Epoch-based Entropy for Early Screening of Alzheimer’s Disease

In this paper, we introduce a novel entropy measure, termed epoch-based entropy. This measure quantifies disorder of EEG signals both at the time level and spatial level, using local density estimation by a Hidden Markov Model on inter-channel stationary epochs. The investigation is led on a multi-centric EEG database recorded from patients at an early stage of Alzheimer’s disease (AD) and age-matched healthy subjects. We investigate the classification performances of this method, its robustness to noise, and its sensitivity to sampling frequency and to variations of hyperparameters. The measure is compared to two alternative complexity measures, Shannon’s entropy and correlation dimension. The classification accuracies for the discrimination of AD patients from healthy subjects were estimated using a linear classifier designed on a development dataset, and subsequently tested on an independent test set. Epoch-based entropy reached a classification accuracy of 83% on the test dataset (specificity = 83.3%, sensitivity = 82.3%), outperforming the two other complexity measures. Furthermore, it was shown to be more stable to hyperparameter variations, and less sensitive to noise and sampling frequency disturbances than the other two complexity measures.

Identification of the binding site of the σ 54 hetero-oligomeric FleQ/FleT activator in the flagellar promoters of Rhodobacter sphaeroides

Expression of the flagellar genes in Rhodobacter sphaeroides is dependent on one of the four sigma-54 factors present in this bacterium and on the enhancer binding proteins (EBPs) FleQ and FleT. These proteins, in contrast to other well-characterized EBPs, carry out activation as a hetero-oligomeric complex. To further characterize the molecular properties of this complex we mapped the binding sites or upstream activation sequences (UASs) of six different flagellar promoters. In most cases the UASs were identified at approximately 100 bp upstream from the promoter. However, the activity of the divergent promoters flhAp-flgAp, which are separated by only 53 bp, is mainly dependent on a UAS located approximately 200 bp downstream from each promoter. Interestingly, a significant amount of activation mediated by the upstream or contralateral UAS was also detected, suggesting that the architecture of this region is important for the correct regulation of these promoters. Sequence analysis of the regions carrying the potential FleQ/FleT binding sites revealed a conserved motif. In vivo footprinting experiments with the motAp promoter allowed us to identify a protected region that overlaps with this motif. These results allow us to propose a consensus sequence that represents the binding site of the FleQ/FleT activating complex.

Orbital and millennial Antarctic climate variability over the past 800,000 years

A high-resolution deuterium profile is now available along the entire European Project for Ice Coring in Antarctica Dome C ice core, extending this climate record back to marine isotope stage 20.2, approximately 800,000 years ago. Experiments performed with an atmospheric general circulation model including water isotopes support its temperature interpretation. We assessed the general correspondence between Dansgaard-Oeschger events and their smoothed Antarctic counterparts for this Dome C record, which reveals the presence of such features with similar amplitudes during previous glacial periods. We suggest that the interplay between obliquity and precession accounts for the variable intensity of interglacial periods in ice core records.

Orbital and millennial Antarctic climate variability over the past 800,000 years

A high-resolution deuterium profile is now available along the entire European Project for Ice Coring in Antarctica Dome C ice core, extending this climate record back to marine isotope stage 20.2, approximately 800,000 years ago. Experiments performed with an atmospheric general circulation model including water isotopes support its temperature interpretation. We assessed the general correspondence between Dansgaard-Oeschger events and their smoothed Antarctic counterparts for this Dome C record, which reveals the presence of such features with similar amplitudes during previous glacial periods. We suggest that the interplay between obliquity and precession accounts for the variable intensity of interglacial periods in ice core records.

Orbital and Millennial Antarctic Climate Variability over the Past 800,000 Years

A high-resolution deuterium profile is now available along the entire European Project for Ice Coring in Antarctica Dome C ice core, extending this climate record back to marine isotope stage 20.2, approximately 800,000 years ago. Experiments performed with an atmospheric general circulation model including water isotopes support its temperature interpretation. We assessed the general correspondence between Dansgaard-Oeschger events and their smoothed Antarctic counterparts for this Dome C record, which reveals the presence of such features with similar amplitudes during previous glacial periods. We suggest that the interplay between obliquity and precession accounts for the variable intensity of interglacial periods in ice core records.

Predicting activities without computing descriptors: graph machines for QSAR

We describe graph machines, an alternative approach to traditional machine-learning-based QSAR, which circumvents the problem of designing, computing and selecting molecular descriptors. In that approach, which is similar in spirit to recursive networks, molecules are considered as structured data, represented as graphs. For each example of the data set, a mathematical function (graph machine) is built, whose structure reflects the structure of the molecule under consideration; it is the combination of identical parameterised functions, called "node functions" (e.g. a feedforward neural network). The parameters of the node functions, shared both within and across the graph machines, are adjusted during training with the "shared weights" technique. Model selection is then performed by traditional cross-validation. Therefore, the designer's main task consists in finding the optimal complexity for the node function. The efficiency of this new approach has been demonstrated in many QSAR or QSPR tasks, as well as in modelling the activities of complex chemicals (e.g. the toxicity of a family of phenols or the anti-HIV activities of HEPT derivatives). It generally outperforms traditional techniques without requiring the selection and computation of descriptors.

Clinical Performance with the Levitronix Centrimag Short-term Ventricular Assist Device

BACKGROUND

The Levitronix ventricular assist device (VAD) is a centrifugal pump designed for extracorporeal support and that operates without mechanical bearings or seals. The rotor is magnetically levitated so that rotation is achieved without friction or wear, which seems to minimize blood trauma and mechanical failure. The aim of this study is to report our early results with the Levitronix Centrimag device.

METHODS

Between June 2003 and April 2005, 18 patients (pts) were supported using the Levitronix at our institution. Fourteen were male. Mean age was 40.3 +/- 18.3 (range 8 to 64) years. Indications for support at implantation were: post-cardiotomy cardiogenic shock in 12 cases (Group A), and bridge to decision regarding long-term ventricular support in 6 cases (Group B).

RESULTS

Mean support time was 14.2 +/- 15.2 days for all patients (range 1 to 64 days). Operative (30-day) mortality was 50% (9 pts). Six pts were in Group A and 3 pts were in Group B. Overall, 6 pts (33%) were discharged home and are presently alive and well (mean follow-up 13 months, range 5 to 17 months). Bleeding requiring re-operation occurred in 8 cases (44%), cerebral thromboembolism in 1 and pulmonary embolism in 1. There were no device failures.

CONCLUSIONS

The Levitronix functioned well and proved to be useful in patients with extremely poor prognosis previously considered non-suitable for a long-term assist device. The device was technically easy to implant and manage. There was no device dysfunction and complications were acceptable or consistent with other devices. Survival to explant or a definitive procedure (VAD or transplantation) was encouraging.

La paragonimose pleuropulmonaire

Paragonimiasis is a food borne zoonosis due to a trematode belonging to the genus Paragonimus. Although present throughout the world, about 90% of the cases occur in Asia where around 20 million people are infected. The parasitic cycle is complex with two different intermediate hosts. Man is infected by ingesting the raw or undercooked flesh of the second host - a freshwater crab or prawn - or possibly of a paratenic mammal host (wild boar), which contains the infective larval stage metacercariae that reaches the lung which is the main target organ. Epidemiological, pathological, and clinical aspects are reviewed. The main symptoms are protracted cough, and recurrent "benign" hemoptysis. Abnormal pleuro-pulmonary imaging features are constant, but protean and non-specific, leading to frequent confusion with tuberculosis. Diagnosis is easily achieved by ova search in the sputum or pleural fluid, or by serology. Evolution is usually considered benign, although not well known. Finally, praziquantel is the effective first choice treatment. Some paradoxical aspects of this disease are underlined such as: underdiagnosis despite a very simple diagnostic procedure, or opposite tendencies according to location, either extinction or re-emergence.

Probable allergic reaction to cyclosporin and early formation of thrombi on a pulmonary artery catheter: two unusual complications during bilateral lung transplantation

We describe a patient who had two rare complications (a probable allergic reaction to cyclosporin and the early formation of a right atrial thrombus) during bilateral sequential single lung transplantation performed under the one anaesthetic. The thrombus, discovered at the end of the procedure, was then removed under cardiopulmonary bypass. Peroperative transoesophageal echocardiography was useful in providing critical diagnostic and therapeutic information.

How to be a gray box: dynamic semi-physical modeling

A general methodology for gray-box, or semi-physical, modeling is presented. This technique is intended to combine the best of two worlds: knowledge-based modeling, whereby mathematical equations are derived in order to describe a process, based on a physical (or chemical, biological, etc.) analysis, and black-box modeling, whereby a parameterized model is designed, whose parameters are estimated solely from measurements made on the process. The gray-box modeling technique is very valuable whenever a knowledge-based model exists, but is not fully satisfactory and cannot be improved by further analysis (or can only be improved at a very large computational cost). We describe the design methodology of a gray-box model, and illustrate it on a didactic example. We emphasize the importance of the choice of the discretization scheme used for transforming the differential equations of the knowledge-based model into a set of discrete-time recurrent equations. Finally, an application to a real, complex industrial process is presented.

The N terminus of FliM is essential to promote flagellar rotation in Rhodobacter sphaeroides

FliM is part of the flagellar switch complex. Interaction of this protein with phospho-CheY (CheY-P) through its N terminus constitutes the main information relay point between the chemotactic system and the flagellum. In this work, we evaluated the role of the N terminus of FliM in the swimming behavior of Rhodobacter sphaeroides. Strains expressing the FliM protein with substitutions in residues previously reported in Escherichia coli as being important for interaction with CheY showed an increased stop frequency compared with wild-type cells. In accordance, we observed that R. sphaeroides cells expressing FliM lacking either the first 13 or 20 amino acids from the N terminus showed a stopped phenotype. We show evidence that FliMDelta13 and FliMDelta20 are stable proteins and that cells expressing them allow flagellin export at levels indistinguishable from those detected for the wild-type strain. These results suggest that the N-terminal region of FliM is required to promote swimming in this bacterium. The role of CheY in controlling flagellar rotation in this organism is discussed.

The hook gene (flgE) is expressed from the flgBCDEF operon in Rhodobacter sphaeroides: study of an flgE mutant

In this work we identified the flgE gene encoding the flagellar hook protein from Rhodobacter sphaeroides. Our results show that this gene is part of a flagellar cluster that includes the genes flgB, flgC, flgD, flgE, and flgF. Two different types of mutants in the flgE gene were isolated, and both showed a Fla(-) phenotype, indicating the functionality of this sequence. Complementation studies of these mutant strains suggest that flgE is included in a single transcriptional unit that starts in flgB and ends in flgF. In agreement with this possibility, a specific transcript of approximately 3.5 kb was identified by Northern blot. This mRNA is large enough to represent the complete flgBCDEF operon. FlgE showed a relatively high proline content; in particular, a region of 12 amino acids near the N terminus, in which four prolines were identified. Cells expressing a mutant FlgE protein lacking this region showed abnormal swimming behavior, and their hooks were curved. These results suggest that this region is involved in the characteristic quaternary structure of the hook of R. sphaeroides and also imply that a straight hook, or perhaps the rigidity associated with this feature, is important for an efficient swimming behavior in this bacterium.

Surgery of acute type A dissection: what have we learned during the past 25 years?

Every acute dissection involving the ascending aorta (Stanford type A) must undergo emergency surgical repair. However, the surgical techniques must vary according to the clinical presentation of the patients or the anatomical patterns observed. Furthermore, surgery is generally difficult because of the poor condition of the aortic tissues. To reduce those difficulties many technical artifacts have been described. In 1977, we proposed the use of gelatin-resorcin-formalin (GRF) biological glue to reinforce the suture areas. From January 1977 to July 1999, 212 patients (pts) (152 males and 60 females) aged from 15 to 80 years (mean age: 54 +/- 11 years) underwent an emergency operation for type A aortic dissection. One-hundred-seventy-eight pts (84%) were operated on within 4 hours after being referred to the hospital. Twenty-eight pts (13.2%) had Marfan's syndrome. In 44 patients (20.7%), the aortic valve was replaced either independently (6 cases--2.8%) or by means of a composite graft (38 cases--17.9%). Because of the location of the intimal tear, the aortic replacement was extended to the transverse arch in 61 pts (28.7%). Hospital mortality amounts to 21.6% (46 pts), 25% in pts with arch replacement and 19.4% in pts without arch replacement (n.s). Analysis of hospital mortality demonstrates that the main causes of death were cardiac tamponade, neurologic disorders and visceral malperfusion. One-hundred-sixty-six pts were discharged and surveyed from 5 months to 22 years postoperatively (mean follow-up: 85 +/- 66 months). During this period of time, 25 pts (15%) had to be reoperated for a total of 33 reoperations. Seven pts (28%) died at reoperation. Using univariate analysis, the presence of Marfan's syndrome (p < 0.05) and absence of arch replacement (p < 0.02) were determinant risk factors for reoperation. Emergency (p < 0.01) and thoraco-abdominal replacement (p < 0.04) were determinant riskfactors for death at reoperation. The freedom from reoperation (Kaplan-Meier, CI: 95%) is 96% (90-98), 87% (79-92), 80% (70-88), 66% (51-78) at 1, 5, 10 and 15 years respectively. A total of 39 pts (24.3%) died during follow-up. The presence of Marfan's syndrome (p < 0.01), reoperation (p < 0.02), stroke (p < 0.05), and cardiac failure (p < 0.05) were determinant risk factors of late mortality. The late survival rate (K-M. C.I.: 95%), including hospital mortality, is 71% (64-77), 66% (58-73), 56% (47-64), 46% (36-56), 37% (28-44) at 1, 10, 15 and 20 years, respectively. From our experience extending over more than 23 years, GRF glue has proved to be extremely useful, making the procedure much easier and safer. Nevertheless, many factors are of importance in the pre-, intra- and postoperative management of the patients. Cardiac tamponade and visceral malperfusion must be properly diagnosed and treated. During aortic repair, the main intimal tear must be resected. The transverse arch must be checked and replaced whenever necessary. The aortic valve should be preserved whenever possible. During CPB, perfusing the aorta in the regular antegrade manner seems to dramatically reduce the rate of malperfusion. The quality of the first emergency operation seems to have a major influence on the late results, especially concerning the rate of late reoperations and aortic ruptures. However, those late results depend also on the patient's basic condition, particularly in Marfan patients.

[Surgery of heart insufficiency]

Apart from heart transplantation for heart failure, the problem arises of which surgical approach should be adopted to treat this disorder. Ischemic heart disease can be surgically managed in three ways: via bypass, the Dor procedure, or by isolated or associated mitral plasty; however, cases of enlarged heart disease can only be surgically treated in two ways: i.e., by mitral plasty, or by the Batista procedure. In cases of ischemic heart disease, the following conditions must be present for coronary bypass: the patients should have an adequate contractile myocardial reserve, that is to say the left ventricle should not be greatly enlarged (< 80 mm in telediastole) or a cardiac output reserve, and there should not be any sign of over-high pulmonary hypertension (an index of > 1.6 or a pulmonary pressure of < 45); an assessment of myocardial viability should then be carried out, mainly based on a thallium fixation at rest and on echographically determined doubtamine-associated stress. In the present study, the mortality rate in a series of 260 patients was 6.3% for subjects aged under 70 years old, with an actuarial survival rate of 82% at one year post-surgery, and of 70% at five years. The Dor procedure can be used in the treatment of dyskinesia, which is now practically non-existent, but also in cases of acute akinesia with resulting left ventricular dysfunction. The aim of this technique is to alter the form of a cavity that has become ovoid to an elliptical form via the insertion of a circular endoventricular patch. The results reported for this technique show an improvement in functional class and ejection fraction. Finally, the technique for repairing mitral failure is more complicated than the two previous methods, as it requires a dynamic assessment of mitral failure, which is best carried out by an evaluation of echographically determined stress. Any mitral failure of ischemic origin of > grade 2 can be corrected during bypass surgery by ring insertion, thereby effecting a simple annuloplasty. On the other hand, the assessment of cases of enlarged heart disease is more complicated, and it is more difficult to carry out palliative surgery. The mitral plasty procedure proposed by Bolling is the technique of choice for patients with severe mitral failure, in general when the ventricle is not too enlarged. However, surgery involving the reduction in size of the left ventricle (the Batista procedure) always includes mitral plasty, and may be performed in patients with a very enlarged ventricle (> 70 mm), in general with moderate mitral failure. These two techniques have been critically assessed both as regards results and when they should be adopted, and their limitations have also been discussed. In conclusion, there are valid surgical alternatives to heart transplantation in cases of heart failure that does not respond to medical treatment, and they should probably be seriously considered before any decision is made to perform heart transplantation. These results appear encouraging, particularly in terms of functional class and left ventricular function, but there are conflicting results for hemodynamic improvement. As regards survival, it is not yet possible to propose prospective randomized trials to compare medical treatment with these surgical techniques. However, further development of these techniques is bound to occur, and an ever-widening gap will exist between the limited number of cases requiring transplantation and the more complex surgical approaches adopted in future, such as permanent circulatory backup or xenografts.

sigma(54) Promoters control expression of genes encoding the hook and basal body complex in Rhodobacter sphaeroides

Gene expression of the flagellar system is tightly controlled by external stimuli or intracellular signals. A general picture of this regulation has been obtained from studies of Salmonella enterica serovar Typhimurium. However, these regulatory mechanisms do not apply to all bacterial groups. In this study, we have investigated regulation of the flagellar genetic system in Rhodobacter sphaeroides. Deletion analysis, site-directed mutagenesis, and 5'-end mapping were conducted in order to identify the fliO promoter. Our results indicate that this promoter is recognized by the factor sigma(54). Additionally, 5'-end mapping of the flgB and fliK transcripts suggests that these mRNAs are also transcribed from sigma(54) promoters. Finally, we showed evidence that suggests that fliC transcription is not entirely dependent on the presence of a complete basal body-hook structure. Our results are discussed in the context of a possible regulatory hierarchy controlling flagellar gene expression in R. sphaeroides.

Assessment of systematic use of intraoperative transesophageal echocardiography during cardiac surgery in adults: a prospective study of 203 patients

OBJECTIVE

To determine the usefulness of systematic intraoperative transesophageal echocardiography in a cardiac surgical unit.

DESIGN

Open prospective observational survey.

SETTING

University Hospital.

PARTICIPANTS

Consecutive adult patients (n = 203) undergoing elective or urgent cardiac operations.

MEASUREMENTS AND MAIN RESULTS

Pre-cardiopulmonary bypass imaging yielded unsuspected findings in 26 patients (12.8%) and changed the planned surgery in 22 patients (10.8%). Transesophageal echocardiography modified the diagnosis in eight patients (17%) operated on for mitral valvulopathy, in seven patients (15.5%) with aortic valvular disease, in four patients (4.6%) with coronary artery disease, in five patients operated on for thoracic aorta diseases regardless of their localization (18.5%), and in two miscellaneous cases. On the basis of the data obtained from the transesophageal echocardiography carried out at the end of cardiopulmonary bypass, an immediate reintervention was required in five cases (2.5%).

CONCLUSIONS

It is concluded that systematic intraoperative transesophageal echocardiography significantly affected decision making in this cardiac surgical unit. Its routine use in all cardiac surgical patients is recommended.

Long term results of mitral valve repair: posterior papillary muscle repositioning versus chordal shortening

OBJECTIVE

Mitral valve repair is considered as the gold standard to treat mitral regurgitation. However anterior leaflet prolapse in the posterior paramedial and paracommissural area remains a challenging problem. Indeed several elongated chordae may arise from a single posterior papillary muscle head which does not allow safe separate chordal shortening (CS). We therefore suggest use of papillary muscle repositioning in such cases.

METHODS

In a cohort of 180 mitral valve repair performed between 1989 and May 1998, we have retrospectively studied 100 consecutive patients who underwent anterior leaflet repair in the posterior paramedial and paracommissural area. Group I (n = 60) had posterior papillary muscle repositioning (PPMR) and group II (n = 40) had CS. There was no statistical difference between the two groups concerning age, functional class and left ventricular function. Etiology was similar in both groups, degenerative process being predominant. At echocardiogram, regurgitation was graded 3.4/4 in both groups. There was no statistical difference concerning preoperative ejection fraction, end systolic and end diastolic left ventricular diameter.

RESULTS

There were no in-hospital deaths in group I and two deaths in group II not related to mitral valve repair. Mean follow up is 26.4 +/- 24.2 months in group I and 46.1 +/- 28.8 months in group II. No patient was lost to follow up. Severe mitral regurgitation was not observed. Mean regurgitation at follow up was 0.8 +/- 0.7 in group I and 0.8 +/- 0.8 in group II (P = n.s.); there was no statistical difference between the two groups concerning postoperative ejection fraction, end systolic and end diastolic left ventricular diameter. There was no late cardiac death in either group and there were no thromboembolic events. Actuarial survival rate is 100% and 94.4% in group I and 92% and 84.4% in group II at 2 and 6 years, respectively.

CONCLUSION

This experience shows that PPMR provides as good longterm results as CS to repair anterior leaflet prolapse in posterior paramedial and paracommissural area with lesser morbidity and mortality.

Interaction of FliI, a component of the flagellar export apparatus, with flagellin and hook protein

FliI is a key component of the flagellar export apparatus in Salmonella typhimurium. It catalyzes the hydrolysis of ATP which is necessary for flagellar assembly. Affinity blotting experiments showed that purified flagellin and hook protein, two flagellar axial proteins, interact specifically with FliI. The interaction of either of the two proteins with FliI, increases the intrinsic ATPase activity. The presence of either flagellin or hook protein stimulates ATPase activity in a specific and reversible manner. A Vmax of 0.12 nmol Pi min-1 microgram-1 and a Km for MgATP of 0.35 mM was determined for the unstimulated FliI; the presence of flagellin increased the Vmax to 0.35 nmol Pi min-1 microgram-1 and the Km for MgATP to 1.1 mM. The stimulation induced by the axial proteins was fully reversible suggesting a direct link between the catalytic activity of FliI and the export process.

Cardiac metaiodobenzylguanidine uptake in patients with moderate chronic heart failure: relationship with peak oxygen uptake and prognosis

OBJECTIVES

This prospective study was undertaken to correlate early and late metaiodobenzylguanidine (MIBG) cardiac uptake with cardiac hemodynamics and exercise capacity in patients with heart failure and to compare their prognostic values with that of peak oxygen uptake (VO2).

BACKGROUND

The cardiac fixation of MIBG reflects presynaptic uptake and is reduced in heart failure. Whether it is related to exercise capacity and has better prognostic value than peak VO2 is unknown.

METHODS

Ninety-three patients with heart failure (ejection fraction <45%) were studied with planar MIBG imaging, cardiopulmonary exercise tests and hemodynamics (n = 44). Early (20 min) and late (4 h) MIBG acquisition, as well as their ratio (washout, WO) were determined. Prognostic value was assessed by survival curves (Kaplan-Meier method) and uni- and multivariate Cox analyses.

RESULTS

Late cardiac MIBG uptake was reduced (131+/-20%, normal values 192+/-42%) and correlated with ejection fraction (r = 0.49), cardiac index (r = 0.40) and pulmonary wedge pressure (r = -0.35). There was a significant correlation between peak VO2 and MIBG uptake (r = 0.41, p < 0.0001). With a mean follow-up of 10+/-8 months, both late MIBG uptake (p = 0.04) and peak VO2 (p < 0.0001) were predictive of death or heart transplantation, but only peak VO2 emerged by multivariate analysis. Neither early MIBG uptake nor WO yielded significant insights beyond those provided by late MIBG uptake.

CONCLUSIONS

Metaiodobenzylguanidine uptake has prognostic value in patients with wide ranges of heart failure, but peak VO2 remains the most powerful prognostic index.

[Giant cell myocarditis. Report of a case]

The authors report a case of giant cell myocarditis leading to rapidly progressive cardiac failure despite immuno-suppressor treatment in a 20 year old woman. The cardiac failure was successfully managed by implantation of a left ventricular assist device and then cardiac transplantation. The problems encountered underline the importance of accurate diagnosis by endomyocardial biopsy before undertaking treatment and the difficulties in the choice of appropriate method of assistance in this indication. Giant cell myocarditis is a rare cause of cardiac failure and should be considered in the differential diagnosis in view of its clinical features and risk of progression. The literature and the therapeutic implications are discussed.

[Alternative surgical options to heart transplantation]

Cardiac transplantation is the treatment of reference for refractory cardiac failure but the limited number of donors, the complications inherent to transplantation and the relative and absolute contra-indications has made it necessary to find alternative surgical solutions. The detection of myocardial viability by Thallium scintigraphy, Dobutamine echocardiography and/or position emission tomography in coronary disease, allows identification of zones which are capable of recovering contractile function after revascularisation. The authors report the results of a series of 91 operated patients with a 10 year follow-up having a 72% 5 year actuarial survival and improved ejection fraction. The other alternative which may improve symptoms and prognosis in patients with severe ischaemic heart disease with left ventricular dysfunction is apical remodelling or Dor's procedure. The results of a haemodynamic study at 1 year of 171 patients clearly show a functional improvement and an increase of the ejection fraction. The advantage of this method is that it can be used in patients with dyskinetic and akinetic plaques resulting from antero-septo-apical infarction. Finally, even if mitral regurgitation is relatively uncommon in chronic ischaemic heart disease, a simple procedure (annuloplasty) is often sufficient to correct the mitral regurgitation and reduce the afterload of a failing ventricle. On the other hand, in dilated cardiomyopathy, two new options have been developed; one, suggested by Steven Bolling, proposes simple mitral annuloplasty whatever the underlying cause (primary or ischaemic cardiomyopathy) with symptomatic improvement and better haemodynamics in terms of increased cardiac output and oxygen consumption on exercise and an actuarial survival much higher than that of cardiac transplantation at one and at two years. The most recent innovation is the Batista procedure which is a method of ventricular reduction associated with correction of mitral regurgitation. The authors have assessed 20 patients for this operation at the Foch Hospital by Dobutamine echocardiography and 5 patients underwent the procedure. All 5 patients reported symptomatic improvement but some had an unchanged haemodynamic status. Others improved at rest and some improved on exercise. The Cleveland Clinic series reported results in 57 cases. Whichever alternative method tested, there is a significant functional improvement but the cardiac output does not always increase. There are no comparative prospective randomised studies and strict selection of patients is required, a problem not yet resolved for all indications. The advantages of these procedures are certain as there is no waiting list, the functional results in good indications have been demonstrated and, if necessary, secondary orthotopic cardiac transplantation is always possible.

[Mesenteric arterial thrombosis in protein S deficiency]

Arterial thrombosis is very rarely described in patients with coagulation factors deficiency. We report the first case of superior mesenteric artery thrombosis of a normal mesenteric artery associated with protein S deficiency, causing massive mesenteric infarction with short bowel syndrome. Eight-month parenteral nutrition and definitive antivitamin K anticoagulation were required in this 72 year-old patient. The initial oral anticoagulant malabsorption disappeared a few months later as clinical and biological course improved. Rapid intestinal adaptation was probably consecutive to early enteral refeeding. The possibility of reintroducing antivitamin K despite initial inefficacy should be stressed, as well as the necessity of an exhaustive coagulation work-up in patients with mesenteric infarction.

The flagellar switch genes fliM and fliN of Rhodobacter sphaeroides are contained in a large flagellar gene cluster

In this work, the genes that encode the FliM and FliN proteins of Rhodobacter sphaeroides were characterized. These genes are part of a large flagellar gene cluster in which six additional open reading frames encoding products homologous to FliL, FliO, FliP, FliQ, FliR, and FlhB proteins from other bacteria were identified. The inactivation of the fliM gene gave a nonflagellate phenotype (Fla-), suggesting that FliM is required for flagellar assembly. Complementation analysis of this fliM mutant indicated that fliM and fliN transcription starts beyond the 5' end of fliK and terminates after fliN.

Toward a principled methodology for neural network design and performance evaluation in QSAR. Application to the prediction of logP

The prediction of properties of molecules from their structure (QSAR) is basically a nonlinear regression problem. Neural networks are proven to be parsimonious universal approximators of nonlinear functions; therefore, they are excellent candidates for performing the nonlinear regression tasks involved in QSAR. However, their full potential can be exploited only in the framework of a rigorous approach. In the present paper, we describe a principled methodology for designing neural networks for QSAR and estimating their performances, and we apply this approach to the prediction of logP. We compare our results to those obtained on the same molecules by other methods.

[Mitral valvuloplasty for asymptomatic or pauci-symptomatic mitral insufficiency]

The aim of this study was to assess the results of mitral valvuloplasty for chronic asymptomatic or paucisymptomatic mitral regurgitation. Of 584 patients operated for chronic mitral regurgitation between January 1989 and December 1994, 175 were in NYHA Classes I and II and made up the study population. All had chronic grade 3 or 4/4 mitral regurgitation suitable for mitral valvuloplasty. The average follow-up was 34.3 months. Mitral valvuloplasty was performed in 174 patients, the other patient requiring mitral valve replacement. Three patients died (1.7%) and the actuarial 5 year survival was 98.2 +/- 1.0%. The probability of absence of reoperation and absence of thrombo-embolic complications at 5 years were 97 +/- 0.8% and 96.3 +/- 1.7% respectively. The residual regurgitation at Doppler echocardiography was minimal or absent in 94% of patients at the last follow-up control. The mean end-systolic and end-diastolic left ventricular dimensions decreased from 40.0 +/- 6.8 mm and 64.8 +/- 7.0 mm before surgery to 34.6 +/- 6.7 mm (p < 0.001) and 52.7 +/- 7.4 mm (p < 0.001) at the last control. The authors conclude that conservative mitral valve surgery for NYHA Classes I and II patients with chronic mitral regurgitation is feasible with a low risk and is associated with a significant reduction in ventricular volumes and stability of valvular continence at medium-term. When performed by teams trained in techniques of mitral valvuloplasty, these results suggest that surgery should be performed early.

[Surgical treatment of acute dissection of the ascending aorta (20 years experience)]

PURPOSE

In 1977, the use of gelatine-resorcine-formaline (GRF) biological glue during surgery of acute type A aortic dissection was proposed. The present study retrospectively analyses the late results obtained with this adjunct in an experience extending over a 20-year period.

PATIENTS AND METHODS

From January 1977 to July 1997, 193 patients (139 males and 54 females) aged from 15 to 79 years (mean age: 53 +/- 14 years) underwent an emergency operation for type A aortic dissection in our institution. All patients suffering from acute type A dissection and 162 (84%) were operated on within 48 hours after the onset of symptoms. Twenty-eight patients (15.2%) had Marfan's syndrome. In all patients the ascending aorta was replaced and the aortic stumps were reinforced with the GRF glue. In 43 patients (22.2%), the aortic valve was replaced either independently (5 cases-2.5%) or by means of a composite graft (35 cases-19.5%). Recently three patients underwent a complete replacement of the ascending aorta and coronary reimplantation with preservation of the native aortic valve. Because of the location of the intimal tear, the aortic replacement was extended to the transverse arch in 58 patients (30%).

RESULTS

Hospital mortality amounted to 21% (40 patients) (22.8% in patients with arch replacement and 20.3% in patients without arch replacement) (ns). The survivors were surveyed from 2 months to 20 years post-operatively (cumulative follow-up: 856 pt/years, mean follow-up: 85 +/- 66 months). During this period of time, 23 patients (15%) had to be reoperated on for a total of 29 procedures. Six of those patients (26%) died at reoperation. At univariate analysis, presence of Marfan's syndrome (P < 0.05) and absence of arch replacement (P < 0.02) were determinant risk factors for reoperation. Emergency (P < 0.01) and thoraco-abdominal replacement (P < 0.04) were determinant risk-factors of death at reoperation. The actuarial freedom from reoperation (Kaplan-Meier, CI: 95%) was: 96.5% (90.9-98.2), 87.6% (79.8-92.7), 80.9% (70.8-88.1), 66.4% (51.1-78.9) at one, 5, 10 and 15 years, respectively. A total of 36 patients (27.7%) died during follow-up. Presence of Marfan's syndrome (P < 0.01), reoperation (P < 0.02), stroke (P < 0.05), cardiac failure (P < 0.05) were determinant risk factors of late mortality. The actuarial late survival rate (Kaplan-Meier. CI: 95%), including hospital mortality, was: 71.5% (64.3-77.8), 66% (58.3-73), 56.4% (47.7-64.7), 46.3% (36.4-56.5) at one, 5, 10 and 15 years.

CONCLUSION

The GRF glue has proved to be extremely useful during initial emergency surgery for acute type A dissection, making the procedure much easier and safer. Through this operative improvement, the use of the GRF glue seems to have a beneficial influence on the late results which, however, depend mainly on the patient's basic condition.

[A prospective comparative study of coronary angiography and endocoronary ultrasonography in the detection of coronary lesions after cardiac transplantation]

Coronary angiography is the reference method for the detection of coronary disease of the cardiac grafts which threatens the long-term prognosis of cardiac transplantation. The primary results of treatment for slowing, stabilising or even improving coronary transplant disease are encouraging and make necessary the development and evaluation of reliable diagnostic methods. The authors undertook a prospective study of 48 asymptomatic patients with normal graft wall motion between January 1995 and March 1997 to compare the results of coronary angiography and endocoronary ultrasonography. The patients had been transplanted in the 10 years preceding the study. The results of the two methods were concordant in 33 cases (69%) (NS), for the confirmation (9 cases) or the information of coronary transplant disease (24 cases). The results were contradictory in 15 cases (31%): in 12 cases, endocoronary ultrasonography showed signs of coronary disease whereas the coronary angiography was estimated to be normal: in the remaining 3 cases, coronary angiography was abnormal but no signs of coronary disease were found on endocoronary ultrasonography. The specificity of coronary angiographic detection was 89% and therefore very satisfactory, but its sensitivity (43%) was poor. In addition, endocoronary ultrasonography allows analysis of the extension of coronary lesions to unstenosed segments, the quantification of intimal thickening. Therefore, endocoronary ultrasonography should become the reference investigation for coronary disease of cardiac transplants.

Structural and genetic analysis of a mutant of Rhodobacter sphaeroides WS8 deficient in hook length control

Motility in the photosynthetic bacterium Rhodobacter sphaeroides is achieved by the unidirectional rotation of a single subpolar flagellum. In this study, transposon mutagenesis was used to obtain nonmotile flagellar mutants from this bacterium. We report here the isolation and characterization of a mutant that shows a polyhook phenotype. Morphological characterization of the mutant was done by electron microscopy. Polyhooks were obtained by shearing and were used to purify the hook protein monomer (FlgE). The apparent molecular mass of the hook protein was 50 kDa. N-terminal amino acid sequencing and comparisons with the hook proteins of other flagellated bacteria indicated that the Rhodobacter hook protein has consensus sequences common to axial flagellar components. A 25-kb fragment from an R. sphaeroides WS8 cosmid library restored wild-type flagellation and motility to the mutant. Using DNA adjacent to the inserted transposon as a probe, we identified a 4.6-kb SalI restriction fragment that contained the gene responsible for the polyhook phenotype. Nucleotide sequence analysis of this region revealed an open reading frame with a deduced amino acid sequence that was 23.4% identical to that of FliK of Salmonella typhimurium, the polypeptide responsible for hook length control in that enteric bacterium. The relevance of a gene homologous to fliK in the uniflagellated bacterium R. sphaeroides is discussed.

[Left ventricular reduction (Batista's technique). A new surgical option in dilated cardiomyopathy]

Cardiac transplantation remains the standard treatment for severe cardiomyopathy resistant to medical therapy. However, new techniques may help to put this off. Two patients with dilated cardiomyopathy were treated surgically since October 1996, one aged 48 and the other 52. They were in NYHA Class IV and one was dependent on inotropic drugs. Both had relative or absolute contra-indications to transplantation. The left ventricular end diastolic dimensions were over 70 mm with mild mitral regurgitation and fractional shortening of less than 12%. Coronary angiography was normal. They were operated in October 1996 and January 1997. The procedure consisted of correction of mitral regurgitation (annuloplasty) and of reduction of left ventricular volume by a triangular resection from the apese to the base of the heart. At histological examination, the resected myocardium measured 11 to 13 cm long and 5 to 7 cm at its base. The two patients were discharged from hospital after 45 and 30 days. There were no clinical signs of cardiac failure. Follow-up investigations showed a marked decrease in ventricular volumes, the end diastolic dimensions changing from 70 to 52 mm in the first, and from 76 to 54 mm in the second patient. The corresponding values of fractional shortening increased from 11 to 20% and from 6 to 17%. Left ventricular volumes decreased from 328 mL (end diastole) and 259 mL (end systole) to 140 mL and 74 mL in the first case, and from 300 mL (end diastole) and 280 mL (end systole) to 122 mL and 83 mL respectively in the second case. The ejection fraction increased from 20 to 40% and from 10 to 32%. These preliminary results show that the theoretical advantages of this surgical technique correspond to a practical reality. Larger series of patients are required to determine the optimal indications.