Paraneoplastic antineuronal antibodies in patients with systemic autoimmune diseases

Sera from 71 patients with primary Sjögren's syndrome (PSS) and from 102 patients with systemic lupus erythematosus (SLE) were tested by immuno-dot blotting against HuD, Ri, Yo and amphiphysin recombinant proteins. For Ri, Yo and amphiphysin antigens, no immunoreactivity was found in the 173 sera tested. One PSS patient with a clinical picture of subacute sensory neuronopathy had high titers of anti-Hu antibodies. An extensive search for an underlying tumor was initially negative but a small cell lung cancer was eventually discovered three years later. Another patient with SLE and a clinical picture of demyelinating polyradiculoneuropathy had anti-Hu antibodies. Repeated search for an underlying tumor remains negative after five years follow-up in this young non-smoking patient. In addition, the neuropathy progressively improved and the anti-Hu antibodies titer slowly decreased from 1:8000 to 1:2000, making the diagnosis of paraneoplastic syndrome unlikely in this patient. This study indicates that the detection of anti-Hu antibodies in patients with known symptomatic systemic autoimmune diseases such as PSS or SLE should induce the same work-up than the detection of these antibodies in the absence of other immune diseases, i.e. repeated search for occult cancer during several years. As illustrated by our first patient, this strategy may be fruitful. Nevertheless, the clinician should know that anti-Hu antibodies may exceptionally (0.6% in this series) occur in systemic autoimmune disorders with neurological complications, in the absence of an underlying neoplastic disease.

Ebstein's anomaly: repair based on functional analysis

OBJECTIVE

'Classical' repair of Ebstein's anomaly is usually performed with transverse plication of the atrialized chamber. However, the anterior leaflet has restricted motion which is an important factor of the tricuspid valve insufficiency. We studied the long term results of mobilization of the anterior leaflet associated with longitudinal plication of the right ventricule.

METHODS

From 1980 to July 2002, 191 patients (mean age 24.4+/-15 years (1-65)) were operated on. Anterior leaflet function was assessed on pre-op echocardiography and on surgical examination. Conservative surgery was possible in 187 patients (98%) and included mobilization of the anterior leaflet, longitudinal plication of the right ventricle and prosthetic annuloplasty in adults. Bidirectional cavo-pulmonary shunt was associated in 60 patients. Four patients had valve replacement.

RESULTS

Hospital mortality occurred in 18 patients: 9% (95%CL: 6-15%) due to right ventricle (RV) failure in nine patients. Mean follow-up was 6.4 years (0.07-22). Actuarial survival was 82% at 20 years. Tricuspid valve insufficiency was 1 or 2+ in 80% of the cases. Reoperation occurred in 8% (16 patients). A successful second repair was obtained in ten patients. Electron beam computerized tomography (20 patients) demonstrated improved left ventricle ejection fraction 56-66% (P<0.05). Supraventricular tachycardia and pre-excitation syndromes were reduced from 23 to 5%.

CONCLUSION

Conservative surgery is indicated for all symptomatic patients. The incidence of valve repair is high when leaflet mobilization is performed. Valve replacement can be avoided in most cases. Functional and hemodynamic results are excellent.

Homograft replacement of the mitral valve in young recipients: mid-term results

OBJECTIVE

Mitral homograft (MH) can represent an interesting alternative for valve replacement in the young. However, concerns have been expressed about the durability of valve allografts in children. We report our experience with MH replacement in young patients.

METHODS

From 1993 to 1997, 13 young patients aged 3-25 years (mean 15+/-6 years) underwent total mitral valve (MV) replacement with a cryopreserved homograft (CH). All but one had previously undergone one or more cardiac operations. The indications were rheumatic disease (6), acute and subacute endocarditis (2), congenital heart disease (4), and systemic lupus endocarditis (1).

RESULTS

No in hospital deaths are reported. Discharge echocardiogram showed a well-functioning MH in all but one patient. One patient was lost to follow-up. Follow-up ranged from 0.7 to 6.6 years (4.1+/-2.2). On follow-up two patients were doing well. Two patients died without reoperation and both had MV stenosis. Seven patients (54%) required reoperation: mean delay 4.17 years (0.7-7). In all cases, thickening, shrinking and calcification of the allograft were present. None of these seven had contributive histopathologic changes. One patient presenting recurrent MV insufficiency will require a reoperation.

CONCLUSION

MV homograft is a safe and reproducible technique, but does not provide durable results and should not be used in young patients.

[Treatment of intracranial cysts in children: peritoneal derivation or endoscopic fenestration?]

OBJECTIVE

The goal of this study is to evaluate the indications, benefit and complications of shunts and endoscopic fenestrations in the treatment of malformative intracranial cysts.

MATERIAL AND METHOD

The records of 172 consecutive children (mean age of 4 years) were reviewed. All had a malformative cyst. Dandy Walker malformation, mega cisterna magna, and cysts from tumoral or porencephalic origin were excluded from the study. The cysts were diagnosed either in utero (n=64) or postnatally (n=108). Most of them were unique (94.8%) and localized in the posterior fossa (26.2%) or at the convexity (23.2%). Indication for surgery was based on clinical symptoms (n=101; 86.3%) or size of the lesion (n=16; 13.7%). Endoscopy was the treatment of choice when cysts were in closed relationship with enlarged ventricles. Shunting procedures were indicated when endoscopy was not feasible and craniotomies when shunt insertion was unsafe or diagnosis uncertain. Fifty children underwent an endoscopic fenestration, 55 a shunting procedure, 7 the puncture or the external drainage of a pericerebral collection and 5 a direct surgical approach. The mean follow-up was 5.5 years. Psycho-motor, intellectual and school performances were evaluated in 93 children (54%). Success was defined by both the disappearance of symptoms of increased intra cranial pressure and regression of the cyst.

RESULTS

Compared to shunts, endoscopic fenestrations were more frequently successful (70% vs 61.8%), led to less complications (6% vs 61.8%) and to a lesser number of reoperations (in average 1.6 operation per child vs 2.2). Median developmental and intellectual quotients for the whole series were respectively 98 and 97 and did not depend upon the type of treatment.

CONCLUSION

The study of this series shows that treatment modalities necessarily vary according to the site of the cysts but that endoscopic fenestrations are preferable to shunts whenever feasible.

[Heschl's gyrus identification using functional MRI: neurosurgical issue]

AIM

Localizing Heschl's gyrus with functional MRI (fMRI) is a particularly difficult challenge due to the noise of the echo planar sequences and the frequent activation of language areas during auditory paradigms. The goal of this study was to search for a paradigm capable of assessing only pure primary auditory cortex activation with fMRI.

MATERIAL AND METHOD

Ten healthy adults were studied. Subjects were asked to continuously perform a visual decisional task while passively listening to an ON-OFF randomized paradigm of tones and rhythmic stimuli. Data were analyzed with SPM.

RESULTS

Auditory cortex activation was assessed by observing activated pixels in functional images. Due to the distraction effect of the visual decisional task, functional images of pure primary auditory cortex were obtained in all subjects, with strong and selective activation in the Heschl's gyrus.

CONCLUSION

This technique, coupled with fMRI data of language areas can be used as a preoperative tool for surgical preplanning in the left superior temporal region. It shows a clear distinction between resectable areas (primary auditory cortex) and not resectable essential areas (language areas).

[Chronic meningitis before diagnosis of celiac disease]

Neurological complications, mainly cerebellar syndrome, have been associated with coeliac disease. We report the first observation of a 56-year-old woman with a chronic meningitis revealing coeliac disease. Neuralgia of the trijeminal nerve and cerebellar syndrome only appeared seven years after the onset of meningitis. MRI examination showed a cerebellar atrophy and a leucoencephalopathy. This case report emphasizes the utility of detection of anti-gliadin antibodies for the diagnosis of a chronic meningitis.

[Acute orthostatic intracranial hypotension]

The case of a young female with an acute idiopathic low cerebrospinal fluid pressure is presented. Clinical-imaging manifestations were typical and two consecutive blood patches resulted in a complete and durable resolution of the symptomatology. We present a review of the various investigation and therapeutic techniques.

[Follow-up study of head-injured children]

The authors reviewed in a retrospective study 61 cases of severely head injury children who where admitted in the rehabilitation centre to evaluate the outcome 1 and 5 years after the brain injury. Neurologic and neuropsychologic status of children was assessed ad admission, 1 and 5 years later. Duration on intubation and age at time of head trauma were the worst functional prognosis.

Obstruction of Magendie's and Luschka's foramina. Cine-MRI, aetiology and pathogenesis

BACKGROUND

Obstruction of the foramina of Magendie and Luschka represents one possible aetiology for a progressive tetra-ventricular hydrocephalus.

METHOD

Our case report is a 58-year-old woman initially presenting with a pseudo-vertebrobasilar insufficiency clinical syndrome. A ventriculo-cisternostomy of the third ventricle was performed by an endoscopic procedure with a clinical and radiological success (three year follow-up).

FINDINGS

Comparative studies of cerebrospinal fluid (CSF) flow measurements by cine magnetic resonance imaging (cine-MRI) showed that Magendie's and Luschka's foramina permeabilities were restored after the ventriculo-cisternostomy. INRTERPRETATION: This case shows that endoscopic ventriculo-cisternostomy of the third ventricle can provide an effective treatment for specific tetra-ventricular hydrocephalus. Cine-MRI findings open the discussion on possible aetiologies and pathophysiologies.

[Tracheal replacement: new perspectives]

Tracheal replacement remains a real challenge in thoracic surgery. For tracheal resections greater than 5 to 6 cm, end to end anastomosis is not possible. Several solutions including prostheses, tracheal homografts and various autologous tissues have been proposed for tracheal replacement but all are associated with multiple complications and surgical difficulties. None of the numerous experimental studies have produced consistent results allowing for a standardized clinical approach. We propose the use of an autologous aortic graft for tracheal replacement. In a series of experiments, we have observed a progressive transformation of the arterial graft into a tracheal tissue after implantation. This observation raises interesting questions concerning histological adaptation and may offer new perspectives in human tracheal replacement.

Effect of increased plasma non-esterified fatty acids (NEFAs) on arginine-stimulated insulin secretion in obese humans

AIMS/HYPOTHESIS

We have shown previously that the increase of plasma non-esterified fatty acids for 48 h results in decreased glucose-stimulated insulin secretion in lean and non-diabetic obese subjects. It is currently not known if a prolonged increase in non-esterified fatty acids also impairs the insulin secretory response to non-glucose secretagogues.

METHODS

Heparin and intralipid (to increase plasma non-esterified fatty acid concentrations by about two- to fourfold) or normal saline was infused intravenously for 48 h in 14 non-diabetic obese subjects. On the third day in both studies, insulin, C-peptide, proinsulin, and insulin secretion rate were assessed in response to an intravenous arginine infusion at fasting glucose concentration and a second arginine infusion after a 60-min 11 mmol/l hyperglycaemic clamp.

RESULTS

There were no significant differences detected in acute (5 min) or total (90 min) arginine-stimulated C-peptide or insulin secretion response in the heparin-intralipid study compared with the control group at fasting glucose or during hyperglycaemia.

CONCLUSION/INTERPRETATION

We have shown that a prolonged increase in plasma NEFA does not blunt arginine-stimulated insulin secretion or plasma insulin concentrations in non-diabetic obese subjects. These findings suggest that the previously demonstrated NEFA-induced impairment in insulin secretory response to glucose cannot be generalized for non-glucose secretagogues.

Management of hydrocephalus in pediatric patients with posterior fossa tumors: the role of endoscopic third ventriculostomy

OBJECT

The authors undertook a study to evaluate the effectiveness of endoscopic third ventriculostomy in the management of hydrocephalus before and after surgical intervention for posterior fossa tumors in children.

METHODS

Between October 1, 1993, and December 31, 1997, a total of 206 consecutive children with posterior fossa tumors underwent surgery at Hĵpital Necker-Enfants Malades in Paris. Excluded were 10 patients in whom shunts had been placed at the referring hospital. The medical records and neuroimaging studies of the remaining 196 patients were reviewed and categorized into three groups: Group A, 67 patients with hydrocephalus present on admission in whom endoscopic third ventriculostomy was performed prior to tumor removal; Group B, 82 patients with hydrocephalus who did not undergo preliminary third ventriculostomy but instead received conventional treatment; and Group C, 47 patients in whom no ventricular dilation was present on admission. There were no significant differences between patients in Group A or B with respect to the following variables: age at presentation, evidence of metastatic disease, extent of tumor resection, or follow-up duration. In patients in Group A, however, more severe hydrocephalus was demonstrated (p < 0.01): the patients in Group C were in this respect different from those in the other two groups. Ultimately, there were only four patients (6%) in Group A compared with 22 patients (26.8%) in Group B (p = 0.001) in whom progressive hydrocephalus required treatment following removal of the posterior fossa tumor. Sixteen patients (20%) in Group B underwent insertion of a ventriculoperitoneal shunt, which is similar to the incidence reported in the literature and significantly different from that demonstrated in Group A (p < 0.016). The other six patients (7.3%) were treated by endoscopic third ventriculostomy after tumor resection. In Group C, two patients (4.3%) with postoperative hydrocephalus underwent endoscopic third ventriculostomy. In three patients who required placement of CSF shunts several episodes of shunt malfunction occurred that were ultimately managed by endoscopic third ventriculostomy and definitive removal of the shunt. There were no deaths; however, there were four cases of transient morbidity associated with third ventriculostomy.

CONCLUSIONS

Third ventriculostomy is feasible even in the presence of posterior fossa tumors (including brainstem tumors). When performed prior to posterior fossa surgery, it significantly reduces the incidence of postoperative hydrocephalus. The procedure provides a valid alternative to placement of a permanent shunt in cases in which hydrocephalus develops following posterior fossa surgery, and it may negate the need for the shunt in cases in which the shunt malfunctions. Furthermore, in patients in whom CSF has caused spread of the tumor at presentation, third ventriculostomy allows chemotherapy to be undertaken prior to tumor excision by controlling hydrocephalus. Although the authors acknowledge that the routine application of third ventriculostomy in selected patients results in a proportion of patients undergoing an "unnecessary" procedure, they believe that because patients' postoperative courses are less complicated and because the incidence of morbidity is low and the success rate is high in those patients with severe hydrocephalus that further investigation of this protocol is warranted.

Soluble HLA-G protein secreted by allo-specific CD4+ T cells suppresses the allo-proliferative response: a CD4+ T cell regulatory mechanism

We recently reported that the nonclassical HLA class I molecule HLA-G was expressed in the endomyocardial biopsies and sera of 16% of heart transplant patients studied. The aim of the present report is to identify cells that may be responsible for HLA-G protein expression during the allogeneic reaction. Carrying out mixed lymphocyte cultures in which the responder cell population was depleted either in CD4(+) or CD8(+) T cells, we found that soluble HLA-G5 protein but not the membrane-bound HLA-G isoform was secreted by allo-specific CD4(+) T cells from the responder population, which suppressed the allogeneic proliferative T cell response. This inhibition may be reversed by adding the anti-HLA-G 87G antibody to a mixed lymphocyte culture. That may indicate a previously uncharacterized regulatory mechanism of CD4(+) T cell proliferative response.

Functional MRI of language processing: dependence on input modality and temporal lobe epilepsy

PURPOSE

Functional magnetic resonance imaging (MRI) using two language-comprehension tasks was evaluated to determine its ability to lateralize language processing and identify regions that must be spared in surgery.

METHODS

Two parallel cognitive language tasks, one using auditory input and the other visual input, were tested in a group of control subjects and in temporal lobe epilepsy patients who were candidates for surgical intervention. The patient studies provide an opportunity to compare functional MRI language localization with that obtained using Wada testing and electrocorticography. All of the patients in this study underwent all three procedures and a battery of neuropsychological testing. Such studies provide an opportunity not only to validate the fMRI findings but also, by comparing the patient results with those obtained in control subjects, to provide insight into the impact of a pathology such as epilepsy on cortical organization or functional patterns of activation.

RESULTS

The results reveal both modality-dependent and modality-independent language-processing patterns for visual versus auditory task presentation. The visual language task activated distinct sites in Broca's area, BA (Brodmann area) 44 that were not activated in the auditory language task. The auditory language task strongly activated contralateral right BA22-21 area (homologous to Wernicke's area on the left). Language lateralization scores were significantly stronger for visual than for auditory task presentation. The conjunction of activation from the two different input modalities (modality-independent areas) likely highlights regions that perform more abstract computations (e.g., syntactic or pragmatic processing) in language processing. Modality-specific areas (e.g., right Wernicke, left fusiform gyrus, Broca BA44, supramarginal gyrus), appear to cope with the computations relevant to making contact with these more abstract dimensions. Patients showed recruitment of contralateral homologous language areas (p < 0.005) that was significantly above that found in a normal control group. Extra- and intraoperative cortical stimulations were concordant with the fMRI data in eight of 10 cases. The fMRI lateralization scores were also consistent with the Wada testing in 8/10 patients.

CONCLUSIONS

The fMRI results demonstrate that the epileptic brain may be a progressive model for cortical plasticity.

Very long-term results (more than 20 years) of valve repair with carpentier's techniques in nonrheumatic mitral valve insufficiency

BACKGROUND

Mitral valve repair is considered the gold standard in surgery of degenerative mitral valve insufficiency (MVI), but the long-term results (>20 years) are unknown.

METHODS AND RESULTS

We reviewed the first 162 consecutive patients who underwent mitral valve repair between 1970 and 1984 for MVI due to nonrheumatic disease. The cause of MVI was degenerative in 146 patients (90%) and bacterial endocarditis in 16 patients (10%). MVI was isolated or, in 18 cases, associated with tricuspid insufficiency. The mean age of the 162 patients (104 men and 58 women) was 56+/-10 years (age range 22 to 77 years). New York Heart Association functional class was I, II, III, and IV in 2%, 39%, 52%, and 7% of patients, respectively. The mean cardiothoracic ratio was 0.58+/-0.07 (0.4 to 0.8), and 72 (45%) patients had atrial fibrillation. Valve analysis showed that the main mechanism of MVI was type II Carpentier's functional classification in 152 patients. The leaflet prolapse involved the posterior leaflet in 93 patients, the anterior leaflet in 28 patients, and both leaflets in 31 patients. Surgical technique included a Carpentier's ring annuloplasty in all cases, a valve resection in 126 patients, and shortening or transposition of chordae in 49 patients. During the first postoperative month, there were 3 deaths (1.9%) and 3 reoperations (2 valve replacements and 1 repeat repair [1.9%]). Six patients were lost to follow-up. The remaining 151 patients with mitral valve repair were followed during a median of 17 years (range 1 to 29 years; 2273 patient-years). The 20-year Kaplan-Meier survival rate was 48% (95% CI 40% to 57%), which is similar to the survival rate for a normal population with the same age structure. The 20-year rates were 19.3% (95% CI 11% to 27%) for cardiac death and 26% (95% CI 17% to 35%) for cardiac morbidity/mortality (including death from a cardiac cause, stroke, and reoperation). During the 20 years of follow-up, 7 patients were underwent surgery at 3, 7, 7, 8, 8, 10, or 12 years after the initial operation. Valve replacement was carried out in 5 patients, and repeat repair was carried out in 2 patients. At the end of the study, 65 patients remained alive (median follow-up 19 years). Their median age was 76 years (age range 41 to 95 years). All except 1 were in New York Heart Association functional class I/II.

CONCLUSIONS

Mitral valve repair using Carpentier's technique in patients with nonrheumatic MVI provides excellent long-term results with a mortality rate similar to that of the general population and a very low incidence of reoperation.

Long-term (29 years) results of reconstructive surgery in rheumatic mitral valve insufficiency

BACKGROUND

Results of conservative surgery are well established in degenerative mitral valve (MV) insufficiency. However, there are controversies in rheumatic disease. This study is the evaluation of one center for rheumatic MV insufficiency based on a functional approach.

METHODS AND RESULTS

From 1970 to 1994, 951 patients with rheumatic MV insufficiency were operated on with the reconstructive techniques elaborated by Alain Carpentier. Aortic valve diseases were excluded. Mean age was 25.8 years (4 to 75), and sinus rhythm was present in 63%. The functional classification used was type I, normal leaflet motion, 71 patients (7%); type II, prolapsed leaflet, 311 patients (33%); and type III, restricted leaflet motion, 345 patients (36%). The combined lesion of prolapse of the anterior leaflet and restriction of the posterior was present in 224 patients (24%). Surgical techniques used were implantation of a prosthetic ring in 95%, shortening of the chords and leaflet enlargement with autologous pericardium, and commissurotomy. Hospital mortality rate was 2%. The mean follow-up was 12 years (maximum, 29 years): 8618 patients per year. Actuarial survival was 89+/-19% at 10 years and 82+/-18% at 20 years. The rate of thromboembolic events was 0.4% patients per year (33 events), with 3 deaths. Freedom from reoperation was 82+/-19% at 10 years and 55+/-25% at 20 years. The main cause (83%) of reoperation was progressive fibrosis of the MV. The actuarial rate of reoperation was 2% patients per year and was correlated to the degree of preoperative fibrosis.

CONCLUSIONS

Conservative surgery of rheumatic MV insufficiency has a low hospital mortality rate and an acceptable rate of reoperation. The results are excellent regarding the minimal risk of thromboembolic events.

Motor unit behaviour and contractile changes during fatigue in the human first dorsal interosseus

1. In 67 single motor units, the mechanical properties, the recruitment and derecruitment thresholds, and the discharge rates were recorded concurrently in the first dorsal interosseus (FDI) of human subjects during intermittent fatiguing contractions. The task consisted of isometric ramp-and-hold contractions performed at 50 % of the maximal voluntary contraction (MVC). The purpose of this study was to examine the influence of fatigue on the behaviour of motor units with a wide range of activation thresholds. 2. For low-threshold (< 25 % MVC) motor units, the mean twitch force increased with fatigue and the recruitment threshold either did not change or increased. In contrast, the twitch force and the activation threshold decreased for the high-threshold (> 25 % MVC) units. The observation that in low-threshold motor units a quick stretch of the muscle at the end of the test reset the unit force and recruitment threshold to the prefatigue value suggests a significant role for fatigue-related changes in muscle stiffness but not twitch potentiation or motor unit synchronization. 3. Although the central drive intensified during the fatigue test, as indicated by an increase in surface electromyogram (EMG), the discharge rate of the motor units during the hold phase of each contraction decreased progressively over the course of the task for motor units that were recruited at the beginning of the test, especially the low-threshold units. In contrast, the discharge rates of newly activated units first increased and then decreased. 4. Such divergent behaviour of low- and high-threshold motor units could not be individually controlled by the central drive to the motoneurone pool. Rather, the different behaviours must be the consequence of variable contributions from motoneurone adaptation and afferent feedback from the muscle during the fatiguing contraction.

The effect of systemic versus portal insulin delivery in pancreas transplantation on insulin action and VLDL metabolism

Combined kidney-pancreas transplantation (KPT) with anastomosis of the pancreatic vein to the systemic circulation (KPT-S) or to the portal circulation (KPT-P) provides a human model in which the chronic effects of portal versus systemic insulin delivery on glucose and VLDL metabolism can be examined. Despite similar plasma glucose and C-peptide levels, KPT-S (n = 9) had an approximate twofold elevation of fasting and intravenous glucose-stimulated plasma insulin levels compared with both KPT-P (n = 7) and healthy control subjects (n = 15). The plasma free fatty acid (FFA) levels were elevated in both transplant groups versus control subjects, but the plasma insulin elevation necessary to lower plasma FFA by 50% was approximately two times higher in KPT-S versus KPT-P and control subjects. Endogenous glucose production was similar in KPT-S and KPT-P, despite approximately 35% higher hepatic insulin levels in the latter, and was suppressed to a greater extent during a euglycemic-hyperinsulinemic clamp in KPT-S versus KPT-P. Total-body glucose utilization during the euglycemic-hyperinsulinemic clamp was approximately 40% lower in KPT-S versus KPT-P, indicating peripheral tissue but not hepatic insulin resistance in KPT-S versus KPT-P. Both transplant groups had an approximate twofold elevation of triglyceride (TG)-rich lipoprotein apolipoprotein B (apoB) and lipids versus control subjects. Elevation of VLDL-apoB and VLDL-TG in both transplant groups was entirely explained by an approximately 50% reduction in clearance of VLDL compared with healthy control subjects. In the presence of increased FFA load but in the absence of hepatic overinsulinization and marked hepatic insulin resistance, there was no elevation of VLDL secretion in KPT-S versus KPT-P and control subjects. These findings suggest that chronic systemic hyperinsulinemia and peripheral tissue insulin resistance with the consequent elevation of plasma FFA flux are insufficient per se to cause VLDL overproduction and that additional factors, such as hepatic hyperinsulinemia and/or gross insulin resistance, may be an essential prerequisite in the pathogenesis of VLDL overproduction in the common form of the insulin resistance syndrome.

Protein adsorption of calcified and noncalcified valvular bioprostheses after human implantation

BACKGROUND

The incidence of calcification of porcine valve bioprostheses shows important, and as yet unexplained, variations. Previous studies by others showed that osteopontin and osteocalcin are expressed in calcified porcine valve bioprostheses. However, no study has yet explored other proteins that could also be involved.

METHODS

Twelve porcine valve bioprostheses were retrieved from 12 patients and were separated into two groups. Group 1 (n = 6) had early calcification after 4 to 9 years (mean, 6+/-2.3 years). The mean age of the patients at the time of implantation was 46+/-9 years. Group 2 (n = 6) had no calcification after 8 to 14 years (mean, 12+/-2.8 years). The mean age was 47+/-13.4 years. These valves were analyzed by electrophoresis, and the bands were quantified by densitometry.

RESULTS

A 14-kd protein showed a 50% increase in the calcified group. A 31-kd protein found in the calcified group was not detected in the noncalcified group. Three other proteins (45, 39, and 28 kd) showed reduced adsorption in the calcified group.

CONCLUSIONS

Important differences were found in the proteins adsorbed in calcified and noncalcified bioprostheses after implantation in patients. Besides osteopontin and osteocalcin, several other proteins may play a role in the process of calcification of valvular bioprostheses.

Cellular therapy reverses myocardial dysfunction

OBJECTIVES

Cellular cardiomyoplasty refers to the implantation of autologous skeletal muscle cells into the myocardium to reinforce its structure and function. In this study a reproducible method for the creation of a myocardial lesion was developed. The functional benefit of cell implantation was evaluated by 2-dimensional echocardiography for global contraction and color kinesis echocardiography, which allows the precise assessment of the regional contraction.

METHODS

A left ventricular intramyocardial injection with snake cardiotoxin was carried out on a sheep model to induce a well-delineated transmural lesion. Three weeks later, the lesion was assessed by echocardiography. Thereafter, autologous skeletal muscle cells or culture media (control) were injected into the lesion. Two months after cell implantation, the myocardial contraction was again evaluated by echocardiography and the implanted cells were analyzed by a fast myosin heavy chain antibody.

RESULTS

1. The snake cardiotoxin produced a well-delineated transmural lesion in all animals. 2. Echocardiographic studies showed a significant improvement in global and regional left ventricular function in cell-treated sheep. 3. Histologic analyses demonstrated satellite cell survival at the periphery of the lesions.

CONCLUSION

Satellite cells implanted in a cardiotoxin-induced myocardial lesion survived for a 2-month period and were associated with a significant functional improvement of both local and global contraction.

Biochemical properties of heat-treated valvular bioprostheses

BACKGROUND

Preliminary studies showed that heat treatment of glutaraldehyde preserved valvular bioprostheses mitigates calcification. This study was carried out to define the physicochemical characteristics of the heat-treated tissues to elucidate the mechanism involved in the mitigation.

METHODS

Glut bovine pericardium or porcine valve samples were treated at 50 degrees C in a 0.625% glutaraldehyde solution for 2 months. Some samples underwent assay for shrinkage temperature, moisture content, ninhydrin test, and acid hydrolysis, and other samples were incubated in human serum for 3 days and then analyzed by electrophoresis to study protein adsorption.

RESULTS

Heat treatment mitigated calcification without adversely affecting shrinkage temperature (84.81 degrees C versus 83.95 degrees C) and moisture content (78.68% versus 78.71%). A significant reduction in free amino groups (0.15 versus 0.37 mol NH2/mol collagen) and a significant increase in resistance to acid hydrolysis were observed. Total protein content was similar, but significant differences were found for four proteins adsorbed in the tissues (167, 45, 11.6, and 10 kDa).

CONCLUSIONS

The anticalcification effect of heat treatment may be attributed to structural changes, lipid extraction, increased resistance, and modifications of the type and concentration of the proteins adsorbed in the tissue.

Effect of human immunoglobulins on the immunogenicity of porcine bioprostheses

BACKGROUND

Glutaraldehyde fixation (GT) is known to reduce immunologic reactions and tissue degeneration after implantation in humans. Sterilization after glutaraldehyde fixation (G-ST) improves the safety and reduces the tendency of GT valves to calcify. Intravenous immunoglobulins (IVIg) have been shown to reduce xenogeneic response against porcine tissue. We have investigated the effect of these fixation procedures combined with and without IVIg on the antigenicity of bioprostheses.

METHODS

Lewis adult rats were implanted subcutaneously with a fresh, GT, or G-ST porcine heart valve pre- or posttreated with different amounts of IVIg. We followed by enzyme-linked immunosorbent assay and IgM and IgG titers against protein extracts from the porcine heart valves after implantation. Cellular reactivity was assessed in xenogeneic lymphoendothelial coculture experiments. Calcification content was also examined.

RESULTS

Glutaraldehyde fixation partially decreased the humoral response against proteins of the implant but elicited a cellular xenogeneic response. Sterilization reduced these reactivities, but retained antigenicity. Intravenous immunoglobulin postincubated with GT valves before implantation reduced the antigenicity of the tissue to the same extent as G-ST valves, but had no effect on valvular tissue calcification.

CONCLUSIONS

Our studies demonstrate that IVIg or the sterilization procedure (ST) reduced the cellular response against glutaraldehyde-fixed valves (GT), whereas reduced calcification was observed only with ST.