[Morphological and functional diagnostics of coronary artery disease by computed tomography]

Computed tomography coronary angiography (cCTA) is a safe option for the noninvasive exclusion of significant coronary stenoses in patients with a low or moderate pretest probability for coronary artery disease (CAD). Furthermore, it also allows functional and morphological assessment of coronary stenoses. The European Society of Cardiology (ESC) guidelines on the diagnosis and management of chronic coronary syndrome published in 2019 have strengthened the importance of cCTA in this context and for this reason it has experienced a considerable upgrade. The determination of the Agatston score is a clinically established method for quantifying coronary calcification and influences the initiation of drug treatment. With technologies, such as the introduction of electrocardiography (ECG)-controlled dose modulation and iterative image reconstruction, cCTA can be performed with high image quality and low radiation exposure. Anatomic imaging of coronary stenoses alone is currently being augmented by innovative techniques, such as myocardial CT perfusion imaging or CT-fractional flow reserve (FFR) but the clinical value of these methods merits further investigation. The cCTA could therefore develop into a gatekeeper with respect to the indications for invasive coronary diagnostics and interventions.

Characteristics of aortic root and vascular anatomy in bicuspid versus tricuspid aortic valve stenosis in patients undergoing transcatheter aortic valve implantation

Background

Transcatheter aortic valve implantation (TAVI) is being increasingly performed in patients with bicuspid aortic valve stenosis (AS).

Objectives

This study sought to compare aortic root and ilio-femoral artery characteristics and clinical outcomes in patients with bicuspid versus tricuspid AS from the Bicuspid AS TAVI multicenter registry.

Methods

88 patients with bicuspid AS and 213 matched patients with tricuspid AS were referred for pre-procedural computed tomography (CT) evaluation before TAVI. We performed a detailed assessment of aortic root anatomy: size of the annulus, sinus of Valsalva (SoV), sino-tubular junction (STJ); we also determined the dimensions of aorta, left subclavian, and ilio-femoral arteries.

Results

Patients with bicuspid AS had significantly larger aortic root dimensions, (annulus mean diameter: 25.5±2.9 mm vs. 23.7±2.4 mm, SoV mean diameter: 35.3±4.7 mm vs. 32±4.4mm, STJ mean diameter: 31.5±4.9 mm vs. 27.6±3.5 mm; respectively) than patients with tricuspid AS (P value for all <0.001), even after adjustment for their larger BSA and height. Dimensions of ascending aorta, left subclavian artery, and ilio-femoral arteries were also consistently larger in bicuspid than in tricuspid AS morphology.

Conclusions

Patients with bicuspid AS had significantly larger aortic root dimensions, larger ascending aorta, subclavian artery and ilio-femoral arteries even after adjustment for their BSA and height.

Funding Acknowledgement

Type of funding source: Public hospital(s). Main funding source(s): Rabin Medical Center

Differences in valve morphology between patients with bicuspid and tricuspid aortic valve

Background

Bicuspid aortic valve (BAV) patients represent a significant minority of severe aortic stenosis (AS) patients undergoing transcutaneous aortic valve implantation (TAVI). These patients demonstrate anatomic differences compared to tricuspid aortic valve (TAV). Ethnicity is associated with different valve morphologies characterized by Siever's classification.

Purpose

We aim to evaluated the prevalence of BAV subtypes and the differences in valve morphology and aortic root dimensions between BAV and TAV in patients undergoing computed tomography (CT) before TAVI.

Methods

In five Israeli medical centers, 131 patients with BAV and 674 patients with TAV underwent CT angiography. BAV morphology was defined according to the number of commissures and raphe, following Siever's classification. Aortic root dimensions were measured at the level of the aortic annulus, sinus of Valsalva (SOV), and sino-tubular junction (STJ). Finally, Agatston score unit (AU) for valve calcification was evaluated.

Results

Type 0 accounted for 27% (36/131), Type IA for 63% (82/131), Type IC for 9% (12/131), and Type 2 for 1% (1/131). Calcium score in BAV patients was significantly higher compared to TAV patients, 4000±1897 vs. 2152±1216 AU; respectively (P<0.001). Distance from the annulus to the left main coronary artery was greater in BAV patients compared to TAV (13.8±3.6 mm vs. 12.8±2.8 mm; respectively, P<0.001), similar distance from annulus to right coronary artery was observed in BAV and TAV patients (16.7±3.7 mm vs. 15±3 mm; respectively, P<0.001). Aortic annulus perimeter was greater in BAV than TAV patients (79.3±11mm vs. 73±8.7mm, respectively, P<0.001), as well as SOV perimeter (35.7±4.5mm vs. 32±3.7mm, respectively, P<0.001), and STJ perimeter (32.3±5mm vs. 27±3.3 mm; respectively, P<0.001).

Conclusion

In Israel, AS patients showed more frequently type 1A BAV. BAV patients have larger aortic root dimensions and higher calcium burden than TAV patients.

Funding Acknowledgement

Type of funding source: None

Dentists' perceptions of their professional roles regarding referrals within primary dental care in England: a qualitative study

OBJECTIVE

To describe dentists' perceptions of their professional roles, including the reasons why they make, accept or decline patient referrals within primary dental care in England.

BASIC RESEARCH DESIGN

Qualitative semi-structured interviews, conducted via Skype, telephone or face-to-face. Transcripts were analysed using thematic analysis and typologies were developed.

PARTICIPANTS

Ten general dental practitioners (GDPs) and 12 community dentists working in England.

RESULTS

Five main themes were identified: professional independence, the nature of dental care, the business of dentistry, obscure rules and 'no man's land'. This final theme described a notional gap between GDPs' and community dentists' responsibilities towards vulnerable people, who were perceived by participants to include frail older people, anxious and socially marginalised adults and children with high levels of disease. Three typologies of dentists were generated. 'Entrepreneurs' felt no allegiance to the National Health Service and no obligation to treat vulnerable patients. 'Altruistic carers' were committed to caring for exceptionally deserving patients. 'Pragmatic carers' tried to provide relational dental care (time and emotional support) for vulnerable patients but encountered discouraging systemic barriers.

CONCLUSION

Dentists' perceptions of their roles may influence whether and how they provide access to primary dental care for vulnerable people through referral systems. Access issues may exacerbate the oral health inequalities experienced by vulnerable groups. Based upon the findings, approaches are proposed that may encourage and enable the dental workforce to support vulnerable people actively to receive primary dental care.

P1370 Correlation of aortic stenosis by integrated transthoracic and transesophageal echocardiography with calcium score

Funding Acknowledgements

None

BACKGROUND

Aortic stenosis (AS) classification depends on left-ventricular ejection-fraction (LVEF <≥50%), aortic valve area (AVA<≥1cm2), mean pressure gradient (MG<≥40mmHg), peak velocity<≥400 cm/sec, and stroke-volume index (SVI<≥35ml/m2). Aortic Valve Agatston CT score (AVC) correlates with AS severity by trans-thoracic echo (TTE), but its association with AS severity determined by integrated TTE and TEE is unknown.

PURPOSE

We investigated correlation of AVC with dichotomous AS grouping by Integrated TTE + TEE vs TTE only.

METHODS

64 TAVI candidates underwent sequential TTE and TEE, of which 24 underwent coronary CT within 4 months. Based on recommended conservative vs invasive treatment implication (A/B respectively), AS types were aggregated separately by TTE or Integrated TTE-TEE into two groups: Group-A (Moderate AS and Normal-Flow Low-Gradient), and Group-B (High-Gradient, Low-EF Low-Flow Low-Gradient, and Paradoxical Low-Flow Low-Gradient). Continuous and dichotomous AVC correlation (cutoffs based on guidelines) with echo binary classification was then determined.

RESULTS

Patients were 81.1(77.3-84.6) years old, 18(48.6%) were women, and had LVEF of 60% (49-65). AVC-score distribution in the two AS A/B Groups by two echo modalities is presented in the boxplot Figure. Only classification by TTE held discriminative accuracy in A/B grouping, with Area-Under-Curve of 0.736 (CI 0.57-0.9), and optimal threshold value of 1946 AU having 77% sensitivity and 74% specificity. Compared with AVC dichotomous classification, integrated TTE + TEE upgraded AS class (from A to B) in 5/6 (83.3%) patients vs 12/18 (66.7%) in which it downgraded AS class from B to A.

CONCLUSIONS

Aortic valve calcification correlates well with AS class dichotomized by operative implication through conventional TTE but not through integrated TTE + TEE. Our preliminary results appear to be caused by initial selection bias of patients in whom coronary CT performance was deemed to be justified by the treating physician rather than reflect a true better correlation between CT score and AS assessment by TTE vs by integrated TTE + TEE.

Abstract P1370 Figure.

COVID-19 Mortality in Transplant Recipients

BACKGROUND

Organ transplant recipients are vulnerable to multiple infectious agents and in a world with a circulating SARS-CoV-2 virus, it would be expected that patients who are immunosuppressed would have higher mortality.

OBJECTIVE

To determine the COVID-19 mortality in transplant recipients.

METHODS

We conducted a search in PubMed and Google scholar databases using the keywords for COVID-19 and transplantation. All related studies between January 1, 2020 and May 7, 2020 were reviewed. All relevant published articles related to COVID-19 in transplant recipients were included.

RESULTS

46 articles were included; they studied a total of 320 transplant patients-220 kidney transplant recipients, 42 liver, 19 heart, 22 lung, 8 HSCT, and 9 dual organ transplant recipients. The overall mortality rate was 20% and was variable among different organs and different countries. 65 transplant recipients died of complications attributable to COVID-19; 33 were males (15% of males in this cohort), 8 females (8% of females in this cohort), and 24 whose sex was not determined. They had a median age of 66 (range: 32-87) years. The median transplantation duration was 8 years (range: 30 days to 20 years). The most frequent comorbidity reported was hypertensions followed by diabetes mellitus, obesity, malignancy, ischemic heart disease, and chronic obstructive pulmonary disease. The most frequent cause of death reported was acute respiratory distress syndrome.

CONCLUSION

Transplant recipients in our cohort had a high mortality rate. However, outcomes were not the same in different countries based on outbreak settings. Mortality was noted in elder patients with comorbidities.

P6160Long term prognosis of intramural course of coronary arteries in patients with hypertrophic cardiomyopathy assessed by coronary CT angiography

Background

The prognostic value of an intramural course of the coronary arteries detected by coronary CTA in patients with hypertrophic cardiomyopathy (HCM) is not well-known.

Purpose

To evaluate in patients with HCM, who were referred for coronary computed tomography angiography (CTA), whether an intramural course of a coronary artery is associated with a worse outcome compared to HCM patients without an intramural course of the coronary arteries.

Methods

The study population consisted of 92 patients with HCM who were referred for coronary CTA and who did not have obstructive CAD. During follow-up, the occurrence of unstable angina pectoris that required hospitalization, myocardial infarction, and all-cause mortality was evaluated (i.e. adverse cardiac events).

Results

Using coronary CTA, 57 patients (62%) had an intramural course of coronary arteries. Patients with HCM were followed over 5.5±3.5 years. The composite of adverse cardiac events occurred in 17/57 (29.8%) patients with, and 11 out of 35 (31.4%) patients without intramural course (P=0.87). The event rate of unstable angina pectoris requiring hospitalization (28.1% vs. 22.9%), myocardial infarction (1.8% vs. 8.6%), and all case mortality (0.0% vs. 0.0%) was similar in patients with and without an intramural course.

Conclusion

Intramural course of coronary arteries in patients with HCM was frequently observed by coronary CTA, but it was not associated with worse cardiovascular clinical outcome.

P3378Differences in valve morphology and aortopathy between patients with bicuspid and tricuspid aortic valves: a Computed Tomography Study

Background

Transcatheter aortic valve implantation (TAVI) has been shown safe and feasible in patients with bicuspid aortic valve (BAV) morphology. Evaluation of differences in valve morphology and aortic root dimensions in patients with BAV in comparison to patients with tricuspid aortic valve (TAV) is important for the spread of TAVI in patients with BAV.

Purpose

The present study evaluated the prevalence of BAV subtypes and the differences in valve morphology and aortic root dimensions between BAV and TAV in patients undergoing computed tomography (CT) before TAVI.

Methods

In five medical centers in Israel, 104 patients (69±13.5 years) with BAV and 105 patients (81±8.22 years) with TAV underwent CT angiography. BAV morphology was defined according to the number of commissures and raphe following Siever's classification. Functional BAV was defined as 3 cusps with focal fusion of 1, 2, or 3 commissures. Aortic root dimensions were measured at the level of the aortic annulus, sinus of Valsalva (SOV), sino-tubular junction (STJ), and ascending aorta (AA). Membranous septum (MS) length was measured in coronal view. The volume and agatston score of aortic valve calcification were evaluated.

Results

Type 0 account for 22% (23/104), type IA for 58% (60/104), Type IC for 9% (9/104), functional BAV for 11% (12/104). Type IB and II were not found in the studied population. As compared with TAV, patients with BAV have significantly larger aortic annulus area, SOV area, STJ area and AA Area; however, the ellipticity index of aortic annulus, SOV, STJ, and AA were similar. MS length was significantly smaller in patients with BAV compared to patients with TAV (6.4±2.3 mm vs. 8.1±2.7mm; retrospectively; P<0.001) and the volume of aortic valve calcifications was significantly higher in BAV compared to TAV patients: 2.3±1.6 ml3 vs. 1.4±1.2 ml3 retrospectively; P=0.003).

Conclusions

In Israel, patients with BAV showed more frequently type 1A BAV. BAV patients have larger aortic root dimensions than patients with TAV without difference in regard to the ellipticity index. MS length was smaller and the amount of aortic leaflet calcifications was higher in patients with BAV. These findings may have important impact on procedural outcome.

Horizontal drying fronts in films of colloidal dispersions: influence of hydrostatic pressure and collective diffusion

The origin and time evolution of heterogeneities in drying colloidal films is still a matter of debate. In this work, we studied the behaviour of horizontal drying fronts in a 1D configuration. The effects of hydrostatic pressure and collective diffusion of charged particles, neglected so far, were introduced. We made use of the new simulation tool based on cellular automata we recently presented (Langmuir 2015 & 2017). To check the simulation results, measurements of film profiles in the wet state and drying front velocities were performed with silica colloids. It was shown that taking hydrostatic pressure into account much improves agreement between theory and experiment. On the other hand, the simulation showed that collective diffusion slows down the drying fronts, even more when the Debye length is increased. This latter effect remains to be checked experimentally. This work opens the way to further improvements of theory and simulation, notably 2D and 3D simulations.

The burden and epidemiology of community-acquired central nervous system infections: a multinational study

Risk assessment of central nervous system (CNS) infection patients is of key importance in predicting likely pathogens. However, data are lacking on the epidemiology globally. We performed a multicenter study to understand the burden of community-acquired CNS (CA-CNS) infections between 2012 and 2014. A total of 2583 patients with CA-CNS infections were included from 37 referral centers in 20 countries. Of these, 477 (18.5%) patients survived with sequelae and 227 (8.8%) died, and 1879 (72.7%) patients were discharged with complete cure. The most frequent infecting pathogens in this study were Streptococcus pneumoniae (n = 206, 8%) and Mycobacterium tuberculosis (n = 152, 5.9%). Varicella zoster virus and Listeria were other common pathogens in the elderly. Although staphylococci and Listeria resulted in frequent infections in immunocompromised patients, cryptococci were leading pathogens in human immunodeficiency virus (HIV)-positive individuals. Among the patients with any proven etiology, 96 (8.9%) patients presented with clinical features of a chronic CNS disease. Neurosyphilis, neurobrucellosis, neuroborreliosis, and CNS tuberculosis had a predilection to present chronic courses. Listeria monocytogenes, Staphylococcus aureus, M. tuberculosis, and S. pneumoniae were the most fatal forms, while sequelae were significantly higher for herpes simplex virus type 1 (p < 0.05 for all). Tackling the high burden of CNS infections globally can only be achieved with effective pneumococcal immunization and strategies to eliminate tuberculosis, and more must be done to improve diagnostic capacity.

A bridging stent to surgery in patients with esophageal and gastroesophageal junction cancer has a dramatic negative impact on patient survival: A retrospective cohort study through data acquired from a prospectively maintained national database

This study aimed to assess the impact of esophageal stenting on postoperative complications and survival in patients with obstructing esophageal and gastroesophageal junction (GEJ) cancer. All patients treated without neoadjuvant therapy that had an R0-resection performed for esophageal and GEJ cancer between January 2003 and December 2010 were identified from a prospectively maintained database. Data on stenting, postoperative mortality, morbidity, recurrence-free survival, complications, and length of hospital stay were collected. Kaplan-Meier plots for survival and recurrence-free survival curves were constructed for R0 resected patients. Data were compared between the stent and no-stent group by nonparametric tests. Two hundred seventy three consecutive R0 resected patients with esophageal or GEJ cancer were identified. Of these patients, 63 had a stent as a bridge to surgery. The male/female ratio was 2.64 (198/75) with a median age in the stent group (SG) of 65.1 versus 64.3 in the no stent group (NSG). Patients were comparable with respect to gender, age, smoking, TNM-classification, oncological treatment, hospital stay, tumor location, and histology. The median survival in the SG was 11.6 months compared with 21.3 months for patients treated without a bridging stent (P < 0.001). There were no statistically significant differences in 30-day mortality between the two groups, but NSG patients exhibited a significantly better two-year survival (P = 0.017). The median recurrence-free survival was 9.1 months for the SG compared with 15.2 months for the NSG. The use of a stent as a bridging procedure to surgery in patients treated without neaoadjuvant therapy for an esophageal or GEJ cancer that later underwent R0 resection decreased the two year survival and the recurrence-free survival.

Drying Mechanisms in Plasticized Latex Films: Role of Horizontal Drying Fronts

This article presents studies on the drying kinetics of latexes with particles made progressively softer by adding increasing amounts of a plasticizer, in relation to speeds of horizontal drying fronts and particle deformation mechanisms. Global drying rates were measured by gravimetry, and speeds of the horizontal fronts were recorded using a video camera and image processing. Particle deformation mechanisms were inferred using the deformation map established by Routh and Russel (RR). This required precise measurements of the rheological properties of the polymers using a piezorheometer. The results show that latexes with softer particles dry slowly, but in our systems, this is not due to skin formation. A correlation between global drying rates and speeds of horizontal fronts could be established and interpreted in terms of the evolution of mass transfer coefficients of water in different areas of the drying system. The speeds of the horizontal drying fronts were compared with the RR model. A remarkable qualitative agreement of the curve shapes was observed; however, the fit could not be considered good. These results call for further research efforts in modeling and simulation.

Simulation of Latex Film Formation Using a Cell Model in Real Space: Vertical Drying

This paper presents a simulation tool applied to latex film formation by drying, a hybrid between a classical numerical resolution method using finite differences and cellular automata, and making use of object-oriented programming. It consists of dividing real space into cells and applying local physical laws to simulate the exchange of matter between neighboring cells. In a first step, the simulation was applied to the simple case of vertical drying of a latex containing only one population of monodisperse particles and water. Our results show how the distribution of latex particles evolves through the different drying stages due to a combination of diffusion, convection, and particle deformation. While repulsive interactions between the particles tend to favor homogeneous distributions in the first drying stage, concentration gradients that develop in opposite ways can be observed depending on the drying regime. The distributions, calculated in various cases, reproduce and extend several theoretical results and are in qualitative agreement with some experimental findings.

Restless legs syndrome in stroke patients

BACKGROUND

Restless legs syndrome (RLS) is associated with cerebrovascular risk factors, but its possible association with cerebrovascular disease has yielded conflicting results.

OBJECTIVE

This was a case-control, in-hospital study to evaluate the association between RLS and acute stroke or transient ischemic attack (TIA).

METHODS

We evaluated patients hospitalized with acute stroke/TIA and an age and gender 2:1 frequency-matched control group, for the presence of RLS.

RESULTS

Twenty-two of 149 patients (15%) and 10 of 298 controls (3%) suffered from RLS (p <0.0001). A multivariate logistic regression model employing cerebrovascular risk factors as predictors, that is, hypertension, hyperlipidemia, diabetes, and body mass index (BMI), determined that stroke/TIA was significantly associated with RLS with odds ratio for RLS among patients with stroke/TIA versus controls of 7.60 (95% confidence interval (CI): 2.07-27.87; p = 0.002). Another multivariate logistic regression model adjusting for possible RLS risk factors, that is, hypertension, hyperlipidemia, diabetes, BMI, anemia, and reduced renal function, determined that stroke/TIA was significantly associated with RLS with odds ratio of 6.85 (95% CI: 6.85-1.79; p = 0.005). Stepwise logistic regression with hypertension, hyperlipidemia, diabetes, BMI, anemia, and reduced renal function as potential predictors revealed that only stroke/TIA predicted RLS with similar odds ratio to the RLS-based multivariate model of 6.54 (95% CI: 2.63-16.27; p <0.0001).

CONCLUSIONS

Examining stroke patients while in hospital allowed us to conclude that RLS and acute stroke/TIA are significantly associated. However, the cross-sectional design did not allow for the determination of a causative relationship between the two.

The effect of glutathione on 2-hydroxyethylmethacrylate cytotoxicity and on resin-dentine bond strength

AIM

To evaluate the influence of reduced glutathione (GSH) application on 2-hydroxyethylmethacrylate (HEMA) cytotoxicity on rat pulpal cells and evaluate the effect of etched-dentine treatment with GSH on the immediate microtensile bond strength (μTBS) of etch-and-rinse adhesive.

METHODOLOGY

The cytotoxicity of 10 mmol L(-1) HEMA, 10 mmol L(-1) HEMA + 1 mmol L(-1) GSH, 10 mmol L(-1) HEMA + 5 mmol L(-1) GSH and 10 mmol L(-1) HEMA + 10 mmol L(-1) GSH was compared (6 h and 24 h). Cells viability was measured by means of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, followed by morphological observation of cells. Etched-dentine surfaces were rinsed and treated with one of the following solutions: 2% GSH, 5% GSH or 10% GSH, bonded with Adper Single Bond Plus (3M, ESPE, St. Paul, MN, USA) and restored with resin composite. The control group received no GSH treatment. After 1 day of water-storage at 37 °C, the specimens were subjected to μTBS testing. Cytotoxicity and μTBS data were analysed by one-way anova and Tukey post hoc tests (P < 0.05).

RESULTS

There were significant differences between the groups. HEMA elicited a remarkable toxic effect. 10 mmol L(-1) GSH prevented HEMA-induced damage at both exposure times. Whilst 5 mmol L(-1) GSH lost its protective effect at 24-h exposure time and 1 mmol L(-1) GSH showed no protective effect at both exposure times, GSH had no significant effect on the immediate μTBS; however, 5% GSH had higher bond strength value when compared to 10% GSH (P = 0.003).

CONCLUSION

Controlled concentrations of GSH had a protective effect against HEMA cytotoxicity. GSH had neither positive nor negative influence on μTBS.

Phenotypic characterization of chicken inbred lines that differ extremely in growth, body composition and egg production traits

Abstract. The development of phenotypically and genetically divergent inbred chicken lines as simplified genetic models facilitates the identification of genes and contributes to the elucidation of gene functions. In this study, we characterized a New Hampshire (NH) population with its partial inbred derivative, New Hampshire inbred (NHI), and a White Leghorn inbred line (WL77). Both NHI and WL77 lines were inbred after selection for high meat yield or low egg weight, respectively. The inbreeding levels in NHI and WL77 are about 86 % and 100 %, respectively. Animals of the NHI line grew twice as fast, were about two times as heavy at 20 weeks, and deposited 9.3 times as much fat as WL77. NHI females reached sexual maturity, indicated by age at first egg, earlier, had a 35 % higher egg production ratio, and their eggs were on average 6 g heavier compared to WL77 females. The NHI and WL77 lines were extremely different for most traits, which makes them suitable for cross-bred experiments to map quantitative trait loci and identify genes contributing to the observed differences.

First-trimester ultrasound examination and the outcome of monochorionic twin pregnancies

OBJECTIVE

To refine the incidence of abnormal first-trimester ultrasound measurements and their correlation with the outcome of monochorionic diamniotic pregnancies.

METHODS

First-trimester crown-rump length (CRL) and nuchal translucency thickness (NT) measurements were studied in three subgroups of a total of 200 monochorionic twin gestations referred to our center between June 2002 and February 2006. Intertwin CRL discordance was defined as > 10% and the 95th percentile of NT thickness for gestational age was used. The first group of 103 consecutive unselected monochorionic diamniotic twin pregnancies was prospectively followed up from 11-14 weeks onwards, throughout the pregnancy. The second group of 136 nonconsecutive monochorionic diamniotic twin pregnancies including 64 that developed TTTS was studied retrospectively. The third group of 100 consecutive cases of TTTS studied retrospectively for the correlation between first trimester measurements and staging and timing of occurrence of TTTS.

RESULTS

In group 1, the incidence of TTTS was 5 in 103 (5%, 95CI [0.7-9]). Large intertwin CRL discordance and increased NT were correlated with perinatal death. In group 2, no significant association was found between first-trimester parameters and the development of TTTS but discordance in early second trimester biometry and Doppler were. In group three, a positive correlation was found between the intertwin discordance in CRL and early occurrence of TTTS before 20 weeks of gestation (p = 0.02).

CONCLUSION

Monochorionic twin gestations who ultimately develop TTTS may exhibit intertwin difference in growth as early as 11-14 weeks of gestation. The earlier the discordance the earlier the development of the disease.

[Congenital dilatation of extrahepatic bile ducts]

The authors present 3 cases of congenital dilatation of extrahepatic bile ducts and performed a review of the bibliography of this frequent pathology. They concluded that the diagnosis could be difficult in the pre-operatory and the cholangeographic methods are the beds. The treatment of choice in the actuality is the ++quistectomy with hepaticojejunostomy in "Y of Roux".

Single-channel currents from recombinant NMDA NR1a/NR2D receptors expressed in Xenopus oocytes

We have investigated the single-channel and whole-cell behaviour of recombinant N-methyl-D-aspartate (NMDA) receptors formed from NR1a and NR2D receptor subunits expressed in Xenopus oocytes. The EC50 for apparent steady-state activation of NR1a/NR2D receptors by glutamate was 450 nM, while extracellular MG2+ produced a voltage-dependent block of glutamate responses with an IC50 of 440 microM at -70 mV. At negative holding potentials glutamate-activated NR1a/NR2D single-channel currents, in 0.85 mM external Ca2+, had slope conductances of 35 pS for the main level, and 17 pS for the sublevel; direct transitions occurred between these two conductance levels. On average 35 pS events had mean open times of 1.01 +/- 0.04 ms, whereas the mean open times of 17 pS events were consistently longer (1.28 +/- 0.06 ms). In 5 mM external Ca2+ the larger conductance level was reduced to 20 pS whereas in Ca(2+)-free solutions it was increased to 50 pS. The frequency of transitions between the main and subconductance levels showed temporal asymmetry: 35-17 pS transitions were more frequent (61%) than 17-35 pS transitions. This asymmetry was not affected by alterations in the external Ca2+ concentration (up to 5 mM). In conclusion, the NR1a/NR2D channel is, like NR1a/NR2C, a 'low conductance' NMDA channel, but it can be distinguished from NR1a/NR2C channels on the basis of transition asymmetry and differences in the open times of its main and sub-conductance levels.