PubMed Health⌕ Search

Biomedical subjects

M Dhouib

Publications and source records attributed to M Dhouib.

11 recordsLinked to original sources
PubMed2006

[Mandibular Langerhans cell histiocytosis].

INTRODUCTION: Langerhan's cell histiocytosis is defined as an abnormal proliferation of Langerhans cells in various organs and tissues (bone, skin, lymph nodes...). Among facial locations, mandibular involvement is the most frequent and occurs in young people less than 20 years. The aim of this report is to review the characteristic features of this disease, the current means of diagnosis and treatment through two case reports. CASES: Two male patients aged 10 and 55 years respectively presented with single mandibular location of Langerhans cell histiocytosis. The diagnosis was confirmed by histological examination of the biopsy specimen. The first patient underwent surgical resection of the tumor. No recurrence was observed. In the second patient, the postoperative course was marked by the appearance of an inflammatory phenomenon in the adjacent skin and mucosa, successfully treated by intralesional corticosteroid therapy. DISCUSSION: Langerhan's cell histiocytosis is a rare disease. The mandibular location has variable clinical expressions which can vary from dental mobility to tumor development in the gingiva. The radiological appearance is also variable; histological proof is required for diagnosis. Treatment depends on the number and locations of the lesions. In case of a single location, the treatment options may vary from a "wait and see" attitude to a non aggressive surgery, with a possible local corticosteroid therapy or radiothe-rapy. For multiples locations, chemotherapy is indicated.

Child↗
PubMed2004

[Lethal osteogenesis imperfecta. Prenatal diagnosis].

INTRODUCTION: Osteogenesis imparfecta (OI) comprises a group of disorders principally affecting type I collagen, which result in increased bone fragility. Lethal forms are rare and are characterised by micromelia with malformation of the limbs. CASE REPORT: A prenatal diagnosis of lethal OI was made by ultrasonography at 18 weeks of gestation and therapeutic abortion was indicated. COMMENTS: Molecular biology and genetic studies offer new possibilities of prenatal diagnosis, but ultrasonography remains the investigation of choice. It confirms the diagnosis by revealing an increase in bone transparency.

Abortion, Therapeutic↗
PubMed1998

Carbon monoxide induces murine thymocyte apoptosis by a free radical-mediated mechanism.

Carbon monoxide (CO) induces acute or chronic toxicity, according to the level and duration of the exposure. Since chronic CO exposure was shown to have immunosuppressive effects (as it decreases the frequency of rat splenic immunocompetent cells and immunoglobulin production), we investigated the effect of CO on thymocytes, since these are the most sensitive cells to oxidative damage from the lymphoid lineage. We exposed thymocytes to CO, then determined their apoptotic index after 6 h of incubation at 37 degrees C using the fluorochrome Hoechst 33342 and electron microscopy and found an increase of apoptosis in CO-exposed thymocytes. Trolox (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid), an antioxidant vitamin E analog, decreased CO-induced thymocyte apoptosis unlike methylene blue, L-nitroarginine methyl ester or pyrrolidine dithiocarbamate. We also observed that lipid peroxidation was increased in the CO-exposed thymocytes and that it was inhibited by Trolox. Our results suggest that CO induces thymocyte apoptosis by a free radical-mediated mechanism which can be inhibited by Trolox but which does not involve the activation of the guanylyl cyclase-cGMP pathway.

Animals↗
PubMed1996

Induction of nitric oxide synthase by chlorinated pesticides (p,p'-DDT, chlordane, endosulfan) in rat liver.

The aim of this study is to investigate the effect of certain polychlorinated pesticides on the induction of rat liver Ca(2+)-independent nitric oxide synthase (NOS) and compare it with the effect of bacterial lipopolysaccharide. Our results show that endosulfan and p, p'-DDT treatment significantly increases the NOS activity while no significant induction by any route of administration was observed in the case of chlordane. Our results show therefore that a wide variety of chlorinated pesticides, which are considered as hepatic tumor promotors, can stimulate the expression of NO synthase in vivo.

Animals↗
PubMed1996

Rapid method for analysis of chloroacetanilide and chloronitrophenoxyaniline herbicides by gas chromatography.

The herbicides Alachlor and Alclonifen are recently used in France for pre-emergent weed control in corn, essentially in association. For this reason, an improved method has been developed by gas chromatography for simultaneously characterising and quantifying the two herbicides. The best conditions were obtained by using a gas chromatograph equipped with an ion trap detector, and a 30 m x 0.25 mm DB-1701 fused silica capillary column. Retention times of Alachlor and Aclonifen were 12.8 and 23.2 min respectively. The limit of detection was of 2.0 ppb for each herbicide.

Acetamides↗
PubMed1995

Kinetics of nitric oxide synthase induction by Propionibacterium avidum and lipopolysaccharide.

Conditions for the induction of rat liver Ca2(+)-independent nitric oxide synthase were determined with killed Propionibacterium avidum, and compared with lipopolysaccharide endotoxin. Similar maximal induction was obtained intraperitoneally with the two types of inducers but killed Propionibacterium avidum gave a long-lasting induction while lipopolysaccharide displayed a rapid and short response. Moreover, the induction resulting from an intravenous administration of killed Propionibacterium avidum reached 60 times that of the control whereas lipopolysaccharide treatment induced a 24-fold stimulation only. It is noteworthy that with the first inducer the nitric oxide activity was stable with time whereas with the second one it dropped after 8 h. Whatever the route of administration of killed Propionibacterium avidum, some huge vacuolated Kupffer cells were found in the liver whose parenchyma was almost normal. Numerous monocytes, and unaltered Kupffer cells, were observed. Kupffer cells were identified to be responsible for the uptake of killed Propionibacterium avidum.

Animals↗
PubMedDate not supplied

Nitric oxide synthase inhibition by haem oxygenase decreases macrophage nitric-oxide-dependent cytotoxicity: a negative feedback mechanism for the regulation of nitric oxide production.

Nitric oxide (NO) production in macrophages by inducible nitric oxide synthase (NOS2) has multiple tissue damaging effects and is involved in the pathogenesis of inflammation and graft rejection. Haem oxygenase (HmOx) is the enzyme which degrades haem. Its inducible isoform, HmOx1, was recently shown to increase cellular resistance against oxidative stress and to decrease inflammation and graft rejection. Since haem is an essential cofactor for NOS2 activity, we investigated the effects of HmOx1-induction upon NO secretion in macrophages. We induced HmOx1 in BALB/c bone-marrow-derived macrophages by short-term exposure to haemin (20 micromol/l, 30 min); then we incubated them for 24 h to allow maximal expression of HmOx1 activity. Next, we activated the macrophages with lipopolysaccharide (LPS) and measured their NO production and their NO-dependent cytotoxicity against P815 cells. We found that HmOx induction 24 h before LPS activation in mouse macrophages suppresses their production of NO, while HmOx inhibition (with zinc protoporphyrin) increases NO secretion. NOS2 inhibition is reflected by the decrease of macrophage NO-dependent cytotoxicity against the P815 targets. We therefore propose that HmOx1 is a physiological inhibitor of NOS2 in activated macrophages because it decreases haem availability for NOS2 synthesis. NOS2 inhibition may explain the antinflammatory effects of HmOx induction which could also be used therapeutically in situations when NO hyperproduction leads to cytotoxic effects such as inflammation or transplant rejection.

Animals↗