Search PubMed⌕ Search

Biomedical subjects

M Zitouni

Publications and source records attributed to M Zitouni.

18 recordsLinked to original sources
PubMed2002

Pemphigus is not associated with allotypic markers of immunoglobulin kappa.

The kappa light chain constant region of immunoglobulins bears polymorphic markers involved in susceptibility to various autoimmune diseases. To determine whether it also contributes to the occurrence of pemphigus, a group of autoimmune blistering skin diseases owing to pathogenic autoantibodies, the genotypic frequencies of Km allotypes were evaluated in patients with pemphigus foliaceus or pemphigus vulgaris and ethnically-matched healthy controls in both Tunisia and France. No difference in the distribution of Km genotype or allele frequencies was observed between patients and controls in either countries. Therefore, Km allotypes do not appear to constitute a genetic factor contributing to pemphigus.

Adult↗
PubMed2002

Tunisian endemic pemphigus foliaceus is associated with desmoglein 1 gene polymorphism.

Desmoglein 1 is the target antigen and probably the initiating immunogen of the autoantibody response in pemphigus foliaceus (PF), a blistering autoimmune skin disease. We previously showed that the desmoglein 1 gene (DSG1) is polymorphic and that one of its variants is associated with the sporadic form of PF observed in France. Herewith, we report, based on a case-control analysis, that the same DSG1 polymorphism participates in susceptibility to the endemic form of PF seen in Tunisia and, thus, show that common genetic factors govern the breakage of tolerance to desmoglein 1 in different epidemiological and environmental situations.

Adolescent↗
PubMed2001

[Tuberculosis, primary biliary cirrhosis and autoimmunity (apropos of a case in Tunisia)].

We report the case of a 70 year-old Tunisian patient who developed antimitochondrial antibodies and anti-ADN during urogenital tuberculosis with clinical and biological signs of primary biliary cirrhosis and systemic lupus erythematosus. We discuss the association of the three diseases and the etiopathogeny of the autoimmune mechanisms induced by Mycobacterium tuberculosis.

Aged↗
PubMed1997

Environmental control of the seasonal variations in the daily pattern of melatonin synthesis in the European hamster, Cricetus cricetus.

Nocturnal patterns of pineal melatonin concentrations were measured at hourly intervals in the European hamster, Cricetus cricetus, maintained under different natural or experimental environmental conditions. There were pronounced variations in the night peak of pineal melatonin both in the duration and the amplitude of the melatonin peak and in the onset and decline of melatonin synthesis. The duration of the melatonin peak increased proportionally with increased dark period. The amplitude increased abruptly from LD 16/8 to LD 15/9 and remained constant in all other photoperiods. The onset of synthesis started 6:00 hours after the onset of darkness in LD 16/8, 15/9, and 14/10, while it started 4:00 hours after dark onset in shorter photoperiods (LD 12/12 and 10/14). This result is opposite to that observed in the rat. The decline of synthesis was delayed as darkness increased and was directly related to lights on in long photoperiods, while it was endogenous in short photoperiods. Temperature, under a long photoperiod, also seems to be implicated in the regulation of the amplitude of the melatonin peak.

Animals↗
PubMed1997

Identification of a new antibody population directed against a desmosomal plaque antigen in pemphigus vulgaris and pemphigus foliaceus.

Pemphigus vulgaris and pemphigus foliaceus are characterized by autoantibodies directed against transmembrane glycoproteins of desmosomes. F12, a human monoclonal autoantibody that binds to the desmosomal plaque, recognizes a 180-190-kDa doublet when immunoblotted against bovine tongue epithelium. Because F12 was derived from the peripheral blood lymphocytes of a patient with pemphigus vulgaris, we looked for the presence of anti-180-190-kDa antibodies in pemphigus vulgaris and pemphigus foliaceus serum. By immunoblot analysis, a third of the pemphigus serum contained anti-180-190-kDa antibodies that belonged to IgG subclass 1 or 3, unlike those that recognized desmogleins 1 and 3 (IgG4). By immunoelectron microscopy analysis on human oral mucosa and human skin with mAb to human IgG3, pemphigus serum containing anti-180-190 kDa antibodies recognized desmosomal plaques. The presence of antibodies with F12 properties in pemphigus serum was further demonstrated by a rabbit anti-F12 idiotype antiserum that allowed detection of F12 idiotype in serum with anti-180-190-kDa antibodies. These results indicate that some pemphigus vulgaris and pemphigus foliaceus serums contain antibodies that react with both intra- and extracellular structures of desmosomes and further demonstrate the heterogeneity of the autoimmune response in both types of pemphigus.

Antibodies, Monoclonal↗
PubMed1996

Brain and pituitary melatonin receptors in male rat during post-natal and pubertal development and the effect of pinealectomy and testosterone manipulation.

Using quantitative autoradiography, melatonin receptors have been studied during post-natal and pubertal development of the rat in 2 brain and 2 pituitary structures. In the pars distalis of anterior pituitary, melatonin receptors decrease gradually in density after birth and disappear in 30 day-old animals. In contrast melatonin binding is only expressed in the paraventricular nuclei of the thalamus at the age of 21-23 days and is always present in adult animals. In the suprachiasmatic nuclei and in the pars tuberalis of the pituitary, melatonin receptor density decreases after birth, remains stable for approximately 1 month and increases again at puberty to reach the birth values in the adult. This increase was absent in pinealectomized and in castrated animals but present in castrated animals receiving testosterone suggesting that it depends upon circulating testosterone and melatonin levels. These results show that melatonin receptors are differentially regulated during post-natal development in each of the 4 structures studied, and that melatonin and testosterone are 2 factors which could be involved in the regulation of melatonin receptor density in the suprachiasmatic nuclei and pars tuberalis.

Analysis of Variance↗
PubMed1995

Influence of maternal melatonin on melatonin receptors in rat offspring.

Using quantitative autoradiography, we have studied the influence of maternal plasma melatonin on the expression and density of melatonin receptors in the brain and pituitary of rat offspring. At birth, the same structures displayed melatonin receptors whether the rats were born to and reared by intact or pinealectomized dams. The receptor density was, however, about 20% lower in the group born to pinealectomized dams. At postnatal day 9, when the pups of both groups synthetize rhythmically their own melatonin, this difference was suppressed. These results indicate that melatonin does not appear to be a requirement for the expression of its receptors, but seems to play a stimulatory role in their synthesis.

Aging↗
PubMed1975

[Determination of hemoglobin in gastric juice].

Among the complications of surgical operations gastric haemorrhages are often unpredictable. Detecting them during the infraclinical stage is possible by measuring hemoglobin in the gastric juice. We have adopted a method allowing the measurement of very low concentrations of hemoglobin.

Gastric Juice↗
PubMedDate not supplied

Delta-sleep-inducing peptide stimulates melatonin, 5-methoxytryptophol and serotonin secretion from perifused rat pineal glands.

The pineal gland is known to synthesize numerous indolamines. Since delta-sleep-inducing peptide (DSIP, a tryptophan nonapeptide) is found in the pineal gland, its effect on the secretion of indolamines was investigated. DSIP stimulated melatonin (MEL), 5-methoxytryptophol (5-ML) and serotonin (5-HT) synthesis and release, whereas it did not affect pineal cyclic AMP levels. The stimulatory effect of DSIP on MEL secretion was dose dependent between 5 x 10(-6) and 10(-4) M, whereas the minimal effective concentration of DSIP on 5-ML secretion was higher than 10(-5) M. The effect of DSIP (10(-4) M) was compared to the effect of isoproterenol (ISO, 10(-6) M) on MEL and 5-HT release. ISO stimulated MEL secretion and concomitantly decreased 5-HT release. With regard to kinetic characteristics, the effect of DSIP (10(-4) M) on MEL release was faster and of shorter duration than the effect of ISO (10(-6) M; 2 and 4 h, respectively). At 10(-4) M, DSIP potentiated the ISO-induced increase of MEL secretion. The DSIP-stimulated release of MEL was not significantly altered when the pineal glands were treated with 10(-5) M propranolol (a beta-adrenergic antagonist), 10(-5) M prazosin (an alpha 1-adrenergic antagonist) or 10(-5) M naloxone (an opioidergic antagonist). This study demonstrates that the DSIP-induced secretion of indolamines from rat pineal glands may not be elicited through the well-known noradrenergic or opioid systems.

Animals↗
PubMedDate not supplied

[Antiphosphoplipid antibodies and retinal occlusive vasculopathy].

PURPOSE: to determine the prevalence of antiphospholipid antibodies in patients with occlusive retinal vascular events, exempt from conventional risk factors of retinal thrombosis. METHODS: eleven patients with retinal vascular occlusion, free of main accepted risk factors for retinal thrombosis, were retrospectively screened for antiphospholipid antibodies (anticardiolipin and anti-beta2 glycoprotein 1 antibodies) by an Elisa method. Prevalence of antiphospholipid antibodies were compared with those in a homogenous control group of 100 patients. RESULTS: the prevalence of antiphospholipid antibodies in the study group was 27% (three of 11). Comparison with control group prevalence (3%) showed a statistically significant difference (p < 0,001). One patient in the study disclosed positivity for IgG anticardiolipine antibodies, one for IgM anticardiolipine antibodies and one for anti-beta2 glycoprotein 1 antibodies. CONCLUSION: our results lead us to recommend a systematic search for specific antiphospholipid antibodies in such young patients which could have an importance for the diagnosis of primary antiphospholipid syndrome.

Adolescent↗