Artificial weathering of plastics used in oyster farming

With the omnipresence of plastic litter from oyster farming in marine coastal areas, the objective of this work was to better understand the weathering of plastics used in this field, focusing on oyster spat collectors. During their use, around fifteen years, collectors made of polypropylene (PP) undergo numerous degradations, alternatively submerged, emerged in seawater, and stored outdoor until the next cycle. They weaken, crack, break, end up fragmenting and disseminated in the environment as microplastics associated to persistent organic pollutants. In this work, a comparison of 55 months of in situ weathering with five months of artificial weathering in air or in artificial seawater in a homemade UV chamber was conducted to better understand the mechanisms involved. Chemical, thermal and surface characterizations of virgin and weathered samples were conducted using Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC) and Environmental Scanning Electron Microscopy (ESEM). After 55 months of in situ weathering, collectors were notably damaged with large fissures and loss of microplastics (MPs) associated with an increase of carbonyl index values and a decrease of melting temperatures and crystallinity rates. Considering only UV irradiation, five months of artificial weathering at 30 °C under continuous irradiation of 6.9 W/m² under UV lamps (295-400 nm) reproduced approximately 4.4 months of natural sunlight. Artificial weathering confirmed that photooxidation by combined effects of UV rays and oxygen was the main weathering mechanism and was reduced in seawater. These results help to understand the mechanisms involved in the weathering of these collectors in the marine environment and provide valuable information for industrials and professionals. Our study suggests a better storage away from UV rays and a reduction of the duration of use compared to current practices.

Pesticides, nonylphenols and polybrominated diphenyl ethers in marine bivalves from France: A pilot study

The present pilot study aimed to provide an overview of organic contaminant concentration levels in the littoral ecosystems of the Pertuis seas. The study determined the concentrations of twenty-nine pesticides, six nonylphenols and seven polybrominated diphenyl ethers (PBDEs) in sediments, seawater, Pacific oysters and blue mussels. Oysters accumulated a higher number of pesticides than blue mussels. Indeed, alpha BHC (0.60-0.72 ng/g, ww), chlorfenvinphos (1.65-2.12 ng/g, ww), chlorpyrifos (0.79-0.93 ng/g, ww), chlortoluron (2.50-4.31 ng/g, ww), metolachlor (up to 0.38 ng/g, ww) and parathion (0.56-0.69 ng/g, ww) were quantified in oysters whereas only alpha BHC (0.24-0.31 ng/g, ww), was quantified in mussels. The present results also revealed that the POPs detected in water or sediments were not ultimately found accumulated in bivalves. Other molecules such as methylparathion and BDE47 were quantified in sediments. These molecules, BDE99 and one nonylphenol (OP2OE) were quantified in seawater. Finally, the comparison with the available environmental guidelines showed that the values measured were at concentrations not considered to cause adverse effects at the populations' level except for chlortoluron in seawater (15-50 ng/L).

Patterns of left ventricular longitudinal myocardial dysfunction in mitral valve prolapse and effects of valve repair

Background

Regional longitudinal left ventricular (LV) dysfunction in patients with mitral regurgitation (MR) due to valve prolapse (MVP) with normal ejection fraction has been recently described, with data pointing at dysfunction of the LV base related to dilatation of the mitral annulus.

Purpose

To investigate degree and extent of regional LV dysfunction and its mechanisms in patients with MVP and severe acute (MRa, n=27) or chronic (MRc, n=41) MR and no coronary disease, undergoing surgical valve repair with 3 months follow-up (FU); 20 normal subjects were used as controls (N).

Methods

Speckle-tracking echocardiography was performed pre- (Bas), 1 week (1w) and 4 months (4mo) post-operatively to measure longitudinal global (GLPSS, %), regional (RPSS, %) and segmental (SPSS) peak systolic strain. Maximum and minimum mitral annulus (MA) diameters were measured with 3D echo at Bas. We also evaluated: LV end-diastolic volume index (EDVi, ml/m2); ejection fraction (EF, %); left atrial end-systolic volume index (LAVi, ml/m2); non-invasive pulmonary systolic pressure (PSP, mmHg).

Results

Risk factors (hypertension, diabetes, atrial fibrillation, smoke and previous stroke) were similar in MRc and MRa. At Bas EDVi was larger by definition in MRc (MRc: 102±21, MRa: 67±10 ml/m2, p<0.001) as LAVi (101±46 vs 76±31 ml/m2, p=0.035). Both EF (65±8 vs 64±8 ml/m2) and GLPSS (−20±4 vs −21±5%) were normal, but RPSS was reduced, only at the base (−13±6 vs −13±6%, p= ns; N: −18±2, p<0.03 vs MRc and MRa) in MRc and MRa, with reduced SPSS localized at anterior, lateral and posterior – but not septal – segments. At 1w, EF decreased in both MRc (47±14%, p<0.001 vs Bas) and MRa (56±10%, p=0.014 vs Bas), together with GLPSS (MRc: −11±4%, p<0.001 vs Bas; MRa; −13±4, p<0.001 vs Bas) driven by a prevalent marked decrease in RPSS (MRc: −7±4%, p<0.001 vs Bas; MRa; −8±5, p<0.001 vs Bas) of the LV base. All patients were alive at 3 months with no MACEs, similar reduction of mean MR grade (MRc: 4±0 to 1.9±0.7, p<0.001; MRa: 3.9±0.3 to 0.9±0.9, p<0.001) and PSP (MRc: 50±23 to 29±5 mmHg, p<0.001; MRa: 42±22 to 32±6 mmHg, p=0.039), normal EDVi (MRc: 70±27, MRa: 49±10 ml/m2), dilated LAVi (MRc: 101±46, MRa: 54±13 ml/m2), and reduced GLPSS (MRc: −12±5%, p<0.001 vs Bas; MRa; −15±3, p=0.001 vs Bas) and base RPSS (MRc: −7±6%, p=0.004 vs Bas; MRa; −10±4, p= ns vs Bas). At multivariate analysis, regional dysfunction was not related to the prolapsing scallop, presence of flail, commissure involvement, dimension and geometry of the MA, EF or pulmonary pressures.

Conclusions

In patients with MVP and severe MR, there is a specific regional longitudinal dysfunction pattern prevalent at the LV base which may be related to the duration of MR but not to annular dilatation or morphology of the prolapsing leaflets. The dysfunction worsens greatly following acute reduction of preload after surgical repair and is still significant at 4mo FU.

Funding Acknowledgement

Type of funding source: None

Latitudinal drivers of oyster mortality: deciphering host, pathogen and environmental risk factors

Diseases pose an ongoing threat to aquaculture, fisheries and conservation of marine species, and determination of risk factors of disease is crucial for management. Our objective was to decipher the effects of host, pathogen and environmental factors on disease-induced mortality of Pacific oysters (Crassostrea gigas) across a latitudinal gradient. We deployed young and adult oysters at 13 sites in France and we monitored survival, pathogens and environmental parameters. The young oysters came from either the wild collection or the hatchery while the adults were from the wild only. We then used Cox regression models to investigate the effect of latitude, site, environmental factors and origin on mortality risk and to extrapolate this mortality risk to the distribution limits of the species in Europe. We found that seawater temperature, food level, sea level atmospheric pressure, rainfall and wind speed were associated with mortality risk. Their effect on hatchery oysters was generally higher than on wild animals, probably reflecting that hatchery oysters were free of Ostreid herpesvirus 1 (OsHV-1) whereas those from the wild were asymptomatic carriers. The risk factors involved in young and adult oyster mortalities were different, reflecting distinct diseases. Mortality risk increases from 0 to 90% with decreasing latitude for young hatchery oysters, but not for young wild oysters or adults. Mortality risk was higher in wild oysters than in hatchery ones at latitude > 47.6°N while this was the opposite at lower latitude. Therefore, latitudinal gradient alters disease-induced mortality risk but interacts with the initial health status of the host and the pathogen involved. Practically, we suggest that mortality can be mitigated by using hatchery oysters in north and wild collected oysters in the south.

149 Acute effects on left ventricular systolic and diastolic function of a post-implant echocardiographic biventricular pacemaker optimization protocol following cardiac resynchronization therapy

Background

Cardiac resynchronization therapy (CRT) has demonstrated efficacy in at least 60% of patients with left ventricular (LV) failure and guideline-based indication to CRT. Whereas lack of response to CRT in up to a third of patients is multifactorial, a relevant factor is thought to be inadequate biventricular pacemaker (BIV) optimization (OPT) of either the intraventricular (VVd) or atrioventricular (AVd) delay

Purpose

In this echocardiographic observational study, we compared the acute effects on LV contractility, output, and diastolic function of BIV intra-implant QRS duration-based (OPTq) and post-implant Doppler echocardiography-based (OPTe) OPT of VVd and AVd.

Methods

In 160 patients with ischemic (n = 86) or idiopathic (n = 74) dilated cardiomyopathy, guideline-based different de novo CRT systems were implanted followed by immediate OPTq. Post-implant (10 days) OPTe was performed measuring: transmitral velocity-time integral (MVFi), % diastolic filling time (MVFt%), and E/A ratio, LV outflow integral (LVOTi), ejection time (LVOTt), and stroke volume (SV), isovolumic contraction (IVCT) and relaxation (IVRT) times, and LV myocardial performance index (MPI). The protocol included, sequentially: 1) Doppler measurements with OPTq settings; 2) measurements (separated by 3’ intervals) during a range (80/200 ms) of AVd with synchronous VVd; 3) algorithm-based AVd selection (at least 2 of following: increase in MVFi or SV, decrease in MPI); 4) measurements, with set AVd, during range of VVd: LV-first (-20, -40ms); RV-first (20, 40ms); synchronous; 5) VVd selection based on same algorithm used for AVd selection. Results. At OPTq, 58.6% of patients were set synchronous, 38.6% LV-first and 3% RV-first, with a 126 ± 29 mean AVd. This increased to 137 ± 36 after OPTe, when 49.1% were set synchronous, 38% LV-first and 12.4% RV-first, resulting in modifications of AVd and VVd in 59% and 36% of patients. Further, gain in SV with OPTe, compared to OPTq, was 8.3% (p<.001), paralleled by an increase in MVFi (21.2 ± 8 cm vs 20.5 ± 8, p<.001) and decrease in E/A (1.25 vs 1.45, p<.001). The greatest increase in SV with OPTe was found in patients in whom both AVd and VVd were modified (n = 48; 81 ± 26 ml vs 71 ± 23, p<.001) vs. patients without modifications (n = 42), or with change of either AVd or VVd (n = 70; 77 ± 20 vs 72 ± 20, p<.01). Only in the first patient group both MVFi (22 ± 9 vs 20 ± 9, p<.001) and MVFt% (52 ± 7 vs 49 ± 8, p=.004) increased, along with a decrease in MPI (.82±.31 vs .92 ± 36, p=.007) and IVRT (144 ± 51 vs 156 ± 62, p=.02.

Conclusions

These preliminary results point to a significant incremental role of post-implant OPTe to enhance LV output, contractility, and diastolic function in patients with CRT. The prognostic role of OPTe-determined AVd and VVD changes remains to be determined.

P1754 Regional left ventricular longitudinal myocardial dysfunction in mitral valve prolapse could be primary

Background

Regional left ventricular dysfunction in patients with mitral valve prolapse (MVP) and normal ejection fraction has been described by different Authors, and recent data point to a dysfunction (prevalently longitudinal strain) of the myocardium of the LV base secondary to dilatation of the mitral annulus.

Purpose

To investigate degree and extent of regional LV dysfunction and its mechanisms in patients with MVP, severe regurgitation and normal global systolic function, compared to patients with equivalent degree of regurgitation but functional etiology (FMR).

Methods

Speckle-tracking echocardiography was performed in 30 controls (N), and in severe primary (MVP, n= 50) or functional (FMR, n= 20) mitral regurgitation, to measure global, regional and segmental longitudinal peak systolic strain (LPSS, %), and time delay of peak maximum strain (TTPd, ms, calculated as time to peak maximum strain - time of aortic valve closure). Maximum and minimum mitral annulus diameters and area were measured with 3D echo. We also evaluated as recommended: LV end-diastolic volume index (EDVi, ml/m2), ejection fraction (EF, %), and left atrial end-systolic volume index (LAESVi, ml/m2) with 2D echo; LV stroke volume index, and non-invasive pulmonary systolic (PSP, mmHg) and diastolic pressures (PDP), mmHg) with Doppler echo.

Results

Age, heart rate, BSA and systolic blood pressure were similar between groups. Atrial fibrillation was present in 34% of MVP and 71% of FMR patients. LV EF was normal in MVP and reduced in FMR (43 ± 14 % vs N, p<.001). LV EDVi (MVP: 77 ± 20 ml/m2; FMR: 107 ± 35, both p<.001 vs N) and LAESVi (MVP: 91 ± 26 ml/m2; FMR: 80 ± 30, both p<.001 vs N) were similarly increased (volume overload) in MVP and FMR, as were PSP (MVP: 42 ± 23 ml/m2; FMR: 52 ± 25, both p<.001 vs N) and PDP (MVP: 16 ± 6 ml/m2; MVP: 15 ± 5, both p<.001 vs N). In FMR, LPSS was reduced globally (-12.8 ± 3.3, p<.001 vs N and MVP) and similarly at LV base, papillary and apical levels. In contrast, in MVP global (-19.4 ± 3.7%) and apical (-23.4 ± 4.5%) LPSS were normal, whereas LV base (-12.3 ± 5.8%, p=.003 vs N) and papillary (-17.1 ± 4%, p=.024 vs N) LPSS were reduced; further, LPSS reduction was localized to the anterior (-16 ± 4, p=.028 vs N), lateral (-17 ± 5, p=.006 vs N) and posterior (-16 ± 6, p=.007 vs N) segments, and was associated with an increased TTPd in the same segments in MVP but not in FMR patients. At multivariate analysis, degree and localisation of regional myocardial dysfunction in patients with MVP was not related to the prolapsing scallop, dimension of the mitral annulus, degree of volume overload or pulmonary pressures, or stroke volume index.

Conclusions

In patients with MVP, severe regurgitation and normal EF, there is a specific dysfunction pattern of regional LV longitudinal function which appears to be primary and not dependent on the degree of preload increase, mitral annulus dilatation, or localization of the prolapsing scallop.

P1748 Left atrial diastolic and systolic functions modulate the response to the standardised Valsalva maneuver in normal subjects

Background

Although the Valsalva maneuver (VM) is being advocated by current guidelines to identify with echocardiography patients with increased left ventricular (LV) filling pressures using a decrease in mitral E/A velocity > 0.5 as cutoff, there are limited published data for both patients and the normal response to the maneuver in healthy subjects.

Purpose

To assess LV and left atrial (LA) physiology during a standardized VM (VMs) in normal subjects.

Methods

The VMs was performed in 50 healthy subjects (M:F 38:12; age 40 ± 12 y.; HR 70 ± 11 bpm; BSA 1.81 ± 11 m2), instructed to forcefully exhale for 20 seconds without an initial deep breath into a tube connected to a sphygmomanometer, maintaining a 25-35 mmHg pressure. The VM was repeated 2 times at 5 minute intervals to record sequentially in the apical 4-chamber view: 1. LV and LA volumes; 2. Transmitral flow velocities. LA diastolic reservoir function (LAres) was calculated as: (maximum – minimum volume) / minimum volume x 100. Results. During the VMs, in all subjects LV indexed end-diastolic (-14 ± 7 ml/m2, -31 ± 15 %) and end-systolic (-6 ± 4 ml/m2, -31 ± 18 %) volumes, and stroke volume index (-9 ± 5 ml/m2, -30 ± 15 %) decreased similarly with unchanged LV ejection fraction %, and LA maximum and minimum volume indices both decreased (respectively -8 ± 6 ml/m2, -3 ± 3 ml/m2;-32 ± 25 %) with high variability. Mitral peak E velocity also decreased (-22 ± 13 cm/s, -27 ± 14 %) in all subjects, whereas peak A velocity change varied, such that a "pseudo-abnormal" decrease of E/A > 0.5 was seen in 18 subjects (37 %). At baseline, this subgroup had lower heart rate (66 ± 11 vs 73 ± 10 bpm, p= .026), higher LAres (193 ± 67 vs 145 ± 47 %, p= .006), lower peak A velocity (50 ± 12 vs 58 ± 12 cm/s, p= .04) and higher E/A (1.8±.6 vs 1.4±.3, p= .004). During VMs, LV and LA volumes decreased similarly in all subjects, but increase in heart rate was higher (12 ± 8 vs 6 ± 5 bpm, p= .023), and peak A wave increased instead of decreasing (20 ± 20 % vs -8 ± 18 %, p< .001) in the subjects with "pseudo-abnormal" decrease of E/A. During VMs, decrease in E/A was mainly determined (regression analysis, r: .76, p= .029) by baseline LAres (B= -.71) and change in LAres during VMs (B= -.47), whereas an increase in peak A velocity (r: .46, p= .031) was mainly determined by degree of HR increase (B= .41) and baseline LV EF (B= .3).

Conclusions

During VMs, a "pseudo-abnormal" decrease of the E/A velocity ratio is present in almost 40 % of normal subjects, and is determined by the interplay of the baseline diastolic compliance and the increase in systolic function of the LA during VM. These results may influence the accuracy of the VMs in the detection of increased LV filling pressures in patients.

Influence of intertidal recreational fisheries and 'bouchot' mussel culture on bivalve recruitment

In coastal environments, fishing and aquaculture may be important sources of disturbance to ecosystem functioning, the quantification of which must be assessed to make them more sustainable. In the Chausey Archipelago, France, recreational fishing and commercial shellfish farming are the only two evident anthropogenic activities, dominated by bivalve hand-raking and 'bouchot' mussel culture, respectively. This study evaluates the impact of both activities on bivalve recruitment dynamics by comparing primary recruitment intensity (short-term effect) and recruitment efficiency (medium-term effect) by sampling bivalves in reference (undisturbed) and disturbed (i.e. subjected to hand-raking or in 'bouchot' mussel culture areas) parcels throughout and at the end of the recruitment season, respectively. Specific hypotheses evaluated were that (H1) bivalve hand-raking negatively affects bivalve recruitment and that (H2) 'bouchot' mussel culture promotes bivalve recruitment. Patterns in bivalve community structure in reference parcels (i.e. natural pattern) differed between initial and final recruitment, underlining the great importance of early post-settlement processes, particularly secondary dispersal. Primary recruitment intensity was inhibited in hand-raking parcels whereas it was promoted in 'bouchot' mussel culture parcels, but the effect on recruitment efficiency was muted for both activities due to post-settlement processes. Nevertheless, the importance of effects that occur during the first step of recruitment should not be ignored as they may affect bivalve communities and induce immediate consequences on the trophic web through a cascade effect. Finally, it is highlighted that hand-raking damages all life stages of the common cockle Cerastoderma edule, one of the major target species, suggesting that this activity should be managed with greater caution than is currently done.

Caulerpenyne from Caulerpa taxifolia has an antiproliferative activity on tumor cell line SK-N-SH and modifies the microtubule network

Caulerpenyne, the major secondary metabolite synthesized by the green marine alga Caulerpa taxifolia, is cytotoxic against several cell lines. To identify possible targets of this toxin, we investigated the effect of caulerpenyne on the neuroblastoma SK-N-SH cell line. Caulerpenyne induced an inhibition of SK-N-SH cell proliferation with an IC50 of 10 +/- 2 microM after 2 hr of incubation. We observed no blockage in G2/M phase and an increase in cell death. On immunofluorescence microscopy, caulerpenyne affected the microtubule network in SK-N-SH cell line; we observed a loss of neurites and a compaction of the microtubule network at the cell periphery. In vitro, after 35 min of incubation, caulerpenyne inhibited the polymerization of pig brain purified tubulin or microtubule proteins, with an IC50 of 21 +/- 2 microM and 51 +/- 6 microM respectively. Analysis by electron microscopy indicated that caulerpenyne induced aggregation of tubulin, which may be responsible for inhibition of microtubule polymerization and bundling of residual microtubules.

In vitro effect of cryptophycin 52 on microtubule assembly and tubulin: molecular modeling of the mechanism of action of a new antimitotic drug

Cryptophycin 52 (C52) is a new synthetic compound of the cryptophycin family of antitumor agents that is currently undergoing clinical evaluation for cancer chemotherapy. The cryptophycin class of compounds acts on microtubules. This report details the mechanism by which C52 substoichiometrically inhibits tubulin self-assembly into microtubules. The inhibition data were analyzed through a model described by Perez-Ramirez [Perez-Ramirez, B., Andreu, J. M., Gorbunoff, M. J., and Timasheff, S. N. (1996) Biochemistry 35, 3277-3285]. We thereby determined the values of the apparent binding constant of the tubulin-C52 complex to the end of a growing microtubule (K(i)) and the apparent binding constant of C52 to tubulin (K(b)). The binding of C52 depended on tubulin concentration, and binding induced changes in the sedimentation pattern of tubulin, which indicates that C52 induces the self-association of tubulin and tubulin aggregates other than microtubules. Using analytical ultracentrifugation and electron microscopy, we show that C52 induces tubulin to form ring-shaped oligomers (single rings). We also show that C52 inhibits the formation of double rings from either GTP- or GDP-tubulin. In addition, the advances made by electron crystallography in understanding the structure of the tubulin and the microtubule allowed us to visualize the putative binding site of C52 and to reconstruct C52-induced ring oligomers by molecular modeling.

Incidence of Reye's syndrome in France: a hospital-based survey

At the time of the study no information was available in France about the incidence of Reye's Syndrome (RS) and no warnings about RS and aspirin. The objective was to evaluate the incidence of RS in France by a hospital-based study. For a period of 1 year from November 1995 to November 1996, all French paediatric departments were required to report any child under 15 years with unexplained noninflammatory encephalopathy (i.e., CDC consciousness level stage I or deeper with normal CSF) and a threefold (or greater) increase in serum aminotransferase and/or ammonia. All suspected cases were classified by a panel of experts as probable RS or excluded RS. In 10% of randomly selected paediatric departments we checked that every suspected case had been reported. Forty-six suspected cases were reported during the year of the survey, of which 14 were classified as RS. Five of these 14 cases had a metabolic disorder. Nine children were definitively diagnosed as having RS (i.e., an estimated incidence of RS of 0.79/1,000,000 children, i.e., below 15/year). Eight children had been exposed to aspirin, four to aspirin alone and four to aspirin and acetaminophen. On the basis of these results the incidence of RS in France in 1996-1997 was not substantially different from that of countries where warning labels were already in use, but it was higher than in the US after 1994. This was probably due to the reduction in aspirin prescription in France because of warnings in Europe and the US and also because many cases of RS are now identified as metabolic disease. On the basis of these results and because the relationship between aspirin and RS has already been proved, public and professional warnings concerning RS on aspirin-containing products in cases of varicella and viral febrile illness have been adopted by the French Drugs Agency.

Proteolysis of microtubule associated protein 2 and sensitivity of pancreatic tumours to docetaxel

We have studied the state of microtubule associated protein 2 (MAP2) in the pancreatic ductal adenocarcinomas P03 and P02 (sensitive and refractory to docetaxel respectively) since they express the corresponding mRNA and MAP2-related peptides. Immunohistochemical localization showed that in tumour P03 the MAP2-related peptides are highly expressed and confined to the epithelial malignant cells while in P02 the Intensity of the immunostaining is lower. However, anti alpha-tubulin staining followed a similar pattern suggesting that the net amount of macromolecular structures in the sensitive tumour is higher than in the refractory one. This may explain its higher sensitivity to docetaxel, because tubulin assembled into microtubules is the target of the drug. We found that protein extracts from both tumours differed in their proteolytic activity on rat brain MAP2. Since the proteolysis pattern obtained was similar to the one produced by Cathepsin D, we studied the effect of MAP2 proteolysed by this enzyme on microtubule formation in vitro. Proteolysis was found to increase the tendency of tubulin to assemble into macromolecular structures (microtubules and aggregates) in the presence of docetaxel. This suggests that in vivo proteolysis of MAP2 might increase microtubule alterations and potentiate the antitumour effect of docetaxel.

Determinants of forward pulmonary vein flow: an open pericardium pig model

OBJECTIVE

To elucidate determinants of pulmonary venous (PV) flow.

BACKGROUND

Right ventricular (RV) systolic pressure (vis a tergo), left atrial (LA) relaxation and left ventricular (LV) systole and relaxation (vis a fronte) have been suggested as determinants of the pulmonary venous (PV) anterograde Doppler flow velocities, but their relative contributions to those flow velocities have not been quantified.

METHODS

We analyzed, by multiple regression analysis, the determinants of PV anterograde velocities in an open-pericardium, paced (70 and 90 beats/min) pig model in which LA afterload was modified by creating LV regional ischemia (left anterior descending coronary artery constriction). We measured high fidelity LA, LV and RV pressures and Doppler flow velocities (epicardial echocardiography). We calculated LV tau, LA relaxation (a through x pressure difference divided by time, normalized by a pressure), LA peak v through x and RV systolic through LA peak v (RVSP-v) pressure differences, LV ejection fraction, long-axis shortening, stroke volume (LV outflow integral x outflow area) and LA four-chamber dimensions, Doppler transmitral and PV flow velocities and velocity-time integrals.

RESULTS

Left ventricular regional ischemia increased mildly LA y trough pressure (8 +/- 1 vs. 6 +/- 1 mm Hg, p = 0.001). Left ventricular stroke volume (coefficient: 0.5 cm/ml, SE: 0.2, p = 0.005) and LA peak v pressure (coefficient: -0.8 cm/mm Hg, SE: 0.3, p = 0.008) determined the PV total systolic integral. Left atrial relaxation determined both PV early systolic peak velocity and integral (coefficient: -0.8 cm/mm Hg, SE: 0.3, p = 0.04). Left atrial maximum area (coefficient: 2 cm(-1) SE: 0.7, p = 0.01) and RVSP-v (coefficient: 0.1 cm/mm Hg, SE: 0.05, p = 0.03) determined the late systolic integral. The PV total systolic integral determined both PV early diastolic peak velocity and integral (coefficient: 1.2, SE: 0.2, p = 0.001).

CONCLUSIONS

In an experimental model of LV acute ischemia of limited duration, the main independent predictors of PV systolic anterograde flow velocities are LA relaxation and compliance (LA peak v pressure) and LV systole--all vis a fronte factors. In the setting of mildly increased LA pressures, PV systolic flow (LA reservoir filling) is an independent predictor of PV early diastolic flow (LA early conduit).

Rapid diagnosis and management of thoracic aortic dissection and intramural haematoma: a prospective study of advantages of multiplane vs. biplane transoesophageal echocardiography

AIMS

The purposes of this study were to compare the accuracy of multiplane vs. biplane transoesophageal echocardiography (TEE) in the diagnosis of aortic dissection and aortic intramural haematoma, and to test whether these techniques provide all the diagnostic information required to make management decisions.

METHODS AND RESULTS

Fifty-eight consecutive patients with clinically suspected aortic dissection were studied with multiplane TEE; all cases who required surgery underwent intraoperative monitoring with multiplane TEE. The following multiplane TEE data were analysed: the angle between current and 0 degrees plane at which each view was obtained; the success rate in the evaluation of true and false lumen, entry tear, coronary artery involvement, aortic regurgitation, pericardial effusion. Advantages of multiplane over biplane TEE have been evaluated by the demonstration of usefulness of views obtained in planes other than 0 degrees-20 degrees or 70 degrees-110 degrees, assuming that with manipulation of a biplane probe a 20 degrees arc could be added to the conventional horizontal and vertical planes. On the basis of TEE findings, aortic dissection was confirmed in 36 cases (18 type A, 12 type B, six intramural haematoma). The specificity and sensitivity of TEE in terms of the presence or absence of aortic dissection or intramural haematoma were 100%. An additional clinical value of multiplane over biplane TEE in the evaluation of ascending aorta, aortic arch, entry tears and coronary artery involvement was demonstrated. All cases with type A aortic dissection or intramural haematoma involving the ascending aorta had an operation that was performed immediately after the diagnosis (hospital mortality, 13%). Patients with type B aortic dissection were treated medically; 25% of these cases were operated later (hospital mortality, 0%).

CONCLUSIONS

Multiplane and biplane TEE have excellent and similar accuracies in the evaluation of aortic dissection and intramural haematoma. Multiplane TEE improves the visualization of coronary arteries, aortic arch and entry tears; it appears to be an ideal method as the sole diagnostic approach before surgery in type A aortic dissection.

G protein-linked receptors: pharmacological evidence for the formation of heterodimers

By means of the expression of two chimeric receptors, alpha(2)/M(3) and M(3)/alpha(2), in which the carboxy-terminal receptor portions, containing transmembrane domains VI and VII, were exchanged between the alpha(2C)-adrenergic and the M(3) muscarinic receptor, it has been shown that G protein-coupled receptors are able to interact functionally with each other at the molecular level to form (hetero)dimers. In the present study, we tested the hypothesis that interaction between two different muscarinic receptor subtypes can lead to the formation of a heterodimeric muscarinic receptor with a new pharmacological profile. Initially, muscarinic M(2) or M(3) wild-type receptors were expressed together with gene fragments originating from M(3) or M(2) receptors, respectively. Antagonist binding, performed with pirenzepine and tripitramine, revealed the presence of two populations of binding sites: one represents the wild-type M(2) or M(3) receptors, the other the heterodimeric M(2)/M(3) receptor. In another set of experiments, we constructed a point mutant M(2) receptor M(2) (Asn404-->Ser), in which asparagine 404 was replaced by serine. Although this receptor alone did not show any binding for N-[(3)H]methylscopolamine (up to 2 nM), when cotransfected with M(3), it resulted in the rescue of a high-affinity binding for tripitramine. These findings demonstrate that M(2) and M(3) muscarinic receptor subtypes can cross-interact with each other and form a new pharmacological heterodimeric receptor.

Left atrial relaxation and left ventricular systolic function determine left atrial reservoir function

BACKGROUND

Determinants of left atrial (LA) reservoir function and its influence on left ventricular (LV) function have not been quantified.

METHODS AND RESULTS

In an open-pericardium, paced (70 and 90 bpm) pig model of LV regional ischemia (left anterior descending coronary constriction), with high-fidelity LV, LA, and RV pressure recordings, we obtained the LA area with 2D automated border detection echocardiography, LA pressure-area loops, and Doppler transmitral flow. We calculated LV tau, LA relaxation (a-x pressure difference divided by time, normalized by a pressure), and stiffness (slope between x and v pressure points of v loop). Determinants of total LA reservoir (maximum-minimum area, cm(2)) were identified by multiple regression analysis. Different mean rates of LA area increase identified 2 consecutive (early rapid and late slow) reservoir phases. During ischemia, LV long-axis shortening (LAS, LV base systolic descent) and LA reservoir area change decreased (7.3+/-0.3 [SEM] versus 5.6+/-0.3 cm(2), P<0.001) and LA stiffness increased (1.6+/-0.3 versus 3.1+/-0.3 mm Hg/cm(2), P=0.009). Early reservoir area change depended on LA mean ejection rate (LA area at ECG P wave minus minimum area divided by time; multiple regression coefficient=0.9; P<0.001) and relaxation (coefficient=4.9 cm(2)xms/s; P<0.001). Late reservoir area change depended on LAS (coefficient=8 cm/s; P<0.001). Total reservoir filling depended on LA stiffness (coefficient=-0.31 cm(4)/mm Hg; P=0. 001) and cardiac output (coefficient=0.001 cm(2)xmin/L; P=0.002). The strongest predictor of cardiac output was LA reservoir filling (coefficient=301 L/minxcm(2); P<0.001). The v loop area was determined by cardiac output, LV ejection time, tau, and early transmitral flow.

CONCLUSIONS

Two (early and late) reservoir phases are determined by LA contraction and relaxation and LV base descent. Acute LV regional ischemia increases LA stiffness and impairs LA reservoir function by reducing LV base descent.

Activation mechanism of human oxytocin receptor: a combined study of experimental and computer-simulated mutagenesis

The aim of this study was to investigate the molecular changes associated with the transition of the human oxytocin receptor from its inactive to its active states. Mutation of the conserved arginine of the glutamate/aspartate-arginine-tyrosine motif located in the second intracellular domain gave rise to the first known constitutively active oxytocin receptor (R137A), whereas mutation of the aspartic acid located in the second transmembrane domain led to an inactive receptor (D85A). The structural features of the constitutively active and inactive receptor mutants were compared with those of the wild type in its free and agonist-bound states. The results suggest that, although differently triggered, the activation process induced by the agonist and the activating mutation are characterized by the opening of a solvent exposed site formed by the 2nd intracellular loop, the cytosolic extension of helix 5, and the 3rd intracellular loop; on the contrary, the D85A mutation prevents oxytocin from triggering the opening of a cytosolic site. On the basis of these findings, we hypothesize that this cytosolic crevice plays an important role in G protein recognition. Finally, comparative analysis of the free- and agonist-bound forms of the wild-type oxytocin receptor and alpha1B adrenergic receptor suggests that the highly conserved polar amino acids and the seven helices play similar mechanistic roles in the different G protein-coupled receptors.

Apomorphine has a potent antiproliferative effect on Chinese hamster ovary cells

Apomorphine is a potent non selective agonist at the D1 and D2 dopamine receptors acting both pre- and post-synaptically. In this report we describe a novel function of apomorphine, independent from its dopaminergic activity. Apomorphine inhibits Chinese hamster ovary (CHO)-K1 cell proliferation in a dose-dependent manner. The EC50 of apomorphine-induced inhibition of CHO-K1 cell proliferation determined by cell counting was 3.24 +/- 0.07 microM. Remarkably, the dose-response curve obtained by measuring the incorporation of [3H]thymidine was practically identical to the previous one giving an EC50 of 3.52 +/- 0.04 microM. The dopaminergic antagonists SCH23390 and spiperone at a concentration of 10 microM (well beyond their Kd values for the dopamine D1- and D2-like receptors respectively) were not able to antagonize the effect of apomorphine on CHO-K1 cell proliferation. Apomorphine exerts its effect early during incubation; CHO-K1 cells exposed to apomorphine for a period as short as 1 h and then allowed to grow for three days were significantly reduced in number with respect to untreated control cells. After four hours of exposition to apomorphine (10 microM) the antiproliferative effect was similar to that seen when this compound was present in the bath for all three days. Concentrations of apomorphine higher than 10 microM induced cell death, and the colony was completely destroyed at 50 microM. Cytometric analyses showed a significant accumulation of CHO-K1 cells in the G2/M phase.

Changes in porcine transmitral flow velocity pattern and its diastolic determinants during partial coronary occlusion

OBJECTIVES

To define the mechanical determinants of transmitral flow and the effect of heart rate during regional ischemia.

BACKGROUND

Myocardial ischemia changes the transmitral flow velocity pattern due to disease-induced changes in the heart's diastolic properties.

METHODS

Regional ischemia was produced in 12 pigs by partially occluding the left anterior descending coronary artery until segment-length shortening in the ischemic region fell by 20%. Transmitral flow velocity patterns and their determinants were measured under two conditions, baseline and ischemia, at two heart rates, 70 and 90 beats/min.

RESULTS

Regional ischemia had a significant effect on two determinants of filling: relaxation, which was slower, and chamber stiffness, which increased. These changes were associated with reduced contractility and increased myocardial stiffness, resulting in an early transmitral flow pattern that was flatter and narrower, but no change in the late flow pattern. Moderate increases in heart rate accelerated relaxation and decreased atrioventricular pressure gradient but had no effect on contractility or myocardial or chamber stiffness, resulting in an early transmitral flow pattern that was flatter and narrower and an increased late flow velocity.

CONCLUSIONS

This model of regional ischemia leads to a flatter and narrower early transmitral flow velocity pattern and no change in late flow due to a combination of slowed left ventricular relaxation and increased chamber stiffness. Reflex increases in heart rate that accompany ischemia tend to mask this effect.

[Cardiovascular abnormalities in Kawasaki disease. An Italian prospective study]

We report a prospective study performed over a 9 year period in 96 children with Kawasaki disease (mean age 35 +/- 29 months), 84 of whom < 5 years of age. The male/female ratio was 1.5 (57/39). A total of 38 patients had cardiac involvement, including flattened T waves in the ECG (10 patients), pericardial effusion (6 patients), myocarditis (1 patient), and coronary artery aneurysms (25 patients; frequency of aneurysms: 26%). All patients were evaluated during the acute phase (first month) of the illness. The first echocardiographic examination was performed 15 days (range 4.30 days) from the appearance of fever, and coronary aneurysms were observed in 23 patients; in 2 patients, however, aneurysms appeared later (2 and 6 months). Aneurysms were small (< or = 4.5 mm) in 12, medium (4.5-7 mm) in 11, and large (> 7 mm) in 12 patients. Male sex (p = 0.02), age < 12 months (p = 0.005), ESR (p = 0.001), platelet count (p = 0.009), and pericardial effusion (p = 0.02) were significantly related to the presence of aneurysm. Among females, incidence of aneurysms was significantly higher in infants < 12 months than in older patients (60 vs 6%, p < 0.001). Intravenous immunoglobulin treatment was started early (within 10 days) in 61 patients and late (> 10 days) in 22. Compared to late treatment, early i.v. immunoglobulin treatment was associated with smaller aneurysms and higher regression rate (67 vs 28%, p < 0.05). No difference was observed concerning frequency and number of dilated vessels as related to therapeutical regimens. Total i.v. immunoglobulin dose (2 g/kg) was administered over 1-2 days in 26 patients (scheme I) or over 4-5 days in 58 (scheme II). Frequency of aneurysms was significantly lower in patients treated early (p = 0.02). No myocardial infarctions or deaths occurred at short- or long-term follow-up.

Heat-shock protein 90 (hsp90) binds in vitro to tubulin dimer and inhibits microtubule formation

Hsp90 interacts with steroid hormone receptors, protein kinases, and cytoskeletal proteins. The mode of action of hsp90 on microtubules and tubulin has not been investigated. Using isolated purified hsp90 and isolated tubulin, we demonstrated in vitro by difference absorption and fluorescence spectroscopy that hsp90 bound to tubulin with an apparent affinity constant of 5 x 10(5) M-1, assuming an apparent stoichiometry of 1 at 25 degrees C. Using microcalorimetry, we found a delta H of -9.8 +/- 0.8 kJ.mol-1. The binding of hsp90 to tubulin was confirmed by a sedimentation assay. Moreover, we showed that hsp90 inhibited tubulin polymerisation.

Antagonist binding profile of the split chimeric muscarinic m2-trunc/m3-tail receptor

Recent evidence suggests that G-protein-coupled receptors can behave as multiple subunit receptors, and can be split into parts, maintaining their binding ability. Transfection of a truncated muscarinic m2 receptor (containing transmembrane domains I-V, named m2-trunc) with a gene fragment coding for the carboxyl-terminal receptor portion of the muscarinic m3 receptor (containing transmembrane domains VI and VII, named m3-tail) results in the formation of a binding site with a high affinity for the muscarinic ligand N-[3H]methylscopolamine. In this paper we analyse the antagonist binding profile of this chimeric m2-trunc/m3-tail receptor in comparison with the wild-type muscarinic m2 and m3 receptors. While many of the substances tested had an intermediate affinity for the chimeric m2-trunc/m3-tail receptor compared with m2 and m3, some compounds were able to distinguish between the chimeric m2-trunc/m3-tail receptor on the one hand and the m2 or the m3 receptor on the other. Among them, tripitramine (a high-affinity M2 receptor antagonist) bound to the m2-trunc/m3-tail receptor with the same affinity as m2, but it bound to the m3 receptor with a 103-fold lower affinity; pirenzepine (a selective muscarinic M1 receptor antagonist) bound to the chimeric receptor with an affinity that was 12- and 3-fold higher than that of m2 and m3, respectively. The results of this study demonstrate that the chimeric m2-trunc/m3-tail receptor has a pharmacological profile distinct from that of the originating muscarinic m2 and m3 receptors.

Effect of sample volume location on Doppler-derived transmitral inflow velocity values in 288 normal subjects 20 to 80 years old: an echocardiographic, two-dimensional color Doppler cooperative study

The aims of the study were to evaluate in a population of 288 normal subjects 20 to 80 years old (1) the normal values of the indexes of the mitral flow velocity pattern measured either at the tips of the mitral leaflets or at the annulus; (2) whether there was a significant difference between the values obtained at the tips compared with those measured at the mitral annulus; (3) the correlation with aging between the indexes measured in the two different positions; and (4) whether certain physiological variables have different effects on diastolic function measured in the two different positions. The highest values were always measured at the tips of the mitral leaflets (p < 0.05); only atrial filling fraction, E acceleration time, and E deceleration velocity had higher values when measured at the level of the annulus (p < 0.05). The A-wave peak velocity had the same mean value when measured at both the tips and at the annulus. A significant difference in the correlation between parameters measured at the tips of the mitral leaflets with age and at the annulus (with age) was observed for the following parameters: (1) peak E velocity, E integral, total integral and E acceleration showed better correlation with age when measured at the annulus (p < 0.02); (2) peak A velocity and A integral showed better correlation with age when measured at the tips of the mitral leaflets (p < 0.001). Multivariate analysis showed that age was the variable that had the most influence on diastolic function parameters; heart rate had less influence on the diastolic function indexes.

Pergolide binds tightly to dopamine D2 short receptors and induces receptor sequestration

Pergolide is an ergotamine derivative with potent D1 and D2 receptor activity. In this study we showed that pergolide binds tightly to dopamine D2 short receptors, as indicated by the long period of occupancy of the receptors after washing. Furthermore, pergolide induces receptor internalization to a larger extent than dopamine, seeing that no recycling of the receptors to the plasma membrane was observed for either agonist. The dissociation of pergolide from dopamine receptors occurs during the endocytotic process, leaving the receptors accessible to [3H]methylspiperone. Pergolide is a lipophilic compound that can reach and compete with [3H]methylspiperone for binding to sequestered receptors. If internalized receptors are still a target for drug action, pergolide could be a suitable compound of therapeutic interest in cases where receptor sequestration could prevent dopamine efficacy, as in levodopa therapy.

The active GTP- and ground GDP-liganded states of tubulin are distinguished by the binding of chiral isomers of ethyl 5-amino-2-methyl-1,2-dihydro-3-phenylpyrido[3,4-b]pyrazin-7-yl carbamate

NSC 613862 (S)-(-) and NSC 613863 (R)-(+) are the two chiral isomers of ethyl-5-amino-2-methyl-1,2-dihydro-3-phenylpyrido[3, 4-b]pyrazin-7-yl carbamate. Both compounds bind to tubulin in a region that overlaps the colchicine site. They induce formation of abnormal polymers from purified GTP-Mg-tubulin, the active assembly form of tubulin, in glycerol-free buffer with magnesium [De Ines, C., Leynadier, D., Barasoain, I., Peyrot, V., Garcia, P., Briand, C., Rener, G. A., and Temple, C., Jr. (1994) Cancer Res. 54, 75-84]. In this study, we observed that the S-isomer can promote polymerization of GDP-tubulin, the inactive assembly-incompetent form of tubulin, into nonmicrotubular structures at a critical protein concentration of 1 mg/mL (12 mM MgCl2). Neither the R-isomer nor colchicine have this ability. By electron microscopy, these tubulin polymers showed the same poorly defined filamentous structure when GDP-tubulin or GTP-Mg-tubulin were used. By HPLC measurements, we demonstrated that a dissociated GTP hydrolysis and exchange of nucleotide occurred during the isomer-induced abnormal assembly. Both isomers inhibited the Mg2+-induced tubulin self-association leading to 42 S double ring formation from GTP-Mg-tubulin or GDP-tubulin. Measurement of their binding under nonassociation conditions revealed a 3-fold decrease in the apparent equilibrium binding constant of the R-isomer to GDP-tubulin relative to GTP-Mg-tubulin. For the S-isomer, the decrease in the binding constant was less pronounced. Binding data, analyzed in terms of a system of linked conformational and association equilibria, provide evidence that the active ("straight") rather than the inactive ("curved") conformation of tubulin differentially recognizes these ligands. Whereas binding of colchicine to tubulin is well-known to induce GTP hydrolysis, this is the first case in which the interaction of a ligand with the colchicine site is shown to be sensitive to the presence of GDP or GTP at the distant nucleotide binding site.