[Risk of recurrent stroke in adults aged under 45 years following a first ischemic stroke: a five-year study of 95 patients]. / Risque de récidive d'infarctus cérébral chez des adultes jeunes âgés de moins de 45 ans ayant présenté un premier infarctus cérébral. Etude à 5 ans d'une population de 95 patients.

Few data are available concerning the risk of recurrence of cerebral ischemic infarction in young adults (less than 45-years-old) after a first episode of ischemic stroke. From 1992 to 1996, 95 patients less than 45 years old were enrolled in a prospective study in order to define the etiology of their ischemic infarction with systematic and exhaustive explorations. They were recalled five years later (mean follow-up of 67,07 +/- 25,6 months) to determine the risk of stroke recurrence, the rate of cardiac and vascular events and the mortality. At 5 years, 4 patients had a recurrence of ischemic stroke (4.7 p. cent). Seven patients had a coronary event (4 myocardial infarction and 4 angina). Eleven patients died (6 during the acute period). No recurrence of stroke was noticed in patients with stroke of undetermined cause or with minor cardiopathy (abnormalities of the atrial septum). The risk of recurrence of ischemic stroke in young adults appears to be very low.

Life span, cancer and non-cancer diseases in mouse exposed to a continuous very low dose of gamma-irradiation.

PURPOSE: To analyse the life-span and pathologies of mice living under a continuous very low-dose gamma-irradiation. MATERIAL AND METHODS: We exposed 300 C57B1/6J female mice, 3 weeks old, to 10 cGy year(-1) gamma-rays while 300 control mice lived in the same room. Irradiation was delivered continuously by thorium nitrate. We kept all the animals until natural death and performed autopsy. RESULTS: No difference was observed in life-span (mean lifespan +/-SE: 805.2 +/- 9.62 days for controls and 815 +/- 9.57 days for irradiated mice), weight curves or food intake. At autopsy, cancer was present in 40.9% of controls and 37.9% of irradiated mice. They were mainly represented by lymphomas (23.7 and 24.9%) and histiocytic sarcomas (12.6 and 8.7%, respectively, for controls and irradiated mice). Vascular diseases occurred in 24.1% of controls and 23% of irradiated mice. Infections were present at autopsy in 14.1 and 12.3%, respectively, of controls and irradiated animals. No statistical difference was observed at the end of the experiment for cancer or non-cancer diseases between the two groups. CONCLUSION: Continuous 10 cGy year(-1) gamma-irradiation had no adverse effect on malignant or non-malignant diseases in this strain of mouse.

Obstetrical brachial plexus palsy. Prediction of outcome in upper root injuries.

Thirty obstetrical brachial plexus palsies involving the upper roots were retrospectively reviewed. There were 20 C5-C6 palsies and ten C5-C6-C7 palsies in which recovery of C7 occurred by the end of the first month. Recovery of elbow flexion at 3 months, C7 involvement and high birthweight were the best early predictors of outcome, but all were unreliable when used separately. In combination, recovery of elbow flexion and birthweight predicted the final outcome reasonably satisfactorily, particularly when elbow flexion at 9 months, and not 3 months was considered (risk of error = 13%). Brachial plexus reconstruction may therefore be justified when there was initial C7 involvement associated with increased birthweight and poor elbow flexion at 6-9 months.

Role of 4 platelet membrane glycoprotein polymorphisms on experimental arterial thrombus formation in men.

This study investigates whether the polymorphisms of 3 important platelet receptors affected experimental thrombus formation in men. Forty healthy male volunteers randomly recruited were genotyped for the variable number of tandem repeat (VNTR) of GPIbalpha, the -5T/C polymorphism in the Kozak sequence of GPIbalpha, the 807C/T polymorphism of GPIa, and the PI(A1)/PI(A2) polymorphism of GPIIb/IIIa. Platelet thrombus formation was induced ex vivo by exposing a collagen-coated coverslip in a parallel plate perfusion chamber to native blood for 4 minutes. The shear rates at the collagen surface were 650 and 2600 x s(-1). At 2600 x s(-1) platelet thrombus formation was significantly related only to the 807C/T polymorphism. In contrast, at 650 x s(-1) thrombus formation was significantly altered only by the Kozak sequence polymorphism. The VNTR and the PI(A1)/PI(A2) polymorphisms did not influence thrombus formation. Thus, platelet thrombus formation is significantly influenced by genetic variations of the GPIbalpha and GPIa receptors. The effect of these polymorphisms was dependent on the blood flow rate.

Peritraumatic dissociation, acute stress, and early posttraumatic stress disorder in victims of general crime.

OBJECTIVE: To compare the relation between peritraumatic dissociation and acute stress and the early development of posttraumatic stress disorder (PTSD) in victims of general crime. METHOD: A total of 48 subjects were assessed within 24 hours of the trauma, using the Peritraumatic Dissociative Experiences Questionnaire Self-Report Version (PDEQ-SRV). They were followed longitudinally to assess acute stress (2 weeks after the assault,) using the Standford Acute Stress Reaction Questionnaire (SASRQ), and posttraumatic stress (at 5 weeks), using the Clinician-Administered PTSD Scale (CAPS) and the Impact of Event Scale (IES). RESULTS: Among PTSD subjects mean PDEQ scores were significantly higher (mean 3, SD 0.9) than in those without PTSD (mean 2.3, SD 0.7) (t = 2.78, df 46, P = 0.007). Among PTSD subjects, mean SASRQ scores were significantly higher (mean 97.9, SD 29.2) than in those without PTSD (mean 54.8, SD 28.2) (t = 4.9, df 46, P = 0.00007). CONCLUSIONS: High levels of peritraumatic dissociation and acute stress following violent assault are risk factors for early PTSD. Identifying acute reexperiencing can help the clinician identify subjects at highest risk.

Correlations between computed tomography findings and family history in otosclerotic patients.

BACKGROUND: Otosclerosis is a heritable disease affecting the otic capsule. Its genetics have been studied since the 19th century, but several issues remain controversial. OBJECTIVE: The goals of this study were to assess the prevalence of sporadic and familial forms of otosclerosis in a population of otosclerotic patients and to compare the radiologic findings between both groups. STUDY DESIGN AND SETTING: This retrospective study was conducted in a single institution. PATIENTS: This study included 211 patients operated on for otosclerosis. MAIN OUTCOME MEASURES: Clinical data, including pure tone audiograms, were available from patients' charts. A questionnaire assessing family history of otosclerosis and deafness was mailed to the otosclerotic patients. A relative was considered otosclerotic if surgery confirmed the disease. The family history was correlated with the computed tomography results. This examination was performed before surgery in all patients. RESULTS: A family history of otosclerosis was found in 24.2% of the patients. The radiologic findings differed between patients with a sporadic form of otosclerosis and those with a familial form. The lesions were more often detectable, bilateral, and severe in the familial forms (p < 0.05). CONCLUSION: These findings lead to the assumption that fenestral radiologic otosclerosis occurs more in sporadic forms, whereas more extensive lesions on computed tomography seem to indicate the familial forms. Hereditary forms demonstrated to be familial seem to lead to more severe disease. The search for a genome locus of otosclerosis may be enlightened by these findings.

Sensorineural hearing loss and otosclerosis: a clinical and radiologic survey of 437 cases.

The aim of this study was to determine if a relationship exists between bone level thresholds and the extension of otosclerotic foci within the otic capsule. The study consisted of a retrospective case review in a university hospital. We included patients who underwent surgery for otosclerosis in our department and who had a CT scan prior to surgery. We analyzed the data charts and CT scans of 437 cases (386 patients). On CT scan, we distinguished patients with fenestral otosclerosis and/or with a pericochlear focus. A pericochlear focus could be extended (Group 2) or not (Group 1) to the cochlear endosteum. Data for Groups 1 and 2 were compared with those for the control group of all patients for whom CT scan showed no cochlear focus (Group 3). Of the 437 CT scans, 399 were positive (91.3%). An anterior focus was reported in 305 cases (69.8%), a footplate thickening in 21 cases (4.8%) and both anomalies were encountered in 60 cases (13.7%). A pericochlear focus was reported in 53 examinations. This focus was extended to the endosteum in 14 cases (26.4% of the pericochlear foci). In Group 1, preoperative air conduction (AC) thresholds were significantly lower than in the control group (p < 0.05). The air--bone gap was also significantly larger in Group 1 (p < 0.05). Bone conduction (BC) thresholds were lower in Group 1 than in the control group but the difference was not significant. In Group 2, preoperative AC thresholds were significantly lower than in the control group (p < 0.05). BC thresholds were also lower in Group 2 than in the control group and the difference was significant (p < 0.05). As a result of this study, we assume that there may be a relationship between bone level thresholds and the radiological extension of otosclerosis within the otic capsule.

Vestibular schwannomas: correlations between magnetic resonance imaging and histopathologic appearance.

BACKGROUND: The indication for surgery of vestibular schwannomas (VS) remains controversial and depends on several factors. The ability to predict their patterns of growth would allow better surgical planning. This growth may depend on tumoral proliferation but also depends on dystrophic changes. OBJECTIVE: The aim of this study was to evaluate the role of magnetic resonance imaging (MRI) in predicting the evolution of VS. For this purpose, the authors attempted (1) to compare the MRI appearance of VS with its histopathologic features, (2) to correlate the MRI appearance of VS and its histopathologic features with its size, and (3) to evaluate the index of proliferation (IP) of each VS. PATIENTS AND METHODS: Thirty VS were studied with MRI before surgery. The VS were measured and classified as homogeneous, heterogeneous, and cystic. After surgery, IP was evaluated with immunohistochemical study using MIB-1 monoclonal antibody, and compared with tumor size. Pathologic studies evaluated the prevalence of Antoni type A and type B tissue, the amount of fibrosis, and the presence of siderin-loaded macrophages, xanthomatous cells, and cysts. RESULTS: The IP was low (0.2%-2.2%) and was not correlated with VS size. On MRI, 13 VS were homogeneous, 12 heterogeneous, and 5 cystic. The 13 homogeneous VS were smaller and were predominantly made of Antoni type A tissue. The 12 heterogeneous and 5 cystic VS were larger and were predominantly made of Antoni type B/mixed tissue. Heterogeneous and cystic VS showed significantly more hemosiderin deposits. There was a significant relation between the amount of hemosiderin deposits and the mean size of VS. Microscopic cysts were observed only in VS with cystic MRI appearance. Fibrosis was present in all tumors regardless of their size and MRI appearance. CONCLUSION: A heterogeneous MRI aspect (correlated with larger mean size) not only is related to the ratio of type A to type B tissue but also is caused by other pathologic changes, mainly hemosiderin deposits and cystic formation. Increasing tumor size probably depends less on IP than on dystrophic changes (hemosiderin, cysts) and/or on the presence of type B tissue.

[Victims of general crimes. Prospective and longitudinal assessment of psychological injuries]. / Victimes d'agression physique: évaluation prospective et longitudinale des blessures psychologiques.

OBJECTIVE: The aim of this study was to assess the relations between acute psychological injury, particularly peritraumatic dissociation, and early development of posttraumatic stress disorder in victims of violence. METHODS: Thirty-five subjects were prospectively assessed in an emergency department, within 24 hours of the trauma, for acute dissociative experiences with the Peritraumatic Dissociative Experiences Questionnaire (PDEQ). All of them were followed longitudinally to assess post traumatic stress disorder (PTSD) 5 weeks after with the Clinician-administered PTSD scale (CAPS) and the Impact of event scale (IES). RESULTS: Of the 35 victims 10 (28%) were diagnosed with a posttraumatic stress disorder at 5 weeks. Among PTSD subjects mean PDEQ scores were significantly higher (3+/-1.1) than in those without PTSD (2.3+/-0.7) (t=2.24, df=33, p=0.029). The PTSD subjects reported more "out of body experience" (p=0.015) and more "sense of body distorsion" (p=0.03) than non PTSD subjects. CONCLUSION: High levels of peritraumatic dissociation following violent assault are risk factors for early posttraumatic stress disorder. Psychological assessment of acute traumatic dissociative experiences must be included in emergency departments.

[Ambulatory surgery of otosclerosis: retrospective study of 102 cases]. / Chirurgie de l'otospongiose en ambulatoire: étude rétrospective à partir de 102 cas.

A retrospective study of 102 selected patients operated for otosclerosis (34 outpatient surgery, 68 hospitalised), having all of them the inclusion criteria of the ambulatory surgery, treated as outpatient in a traditional health sector or hospitalised, depending on their own choice, has been lead. We analysed the results of the pure tone audiometric tests two to six months after surgery. No significative difference was found between the two groups on audiometric results as for the postoperative complications. On the other side, it seems that young patients are more interested by the one-day surgery. The failure of the ambulatory surgery could be explained by the vertigo or dizziness per- or postoperatively. Finally, the evaluation of the cost-benefit shows that the ambulatory surgery in a traditional health sector could lead a budgetary saving policy. A saving way that will grow in a specialized sector devoted to the ambulatory practice.

Effectiveness of conservative management of acoustic neuromas.

OBJECTIVE: The goal of this study was to assess the effectiveness of the conservative management in patients with acoustic neuroma (vestibular schwannoma). STUDY DESIGN: This retrospective study was performed in a university hospital. PATIENTS: Patients were selected for this wait-and-see policy on the basis of age, general condition, audiometric results, tumor size, and patient preference. The study group included 97 patients, 87 of whom had at least two neuroradiologic examinations. The mean age of this population was 63 years (29 to 89 years). The mean length of follow-up of this population was 31 months. Eighty-seven of these patients had at least two radiologic examinations (magnetic resonance imaging or computed tomography). The mean interval between the initial and follow-up radiologic examinations was 15 months. MAIN OUTCOME MEASURES: Tumor size was measured by use of two-dimensional data in all patients. The mean tumor size was 12 mm. The growth rate of the tumor was estimated by comparison of the results of the measurements from the initial and follow-up neuroradiologic examinations. RESULTS: Of the 97 patients studied, 6 patients required surgery and 6 required radiotherapy. Sixty patients (62%) were still being treated conservatively at the end of the study period. Three patients of 28 who were classified as candidates for hearing preservation surgery lost their candidacy during the observation period. The mean annual tumor growth rate was 1.52 mm/year. The tumor was stable in size in 36% of patients, regressed in 11% of patients, or grew in 53% of patients. The growth patterns of the acoustic neuroma fell into five categories: continuous growth in 15% of patients, negative growth in 5%, growth followed by negative growth in 40%, negative growth followed by growth in 20%, and no variation of tumor size in 20%. CONCLUSION: Conservative management of acoustic neuromas carries difficulties: long-term follow-up of the patients and unpredictability of the tumor growth pattern. A reliable and reproducible radiologic method for evaluating tumor size is of great importance.

Study of host- and virus-related factors associated with spontaneous hepatitis C virus clearance.

Epidemiologic parameters, virologic characteristics and frequency of HLA class II DR and DQ antigens were compared between 63 subjects with spontaneous hepatitis C virus clearance (group 1) and 282 patients with chronic active hepatitis C virus infection (group 2). DRB1*1101 and moreover DQB1*0301 alleles were more frequent in group 1 than in group 2 (33.8% vs. 14.7% and 64.4% vs. 28.6%; P=0.012 and P=0.003, respectively). The frequency of DQB1*02 was lower in group 1 than in group 2 (25.4% vs. 49%; P=0.04). No difference was observed in viral genotype distribution between group 1 and group 2. Univariate analysis showed that female sex and contamination by intravenous drug use were associated with self limited infection. However, by multivariate analysis, the only independent factor associated with hepatitis C virus RNA clearance was female sex (P=0.004). In conclusion, spontaneous hepatitis C virus RNA clearance is determined by class II antigens (mainly DQB1*0301) and female sex, while viral genotype plays no role.

High concentration of leptin stimulates myeloid differentiation from human bone marrow CD34+ progenitors: potential involvement in leukocytosis of obese subjects.

OBJECTIVE AND DESIGN: As well as its involvement in control of adipose mass and body energy balance, several reports suggest a link between leptin and hemopoiesis. To test its putative role in human hemopoiesis, we developed a homologous system, ie recombinant human leptin treatment of purified CD34+ progenitors from adult human bone marrow. RESULTS: Leptin (50-100 ng/ml) significantly stimulated the appearance of granulocyte-macrophage colonies in the presence or absence of erythropoietin. The concentration of leptin required for this effect was rather high but within the range of plasma leptin levels observed in obesity. Two results further support the hypothesis that leptin may be involved in the leukocytosis associated with obesity: (i) leptin concentrations in bone marrow and plasma of subjects studied were highly correlated; (ii) leptin and leukocyte count were correlated only in obese subjects. Paracrine effects of locally released leptin from bone marrow adipocytes could also be involved in the regulation of hemopoiesis, a hypothesis supported by marrow immunocytochemistry revealing the close association of CD34+ cells with adipocytes and by previous demonstration that leptin is secreted at a high level by these cells. CONCLUSION: These results indicate that leptin acts on human multilineage CD34+ cells and that high plasma leptin levels associated with obesity could participate in the differentiation of granulocytes from hemopoietic progenitors.

Increase in scrotal temperature in car drivers.

Several recent studies have reported a gradual decline in sperm production in men. Endocrine disrupters as well as lifestyle have been suggested as risk factors. One lifestyle factor that may affect human fertility is driving a vehicle for a prolonged period. Several authors have suggested that driving position may increase the scrotal temperature. In order to validate this hypothesis we conducted continuous monitoring of scrotal temperature in real conditions, i.e. in men driving a car for a prolonged period. Nine volunteer men were asked to walk outside for 40 min and then to drive a car for 160 min. Scrotal temperatures were measured from thermocouples and values recorded every 2 min on a portable data recorder. Scrotal temperature increased significantly (P < 0.0001) in driving posture after 2 h of driving, reaching a value 1.7-2.2 degrees C higher than that recorded while walking. This link between driving position and increased scrotal temperature indicates a potential exposure of male reproductive function to lifestyle factors.

[Results of 248 patients with sleep apnea syndrome treated by continuous positive pressure ventilation between 1990 and 1995. A study of compliance and outcome of the apnea-hypopnea index]. / Suivi de 248 patients présentant un syndrome d'apnée du sommeil traités par pression positive continue entre 1990 et 1995. Etude de l'observance et du devenir de l'index d'apnée-hypopnée.

Between 1990 and 1995, 369 patients were investigated for obstructive sleep apnea syndrome (OSAS) by polysomnography. Among them, 248 patients with a mean Apnea-Hyponea index (AHI) of 37.7 per hour were treated by nasal continuous positive airway pressure (n-CPAP). Mean follow up was 39.5 +/- 20.4 months. In this group, 23 patients (9.2%) refused nCPAP immediately or after the first night and 39 (15.7%) gave up later. 15 patients (6%) died during the period of the study. The cumulative compliance reached 70% at 72 months. Non compliant patients usually gave up n-CPAP before the end of the first year. We compared the group of 150 patients always treated at the date of 31/12/95 with the group of 62 patients who refused nCPAP initially or gave up later. There was no difference in clinical parameters or polysomnographic data between the two groups. In 94 patients treated by nCPAP for more than a year we evaluated the outcome of AHI by a polysomnography performed after 72 hours of nCPAP cessation. Mean AHI of the group at this time was 38.2 +/- 20.3/h and was well correlated with the initial index (r = 0.41, p < 0.0001). However for 28 patients (29.7%) we observed, at the time of this second AHI determination, a variation (plus or minus) of at least 50% of the index. 6 patients, without any significative weigth loss, had an AHI below 5/h at this second determination. In this small group nCPAP was interrupted for 6 to 12 months, then another polysomnography was performed. At this time mean AHI was 42.4/h and clinical symptoms had reappeared in all patients. This study demonstrated that compliance to nCPAP in OSAS patients is good. No clinical or polysomnographic factors allow to predict non compliance. AHI is not modified by long term treatment with nCPAP.

Intrathecal grafting of unencapsulated adrenal medullary tissue can bring CD4 T lymphocytes into CSF: a potentially deleterious event for the graft.

Adrenal medullary tissue including chromaffin cells was grafted intrathecally in cancer patients to relieve intractable pain. The central nervous system (CNS) is considered an immune privileged site. Therefore, non-HLA-matched and unencapsulated tissue was grafted in 15 patients and 1 sham control in a series of at least 20 grafts. We observed an increase in CSF lymphocyte counts in 15/20 allografts (75%). In contrast to peripheral blood, CD4 T cells predominated in the CSF, but failed to exhibit an activated phenotype (CD25+ CD45RO+ HLA-DR+). The positive effect of graft on pain, the high met-enkephalin levels, the absence of any increase in CSF cytokine levels particularly for IFN-gamma or IL-2 (but not IL-10 and IL-6), indirectly indicated that the graft was tolerated despite the presence of CSF lymphocytes. The single treatment failure and three of four cases of partial efficacy occurred in grafts where CSF lymphocytes were present. Moreover, when assayed (n = 7), the CD4+ CSF lymphocytes still retained the capacity to exhibit ex vivo a normal or enhanced frequency of T CD4 cells producing IFN-gamma and IL-2. Taken together, our observations indicate that impairment of the local immunosuppressive balance can lead to activation of those CSF CD4 T cells and drive a rejection process. This study suggests further work on the purification and/or the immunoisolation of tissues grafted in the CNS will be necessary, particularly when the possibility of long-term and repeated grafting is considered.

Role of preoperative positive apical biopsies in the prediction of specimen-confined prostate cancer after radical retropubic prostatectomy: a multi-institutional study.

OBJECTIVES: A multi-institutional study of 280 radical prostatectomy specimens obtained from three independent academic hospitals was undertaken to validate a nomogram developed for the prediction of specimenconfined protstate cancer after prostatectomy. METHODS: Three preoperative factors - the Gleason score, prostatespecific antigen (PSA) and apical location of positive biopsies - that were identified with a previous logistic regression formula were collected. Links between margin status and preoperative criteria were confirmed by univariate methods. Subsequently, the predictive indexes of positive margins were calculated and compared to the actual margin status in terms of predictive characteristics. RESULTS: This control series, independent of the initial series that was used to identify the relevant preoperative factors, confirmed that positive apical biopsies(p<0.001), PSA (p<0.005) and the Gleason score (p<0.005) were strongly linked to the occurrence of positive margins. Different cutoff values for the predictive index were compared in a receiver operating characteristic curve. A value of 0.5, similar to the one described in the original series, gave an adequate compromise between sensitivity and specificity with respective values of 68 and 73% and a test accuracy of 72%. In practical terms, it was possible to predict 85% of negative margins, and to delineate two groups with different rates of positive margins (14.5 vs. 50%). CONCLUSIONS: We demonstrated that PSA, the Gleason score and apical biopsy status are cumulative risk factors for positive margins. Risk of positive margins increases when it is not possible to obtain a wide excision of periprostatic fascia, as at the apex. This study substantiates the independent prognostic value of positive preoperative apical biopsies for predicting positive surgical margins.

Ex vivo flow cytometry determination of intracytoplasmic expression of IL-2, IL-6, IFN-gamma, and TNF-alpha in monocytes and T lymphocytes, in chronic hemodialysis patients.

AIMS: To determine the intracytoplasmic expression of TNF-alpha, IL-2, IL-6 and IFN-gamma, ex vivo and in vitro, in both monocytes and T lymphocytes by flow cytometry after appropriate stimulation using phorbol myristate acetate (PMA)/ionomycin or lipopolysaccharides (LPS) in the presence of monensin, in order to assess the bio(in)compatibility of different dialysis membranes. METHODS: We examined monocytes and T lymphocytes taken from chronic hemodialysis patients (using either cuprophane (CUP), n = 6; polyacrylonitrile (AN 69), n = 6; or polysulfone (PS), n = 6 membranes), before and after a dialysis session. We compared the results with those obtained from end-stage chronic renal failure patients (n = 3) and healthy volunteers (n = 11). RESULTS: Before any stimulation there was a statistically significant difference in the percentages of TNF-alpha, IL-6, and IFN-gamma- expressing monocytes with respect to the dialysis membrane used. The highest percentages were observed for CUP and AN69 patients with figures of around 30% for each cytokine; the lowest percentages were found in PS patients and healthy volunteers. One hour after LPS stimulation the patterns remained unchanged for TNF-alpha and IFN-gamma, whereas the percentages of IL-6-expressing cells in PS patients and in healthy volunteers reached the figures obtained in the other groups. When we examined the percentage of IFN-gamma-, TNF-alpha- and IL-6-expressing monocytes in patients before and after a dialysis session, before any stimulation, we found that the results were significantly different for the three membranes (p = 0.01). Thus, a dialysis session with polysulfone membranes had no significant effect on the precentages of IFN-gamma-, TNF-alpha-, and IL-6-expressing monocytes, whereas percentages were significantly lower after the dialysis session when using cuprophane or AN69 membranes, suggesting a release of these cytokines by the monocytes during dialysis. A significant number of IFN-gamma- and IL-2-expressing T lymphocytes were only detected after 18 hours of PMA/ionomycin stimulation. The percentages of IFN-gamma-expressing T cells recorded for the different membranes were not statistically different from those recorded for healthy subjects or pre-dialysis patients, i.e., they were between 11.5 and 20%. However, the percentages of IL-2-expressing T lymphocytes were significantly different between the 5 groups, i.e., 31.3, 30.5, 18.6, 13.9 and 7. 6%, respectively, for CUP patients, pre-dialysis patients, healthy volunteers, PS and AN69 patients. This suggests that pre-dialysis and CUP patients have, at baseline, a stimulation of their T lymphocytes. Finally, a 4-hour dialysis session had no impact on the percentages of IL-2-expressing T lymphocytes, whereas it was associated with a significant decrease in the percentage of IFN-gamma-expressing cells, but only when cuprophane membranes were used. CONCLUSION: Cytokine flow cytometry enables one to study, ex vivo, i.e., without any stimulation of the cells, and in vitro after appropriate stimulation, the bio(in)compatibility of dialysis membranes assessed by the intracytoplasmic cytokine profiles of TNF-alpha, IFN-gamma, IL-6 and IL-2, evaluated at the single cell level.