand vein of an active drug, can mainly be attributed to its local effect on the venous wall. At the same time, a cubital vein in the other arm was cannulated in order to provide information to distinguish systemic from regional effects.