Impact of COVID-19 lockdown in patients with implantable cardioverter and cardiac resynchronization therapy defibrillators: insights from daily remote monitoring transmissions

Funding Acknowledgements

Type of funding sources: None.

Background

In Italy, a strict lockdown was imposed from 8 March 2020 to stop the spread of the Coronavirus Disease 2019 (COVID-19).

Purpose

To explore the effect of this lockdown on data transmitted by remote monitoring (RM) of implantable cardioverter and cardiac resynchronization therapy defibrillators (ICDs/CRT-Ds).

Methods

RM daily transmissions from ICDs and CRT-Ds were analyzed and compared in two consecutive 1-month frames pre- and post-lockdown: Period I (7 February–7 March 2020) and Period II (8 March–7 April 2020).

Results

The study cohort included 180 patients (81.1% male, 63.3% ICDs and 36.7% CRT-Ds) with a median age of 70 (interquartile range 62-78) years. The median value of physical activity provided by accelerometric sensors showed a significant reduction between Period I and II (13.1% [8.2-18.1%] versus 9.4% [6.3-13.8%], p < 0.001]. Eighty-nine percent of patients decreased their activity, for 43.3% the relative reduction was ≥25%. The mean heart rate decreased significantly (69.2 [63.8-75.6] bpm vs 67.9 [62.7- 75.3] bpm, p < 0.001), but with greater reduction (≈3 beats/minute) in patients aged < 70 years. Resting heart rate and thoracic impedance showed minor variations. No differences were observed in device pacing percentages and arrhythmias.

Conclusions

In cardiac patients, the lockdown imposed to contain COVID-19 outbreak significantly reduced the amount of physical activity and the mean heart rate. These side effects of in-home confinement quarantine should be taken in consideration for frail patients.

Remote monitoring temporal trends during COVID-19 pneumonia in patients with implanted defibrillators

It is unknown whether some of the clinical parameters transmitted by remote monitoring (RM) of cardiac implanted devices could show recurrent patterns caused by COVID-19 infection. Our aim was to describe RM daily temporal trends for implantable cardioverter defibrillator (ICD) or cardiac resynchronization therapy defibrillator (CRT-D) recipients during COVID-19 infection. A 65-year-old woman with a CRT-D had a sudden increase of approximately 15 bpm and 10 bpm in nocturnal and mean heart rate, respectively, 11 days before hospitalization for COVID-19 pneumonia. At the same time physical activity decreased progressively and continuously. A 78-year-old woman with an ICD showed significant changes in RM trends starting from the COVID-19-related symptoms: strong decrease in physical activity, progressive increase in mean and nocturnal heart rate, irregular trend of heart rate variability, and rapid drop in thoracic impedance. Two months later, on hospitalization, computed tomography showed a "crazy-paving" pattern of the lungs, which is a clinical picture of COVID-19 pneumonia with concomitant pleural effusion. <Learning objective: Patients with complications related to the COVID-19 infection appeared to show variations in the remote monitoring (RM) temporal trends of clinical variables daily transmitted from implanted cardiac devices. These changes may not be specific to COVID-19, but owing to the severity of the pandemic, the use of RM to capture patient's condition makes intuitive sense for early diagnosis, intervention, and additional follow-up in this high-risk population.>.

Effects of immune system status on long-term results of cardiac resynchronization therapy

AIM

Cardiac resynchronization therapy (CRT) is an effective therapy for patients with reduced systolic function and enlarged QRS. Recently, some Authors have demonstrated that the presence of positive antinuclear antibodies (ANAs) may play a role in the development of heart failure in a population of patients implanted with PM.

METHODS

We investigated the effect of positive ANAs in 90 patients (mean age 71±8 years) implanted with a CRT device in our Centre between May 2010 and June 2013. To assess for immunologic contribution to CRT outcome, patients were divided into positive and negative ANAs (ANA +, ANA -), considering as positive patients with an ANAs dilution > 1:80. The primary endpoint was constituted by a combined endpoint of death or first hospitalization for heart failure; secondary endpoints were constituted by: 1) incidence of first hospitalization for heart failure; and 2) total cause mortality.

RESULTS

After a mean follow-up of 1200 days, primary endpoint occurred in 11 patients (30%) of ANA+ group and in 8 patients (15.1%) of ANA-group. The significant difference is due to difference in heart failure events (27% vs. 11.3%, P<0.05), whilst difference in total mortality did not reach statistical significance (10.8% vs. 3.8%).

CONCLUSION

Immune status seems to play a role in patients with congestive heart failure. If this immunological alteration is a determinant or a consequence of heart failure remains unclear.

A Guide to the Use of Left Ventricular Analysis with 3D Echo in Dyssynchrony

Data from single-centre studies suggest that echocardiographic parameters of mechanical dyssynchrony may improve patient selection for cardiac resynchronisation therapy (CRT). To our knowledge, the only published multicentre trial that compared 12 echocardiographic methods, the Predictors of response to cardiac resynchronization therapy (PROSPECT) trial, stated that none of the echocardiographic measurements of ventricular dyssynchrony applied in the study were able to distinguish responders from non-responders. Realtime 3D echocardiography is able to measure left ventricular (LV) size, function and dyssynchrony to identify the presence and extension of scar tissue and to evaluate where the site of latest mechanical activation is. After CRT device implantation, it also allows physicians to detect where the first mechanical activation secondary to LV pacing is located. Indeed, it can be useful in interventricular (VV) delay optimisation of the device after the implantation and, in single-centre studies, it was able to predict response to CRT and to identify responders from non-responders. Care must be taken to optimise temporal resolution, but now volume rates of 70–80vps can be easily obtained in the majority of cases. VV optimisation using realtime 3D echocardiography is feasible and intuitive, but time-consuming compared with traditional methods based on Doppler or algorithms. In this article we illustrate our approach to LV analysis with realtime 3D echocardiography in the study of dyssynchrony.

Effect of remodelling, stretch and ischaemia on ventricular fibrillation frequency and dynamics in a heart failure model

OBJECTIVE

The dynamics of ventricular fibrillation (VF) in the presence of heart failure (HF) are different from those in the normal heart. This has been attributed solely to HF-induced electrophysiologic remodelling. We hypothesized that acute stretch and ischaemia, which are normally present during VF, might contribute significantly to the altered VF dynamics in HF.

METHODS

HF was induced in eight sheep by rapid ventricular pacing for 4-6 weeks. Eight sheep served as controls. Optical mapping of isolated hearts was performed during VF at low intraventricular pressure (0-5 mm Hg), high pressure (25-30 mm Hg, in six HF and six controls), and at low pressure after 5 min of global ischaemia (six HF, five controls). Maximum dominant frequency (DF(max)), singularity point (SP) density and number of SP lasting more than one revolution (rotors) were analyzed. Possible statistical interactions between HF and ischaemia (HF x ischaemia) or stretch (HF x stretch) were evaluated.

RESULTS

At low pressure, VF in HF was slower (13% reduction in DF(max)) and more organized than in control: 33% less SPs and 74% less rotors with 20% longer life spans. Acute stretch did not affect DF(max) but increased SP and rotors density similarly in both groups (no interaction HF x stretch). In controls, ischaemia caused a marked decrease in DF(max), SP density and incidence of rotors. However, in HF animals, the ischaemia-induced decrease in SP density was virtually abolished, indicating a significant interaction HF x ischaemia (p<0.005).

CONCLUSIONS

HF remodelling decreases VF rate and increases VF organization. Acute stretch partially reverses these effects by a mechanism that is independent of remodelling. The effects of acute ischaemia on VF dynamics are significantly attenuated in HF compared to normal hearts.

From mouse to whale: a universal scaling relation for the PR Interval of the electrocardiogram of mammals

BACKGROUND

On the ECG, the PR interval measures the time taken by an electrical impulse generated in the sinoatrial node to propagate from atria to ventricles. From mouse to whale, the PR interval increases approximately 10(1), whereas body mass (BM) augments approximately 10(6). Scaling of many biological processes (eg, metabolic rate, life span, aortic diameter) is described by the allometric equation Y=Y(0) x BM(b), where Y is the biological process and b is the scaling exponent that is an integer multiple of 1/4. Hierarchical branching networks have been proposed to be the underlying mechanism for the 1/4 power allometric law.

METHODS AND RESULTS

We first derived analytically the allometric equation for the PR interval. We assumed that the heart behaves as a set of "fractal-like" networks that tend to minimize propagation time across the conducting system while ensuring a hemodynamically optimal atrioventricular activation sequence. Our derivation yielded the relationship PR proportional, variant BM1/4. We subsequently obtained previously published values of PR interval, heart rate, and BM of 541 mammals representing 33 species. Double-logarithmic analysis demonstrates that PR interval increases as heart rate decreases, and both variables relate to BM following the 1/4 power law. Most important, the best fit for PR versus BM is described by the equation PR=53 x BM0.24. Hence, the empirically determined exponent (0.24) is close to 1/4, as predicted.

CONCLUSIONS

We have demonstrated that the PR interval of mammals scales as the 1/4 power of the BM, following the universal law for allometric scaling to ensure an optimal atrioventricular activation sequence.

[Usefulness and limitations of contrast echocardiography during dobutamine stress test]

BACKGROUND

The aim of this study was to evaluate whether the use of contrast agent in addition to second harmonic imaging during dobutamine stress echocardiography can improve endocardial visualization and interobserver agreement in the evaluation of regional wall motion in patients with suboptimal or poor acoustic window.

METHODS

Twenty-one patients with a poor or suboptimal acoustic window underwent dobutamine stress echocardiography. Echocardiographic images in parasternal long-axis and short-axis, apical 4-chamber and 2-chamber views were cine-looped at baseline and peak stress before and after injection of contrast medium (Levovist at a concentration of 400 mg/ml). Endocardial visualization and regional wall motion were evaluated by two blinded observers.

RESULTS

The contrast medium improved segment visualization both at baseline (complete visualization in 74% of segments with contrast vs 71% without, p = NS) and at peak stress (76 vs 64%, p < 0.001). Contrast medium improved significantly segment visualization in apical 4-chamber view both at baseline (complete visualization in 87% of segments with contrast vs 72% without, p < 0.01) and at peak (89 vs 66%, p < 0.001) and in apical 2-chamber view both at baseline (81 vs 61%, p < 0.001) and at peak (89 vs 55%, p < 0.001). When individual segments were analyzed, endocardial visualization improved significantly in all segments of the anterior wall and in the mid and distal segments of the lateral wall both at baseline and at peak stress. The use of contrast medium did not improve significantly interobserver agreement in the evaluation of regional wall motion at peak stress (k = 0.63 vs 0.67 without and with contrast, respectively).

CONCLUSIONS

The use of Levovist during dobutamine stress echocardiography improves significantly segment visualization in the apical views both at baseline and at peak stress and increases interobserver agreement in the evaluation of regional wall motion at peak stress.

Noninvasive estimation of both systolic and diastolic pulmonary artery pressure from Doppler analysis of tricuspid regurgitant velocity spectrum in patients with chronic heart failure

BACKGROUND

Noninvasive estimation of pulmonary artery systolic and diastolic pressures usually requires the investigation of both tricuspid and pulmonary regurgitant jets and an estimate of right atrial pressure. A new, noninvasive method to obtain pulmonary diastolic pressure (based on the hemodynamic demonstration that right ventricular systolic pressure and pulmonary artery diastolic pressure are equal at the time of pulmonary valve opening) from the analysis of tricuspid regurgitation alone has been described in a small cohort of patients. We sought to verify the accuracy of this method in a large population of patients with heart failure.

METHODS

An estimate of pulmonary artery diastolic pressure was obtained by transposing the pulmonary opening time (from the onset of the R wave on the electrocardiographic tracing to the beginning of pulmonic forward flow on Doppler examination) onto the tricuspid regurgitant velocity curve and calculating the pulmonary artery diastolic pressure value as the pressure gradient between the right ventricle and right atrium at this time. The study group included 86 consecutive patients (64 men, aged 52 +/- 11 years) with heart failure (New York Heart Association class > or =II, 94%) who were in stable clinical condition with a chiefly idiopathic (57%), ischemic (24%), or other form (13%) of dilated cardiomyopathy. Noninvasive, right-sided pressures were compared with invasive measurements obtained during right heart catheterization performed within 24 hours. The Bland and Altman graphic method was used together with the calculation of the Lin concordance correlation coefficient and its 95% CI to assess the agreement between hemodynamic and echocardiographic measurements.

RESULTS

Catheter-derived pulmonary artery systolic pressure ranged from 8 to 119 mm Hg (mean 42 +/- 21 mm Hg), pulmonary artery diastolic pressure from 1 to 59 mm Hg (mean 20 +/- 11 mm Hg), and right atrial pressure from -5 to 20 mm Hg (mean 6 +/- 5 mm Hg). Tricuspid regurgitation was detected in 75 of 86 patients (87%). Pulmonary artery systolic pressure ranged from 13 to 110 mm Hg (mean 44 +/- 21 mm Hg); the pressure gradient between the right ventricle and right atrium at time t of the pulmonary valve opening on the tricuspid regurgitation velocity curve was measurable in 70 of 75 (93%) cases and ranged from 3.5 to 64 mm Hg (mean 22 +/- 11 mm Hg). Good agreement was observed not only for pulmonary artery systolic pressure but also for pulmonary artery diastolic pressure, based on the analysis of the tricuspid regurgitation velocity jet, with a slight difference between measurements (-1.8 and 0.1, respectively), no evident pattern of point scattering, and a high concordance correlation coefficient that was elicited by the virtually total overlapping of lines on the graph. Overall results were not significantly different whether patients with depressed right ventricular function (right ventricular ejection fraction < or =35%), with a tricuspid regurgitation grade > or =2 and atrial fibrillation were included in the analysis.

CONCLUSIONS

The narrow paired difference for the estimate of pulmonary artery systolic pressure and the even better difference for pulmonary artery diastolic pressure using the tricuspid regurgitation velocity curve analysis indicates that this new method reliably estimates invasive right-sided pressures over a wide range of pressure values in patients with heart failure. The overall good correlation with invasive values indicates that Doppler examination of tricuspid regurgitation alone may provide a simple and comprehensive new method for the noninvasive evaluation of right ventricular and pulmonary hemodynamics in patients with heart failure.

[Cor triatriatum dextrum resulting from the persistence of embryonic remnants of the right valve of the sinus venosus: prevalence and echocardiographic aspects in a large consecutive non-selected patient population]

BACKGROUND

Cor triatriatum destrum is a rare congenital malformation, usually associated with complex right heart abnormalities, characterized by a membrane that divides the right atrium into two chambers. It is considered the result of the incomplete and abnormal regression of the embryonic right valve of the sinus venosus. When the valve regresses the cephalic portion forms the crista terminalis and the caudal portion develops into the Eustachian and Thebesian valve. With an incomplete regression, a fenestrated or an unfenestrated membrane may persist in the right atrium. We describe the clinical and echocardiographic characteristics of this type of remnants in the right atrium.

METHODS

In a 4-month period, 1728 transthoracic two-dimensional and Doppler echocardiographic studies were consecutively performed.

RESULTS

Twenty-seven patients (16 males, 11 females, mean age 55 +/- 21 years, range 1-87 years) were occasionally recognized to be affected by a membrane inside the right atrial cavity. On the basis of its echocardiographic appearance (a membranous structure connecting the orifice of the inferior vena cava to the atrial septum with evident fenestration in 74% of cases), absence of associated congenital abnormalities (92.5% of cases), interatrial shunt or abnormal flow pattern of venous systemic return, a diagnosis of a normal benign anatomic variant of sinus venous remnants (similar to the so-called "Chiari's network") could be made in every case.

CONCLUSIONS

The incomplete regression of the embryonic right valve of the sinus venosus may leave a fenestrated or an unfenestrated membrane in the right atrium that should be considered a normal benign variant of the so-called "Chiari's network".

Extracellular calcium deprivation in astrocytes: regulation of mRNA expression and apoptosis

Cell viability and gene expression were studied in primary astroglial cells cultured in a nominally calcium-free medium. Ca2+ deprivation reduced progressively the astrocytes' viability, starting from 12 h; the restoration of a normal Ca2+ concentration (1.8 mM) in the medium after 12-h deprivation reversed the degenerative effect within 24 h. Biochemical and morphological examinations indicated that cell death induced by Ca2+ deprivation was mediated by apoptosis. This was associated with the expression of c-fos, c-jun, and c-myc, which, with different time courses, were induced in astrocytes after Ca2+ deprivation. Furthermore, shifting to a Ca2+-free medium modified the expression of Ich-1S transcript and rapidly increased intracellular cyclic AMP, which has been implicated in the transcriptional activation of immediate-early genes. The absence of Ca2+ in the medium reduced the expression of constitutive proteins such as alpha-actin, clusterin, glial fibrillary acidic protein, amyloid precursor protein, and glucose-6-phosphate dehydrogenase. The expression of these mRNAs was reduced >50% after 8 h of Ca2+ deprivation, when the effect on cell viability was negligible. When Ca2+ deprivation was prolonged for 24 h the expression of mRNA dropped completely, and restoration of the Ca2+ ions in the medium for 48 h did not reverse this effect. In contrast with general assumption, the apoptotic machinery in astrocytes is activated similarly not only by increased Ca2+ influx but also with the extracellular Ca2+ deprivation.

Densitometric quantification of neuronal viability by computerized image analysis

A new method is presented for the quantification of cell viability based on densitometry with computerized image analysis. Neuronal cells were stained with crystal violet and densitometric analysis was performed with an IBAS 2.0 image analyzer (Kontron/ Zeiss), using specially implemented dedicated software which integrates the optical density of the culture in each well with the area covered by the stained cells. To test the reliability of the densitometric method cortical cells were plated at different concentrations (5 x 10(4)-10(6)/ml); the standard curve obtained by analysis of crystal violet staining showed a linear proportion between cell number and optical density signal. The validation and accuracy of the method were assessed and compared with other methods using rat cortical cells cultured in vitro for 10 days and exposed to kainic acid (250 microM) for 24 h. Neuronal viability was reduced by 40-50% and comparison with direct cell counting, MTT assay, and spectrophotometric analysis confirmed that the method is simple, quick, and reliable.

Amidation of beta-amyloid peptide strongly reduced the amyloidogenic activity without alteration of the neurotoxicity

Beta-amyloid accumulates in cerebral deposits in Alzheimer's disease, so to test the correlation between the neurotoxic and fibrillogenic capacity of beta-amyloid, we synthesized a peptide homologous to fragment 25-35 of beta-amyloid (beta25-35) and amidated at the C-terminus (beta25-35-NH2). As the amidation strongly reduced the amyloidogenic capacity of beta25-35, we compared its neurotoxic activity in the amidated (beta25-35-NH2) and nonamidated forms. The viability of primary cultures from fetal rat hippocampus was reduced in a dose-related manner (10-100 microM) similarly by beta25-35 and beta25-35-NH2, whereas a scrambled peptide, amidated or nonamidated, did not alter the neuronal viability. The neurotoxic activity of beta25-35-NH2 is mediated by apoptosis as demonstrated by morphological and biochemical investigations. Electron microscopy examination of culture media with beta25-35 or beta25-35-NH2 incubated with neuronal cells for 7 days confirmed the high level of fibrillogenic activity of beta25-35 and the almost total absence of fibrils in the solution with beta25-35-NH2. Furthermore, staining with thioflavine S was used to identify amyloid fibrils, and only the cultures exposed to beta25-35 exhibited intense staining associated with neuronal membranes. These data indicate that the neurotoxic activity of the beta-amyloid fragment is independent of the aggregated state of the peptide.

Beta-amyloid fragment potentiates IL-6 and TNF-alpha secretion by LPS in astrocytes but not in microglia

The effect of a peptide homologous to the biologically active fragment of beta amyloid 25-35 (beta 25-35) was studied on interleukin 6 (IL-6) and tumour necrosis factor (TNF-alpha) secretion induced by lipopolysaccharide (LPS) in primary rat astrocytes and microglia. Twenty-four hour exposure to LPS (50 ng/ml) induced IL-6 and TNF-alpha both in astrocytes and in microglial cells, while the effect of beta 25-35 (50 microM) per se was negligible in both cell types. In microglial cells, the application of beta peptide did not alter the production of either cytokine induced by LPS. However, beta 25-35 strongly amplified the production of both IL-6 and TNF-alpha in astrocytes. These findings confirm the complex interaction between cytokines and amyloidogenesis in Alzheimer's disease and indicate that astrocytes rather than microglia respond to the beta amyloid fragment, suggesting that these cells may be actively involved in cytokine-mediated events in AD.

Influence of cell culture conditions on the protective effect of antioxidants against beta-amyloid toxicity: studies with lazaroids

The mechanisms of cell death of rat cortical neurons chronically exposed to the beta-amyloid (betaA) biologically active fragment beta-(25-35) involve oxidative stress. We examined the influence of culture conditions on the neuroprotective activity of antioxidants against beta-(25-35) toxicity. Common radical scavengers such as N-acetylcysteine (250 microM) and N-t-butyl-phenylnitrone (500 microM) only protected cortical cells cultured in the presence of fetal calf serum (FCS) from betaA insult. The neuroprotective effect of lazaroids (U74389G and U83836E), 21-aminosteroids with antioxidant activity, was tested in cells grown with or without FCS. U74389G did not interfere with beta-(25-35) toxicity in either condition, while U83836E at a very low concentration (15 nM) protected cortical cells exposed to the beta peptide only when the neurons were cultured in the presence of FCS. These data show that a lazaroid can prevent beta-(25-35) toxicity and that the antioxidants exerted their protective effect in certain conditions.

Prion protein fragment 106-126 differentially induces heme oxygenase-1 mRNA in cultured neurons and astroglial cells

Heme oxygenase (HO), which catalyzes the degradation of heme, has two isozymes (HO-1 and HO-2). In brain the noninducible HO-2 isoform is predominant, whereas the inducible HO-1 is a marker of oxidative stress. Because brain oxidative stress might be present in prion-related encephalopathies (PREs), as in other neurodegenerative diseases, we investigated whether HO-1 mRNA was induced in neuronal and astroglial cell cultures by a peptide corresponding to residue 106-126 of human prion protein (PrP). This peptide is amyloidogenic, and when added in vitro to cultured cells it reproduces the neuronal death and astroglial proliferation and hypertrophy occurring in PREs. HO-1 mRNA did not accumulate in rat cultured neurons from hippocampus or cortex exposed to PrP 106-126 (50 microM for 5 days). PrP 106-126 induced HO-1 mRNA accumulation in rat astroglial cultures depending on the exposure time and concentration, being maximal (33-fold) after 7 days of exposure at 50 microM. The nonamyloidogenic amidated or amidated-acetylated PrP 106-126 was ineffective, as was a scrambled peptide used as control. N-Acetylcysteine reduced (50%) the accumulation of HO-1 mRNA in astroglial cells after PrP 106-126 (25 microM) given for 5 days. Thus, oxidative stress is apparently a feature of the toxicity of PrP 106-126, and it might also occur in PREs; induction of HO-1 could contribute to the greater resistance of astrocytes compared with neurons to PrP 106-126 toxicity.

Neuroprotective effect of somatostatin on nonapoptotic NMDA-induced neuronal death: role of cyclic GMP

Somatostatin (SRIF) exerts a modulatory function on neuronal transmission in the CNS. It has been proposed that a reduction of calcium currents is the major determinant of the inhibitory activity of this peptide on synaptic transmission. Because the neurotoxicity induced by activation of the NMDA subtype of glutamate receptor is mediated through excessive Ca2+ influx, we investigated whether SRIF counteracted NMDA-induced neuronal cell death. Neurons from embryonic rat cerebral cortex were cultured for 7-10 days and then exposed to 0.5 and 1 mM NMDA for 24 h. The neuronal viability, as assessed by the colorimetric method, decreased by 40 and 60%, respectively, compared with the control condition. Morphological and biochemical evidence indicated that cell death occurred by necrosis and not through an apoptotic mechanism. SRIF (0.5-10 microM), simultaneously applied with excitatory amino acid, significantly reduced in a dose-dependent manner the neurotoxic effect of NMDA but not that of KA (0.25-0.5 mM). GABA (10 microM) partially protected neurons to a similar extent from NMDA- or KA-induced toxicity. SRIF type 2 receptor agonists, octreotide (SMS 201-995; 10 microM) and vapreotide (RC 160; 10 microM), did not influence the NMDA-dependent neurotoxicity. The intracellular mechanism involved in SRIF neuroprotection was investigated. Pertussin toxin (300 ng/ml), a G protein blocker, antagonized the protective effect of SRIF on NMDA neurotoxicity. Furthermore, the neuroprotective effect of SRIF was mimicked by dibutyryl-cyclic GMP (10 microM), a cyclic GMP analogue, whereas 8-(4-chlorphenylthio)-cyclic AMP (10 microM), a cyclic AMP analogue, was ineffective. The cyclic GMP content was increased in a dose-dependent manner by SRIF (2.5-10 microM). Finally, both specific (Rp-8-bromoguanosine 3',5'-monophosphate, 10 microM) and nonspecific [1-(5 isoquinolinylsulfonyl)-2-methylpiperazine (H7), 10 microM] cyclic GMP-dependent protein kinase (cGMP-PK) inhibitors did not interfere with NMDA toxicity but substantially reduced SRIF neuroprotection. Our data suggest a selective neuroprotective role of SRIF versus NMDA-induced nonapoptotic neuronal death in cortical cells. This effect is likely mediated by cGMP-PK presumably by regulation of the intracellular Ca2+ level.

[Solid papillary tumor of the pancreas. A clinical case]

The solid papillary tumor of the pancreas is a relative rare neoplasm that often is unknown because of its diagnostic difficulties. It is frequent in young women. It has no typical clinical signs, sometimes produces abdominal mass, sometimes is found casually during investigations for other diseases. Instead the prognosis of this tumor is more typical: long-term survival is good. The natural history of the solid papillary is the same as neoplasm with a low malignancy potential. For this reason, it's important to make up a differential diagnosis between it and the other pancreatic tumors. Unlike the other malignancies, surgical conservative therapy is enough without making great demolitions of the pancreas. Lumpectomy gives a complete cure, decreasing surgical risk and dangerous functional complications. In the present paper, a case of solid papillary tumour of the pancreas is reported. It was diagnosed in a young woman and treated with simple lumpectomy. She is alive and disease free.

Clusterin (SGP-2) induction in rat astroglial cells exposed to prion protein fragment 106-126

Prion-related encephalopathies are characterized by the accumulation of an abnormal prion protein isoform (PrPSc) associated with neuronal degeneration and astrogliosis. The synthetic peptide homologous to PrP fragment 106-126 (PrP 106-126) induced in vitro neuronal apoptosis and glial proliferation. We used Northern blot analysis and the RNA polymerase chain reaction to assess the expression of several genes associated with programmed cell death and proliferation. Blots of total RNA extracted from neuronal and astroglial cells exposed to PrP 106-126 for between 1 h and 7 days were hybridized with probes recognizing c-fos, c-jun, c-myc, p53, hsp-70 and bcl-2 mRNA. Except for a slight decrease in bcl-2 mRNA in neuronal cells, no change in other transcripts was evident. Since clusterin (apolipoprotein J) mRNA levels are increased in prion-related encephalopathies and clusterin immunoreactivity has been located in association with PrPSc in Gerstmann-Sträussler-Scheinker brain, the expression of clusterin was determined in neuronal and astroglial cells chronically exposed to PrP 106-126. Although the induction of clusterin has been involved in the apoptotic mechanism in other experimental conditions, its expression was unchanged in PrP 106-126-treated neurons, while a three-fold induction of clusterin mRNA was observed in astrocytes exposed to PrP 106-126. To investigate whether the clusterin up-regulation was simply associated with the astroglial proliferative stimulus of PrP 106-126 or was specifically induced by the peptide, we measured clusterin expression in astrocytes cultured in fetal calf serum-free medium and exposed to PrP 106-126 or fetal calf serum restoration. In this condition the PrP peptide, like fetal calf serum, increased the glial proliferation rate, but only PrP 106-126 doubled clusterin mRNA. The selectivity of this effect indicates that PrPSc is directly involved in the clusterin up-regulation seen in prion-related encephalopathies and is associated with astroglial cells.

Oxidative stress after acute and chronic application of beta-amyloid fragment 25-35 in cortical cultures

The aim of this work was to investigate whether free radical reactions play a role in beta-amyloid neurotoxicity. Rat cortical neurons were exposed acutely (24 h) or chronically (3, 7 days) to beta-amyloid biologically active fragment beta 25-35 (50 microM). In these conditions, where only the longest exposure induced neuronal death, superoxide dismutase activity was increased after acute exposure but no change was detected after chronic treatments, whereas a different pattern was observed for glutathione peroxidase. In the basal condition, there was an eight-fold increase in dichlorofluoroscein, used as peroxide production marker, in neuronal cells after 7 days treatment with beta 25-35. Moreover, the intracellular peroxide production induced by Fe2+/ascorbate stimulation was amplified by beta 25-35, increasingly up to 7 days of exposure, by which time the dichlorofluoroscein-stimulated levels were 33 times higher than in controls. In conclusion, our results show that oxidative stress and free radical production are linked to beta 25-35 exposure and may contribute to neurodegenerative events associated with beta-amyloid deposits in Alzheimer's disease.

Reciprocal control of inflammatory cytokines, IL-1 and IL-6, and beta-amyloid production in cultures

To investigate the role of IL-6 in the pathogenesis of Alzheimer's disease (AD) its effect on amyloid precursor protein (APP) mRNA expression was evaluated. The levels of APP mRNA were determined by Northern blot analysis in primary cultured rat cortical neurons and glial cells exposed to IL-6 (50-200 ng/ml). The cytokine increased neuronal APP mRNA expression about 100% at the highest dose after 6 h of exposure. APP mRNA expression was unaffected in astroglial cells exposed to IL-6. Since IL-1 beta also increased neuronal APP mRNA, the combination of IL-1 beta and IL-6 was tested. The effects were partially additive. The ability of beta-amyloid fragment 25-35 to induce IL-1 or IL-6 mRNA was also investigated in astroglial cells. IL-1 beta mRNA was strongly induced by beta 25-35 (25-100 microM) while the expression of IL-6 mRNA remaining unchanged. The results suggest roles for both IL-1 and IL-6 in the neuronal mechanisms related to beta-amyloid protein deposition in AD.