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Biomedical subjects

C Mottet

Publications and source records attributed to C Mottet.

14 recordsLinked to original sources
PubMed2005

[Infectious diarrhea].

Traveler's diarrhea is generally a benign condition which resolves spontaneously in 48 h. Information on dietary hygiene, severity of symptoms and dehydration, as well as their management, is essential. Chemoprophylaxis and antibiotic treatment are not recommended, except in very specific situations. The incidence of chronic diarrhea in HIV-positive patients has dramatically decreased since the introduction of HAART. In the absence of any correlation with the initiation of HAART, a stepwise diagnostic workup is indicated (bacteriological cultures and microscopic examination of fecal samples followed by ileocolonoscopy and gastroduodenoscopy). Specific treatment of any pathogens identified, and HAART in the case of microsporidiasis or cryptosporidiosis, constitute the mainstay of therapeutic management of chronic diarrhea in these patients.

Anti-Bacterial Agents↗
PubMed2005

[Inflammatory bowel diseases].

COX-2 specific anti-inflammatory agents appear as able to induce a flare of inflammatory bowel disease as classical anti-inflammatory agents. The use of steroids, immunomodulators or infliximab prior to surgery does not appear to increase post-operative complication rates. Cases of hepatitis B reactivation have been described after infliximab therapy, suggesting that hepatitis B serological status should be verified prior to infliximab therapy. Adalimubab, a fully humanized antibody directed against TNF-alpha, is efficacious in patients that have lost response or did not tolerate infliximab. Approval of this agent is still awaited. Leucoapheresis is a promising tool in ulcerative colitis.

Humans↗
PubMed2004

Magic polyicosahedral core-shell clusters.

A new family of magic cluster structures is found by genetic global optimization, whose results are confirmed by density functional calculations. These clusters are Ag-Ni and Ag-Cu nanoparticles with an inner Ni or Cu core and an Ag external shell, as experimentally observed for Ag-Ni, and present a polyicosahedral character. The interplay of the core-shell chemical ordering with the polyicosahedral structural arrangement gives high-symmetry clusters of remarkable structural, thermodynamic, and electronic stability, which can have high melting points (they melt higher than pure clusters of the same size), large energy gaps, and (in the case of Ag-Ni) nonzero magnetic moments.

Journal Article↗
PubMed2003

Growth of three-shell onionlike bimetallic nanoparticles.

We show by molecular dynamics simulations on three systems (B/A=Pd/Ag, Cu/Ag, and Ni/Ag) that three-shell metallic nanoparticles made by a core of a metal A, an intermediate shell of metal B and an external shell of metal A (A-B-A nanoparticles) can be grown by deposition of B atoms onto an A core. The growth of the intermediate B shell is triggered by the fact that the most favorable positions for isolated B impurities inside A clusters are located just one layer below the cluster surface.

Journal Article↗
PubMed2001

Human CD4(+)CD25(+) thymocytes and peripheral T cells have immune suppressive activity in vitro.

CD4(+)CD25(+) T cells in mice and rats are capable of transferring protection against organ-specific autoimmune disease and colitis and suppressing the proliferation of other T cells after polyclonal stimulation in vitro. Here we describe the existence in humans of CD4(+)CD25(+) T cells with the same in vitro characteristics. CD4(+)CD8(-)CD25(+) T cells are present in both the thymus and peripheral blood of humans ( approximately 10 % of CD4(+)CD8(-) T cells), proliferate poorly in response to mitogenic stimulation and suppress the proliferation of CD4(+)CD25(-) cells in co-culture. This suppression requires cell contact and can be overcome by the addition of exogenous IL-2. CD4(+)CD25(+) cells from thymus and blood were poor producers of IL-2 and IFN-gamma, and suppressed the levels of these cytokines produced by CD4(+)CD25(-) cells. However, CD4(+)CD25(+) PBL produced higher levels of IL-4 and similar amounts of IL-10 as CD4(+)CD25(-) cells. Regulatory CD4(+)CD25(+) T cells have an activated phenotype in the thymus with expression of CTLA-4 and CD122 (IL-2Rbeta). The fact that CD4(+)CD25(+) regulatory T cells are present with a similar frequency in the thymus of humans, rats and mice, suggests that the role of these cells in the maintenance of immunological tolerance is an evolutionarily conserved mechanism.

Autoimmunity↗
PubMed2001

Control of intestinal inflammation by regulatory T cells.

Transfer of CD4+ T cells to immune-deficient mice in the absence of the CD25+ subset leads to the development of colitis, indicating that regulatory cells capable of controlling a bacteria-driven inflammatory response are present in normal mice. Cells with this function are present in the thymus as well as in the periphery of germ-free mice, suggesting they may be reactive with self-antigen. These cells resemble CD4+CD25+ cells that inhibit organ-specific autoimmunity, suggesting that a similar subset of regulatory T cells may control responses to self and foreign antigens. Development of colitis is dependent on accumulation of activated CD134L+ dendritic cells (DC) in the mesenteric lymph nodes, which is inhibited by CD4+CD25+ cells, indicating that regulatory T cells may control DC activation in vivo. Whilst inhibition of T-cell activation in vitro by CD4+CD25+ cells does not involve interleukin-10 and transforming growth factor-beta, these cytokines are required for the suppression of colitis. It may be that control of responses that activate the innate immune system requires multiple mechanisms of immune suppression. Recently, we identified CD4+CD25+ cells with immune suppressive activity in the thymus and peripheral blood of humans, raising the possibility that dysfunction in this mechanism of immune regulation may be involved in the development of autoimmune and inflammatory diseases.

ADP-ribosyl Cyclase↗
PubMed2001

Role of gender upon basal and postprandial systemic and splanchnic haemodynamics in humans.

BACKGROUND: Food intake, accompanied by systemic and splanchnic haemodynamic changes, has only been studied in males. The extent to which splanchnic postprandial hyperaemia shows gender differences is unknown. METHODS: We tested 1) the splanchnic hyperaemic response to food in females and 2) whether postprandial haemodynamic changes show gender differences. Twenty-four healthy women (aged 20-35 years) and 20 healthy men (aged 21-34 years) participated in the study. A liquid test meal (Ensure plus, 1.5 kcal/ml) was perfused intraduodenally for 75 min through an enteral feeding tube at a rate of 3 ml/min after a 45-min basal period. Blood flow parameters were measured using Echo-Doppler technology. RESULTS: Basal diastolic arterial blood pressure was significantly (P < 0.05) lower in females (66+/-2 versus 72+/-2 mmHg), whereas heart rate was the same (58+/-2 b/min, ns). Postprandially, diastolic blood pressure fell, but reached significance only in males (-10+/-3 mmHg; P < 0.05). Mean velocity in the superior mesenteric artery (SMA) was significantly (P < 0.05) higher in females compared to males at baseline (47+/-3 versus 39+/-2 cm/s), whereas maximal postprandial changes were similar (64+/-6 versus 56+/-6 cm/s, ns). Volume flow in the portal vein (PV) at baseline was 656+/-29 and 716+/-35 ml/min females and males, respectively (ns between gender). Maximal postprandial changes amounted to 808+/-86 and 884+/-107 ml/min, respectively (ns). CONCLUSIONS: 1) Perfusion of a liquid test meal induces significant increases in flow parameters in the SMA and PV in both genders. 2) These changes are partly paralleled by alterations in systemic haemodynamics. 3) Postprandial splanchnic flow parameters are qualitatively and quantitatively not different between genders.

Adult↗
PubMed2000

Reentrant morphology transition in the growth of free silver nanoclusters

The growth of free silver nanoclusters is studied by molecular dynamics simulations, from a small seed up to sizes N approximately 150. It is shown that the final outcome of the growth process depends crucially on the growth conditions (deposition flux straight phi and temperature T). A reentrant morphology transition is obtained: at intermediate values of T and straight phi a "decahedral window" is found; the window is surrounded by regimes where icosahedra are preferentially grown.

Journal Article↗
PubMed2000

Locally inducible CD66a (CEACAM1) as an amplifier of the human intestinal T cell response.

CD66a is an adhesion molecule member of the carcinoembryonic antigen immunoglobulin-like family present on the surface of epithelial cells, granulocytes and IL-2 activated T cells. We studied whether CD66a is expressed in vivo by T lymphocytes and whether it affects TCR-mediated activation. CD66a was detected by histochemistry, flow cytometry analysis, reverse transcription PCR and Western blot on fresh colon biopsies and T cell clones. A fraction of T cells in the lamina propria express CD66a, which is induced by IL-7 and IL-15 cytokines. T cells express four different CD66a splice variants and at least two forms of the protein are glycosylated in a cell type-specific manner. Triggering of CD66a on T cells with physiological ligands or with specific mAb increases TCR-mediated lymphokine release, in an antigen dose-independent manner. This effect requires the presence of the CD66a intracytoplasmic domain, which contains two immunoglobulin receptor family tyrosine-based inhibitory motif-like domains, as shown by stimulation of Jurkat cells transfected with different CD66a isoforms and is associated with increased induction of AP1 and NFkappaB transcription factors. These data indicate that CD66a amplifies T cell activation and thus could facilitate crosstalk between epithelial cells and T lymphocytes in intestinal immune response.

Antigens, CD↗
PubMed1999

Dose-dependent gastrointestinal effects of the somatostatin analog lanreotide in healthy volunteers.

OBJECTIVE: To investigate the gastrointestinal effects of intravenous lanreotide. METHODS: Twenty healthy male subjects participated in 2 subsequent placebo-controlled, double-blind crossover studies. The effects of 3 doses of lanreotide (50, 100, and 200 microg/h) were investigated on 24-hour intragastric acidity (study I), food-stimulated gallbladder contraction, and plasma cholecystokinin release (study II). RESULTS: Lanreotide showed linear pharmacokinetics. It raised median intragastric pH significantly and in a dose-dependent manner: from 1.4+/-0.2 (placebo) to 2.5+/-0.8 (P < .002) during administration of 50 microg/h lanreotide, to 3.2+/-0.7 (P < .001) during 100 microg/h lanreotide, and to 4.3+/-0.7 (P < .001) during 200 microg/h lanreotide. However, no significant inhibition of gastrin secretion could be established. All doses completely inhibited postprandial gallbladder contraction. CONCLUSION: Intravenous administration of lanreotide at rates applied in this study was able to significantly inhibit intragastric acid secretion and postprandial gallbladder contraction; under these conditions few untoward effects were noted.

Adult↗
PubMed1998

Hemodynamic effects of the somatostatin analog lanreotide in humans: placebo-controlled, cross-over dose-ranging Echo-Doppler study.

Because of their vasoactive effects, somatostatin and its analogs are increasingly used in the management of complications of chronic liver diseases such as variceal bleeding. Postprandial hyperemia augments splanchnic blood flow, subsequently increasing portal pressure. The aim of this study was to explore effects of the somatostatin analog, lanreotide, on food-stimulated hemodynamic parameters in healthy human subjects. A dose-response curve was constructed in eight healthy male subjects in a placebo-controlled cross-over study. On 4 different days, either 0 (placebo), 50, 100, or 200 microg/h of lanreotide was infused intravenously in random order, starting at 45 minutes for 7 hours. On each day, a liquid test meal (Ensure plus, 1.5 kcal/mL) was perfused intraduodenally at a rate of 3 mL/min over 7 hours after a 45-minute basal period. Diastolic arterial pressure (dBP), heart rate (HR), superior mesenteric arterial (SMA) average flow velocity (SMA-V), SMA pulsatility index (SMA-PI), portal venous volume flow (PV-F), and renal artery (RA) resistance index (RA-RI) were measured on regular intervals (flows using Echo-Doppler technology). Lanreotide at all doses abolished food-stimulated splanchnic hyperemia both in the SMA and PV over 7 hours. The fall in dBP and increase in HR after food perfusion were blunted under lanreotide. Food as well as lanreotide did not modify RA-RI. In summary: 1) lanreotide inhibits food-induced splanchnic hyperemia in normal subjects; 2) in parallel, systemic hemodynamic alterations to food stimulation are abolished with lanreotide; and 3) renal vascular resistance is unchanged. Because of its persistent splanchnic vasoconstrictive effect, lanreotide should be tested in patients with portal hypertension.

Adult↗
PubMedDate not supplied

Cisplatin-based chemotherapy regimen (DECAV) for uterine sarcomas.

Uterine sarcomas are an extremely rare event. There is no standard therapy for cases of relapse, although chemotherapy is commonly used. We studied the use of a cisplatin-based chemotherapy regimen for uterine sarcomas with an unusually long follow-up. Thirty-nine women with a median age of 50 years (32-71) entered the study. Histologically, leiomyosarcomas (26), carcinosarcomas (8), and stromal sarcomas (5) were represented. Group 1 consisted of patients undergoing adjuvant therapy (for initial disease, eight patients; for pelvic recurrence, two patients); Group 2 consisted of patients with advanced disease (locoregional after initial local therapy, five patients; local recurrence, six patients) or metastatic disease (stage IV, four patients; recurrence, 14 patients). DECAV therapy consisted of doxorubicin 50 mg/m2 d1, dacarbazine (DTIC) 200 mg/m2/d d1-3, vindesine 2 mg/day d1-2, cisplatin 100 mg/m2 d3, and either cyclophosphamide (CPM) 200 mg/m2/d d1-3 (n = 21), or ifosfamide (IFM) 2 g/m2/d d1-3 with mesna every 4 weeks Toxicity included 18 hospital stays for cytopenia (nine patients), including 13 cases of febrile neutropenia. Twenty blood transfusions in 10 patients and 12 platelet transfusions in seven patients were required. One toxicity-related death (hemorrhage) occurred. The overall response rate was 54% (3 complete response, 11 partial response) with a median duration of 13 months (4-36). Median overall survival was 14 month overall, 45 months for Group 1 and 13 months for Group 2. We conclude that the DECAV regimen is clearly active in uterine sarcomas but is too toxic to be recommended routinely.

Adult↗