Cooperative effects on the compaction of DNA fragments by the nucleoid protein H-NS and the crowding agent PEG probed by Magnetic Tweezers

BACKGROUND

DNA bridging promoted by the H-NS protein, combined with the compaction induced by cellular crowding, plays a major role in the structuring of the E. coli genome. However, only few studies consider the effects of the physical interplay of these two factors in a controlled environment.

METHODS

We apply a single molecule technique (Magnetic Tweezers) to study the nanomechanics of compaction and folding kinetics of a 6 kb DNA fragment, induced by H-NS bridging and/or PEG crowding.

RESULTS

In the presence of H-NS alone, the DNA shows a step-wise collapse driven by the formation of multiple bridges, and little variations in the H-NS concentration-dependent unfolding force. Conversely, the DNA collapse force observed with PEG was highly dependent on the volume fraction of the crowding agent. The two limit cases were interpreted considering the models of loop formation in a pulled chain and pulling of an equilibrium globule respectively.

CONCLUSIONS

We observed an evident cooperative effect between H-NS activity and the depletion of forces induced by PEG.

GENERAL SIGNIFICANCE

Our data suggest a double role for H-NS in enhancing compaction while forming specific loops, which could be crucial in vivo for defining specific mesoscale domains in chromosomal regions in response to environmental changes.

P4726Functional mitral regurgitation treated with percutaneous repair: a relative survival analysis of a national Swiss cohort

Introduction

Percutaneous treatment of functional mitral regurgitation (FMR) with MitraClip (MC) has led to discordant results in recent randomized clinical trials. We aimed at estimating excess mortality (EM) and to evaluate its predictors in a large Swiss FMR population treated with MC.

Methods

FMR patients enrolled in the MitraSwiss Registry (479 pts) with a mean age of 74.7±9.42 years were evaluated. We computed and plotted EM up to 5 years after implant using the Swiss 2008–20013 mortality tables, stratified by age and sex. A Poisson regression was used to model EM as a function of age, sex, pre-implant RV/RA gradient, calendar period (2011–2013; 2014–2015,2016–2017), ischemic vs non ischemic aetiology, acute procedural success and residual MR.

Results

Patient's survival at 1,2,3,4 and 5 years were respectively 0.84, 0.72, 0.59, 0.53 and 0.48. FMR patients treated with MC showed excess mortality of +13% (95% CI,10%-18%), +22% (95% CI,17%-28%), +34% (95% CI,27%-41%), +37% (95% CI,28%-46%) and +39% (95% CI,28%-50%) at each time point as compared to the Swiss population, with not differences over the entire follow up (p=0.481). Age group, sex, RV/RA gradient calendar period, ischemic vs non ischemic and residual MR were not associated with excess mortality while a clear association was recognized with acute procedural success (p=0.011).

Conclusions

In FMR patients treated with MC a persistent EM was observed at a 5 years follow up. Acute procedural success is the only determinant of EM with a 65% lower EM as compared to procedural failures.

Simulating rewetting events in intermittent rivers and ephemeral streams: A global analysis of leached nutrients and organic matter

Climate change and human pressures are changing the global distribution and the extent of intermittent rivers and ephemeral streams (IRES), which comprise half of the global river network area. IRES are characterized by periods of flow cessation, during which channel substrates accumulate and undergo physico-chemical changes (preconditioning), and periods of flow resumption, when these substrates are rewetted and release pulses of dissolved nutrients and organic matter (OM). However, there are no estimates of the amounts and quality of leached substances, nor is there information on the underlying environmental constraints operating at the global scale. We experimentally simulated, under standard laboratory conditions, rewetting of leaves, riverbed sediments, and epilithic biofilms collected during the dry phase across 205 IRES from five major climate zones. We determined the amounts and qualitative characteristics of the leached nutrients and OM, and estimated their areal fluxes from riverbeds. In addition, we evaluated the variance in leachate characteristics in relation to selected environmental variables and substrate characteristics. We found that sediments, due to their large quantities within riverbeds, contribute most to the overall flux of dissolved substances during rewetting events (56%-98%), and that flux rates distinctly differ among climate zones. Dissolved organic carbon, phenolics, and nitrate contributed most to the areal fluxes. The largest amounts of leached substances were found in the continental climate zone, coinciding with the lowest potential bioavailability of the leached OM. The opposite pattern was found in the arid zone. Environmental variables expected to be modified under climate change (i.e. potential evapotranspiration, aridity, dry period duration, land use) were correlated with the amount of leached substances, with the strongest relationship found for sediments. These results show that the role of IRES should be accounted for in global biogeochemical cycles, especially because prevalence of IRES will increase due to increasing severity of drying events.

One for All, All for One: A Global River Research Network

Intermittent rivers are an increasing share of the world's river network, but current models don't include them. One research network is gathering knowledge about these rivers from around the world.

[Functional dyspepsia and the satiety test: its usefulness in clinical practice]

INTRODUCTION

According to the Rome III Criteria, functional dyspepsia (FD) is classified as postprandial distress syndrome (PDS) and epigastric pain syndrome (EPS). On the other hand, the satiety test (ST) has been used to evaluate gastric accommodation and emptying, distinguishing healthy individuals from those with dyspepsia.

AIMS

To determine whether the ST can distinguish dyspeptic individuals from healthy ones and to evaluate its usefulness in differentiating the two FD subtypes.

METHODS

Adults with FD were consecutively enrolled in a cross-sectional study within the time frame of August 2011 and October 2012. Healthy subjects participated as controls. The ST consisted of the intake of a nutritional supplement (Fortisip®, Nutricia Bagó®) at a constant speed; satiety was graded at 5-minute intervals (1 to 5 points). Intake was suspended when the maximum score was reported. The total ingested volume and caloric intake was recorded and the Mann-Whitney U test was used in the statistical analysis.

RESULTS

The study included 39 dyspeptic patients and 20 control individuals. The patients were predominantly women (84.6 vs. 25%; p < 0.0001) and they were similar in age (39.59 ± 13.53 vs. 34.70 ± 9.85 years) and BMI (24.32 ± 3.52 vs. 25.82 ± 3.34 kg/m2) with respect to the controls. The FD subtype percentages were PDS: 61%, EPS: 31%, and Mixed syndrome: 8%. There was a lower ingested volume and caloric intake on the part of the dyspeptic patients (185 vs. 300 ml and 277 vs. 520 Kcal, respectively. Both: P<.001). No differences in the ST were observed between the two pure dyspepsia subtypes.

CONCLUSIONS

There was a difference in the ST between healthy individuals and those with dyspepsia, but the ingested volume and caloric intake in the two FD subtypes were similar.

Long-term patient benefit with biodegradable polymer biolimus eluting stent

The introduction of bare metal stents in the early 1990 and of 1st generation drug eluting stents (DES) in the early 2000 defined a new era in interventional cardiology. DES dramatically reduced instant restenosis and the need of revascularization after percutaneous coronary intervention. However, this increased efficacy came at the cost of delayed vascular healing and subsequent late adverse event such as late stent thrombosis. Second generation DES appears even more efficient and safer than 1st generation DES, providing exciting perspectives for the near future. A new era has started with the development of bio-absorbable polymers. Biodegradable polymer eluting stents, such as the biolimus A9 eluting stent showed non-inferiority to durable polymer sirolimus eluting stent and, by reducing the risk of cardiac events associated with very late stent thrombosis, might improve long-term clinical outcomes in a variety of patients including chronic stable coronary artery disease and acute coronary syndromes. Biodegradable polymer DES are more likely to define the 3rd generation DES. The goal of future development is to further increase safety and efficacy of DES.

[Cocoa--a literature survey]

Schokolade hat sowohl in der Zahnheilkunde als auch in der Humanmedizin nach wie vor einen schlechten Ruf und wurde für Karies, Übergewicht und dessen Folgen – Bluthochdruck und Diabetes – verantwortlich gemacht. Aktuell scheint die süsse Sünde wieder auf dem Weg zu ihrer Rehabilitierung zu sein. Kürzlich konnte gezeigt werden, dass dunkle Schokolade unter gewissen Umständen zu einer Verbesserung wichtiger Surrogatmarker der Atherosklerose wie der Endothel- und Plättchenfunktion führen kann. Zusätzlich zeichnet sich ab, dass sich Schokolade auch positiv auf den Blutdruck, die Plasmalipide und sogar auf die Insulinresistenz auswirkt. Diese günstigen Effekte sind vermutlich am ehesten durch antioxidative und NO-abhängige Mechanismen zu erklären.

Effects of percutaneous transluminal angioplasty and endovascular brachytherapy on vascular remodeling of human femoropopliteal artery: 2 years follow-up by noninvasive magnetic resonance imaging

OBJECTIVES

We aimed to assess in vivo the long-term effects of percutaneous transluminal angioplasty (PTA) and endovascular brachytherapy (EVBT) on vessel wall by serial MRI.

METHODS

Twenty patients with symptomatic stenosis of the femoropopliteal artery were randomly assigned to PTA (n=10) or PTA+EVBT (n=10, 14Gy by gamma-source). High-resolution MRI was performed prior, at 24-hours, 3-months, and 24-months after intervention. MRI data were analyzed by an independent, blinded observer.

RESULTS

The effects of both procedures on vessel wall at 24-hours and 3-months have been reported. Despite similar percent decrease in lumen area between 3- and 24-months in both groups (-8% for PTA and -11% for PTA+EVBT), at 24-months lumen area gain compared to baseline was +30% in PTA versus +82% in PTA+EVBT (p<0.05). Total vessel area, which was increased at 24-hours and 3-months, returned to pre-treatment value in both groups.

CONCLUSIONS

We demonstrated non-invasively that restenosis and inward remodeling after PTA are delayed by EVBT. At 24-months, patients treated with brachytherapy have larger lumen than those treated with PTA alone. The decrease in luminal and total vessel area between 3- and 24-months after EVBT indicates that the restenotic and remodeling process is not abolished but delayed with this therapy.

Elevated gastric lesions: virtual gastroscopy

With the development of multidetector computed tomography and the improvement in the capabilities of workstations, the use of high-quality three-dimensional reconstructions and virtual images can be applied to organs other than the colon such as the stomach. As a noninvasive technique, virtual gastroscopy represents an alternative to conventional endoscopy for the detection of elevated lesions. Findings of this technique are illustrated.

Das süße Geheimnis der dunklen Schokolade

Dunkelschokolade ist seit Jahrhunderten für ihren Geschmack, aber auch für ihre gesundheitsförderlichen Wirkungen bekannt. Verantwortlich für die positiven Effekte ist die heterogene Gruppe der Polyphenole. Der Polyphenol-Gehalt steigt parallel zum Kakaogehalt, weswegen sich die Dunkelschokolade deutlich in der Wirkung von Milchschokolade abhebt. Neben antioxidativen Wirkungen besitzen Polyphenole auch immunmodulatorische Effekte und können die primäre Hämostase wie auch die Plättchenaktivierung und -aggregation hemmen.

Kaffee – Gift oder Medizin?

Der Genuss von Kaffee, dem weltweit am weitesten verbreiteten Getränk, wurde in den Vergangenheit immer wieder als möglicher kardiovaskulärer Risikofaktor diskutiert. Deutliche Beweise dafür aber fehlen und neuere Studien lassen sogar einen eher günstigen Effekt vermuten. Trotz vielfältiger Untersuchungen konnte bis heute keine klare Assoziation zwischen Kaffee-Genuss und dem Risiko für eine arterielle Hypertonie, Myokardinfarkt und andere kardiovaskuläre Krankheiten bewiesen werden. Im Gegensatz zu den früheren Theorien weisen die neusten Publikationen darauf hin, dass mäßiger Kaffeegenuss kein konkretes gesundheitliches Risiko darstellt und sogar eine gewisse protektive Wirkung hat.

Real time magnetic resonance guided endomyocardial local delivery

OBJECTIVE

To investigate the feasibility of targeting various areas of left ventricle myocardium under real time magnetic resonance (MR) imaging with a customised injection catheter equipped with a miniaturised coil.

DESIGN

A needle injection catheter with a mounted resonant solenoid circuit (coil) at its tip was designed and constructed. A 1.5 T MR scanner with customised real time sequence combined with in-room scan running capabilities was used. With this system, various myocardial areas within the left ventricle were targeted and injected with a gadolinium-diethylenetriaminepentaacetic acid (DTPA) and Indian ink mixture.

RESULTS

Real time sequencing at 10 frames/s allowed clear visualisation of the moving catheter and its transit through the aorta into the ventricle, as well as targeting of all ventricle wall segments without further image enhancement techniques. All injections were visualised by real time MR imaging and verified by gross pathology.

CONCLUSION

The tracking device allowed real time in vivo visualisation of catheters in the aorta and left ventricle as well as precise targeting of myocardial areas. The use of this real time catheter tracking may enable precise and adequate delivery of agents for tissue regeneration.

Integration of vascular biology and magnetic resonance imaging in the understanding of atherothrombosis and acute coronary syndromes

The interaction between the vulnerable atherosclerotic plaque prone to disruption and thrombus formation is the cornerstone of acute coronary syndrome (ACS). Although distinct from one another, the atherosclerotic and thrombotic processes appear to be interdependent, hence the term atherothrombosis. Inflammation is a crucial common pathophysiological mechanism. Overall, the association of plaque vulnerability and ACS has been well documented. Given the multifactorial origin of atherothrombosis the best preventive approach should be aggressive management of all the risk factors. New interventions should be directed toward decreasing vulnerability of the lesions thereby decreasing the risk of ACS.

[Virtual Colonoscopy. Experience in 500 patients]

OBJECTIVE

To show our experience and results in Virtual Colonoscopy (VC).

MATERIAL AND METHOD

Five hundred patients with personal or familial history of colorectal carcinoma and/or adenomas, or any kind of coloproctologic symptoms were studied. VCs were practiced using a helical CT scanner (300 patients) and a multislice CT scanner (200 patients) a few hours after Conventional Colonoscopy (CC), considered the gold standard. The patients were evaluated in a prospective blind study, to determine sensitivity and specificity of VC. Findings were classified as: 1) normal studies; 2) studies with pathological findings. This one was subdivided into: 2a) Lesions below 5 mm., 2b) Lesions between 5-9 mm., 2c) Lesions above 9 mm.

RESULTS

VC detected 253 normal studies whereas CC only detected 233. The sensitivity and specificity for each subgroup were: 2a) 87.8% and 86.9%; 2b) 95.6% and 91.4%; 2c) 100.0% and 100.0% respectively.

CONCLUSION

VC is a feasible and useful method for evaluating the entire colon. It is well tolerated, it has no complications and a high sensitivity and specificity for elevated lesions, especially the ones above or equal to 5 mm.

[Acid-supressing capacity of omeprazole 20 mg tablets vs pantoprazole 20 and 40 mg tablets. A pilot study in volunteers]

OBJECTIVE

To compare the acid-supressing capacity of omeprazole (OZ) 20 mg tablets vs pantoprazole (PZ) 20 and 40 mg tablets, in healthy volunteers, with 24-h intragastric pH-metry.

MATERIAL AND METHODS

Open, randomized, cross-over trial in 10 healthy volunteers; on days 0.8 and 22, 24-h intragastric pH-metry. Day 0, basal, thereafter 7 days with OZ or PZ 20 mg/day; day 8, pH-metry, then "wash out" for 7 days and thereafter 7 more days' therapy with PZ or OZ. On day 22 a 24-h intragastric pH control was performed again. In the last treatment stage, all of them were administered pantoprazole 40 mg/day for 8 days again with a 24-h pH recording at the end.

RESULTS

24-h pH-metry expressed as the time (hours) in which the pH was < or = 4 and the values as mean +/- standard deviation. BASAL 22.12 +/- 1.54, POST-OZ 9.78 +/- 6.72, POST-PZ 20 15.65 +/- 5.65, POST-PZ 40 8.57 +/- 5.93. Statistical evaluation with two way repeated measures ANOVA p < 0.0001. Newman Keuls post-hoc test: (1) vs (2) p < 0.003; (1) vs (3) p < 0.03; (2) vs (4) 0.65.

CONCLUSIONS

According to the results it might be stated that both proton pump inhibitors have acid-supressing capacity and omeprazole in equal dosis is more effective than pantoprazole as acid-supressor, with statistically significative differences. There was no difference between 20 mg omeprazole and 40 mg pantoprazole.

[Primary esophageal lymphoma in a patient with AIDS]

Primary esophageal lymphomas are extremely rare. We report a primary esophageal T cell lymphoma of a diffuse large cell phenotype B in a patient with AIDS. Also we reviewed other published cases. The diagnosis of this complication should be considered in HIV seropositive patients with progressive displagia and endoscopic findings of masses, polyps or ulcerations and, specially in those unresponsive to antifungal or antiviral therapy. Biopsy and histopathologic studies are needed to confirm the diagnosis.

[Virtual gastroscopy. Preliminary experience]

OBJECTIVE

To define the role of virtual gastroscopy (VG) in the detection of elevated lesions comparing its results with conventional endoscopy (CE) as the gold standard method.

MATERIALS AND METHODS

Between December 2000 and July 2001, 19 patients were evaluated. The age ranged between 41 and 72 (mean 58.8 years old). VG and CE were performed in all the patients during the same week. VG were carried out with a multislice CT scanner (Mx 8000, Marconi Medical Systems). The technical parameters used were 3 mm with slices and 1.5 mm reconstruction intervals. The acquisition time was 22 seconds. Images were sent to a workstation (MxView, Marconi Medical Systems) where they were reprocessed in three different ways: 1) Bidimensionally 2) Tridimensionally 3) Virtual Endoscopy Findings of VG were compared with CE.

RESULTS

VG detected 39 lesions, whereas CE detected 40 lesions. There were 39 true-positive findings, 2 true-negative findings, 0 false-positive findings and 1 false-negative findings. The Sensitivity (Se) was 97.5%; Specificity (Sp) was 100%, positive predictive value 100% and Negative predictive value 66%.

CONCLUSIONS

VG is a new non-invasive method with high Se and Sp in the detection of elevated lesions. The actual role of VG consist in identification of gastric lesions and possibility to diagnose gastric disease.

New understanding of atherosclerosis (clinically and experimentally) with evolving MRI technology in vivo

Atherosclerosis and its thrombotic complications are the major cause of morbidity and mortality in industrialized countries. Despite advances in our understanding of the pathogenetic mechanisms and new treatment modalities, the absence of an adequate noninvasive method for early detection limits the prevention or treatment of patients with various degrees and localizations of atherothrombotic disease. High-resolution magnetic resonance (MR) has recently emerged as one of the most promising techniques for the noninvasive study of atherothrombotic disease. Most importantly, MR can be used to characterize plaque composition and monitor progression. Thus, MR opens new strategies, ranging from the screening of high-risk patients for early detection and treatment as well as the monitoring of target areas for pharmacological intervention.

Value or desirability of hemorheological-hemostatic parameter changes as endpoints in blood lipid-regulating trials

High levels of plasma lipids have been recognized as a major risk factor in the development and progression of atherosclerosis, and to influence hemorheological factors that may predispose to thrombotic complications. Lipid-lowering interventions have been associated with a significant reduction of morbidity and mortality. Several mechanisms have been postulated for the observed clinical effect. Serum lipid-regulating therapies may reduce cardiovascular risk not only by altering the arterial wall, improving disturbed endothelial function, atherogenesis and plaque stability, but also through their antithrombogenic effects and influence on blood flow properties associated with hyperlipidemia. In this article, we will review the recent literature and discuss the value of hemorheological-hemostatic findings as surrogate endpoints for clinical trials in dyslipidemic patients.

Vasopeptidase inhibitors: a new therapeutic concept in cardiovascular disease?

The cardiovascular system is regulated by hemodynamic and neurohumoral mechanisms. These regulatory systems play a key role in modulating cardiac function, vascular tone, and structure. Although neurohumoral systems are essential in vascular homeostasis, they become maladaptive in disease states such as hypertension, coronary disease, and heart failure. The clinical success of ACE inhibitors has led to efforts to block other humoral systems. Neutral endopeptidase (NEP) is an endothelial cell surface zinc metallopeptidase with similar structure and catalytic site. NEP is the major enzymatic pathway for degradation of natriuretic peptides, a secondary enzymatic pathway for degradation of kinins, and adrenomedullin. The natriuretic peptides can be viewed as endogenous inhibitors of the renin angiotensin system. Inhibition of NEP increases levels of atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP) of myocardial cell origin, and C-type natriuretic peptide (CNP) of endothelial cell origin as well as bradykinin and adrenomedullin. By simultaneously inhibiting the renin-angiotensin-aldosterone system and potentiating the natriuretic peptide and kinin systems, vasopeptidase inhibitors reduce vasoconstriction, enhance vasodilation, improve sodium/water balance, and, in turn, decrease peripheral vascular resistance and blood pressure and improve local blood flow. Within the blood vessel wall, this leads to a reduction of vasoconstrictor and proliferative mediators such as angiotensin II and increased local levels of bradykinin (and, in turn, nitric oxide) and natriuretic peptides. Preliminary clinical experiences with vasopeptidase inhibitors are encouraging. Thus, the combined inhibition of ACE and neutral endopeptidase is a new and promising approach to treat patients with hypertension, atherosclerosis, or heart failure.

Effects of lipid-lowering by simvastatin on human atherosclerotic lesions: a longitudinal study by high-resolution, noninvasive magnetic resonance imaging

BACKGROUND

This study was designed to investigate the effects of lipid-lowering by simvastatin on human atherosclerotic lesions.

METHODS AND RESULTS

Eighteen asymptomatic hypercholesterolemic patients with documented aortic and/or carotid atherosclerotic plaques were selected for the study. A total of 35 aortic and 25 carotid artery plaques were detected. Serial black-blood MRI of the aorta and carotid artery of the patients was performed at baseline and 6 and 12 months after lipid-lowering therapy with simvastatin. The effects of the treatment on atherosclerotic lesions were measured as changes in lumen area, vessel wall thickness, and vessel wall area, a surrogate of atherosclerotic burden. Simvastatin induced a significant (P<0.01) reduction in total and LDL cholesterol levels at 6 weeks that was maintained thereafter. At 6 months, no changes in lumen area, vessel wall thickness, or vessel wall area were observed. However, at 12 months, significant reductions in vessel wall thickness and vessel wall area, without changes in lumen area, were observed in both aortic and carotid arteries (P<0.001).

CONCLUSIONS

This in vivo human study demonstrates that effective and maintained lipid-lowering therapy by simvastatin is associated with a significant regression of atherosclerotic lesions. Our observation suggests that statins induce vascular remodeling, as manifested by reduced atherosclerotic burden without changes in the lumen.

Predictors of long-term survival after valve replacement for chronic aortic regurgitation. Is M-mode echocardiography sufficient?

AIMS

The clinical importance of pre-operative and follow-up echocardiographic studies in patients operated on for chronic severe aortic valve regurgitation is still a matter of debate. The prognostic significance of M-mode echocardiography has never been directly compared with clinical and angiographic data.

METHODS AND RESULTS

Univariate and multivariate analyses of cumulative survival were performed for clinical, echocardiographic and angiographic data of 125 patients operated on between 1975 and 1983, and followed for 13.3+/-6.4 years. Ten and 20 year survival rates were 77% and 48%, respectively. Age, NYHA class, angiographic volumes, ejection fraction, as well as M-mode echocardiographic end-systolic dimension and shortening fraction were the main pre-operative prognostic parameters for long-term survival. In a multivariate analysis the angiographic end-systolic volume index, age and preoperative NYHA class were independent pre-operative prognostic variables of long-term survival. A postoperative reduction in end-diastolic dimension of >20% predicted a significantly better late survival (74% vs 44% after 20 years, P<0.001).

CONCLUSIONS

Age, pre-operative NYHA class and left ventricular systolic function are the main determinants of long-term survival after valve replacement for chronic aortic regurgitation. Despite a slightly lower predictive value of echocardiography when compared to angiography, it appeared sufficient for everyday clinical decision making for valve replacement. Echocardiography within 6 months postoperatively is able to detect recovery of left ventricular function, and enables additional risk-stratification, regardless of pre-operative findings.

Autonomic nervous system-controlled cardiac pacing: a comparison between intracardiac impedance signal and muscle sympathetic nerve activity

A recently introduced rate responsive cardiac pacing system is based on information derived from the intracardiac impedance signal containing information on the inotropic state of the ventricle. This study compared the inotropic state index (ISI) with muscle sympathetic activity (MSA), both being modulated by the autonomic nervous system. Nine patients (66 +/- 3 years, mean +/- SEM) with Inos2DR pacemakers were included. Each patient was studied at rest and during cold pressor test (CPT). Microneurography of the peroneal nerve was performed to measure MSA continuously, which was digitally stored along with continuous surface ECG and blood pressure. The intracardiac impedance signal was transmitted by the pacemaker and stored simultaneously. Linear correlation between ISI and MSA was calculated for the period of the CPT. During CPT, mean systolic blood pressure increased from 122 +/- 4 to 149 +/- 6 mmHg (P < 0.0001), diastolic blood pressure increased from 74 +/- 8 to 86 +/- 4 mmHg (P = 0.02), and intrinsic heart rate increased from 69 +/- 7 to 75 +/- 7 beats/mill (P = 0.019). ISI increased by 21 +/- 7% (P = 0.018), MSA by 26 +/- 6% (P = 0.004). ISI and MSA were positively correlated during the CPT in eight of nine patients (R2 = 0.86-0.99, P < 0.0001). Negative correlation was found in one patient (R2 = 0.94). This study demonstrates parallel increases of the ISI and MSA during CPT. ISI and MSA showed a close linear relationship during provoked changes of sympathetic activity. These results provide further evidence that the sympathetic nervous system is responsible for the observed ISI changes.

Baroreceptor dysfunction induced by nitric oxide synthase inhibition in humans

OBJECTIVES

We sought to investigate baroreceptor regulation of sympathetic nerve activity and hemodynamics after inhibition of nitric oxide (NO) synthesis.

BACKGROUND

Both the sympathetic nervous system and endothelium-derived substances play essential roles in cardiovascular homeostasis and diseases. Little is known about their interactions.

METHODS

In healthy volunteers, we recorded muscle sympathetic nerve activity (MSA) with microneurography and central hemodynamics measured at different levels of central venous pressure induced by lower body negative pressure.

RESULTS

After administration of the NO synthase inhibitor NG-monomethyl-L-arginine (L-NMMA, 1 mg/kg/min), systolic blood pressure increased by 24 mm Hg (p = 0.01) and diastolic blood pressure by 12 mm Hg (p = 0.009), while stroke volume index (measured by thermodilution) fell from 53 to 38 mL/min/m2 (p < 0.002). Administration of L-NMMA prevented the compensatory increase of heart rate, but not MSA, to orthostatic stress. The altered response of heart rate was not due to higher blood pressure, because heart rate responses were not altered during infusion of the alpha-1-adrenoceptor agonist phenylephrine (titrated to an equal increase of systolic blood pressure). In the presence of equal systolic blood pressure and central venous pressure, we found no difference in MSA during phenylephrine and L-NMMA infusion.

CONCLUSIONS

This study demonstrates a highly specific alteration of baroreceptor regulation of heart rate but not muscle sympathetic activity after inhibition of NO synthesis in healthy volunteers. This suggests an important role of NO in reflex-mediated heart rate regulation in humans.

[Detection of Helicobacter pylori by polymerase reaction in bile samples from gallbladder and bile stones]

Some papers report helicobacter pylori existence in bile from surgical specimens obtained during gallbladder or bile ducts surgery. The aim of this work was search by PCR, H. Pylori presence in bile specimens from patients suffering of gallbladder stones or by bile ducts stones. Bile samples were obtained by gallbladder punction during cholecystectomy in 26 patients, 19 of them with gallbladder stones and 7 also with gallbladder stones and bile duct stones. Age ranged from 22-69 years old, median 49.6 years old. Samples were sent to specialized biomolecular laboratory to perform PCR techniques. Two of 26 patients (7.6%) had positive reaction for the presence of DNA of H. Pylori in bile samples. Our research suggest that DNA of H. Pylori can be founded in bile samples patients with gallbladders and duct stones in Argentina.

[Absence of bleeding recurrence of peptic ulcer after long term follow-up of successful eradication of Helicobacter pylori]

Helicobacter pylori (HP) eradication reduces dramatically the peptic ulcer relapse rate, but information regarding recurrence of peptic ulcer bleeding after eradication is still scanty. Available data show rebleeding rates of 0-3% per year in successfully eradication patients, compared with figures between 12 and 33% among the non eradicated ones. The aim of this study was to determine the rebleeding rate among successfully eradicated patients with a prior history of rebleeding peptic ulcer. 42 patients (34 male, mean age 49, range 18-74) hospitalised for Hp positive bleeding peptic ulcer undergoing conservative treatment, were given as soon as oral route was re-established, a one-week eradication treatment, followed by the same proton pump inhibitor for three or five weeks for duodenal and gastric ulcer healing respectively. No maintenance antiulcer therapy was indicated. Patients were advised not to take nonsteroideal anti-inflammatory drug. Ulcer healing and Hp eradication was confirmed in all 42 patients by means of endoscopy and biopsies for urease rapid test and histology four weeks after completion of the treatment. After this patients were invited to enter a long-term follow-up program with periodical visits. End point of the study was occurrence of rebleeding. Further endoscopies were planned when rebleeding or symptomatic relapse. Median follow-up time was 24.02 months, ranging from 3 up to 27 months. All patients were compliant with the follow-up visits. None of the patients presented with symptoms suggestive of ulcer relapse or upper gastrointestinal bleeding. Our data suggest, that Hp eradication can prevent bleeding relapses in patients with Hp positive bleeding peptic ulcers.

A rationale for treatment of endothelial dysfunction in hypertension

Strategically located between the circulating blood and the vascular smooth muscle, endothelial cells release numerous vasoactive substances that regulate the function of vascular smooth muscle and circulating blood cells. Important endothelium-derived vasodilators are prostacyclin, bradykinin, nitric oxide (NO) and, independent of the former, endothelium-derived hyperpolarizing factor. In particular, NO inhibits cellular growth and migration. In concert with prostacyclin, NO exerts potent antiatherogenic and thromboresistant properties by preventing platelet aggregation and cell adhesion. These effects are counterbalanced by vasoconstrictors, angiotensin II and endothelin-1, both of which exert prothrombotic and growth-promoting properties. In hypertension, elevated blood pressure transmits into cardiovascular disease by causing endothelial dysfunction. Hence, modern therapeutic strategies in human hypertension focus on preserving or restoring endothelial integrity. Calcium antagonists counteract angiotensin II and endothelin-1 at the level of vascular smooth muscle by reducing the inflow of Ca2+ and facilitating the vasodilator effects of NO. Besides inhibiting the renin-angiotensin system, angiotensin-converting enzyme inhibitors diminish the inactivation of bradykinin, leading to an augmented release of NO. Newly developed vasopeptidase inhibitors induce potent antihypertensive effects in low-, normal-, and high-renin models of hypertension, not only because of the decreased breakdown of natriuretic peptides, but also because of the inhibition of endothelin-1 generation. Furthermore, experimental studies suggest that endothelin antagonists effectively lower blood pressure and prevent target-organ damage in salt-sensitive forms of hypertension. Further clinical studies are already underway to examine whether restoring endothelial dysfunction results in a clinical benefit in hypertension.

[Seroprevalence of helicobacter pylori infection in the republic of Argentina: influence of age, sex, socioeconomic level, geographical area, and health infrastructure. Multicenter study by the Club Argentino del Estomago y Duodeno]

Helicobacter pylori (Hp) infection affects almost half of the world population, it is almost a pandemia, and has been associated to poverty in underdeveloped countries. The Club Argentino del Estómago y Duodeno decided to fulfill the lack of information upon this subject in Argentina designing a seroprevalence, multicentric, prospective study performed in voluntary adults donors in blood banks and in children seen during normal growth controls. Seven hundred and nineteen individuals were evaluated, 645 of them were included: 178 children (age 0-18 years) and 467 adults. In all cases a serological IgG Hp test (Flex-Pack Abbott) was performed and an epidemiological questionnaire was completed by a physician. General prevalence of Hp infection was 44.8% of individuals. In the paediatric population prevalence was 15.7% and in adults 55.9%. The highest prevalence was observed in the fifth decade: 64%. In concordance with other similar studies carried out in different countries, we may conclude that the risk of acquisition of Hp infection is directly related to age, area of residence, social-economical status, sanitary facilities, and educational level reached. Even though the prevalence of Hp infection in Argentina is intermediate between highly developed and underdeveloped countries, the number of people infected is very high and the incidence of Hp-associated pathologies in the future represents a formidable task for gastroenterologists and sanitary authorities.

Spiral computed tomography: a novel diagnostic approach for investigation of the extracranial cerebral arteries and its complementary role in duplex ultrasonography

BACKGROUND

For the detection of atherosclerotic lesions of the extracranial cerebral arteries, duplex ultrasonography (US) is an established operator-dependent method, whereas arteriography is associated with the not-insignificant risk of embolic complications. Spiral CT is a promising novel diagnostic tool that allows noninvasive, operator-independent diagnosis of obstruction of extracranial cerebral arteries. The aim of our prospective study was to evaluate in a clinical setting the complementary role of duplex US and spiral CT.

METHODS AND RESULTS

We compared the results obtained independently by spiral CT and duplex US in 59 consecutive patients with clinical suspicion of an obstructive lesion affecting the carotid arteries. We analyzed a total of 354 segments from the extracranial carotid arteries, including the common, internal, and external carotid arteries. A total of 4 complete occlusions, 38 severe stenoses (70% to 99%), and 32 moderate stenoses (30% to 69%) were concordantly identified by means of duplex US and spiral CT. In 5 cases in which duplex US did not allow sufficient evaluation of the carotid artery because of a poor US window or severe calcification, spiral CT allowed identification and correct measurement of the stenotic lesion. The comparison of the percentage of stenosis with both methods was good (r=0.91, P=0.024).

CONCLUSIONS

Our results indicate that spiral CT of the extracranial cerebral arteries is a promising noninvasive complementary and non-operator-dependent examination. Its application is particularly attractive in cases in which duplex US is not reliable (ie, severe kinking, severe calcification, short neck, and high bifurcation) and particularly when an overall view of the vascular field is required.

[Is dental plaque a normal Helicobacter pylori reservoir?]

The mechanisms of transmission and reservoir of Helicobacter pylori is still unclear; even it has been suggested that dental plaque could be the bacterial reservoir and one important factor in the reinfection. The aim of the study was to evaluate the prevalence of Helicobacter pylori in dental plaque in 20 patients with non ulcer dyspepsia (12 females, 7 males; mean age 40.5 years) and antral infection; and to establish the presence of bacteria in dental plaque and gastric mucosa after eradication. Gastric colonization in all of them was confirmed by five samples (three of antrum and two of body) with Giemsa conventional technique, clotest and culture. When clotest was positive in gastric mucosa, we performed the scrape of dental plaque and sending the material for culture. All patients were treated with a scheme of seven days with one protom pump inhibitor and two antibiotics. After four weeks all the patients were controlled with endoscopy and culture of dental plaque to confirm eradication. Dental plaque culture was positive in 1/20 patients (5%), and this results was similar to developed countries, using as detection method culture or polymerase chain reaction (PCR).

[Evaluation of sensitivity, specificity and predictive value of six qualitative serological methods for the detection of Helicobacter pylori antibodies]

Screening tests for IG g antibodies against Helicobacter pylori are usefull for a long follow up of patients who were well eradicated. The aim of this study was to determinate and compared sensibility, specificity, positive and negative predictive value of six qualitative serological tests for IG g antibodies detection in the diagnosis of H. Pylori infections. Between May and October 1996 52 patients (30 males and 22 females; median age 42.4 years, range 21-68) with H. Pylori infection assessed on two antral and two corpus biopsies by means of Giema stain and a rapid urease test were tested for IG g antibodies detection. The serological tests used were: Inmunocomb II (Orgenics) Enzimo Inmuno Assay Inmunoadsorbent qualitative, Flex Pack (Smith Kline Diagnostics, Abbott) inmunocromatographic cualitative, Pylori Stat test (Biowhittaker) Enzimo Inmuno Assay (ELISA) qualitative, Premier (Meridian Diagnostics) Enzimo Inmuno Assay ELISA) qualitative. Pyloristest (Orion Diagnóstica) latex aglutination qualitative, H. Pylori (Bio Tre) Enzimo Inmuno Assay cualitative. 10 healthy subjects with negative gastric biopsies and negative rapid ureasa test were used as control group. The six evaluated serological tests have a comparable sensibility (89-95%) and specificity (77-83%) for the diagnosis of HP infection. The presence of specific HP antibodies in infected patients revealed a strong correlation with the histological demonstration of the microrganisms. We can recommend this qualitative serological tests due to their high sensibility and specificity, simplicity and low cost.