Protein adsorption in glutaraldehyde-preserved bovine pericardium and porcine valve tissues

BACKGROUND

Proteins adsorbed by bioprosthetic tissues after implantation play a major role in the process of calcification. We investigated whether there are differences in protein adsorption between bovine pericardial and porcine valvular tissues that could correlate with the differences observed clinically.

METHODS

Glutaraldehyde-treated bovine pericardial and porcine valve samples were implanted subcutaneously in rats and retrieved 1 month after implantation. Total protein content was assessed by Lowry's method. Qualitative analysis was performed by polyacrylamide gel electrophoresis. Quantitative analysis was performed by densitometry.

RESULTS

Total protein content showed a higher protein concentration in porcine valve tissue than in pericardial tissue: 149+/-22.6 microg/mg dry tissue versus 108+/-12.7 microg/mg dry tissue (38% increase). In pericardial tissue, four protein bands (17, 16, 15.5, and 13.5 kd) showed decreased concentration when compared with porcine valve tissue, whereas one band (11 kd) showed increased concentration.

CONCLUSIONS

Significant differences were found in protein content between bovine pericardial and porcine valve tissues. Correlations with clinical findings may lead to a better understanding of the mechanism involved in the process of calcification, particularly the role played by the structure of the tissues.

Effect of ethanol and ether in the prevention of calcification of bioprostheses

BACKGROUND

Lipids play a significant role in the process of calcification of bioprostheses. We assessed whether lipid extraction by ethanol, ether, or a surfactant could mitigate calcification of glutaraldehyde-treated bioprostheses.

METHODS

On 200 bovine pericardium samples pretreated with 0.6% glutaraldehyde, lipid extraction was carried out by ethanol, ether, or the tween 80 surfactant, and combinations thereof. The treated tissues were implanted subcutaneously in 50 juvenile rats for 4 and 6 months. Lipids were analyzed by Fourier transform infrared spectrophotometer and chromatography before implantation. Calcium content of implanted tissues was assessed by atomic absorption spectrometer.

RESULTS

Ethanol, ether, or surfactant did mitigate calcification. The most efficient pretreatments were the combination of ethanol and surfactant (calcium content: 15.5+/-6.8 microg/mg dry tissue after 6 months implantation) or the combination of ethanol, ether, and surfactant (13.1+/-6.2 microg/mg dry tissue) when compared with surfactant alone (42.9+/-12.7 microg/mg dry tissue).

CONCLUSIONS

Ethanol or the combination of ethanol and ether added to the currently used glutaraldehyde-surfactant treatment further mitigates calcification.

A recovery model of partial cardiopulmonary bypass in the rat

This study was undertaken to develop a recovery model of cardiopulmonary bypass (CPB) in rats. Twenty male Wistar rats (475-550 g) were anaesthetized, mechanically ventilated and the femoral vessels cannulated. The extracorporeal circulation circuit comprised a roller pump, a venous reservoir and a modified Capiox 308 paediatric membrane oxygenator. Priming consisted of 20 ml of fresh homologous blood and 15 ml of colloid. Anticoagulation was achieved with heparin (500 IU/kg). Blood gas analysis, blood pressure monitoring and survival studies were performed in CPB (n=10) and Sham (n=10) rats. Partial CPB was always easily established and was conducted at a flow rate of 100 ml/kg/min for 90 min Blood gas analysis and blood pressure data did not differ between the two groups. All CPB rats survived and the 3-week follow-up period remained uneventful. The rat model of CPB was easy to perform and was associated with excellent survival. This recovery model should allow us to study the pathophysiological processes underlying post-CPB multiple organ dysfunction.

Results of up to 9 years of high-temperature-fixed valvular bioprostheses in a young population

BACKGROUND

Bioprosthetic valve replacement in young patients remains a controversial issue due to a high rate of early calcification. Previous studies in our laboratory have shown that high-temperature fixation of glutaraldehyde preserved bioprosthesis (HTF) mitigates calcification. The first clinical application of this technique was started in 1991.

METHODS

From January 1991 to September 1998, 50 patients in whom anticoagulants were contraindicated underwent single aortic valve replacement (n = 33) or mitral valve replacement (n = 17) using HTF bioprostheses. The age of the patients ranged from 7 months to 35 years (mean 22.7+/-6.8 years). The mean New York Heart Association status was 2.4. Mean follow-up 4 years +/- 1.8 for a total follow-up of 196 patient-years.

RESULTS

There were no operative deaths and but there were two late deaths, one valve related. Structural failure occured in 4 patients (2%/patient-year) requiring a reoperation in 3 patients (1.5%/patient-year). No endocarditis or thromboembolic episodes were observed. At late examination (June 2000), 46 patients (92%) were in New York Heart Association class I or II, with a well functioning valve.

CONCLUSIONS

Replacement with HTF bioprostheses in young patients has demonstrated encouraging midterm results with a low incidence of structural failure

Suboccipital and cervical chordomas: radical resection with vertebral artery control

Object

Radical resection of chordomas seems to improve a patient's long-term prognosis. At the suboccipital and cervical levels, the vertebral artery (VA) is often considered as a limit in surgical possibilities. The authors report on the management of the VA in a series of 36 patients with chordomas located in the cervical region.

Methods

Over an 11-year period, 36 patients with chordomas located at the suboccipital (28 patients) or cervical (eight patients) level were treated in the authors' neurosurgical department. In 30 patients, the tumors extended laterally toward the VA and required surgical control of the VA. Sixteen of these 30 patients harbored primary tumor, whereas 14 were treated for recurrent disease.

The VA was encased in the tumor in 23 patients, with stenosis in six cases. A balloon occlusion test was performed in seven patients and the VA was resected in four. Extensive resection, via a lateral approach on one (22 cases) or on both (eight cases) sides, did not cause any permanent postoperative deficits. In five patients a complementary approach was performed: posterolateral in one and transoral in four. Spinal fixation was performed via the lateral approach (eight cases) or via a complementary posterior approach (five cases). All but two patients underwent radiotherapy, including 10 who underwent proton-beam radiotherapy.

Conclusions

Chordomas extending laterally to the VA can be radically resected via a lateral approach without causing significant morbidity. A complementary approach is often necessary. The best results are achieved in patients with primary compared with recurrent tumor.

T-Cell suicide gene therapy for organ transplantation: induction of long-lasting tolerance to allogeneic heart without generalized immunosuppression

Standard immunosuppressive drugs used for allogeneic organ transplantation do not specifically target alloreactive T cells and must be given for the lifetime of the patient, resulting in significant morbidity and mortality. We aimed to induce experimental immune tolerance to vascularized heart allograft using a suicide gene allowing selective elimination of dividing T cells expressing Herpes simplex virus type 1 thymidine kinase upon ganciclovir administration. We show that without ganciclovir, transgenic mice selectively expressing thymidine kinase in T cells rejected a vascularized cardiac allograft in 7 days. In contrast, allograft was definitively accepted after a 7-day course of ganciclovir initiated at the time of allotransplantation. Interestingly, T cells from both rejecting and tolerant mice proliferated in response to donor or third-party allogeneic stimulation. This state of tolerance was challenged through a second vascularized cardiac allotransplantation. Third-party allografts were rejected while those syngeneic to the first allograft were accepted without any additional treatment. These results show that short-term pharmacogenetic immunosuppression can induce long-lasting, robust, and specific tolerance to solid vascularized allograft without generalized continuous immunosuppression.

Portal venous and enteric exocrine drainage versus systemic venous and bladder exocrine drainage of pancreas grafts: clinical outcome of 40 consecutive transplant recipients

OBJECTIVE

To test the hypothesis that pancreas transplantation using the more physiologic method of portal venous-enteric (PE) drainage could be performed without compromising patient and graft outcome, compared with the standard method of systemic venous-bladder (SB) drainage.

METHODS

Between November 1995 and November 1998, the authors prospectively followed up 20 consecutive patients with SB drainage followed by 20 consecutive patients with PE drainage. All patients underwent simultaneous pancreas-kidney transplantation, and all were immunosuppressed with antilymphocyte serum, cyclosporin, azathioprine, and steroids.

RESULTS

The actuarial patient survival rate at 1 year was 95% in the SB group and 100% in the PE group. Death-censored kidney graft survival was 100% in both groups; pancreas graft survival was 95% in the SB group and 100% in the PE group. The mean initial hospital stay was 15 days for both groups. However, during the first 6 months after transplantation, the SB group required more medical day-unit visits, mostly for treatment of metabolic acidosis and dehydration. The incidence of urinary tract infections was similar in both groups. The incidence of cytomegalovirus infections was significantly less in the PE group. The incidence of acute rejection was 37% in the SB group and 15% in the PE group. Mean serum creatinine levels 6 months after transplantation were significantly lower in the PE group than in the SB group. Glycemic control was excellent in both groups, but fasting serum insulin levels were significantly lower in the PE group.

CONCLUSIONS

The PE method of pancreas transplantation can be performed with excellent patient and graft outcomes.

Muscle fatigue during concentric and eccentric contractions

We compared the contribution of central and peripheral processes to muscle fatigue induced in the ankle dorsiflexor muscles by tests performed during concentric (CON) and eccentric (ECC) conditions. Each fatigue test consisted of five sets of 30 maximum voluntary contractions at a constant speed of 50 degrees /s for a 30 degrees range of motion of the ankle joint. The torque produced by the dorsiflexors and the surface electromyogram (EMG) of the tibialis anterior muscle were recorded during the fatigue tests. Before, during, and after the tests, the compound muscle action potential (M wave) and the contractile properties in response to single and paired electrical stimuli, as well as the interpolated-twitch method and postactivation potentiation (PAP), were recorded during isometric conditions. Compared with ECC contractions, the CON ones resulted in a greater (P < 0.05) loss of force (-31.6% vs. -23.8%) and a decrease in EMG activity (-26.4% vs. -17.5%). This difference was most pronounced during the first four sets of contractions, but was reduced during the last set. Activation was not altered by the tests because neither the interpolated-twitch response nor the ratio of the voluntary EMG to the amplitude of the M wave was changed in the two fatigue tests. Although there was no significant difference in M-wave amplitude between the two tests, changes in the twitch parameters and in the PAP were found to be greater in the CON than ECC contractions. It is concluded that the greater alterations in the contractile properties observed during the CON contractions indicate that intracellular Ca(2+)-controlled excitation-contraction (E-C) coupling processes, possibly associated with a higher energy requirement, are affected to a much greater degree than during ECC contractions.

[Human valvular substitutes for the treatment of complex progressive endocarditis. Application to aortic, mitral and tricuspid valves]

The aim of this study was to assess the immediate and long-term results of human valvular substitutes (homografts and autografts) in the treatment of complex progressive endocarditis in aortic, mitral and tricuspid valves. Since 1992, 80 patients (64 men, 16 women) aged 44 +/- 16 years (range 15 to 76 years), were treated. In 53 patients, the endocarditis involved native valves, 4 on previously plastified valves, or prosthetic valves in 27 patients. The endocarditis was recurrent 6 patients. The lesions were situated on the aortic valve (N = 59), mitral valve (N = 5), aortic and mitral valves (N = 12), aortic and tricuspid valves (N = 3), mitral and tricuspid valves (N = 1). The peroperative findings confirmed the lesions diagnosed at echocardiography: prosthetic valve dehiscence (27 patients), prosthetic cusp tear (N = 7), vegetations (N = 61), perforations (N = 48), periannular abscess (N = 47), aorto-ventricular discontinuity (N = 12), aorto-mitral discontinuity (N = 7), right ventricular aortic fistula (N = 1), aorto-pulmonary fistula (N = 1), pseudo-aneurysm (N = 1), ventricular septal defect (N = 1). Eighty-six human valvular substitutes were used (double homograft in 6 patients): aortic homograft (N = 63), pulmonary in the aortic position (N = 1), the mitral position (N = 12), of which 8 were in the mitral and 4 in the tricuspid position, pulmonary autograft (N = 10). Ten mitral valve repairs were performed on infected lesions. Associated procedures included mitral valve repair (N = 5), tricuspid valve repair (N = 1) for non-infarcted valve lesions, replacement of the ascending aorta (N = 2), the aortic arch (N = 1), coronary bypass surgery (N = 2) and one nephrectomy. The hospital mortality was 5% (4 patients). The causes of death were: infarction (N = 2), myocardial failure (N = 1) and multiorgan failure (N = 1). Four early reoperations were required for technical problems, none for endocarditis. Seventy-three of the 76 survivors were followed up for 43 +/- 24 months (range 1 to 84 months). Eight patients died during follow-up, but only 1 of cardiac causes (operation for recurrent endocarditis in a drug abuser). Seven operations were performed, 3 for technical problems or structural failure, 4 for recurrent endocarditis. At 5 years' follow-up, the survival was 81 +/- 5%; 88 +/- 6% of patients were free of endocarditis, 77 +/- 6% had no reoperation: no patient had thromboembolic complications. These results show that human valvular substitutes are adapted for the treatment of complex, progressive aortic, mitral and tricuspid valve endocarditis when techniques of valvular repair are no longer feasible.

Coronary reoperations: indications, techniques and operative results. Retrospective study of 240 coronary reoperations

BACKGROUND

We review twelve-year experience with coronary reoperations so as to better identify indications, techniques and results.

METHODS

Between January 1986 and March 1998, 240 coronary reoperations (228 redux, 12 tridux) were performed. There were 223 male and 17 female patients, with a mean age of 63.6+/-7.9 years at the time of reoperation. Mean time interval between operations was 10+/-4.8 years. Symptomatology consisted of: stable recurrent angina (40%), unstable (57%), or congestive heart failure (3%). Pathological feature of the primary grafts was implicated in 95% of cases and atheroma sole progression over native network in 5% of cases. During reoperations 521 (2.2+/-0.8/patient) bypass [venous (40%), arterial (60%)] were performed as well as 15 associated procedures.

RESULTS

Operative mortality represented 10% (n=24). Causes of death included infarct (7), left ventricular failure (12), rhythm disorders (2), mediastinitis (1) and multiorgan failure (2). Mortality risk factors were operation date (16.6% before 1992 and 7.4% after, p=0.03), age (13.1% after 60 years old, 2.7% before, p=0.01) time interval between intervention (12% after 8 years, 4% before, p=0.05) and anterograde cardioplegia only (11.8% versus 4.5% when a combined anterograde and retrograde access was used, p=0.06). Morbidity was 31% (71/240). Among the survivors 169 patients (78%) did not experience any complication.

CONCLUSIONS

Thanks to a better medico-surgical management, the mortality rate of coronary reoperations is steadily decreasing.

[Staphylococcus epidermidis infective endocarditis after mitral surgery, successfully treated with aspirin and antibiotics: a case report]

We report a case of infectious endocarditis from Staphylococcus epidermidis that occurred early after mitral valve repair (one month), suggested by fever of 38.5 degrees C and valvular vegetations of less than 10 mm on the mitral valve. In the absence of standard recommendations (medical or surgical) in treating patients with infectious endocarditis occurring after mitral valve repair, and in the absence of complications, a medical regimen was chosen associating aspirin (anti-aggregant dosages) with antibiotics. The benefit of aspirin in endocarditis has been demonstrated in experimental studies with regards to valvular vegetations and embolic risk but remains to be studied in human clinical trials. With the association of aspirin (100 mg/d) and triple antibiotic therapy (rifampicin 1200 mg/d, vancomycin 2 g/d, gentamycin 180 mg/d), the clinical status improved with complete regression of vegetations in less than 24 days and the absence of recurrence at one-year follow-up.

[Pre and Postoperative evaluation of the incidence of arrhythmia in patients undergoing corrective intervention for Ebstein anomaly]

BACKGROUND

Patients with Ebstein's anomaly frequently have troublesome cardiac arrhythmias. In particular, this malformation is the most common congenital defect associated with the Wolff-Parkinson-White syndrome. The aim of this study was to investigate the postoperative evolution of arrhythmias without the aid of any surgical techniques for arrhythmia.

METHODS

Between 1980 and 1999, 48 patients (22 males, 26 females), with a preoperatively documented arrhythmia, underwent an operation for the correction of Ebstein's anomaly at the Hôpital Broussais. Of these, 24 had paroxysmal supraventricular tachycardia, 12 had atrial fibrillation or flutter, 8 had Wolff-Parkinson-White syndrome, 1 had non-sustained ventricular tachycardia, and the remaining 3 patients had atrioventricular block.

RESULTS

The operative mortality was 8% (4/48). After operation 46% (20/44) of the patients regained permanent sinus rhythm (20/44 vs 2/48, p < 0.01), supraventricular tachyarrhythmia occurred in 16% of the patients (7/44), 8 patients (18%) had atrial fibrillation, and ventricular preexcitation syndrome was present in 3 patients (7%). The incidence of pacemaker implantation for complete heart block was 11% (5/44). Follow-up was achieved in 95% of patients (40/44) who survived the operation and the perioperative period. The mean follow-up was 63 +/- 54 months (range 4-226 months). During this time there were 6 additional deaths. Eight patients continued to have symptomatic arrhythmias (2 had paroxysmal supraventricular tachycardia, 6 had atrial fibrillation), but 55% of patients (20/36) reported no symptoms of arrhythmia (20/36 vs 2/48, p < 0.01).

CONCLUSIONS

Surgical repair improves the quality of life of these patients by reducing the incidence of arrhythmias, in fact less than one sixth of patients continued to have postoperative symptomatic arrhythmias. This can be explained by the interruption of accessory pathways that seem to be a major cause of arrhythmia in Ebstein's anomaly.

[Utilization of aortomyoplasty as a biological pumping system]

Aortomyoplasty is a surgical technique of constructing a neo-ventricle on the ascending or descending aorta with the latissimus dorsi muscle. This is electrically stimulated to contract during diastole, thereby creating a system of chronic, haemo-compatible aortic pumping. Long-term experimental studies have shown increases in cardiac output (from 3.6 to 5.5 l/min), decreases in peripheral resistances (from 1574 to 1134 dyne.sec.cm-5) and increases in indices of subendocardial viability (DPTI/TTI: 1.1 to 1.4). These experimental studies have been confirmed by the initial clinical results. To date, world experience includes thirty-six patients. With cardiomyoplasty, aortomyoplasty is a new arm in the therapeutic arsenal against severe cardiac failure by providing a new system of chronic circulatory assistance which is implantable and biocompatible.

Hepatitis C-related cirrhosis: a predictor of diabetes after liver transplantation

Hepatitis C virus (HCV) infection has recently been suggested to be a risk factor for the development of diabetes mellitus. The aim of our study was to investigate whether the prevalence of diabetes is increased among liver transplant recipients infected with HCV. We compared the prevalence of diabetes among 278 liver transplant recipients whose original cause of liver failure was HCV infection (110 patients), hepatitis B virus infection (HBV; 53 patients), and cholestatic liver disease (CLD; 115 patients). The pretransplantation prevalence of diabetes was higher in the HCV group (29%) compared with the HBV (6%) and CLD (4%) groups (P <.001). The prevalence of diabetes remained higher in the HCV group 1 year after transplantation: 37%, 10%, and 5% in the HCV, HBV, and CLD groups, respectively (P <.001). The cumulative steroid dose during the first year of transplantation was significantly lower in the HCV group compared with the CLD group. Multivariate analysis revealed that HCV-related liver failure (P =.002), pretransplantation diabetes (P <.0001), and male sex (P =.019) were independent predictors of the presence of diabetes 1 year after transplantation. The high prevalence of diabetes persisted in the HCV group, with 41% diabetic at 5 years. The majority of patients with diabetes mellitus (89%) required insulin therapy after transplantation. Patient and graft survival rates were similar among patients with and without diabetes. In conclusion, our study shows that there is a high prevalence of diabetes among liver transplant recipients infected with HCV both before and after transplantation.

Investigation of the human hippocampal formation using a randomized event-related paradigm and Z-shimmed functional MRI

Functional neuroimaging of the hippocampal formation has presented a challenge to neuroscientists because of the small size of the hippocampus proper and its location at the basal level of the brain. Choosing the appropriate control condition for subtraction-based studies has also proved difficult. Event-related experimental designs are a powerful tool in behavioral and electrophysiological studies. Recently, such experimental designs have been applied to functional MR imaging studies but these studies used large intertrial intervals in order to separate the slow blood flow response from temporally adjacent events, severely limiting the number of events that can be presented in a single run. This leads to poor statistical power and restrictions on the design of the experimental paradigm. We present data obtained using a rapidly presented, randomized event-related paradigm, combined with a novel fMRI imaging method designed to improve imaging in basal brain regions. The results demonstrate bilateral activation in the hippocampal formation in identification of novel complex scenes distinct from a learned basis set of complex scenes. Differential activation is obtained in the counter task of identifying a learned target complex scene against a background of novel scenes. The results are also compared with the more conventional block design complex scene paradigms previously reported by others. The block design provides strong posterior activation, likely related more to visual scene processing, whereas the event-related design provides more anterior hippocampal activation with the encoding of novel scenes.

Implication of HLA-G molecule in heart-graft acceptance

HLA-G found in five of 31 heart-transplant recipients was associated with a decrease of acute and chronic rejection episodes.

[Cardiac fibroelastoma. Six operated cases and review of the literature]

The authors reviewed the cases of 6 patients operated between September 1994 and February 1999 for a rare benign tumour: papillary fibroelastoma of the heart. These patients, aged 51 +/- 14 years, all have single valvular involvement: mitral (N = 3), aortic (N = 2), tricuspid (N = 1). Five patients were symptomatic: transient ischaemic cerebral events (N = 3) associated with mesenteric infarction requiring ileal resection in 1 case; constituted cerebrovascular accident (N = 1); syncope (N = 1). In this last patient, the fibroelastoma was diagnosed fortuitously on the tricuspid valve. The features and location of the tumours were determined by transoesophageal echocardiography. Surgical treatment in all patients consisted in excising the tumour and preserving the valve. One aortic cusp was reconstructed after excising the tumour with a cryopreserved partial aortic homograft. Peroperative transoesophageal echocardiography confirmed the absence of regurgitation after the procedures in all patients. There were no postoperative complications in any of the cases. No cases of valvular regurgitation or of tumour recurrence were observed during follow-up. Despite the benign histology, cardiac fibroelastomas should be excised because of their embolic complications. Absence of recurrence justifies conservative reconstruction of the affected valve.

Motor cortex stimulation in the treatment of central and neuropathic pain

BACKGROUND

Motor cortex stimulation has been proposed for the treatment of central pain.

METHODS

Thirty-two patients with refractory central and neuropathic pain of peripheral origin were treated by chronic stimulation of the motor cortex between May 1993 and January 1997. The mean follow-up was 27.3 months. The first 24 patients were operated on according to the technique described by Tsubokawa. The last 13 cases (8 new patients and 5 reinterventions) were operated on by a technique including localization by superficial CT reconstruction of the central region and neuronavigator guidance. The position of the central sulcus was confirmed by the use of intraoperative somatosensory evoked potentials. The somatotopic organization of the motor cortex was established preoperatively by studying the motor responses at stimulation of the motor cortex through the dura.

RESULTS

Ten of the 13 patients with central pain (77%) and 10 of the 12 patients with neuropathic facial pain experienced substantial pain relief (83.3%). One of the three patients with post-paraplegia pain was clearly improved. A satisfactory result was obtained in one patient with pain related to plexus avulsion and in one patient with pain related to intercostal herpes zoster. None of the patients developed epileptic seizures.

CONCLUSIONS

Our results confirm that chronic stimulation of the motor cortex is an effective method in treating certain forms of refractory pain.

[Metaplasia of aortic tissue into tracheal tissue. Surgical perspectives]

Tracheal reconstruction after extensive resection remains an unsolved surgical problem. Numerous attempts have been made using tracheal grafts or prosthetic conduits with disappointing results. In this study, we propose a new alternative using an aortic autograft as tracheal substitute. In a first series of experiments, a half circumference of two rings was replaced with an autologous carotid artery patch. In a second series, a complete segment of trachea was replaced with an autologous aortic graft supported by an endoluminal tracheal stent. No dehiscence or stenosis was observed. Microscopic examinations at 3 and 6 months showed the replacement of the aortic tissue by tracheal tissue comprising neoformation of cartilage and mucociliary or non-keratinizing metaplastic polystratified squamous epithelium. Although these results need to be confirmed by a larger series of experiments, they showed that a vascular tissue placed in a different environment with a different function can be submitted to a metaplastic transformation which tends to restore a normal structure adapted to its new function. These remarkable findings offer new perspectives in tracheal reconstruction in human.

Correspondence between functional magnetic resonance imaging somatotopy and individual brain anatomy of the central region: comparison with intraoperative stimulation in patients with brain tumors

OBJECT

The goal of this study was to determine the somatotopical structure-function relationships of the primary motor cortex in individual patients by using functional magnetic resonance (fMR) imaging. This was done to assess whether there is a displacement of functional areas compared with anatomical landmarks in patients harboring brain tumors close to the central region, and to validate these findings with intraoperative cortical stimulation.

METHODS

One hundred twenty hemispheres in 60 patients were studied by obtaining blood oxygen level-dependent fMR images in patients while they performed movements of the foot, hand, and face on both sides. There was a good correspondence between anatomical landmarks in the deep portion of the central sulcus on axial slices and the somatotopical organization of primary motor areas. Pixels activated during hand movements were centered on a small characteristic digitation; those activated during movements in the face and foot areas were located in the lower portion of the central sulcus (lateral to the hand area) and around the termination of the central sulcus, respectively. In diseased hemispheres, signal-intensity changes were still observed in the projection of the expected anatomical area. The fMR imaging data mapped intraoperative electrical stimulation in 92% of positive sites.

CONCLUSIONS

There was a high correspondence between the somatotopical anatomy and function in the central sulcus, which was similar in normal and diseased hemispheres. The fMR imaging and electrical stimulation data were highly concordant. These findings may enable the neurosurgeon to locate primary motor areas more easily during surgery.

[Surgery of epilepsy: current status]

PRELIMINARY EXPLORATIONS: The advent of magnetic resonance imaging and its capacity to detect fine structural injury and SPECT and PET functional imaging as well as the generalization of EEG-video and the simplification of intracranial electrode implantation techniques has given a whole new life to surgery in epilepsy. Preoperative explorations are shorter and less invasive, allowing surgery without implantation of intracranial electrodes in more than 70% of the cases.

SURGERY

New surgical techniques (subpial transection, neuro-navigation...) and improvement in well-known procedures (amygdalo-hippocampectomy...) has made it possible to propose lower risk procedures with minimal trauma (overall complication rate < 10%), particularly for temporal epilepsy where the success rate is greater than 80%.

FUNDAMENTAL RULE

The key to success however directly depends on rigorous application of the fundamental rule of anatomo-electro-clinical correlation.

Mechanisms of hepatic very low density lipoprotein overproduction in insulin resistance. Evidence for enhanced lipoprotein assembly, reduced intracellular ApoB degradation, and increased microsomal triglyceride transfer protein in a fructose-fed hamster model

A novel animal model of insulin resistance, the fructose-fed Syrian golden hamster, was employed to investigate the mechanisms mediating the overproduction of very low density lipoprotein (VLDL) in the insulin resistant state. Fructose feeding for a 2-week period induced significant hypertriglyceridemia and hyperinsulinemia, and the development of whole body insulin resistance was documented using the euglycemic-hyperinsulinemic clamp technique. In vivo Triton WR-1339 studies showed evidence of VLDL-apoB overproduction in the fructose-fed hamster. Fructose feeding induced a significant increase in cellular synthesis and secretion of total triglyceride (TG) as well as VLDL-TG by primary hamster hepatocytes. Increased TG secretion was accompanied by a 4.6-fold increase in VLDL-apoB secretion. Enhanced stability of nascent apoB in fructose-fed hepatocytes was evident in intact cells as well as in a permeabilized cell system. Analysis of newly formed lipoprotein particles in hepatic microsomes revealed significant differences in the pattern and density of lipoproteins, with hepatocytes derived from fructose-fed hamsters having higher levels of luminal lipoproteins at a density of VLDL versus controls. Immunoblot analysis of the intracellular mass of microsomal triglyceride transfer protein, a key enzyme involved in VLDL assembly, showed a striking 2.1-fold elevation in hepatocytes derived from fructose-fed versus control hamsters. Direct incubation of hamster hepatocytes with various concentrations of fructose failed to show any direct stimulation of its intracellular stability or extracellular secretion, further supporting the notion that the apoB overproduction in the fructose-fed hamster may be related to the fructose-induced insulin resistance in this animal model. In summary, hepatic VLDL-apoB overproduction in fructose-fed hamsters appears to result from increased intracellular stability of nascent apoB and an enhanced expression of MTP, which act to facilitate the assembly and secretion of apoB-containing lipoprotein particles.