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Biomedical subjects

Frédéric Michel

Publications and source records attributed to Frédéric Michel.

14 recordsLinked to original sources
PubMed2005

Thromboxane A2/prostaglandin H2 receptor activation mediates angiotensin II-induced postischemic neovascularization.

OBJECTIVE: We analyzed the involvement of thromboxane (TX) A2/prostaglandin (PG) H2 (TP) receptor in ischemia-induced neovascularization in mice. METHODS AND RESULTS: Unilateral hindlimb ischemia was induced by right femoral artery ligature in male C57BL/6J mice (n=7 per group). Animals were then treated with or without TP receptor antagonist (S18886, 5 or 10 mg/kg per day; ramatroban, 10 mg/kg per day) or aspirin (30 mg/kg per day) in drinking water for 21 days. Hindlimb ischemia raised plasma level of TXB2, the stable metabolite of TXA2, by 4.7-fold. This increase was blocked by aspirin treatment whereas S18886 (5 or 10 mg/kg per day) had no effect. However, neither S 18886 nor aspirin affected postischemic neovascularization. We next assessed the putative involvement of TXA2 signaling in angiotensin II (Ang II) proangiogenic pathway. Ang II (0.3 mg/kg per day) enhanced TXB2 plasma levels by 2.6-fold over that of control (P<0.01). Ang II-induced TXB2 upregulation was reduced by cotreatment with Ang II type I receptor antagonist (candesartan, 20 mg/kg per day). Angiographic score, capillary number, and foot perfusion were improved by 1.7-, 1.7-, and 1.4-fold, respectively, in Ang II-treated mice compared with controls (P<0.05). Ang II proangiogenic effect was associated with a 1.6-fold increase in VEGF-A protein content (P<0.05) and a 1.4-fold increase in the number of Mac-3-positive cells (ie, macrophages) in ischemic areas (P<0.05). Interestingly, treatments with TP receptor antagonists or aspirin hampered the proangiogenic effects of Ang II. CONCLUSIONS: Endogenous activation of TXA2 receptor by eicosanoids did not modulate spontaneous neovascularization in the setting of ischemia. Conversely, TXA2 signaling is involved in Ang II-induced AT1-dependent vessel growth.

Angiotensin II↗
PubMed2005

[Angiomyolipoma with epithelioid contingent mimicking renal cell carcinoma].

The authors report the case of a patient followed for renal angiomyolipoma. On CT surveillance, this lesion developed features of a malignant tumour with loss of the fatty component and the patient was treated by nephrectomy. Histological examination demonstrated renal angiomyolipoma with an epithelioid contingent. The various aspects of this histological and radiological variant are discussed.

Adult↗
PubMed2005

[Urinary bovine tuberculosis in man].

Human infestation by Mycobacterium bovis has become rare since eradication of bovine tuberculosis. However, this aetiology must be envisaged, as the sensitivity of the micro-organism is variable and its demonstration requires specific techniques.

Animals↗
PubMed2004

Aldosterone enhances ischemia-induced neovascularization through angiotensin II-dependent pathway.

BACKGROUND: We analyzed the role of aldosterone in ischemia-induced neovascularization and the involvement of angiotensin II (Ang II) signaling in this effect. METHODS AND RESULTS: Ischemia was induced by right femoral artery ligature in mice treated or not with aldosterone (4.5 microg/day), aldosterone plus spironolactone (aldosterone receptor blocker; 20 mg/kg per day), or aldosterone plus valsartan (angiotensin type 1 [AT1] receptor blocker; 20 mg/kg per day). After 21 days, neovascularization was evaluated by microangiography, capillary density measurement, and laser-Doppler perfusion imaging. Protein level of vascular endothelial growth factor (VEGF) was determined by Western blot analysis in hindlimbs. mRNA levels of renin-angiotensin system components were also assessed by semiquantitative reverse transcription-polymerase chain reaction. Angiographic score, capillary number, and foot perfusion were improved in ischemic/nonischemic leg ratio by 1.4-, 1.5-, and 1.4-fold, respectively, in aldosterone-treated mice compared with controls (P<0.05). Aldosterone proangiogenic effect was associated with 2.3-fold increase in VEGF protein content (P<0.05). Treatments with spironolactone or with neutralizing VEGF antibody hampered the proangiogenic effect of aldosterone (P<0.05 versus aldosterone-treated mice). Interestingly, AT1 receptor blockade completely abrogated the aldosterone proangiogenic effect, emphasizing the involvement of Ang II-related pathway in aldosterone-induced vessel growth. In this view, angiotensinogen mRNA content was 2.2-fold increased in aldosterone-treated mice in reference to controls (P<0.05), whereas that of renin, angiotensin-converting enzyme, and AT1 receptor subtype was unaffected. Aldosterone treatment also decreased AT2 mRNA content by 2-fold (P<0.05 versus controls), suggesting that aldosterone may switch the Ang II pathway toward activation of vessel growth. CONCLUSIONS: This study shows for the first time that aldosterone increases neovascularization in the setting of ischemia through activation of Ang II signaling.

Aldosterone↗
PubMed2004

Minimally invasive, in vivo exploration of mouse small artery reactivity.

The aim of the study was to investigate in vivo arterial reactivity in the mouse hind limb using Orthogonal Polarisation Spectral (OPS) imaging, which delivers high-contrast images of vascular beds by visualizing red blood cells. After minimal skin invasion of anesthetized mice, the OPS probe was placed on the hind limb continuously superfused with physiological saline solution. Then, the response of the saphenous artery (average luminal diameter 127 +/- 3 microm; n = 15) to topical application of increasing concentrations of acetylcholine or phenylephrine was examined. Mean carotid arterial blood pressure was unaffected during the experiment. The basal diameter decreased by 70% during exposure to phenylephrine (pD2: 5.65 +/- 0.08; n = 9), while acetylcholine augmented basal diameter up to 199% (pD2: 6.55 +/- 0.12; n = 6). Application of sodium nitroprusside did not further increase arterial diameter following acetylcholine exposure. After washing out, arterial luminal diameters returned to initial values. Second exposure to vasoactive agents demonstrated that changes in diameter were reproducible with time and not different between left and right saphenous arteries. Thus, OPS imaging is an in vivo dye-free, simple and minimally invasive approach, which provides unique information regarding the behavior of vascular network within conditions of cellular and physiological homeostasis.

Acetylcholine↗
PubMed2004

Pathology of the ossicular chain: comparison between virtual endoscopy and 2D spiral CT-data.

OBJECTIVE: The purpose of this study was to assess the value of virtual endoscopy (VE) in the diagnosis of lesions of the ossicular chain and to compare virtual endoscopy and two-dimensional (2D) spiral computed tomography (CT) data. STUDY DESIGN: Retrospective study. SETTING: A university hospital. PATIENTS: Fifty-eight patients with suspected ossicular chain lesions underwent a high-resolution CT of the temporal bone with both 2D data and VE before surgery. MAIN OUTCOME MEASURES: Two views were chosen for VE. The CT data obtained (2D, VE, and both 2D and VE) were compared with the lesions noted during surgery. RESULTS: In the diagnosis of dislocation of the ossicles or prostheses, VE seemed to be a better technique than 2D CT. Views chosen for the VE proved to be ineffective for diagnosing epitympanic fixations. VE was not adapted to the study of otosclerosis. We found it necessary to use the data provided by the addition to 2D CT data in the diagnosis of ossicular lysis and minor aplasia. Radiologic analysis of the lesions of the long process of the incus and the incudostapedial joint was improved by performing both 2D CT and VE. VE reconstruction of the stapes proved to be difficult, especially in cases of inflammation of the middle ear. CONCLUSION: This study demonstrates the value of VE in the diagnosis of dislocation of the ossicles and ossicular prostheses. VE was less effective in diagnosing other pathologies of the ossicular chain.

Ear Ossicles↗
PubMed2004

[Adrenal metastasis from follicular thyroid carcinoma with intra-cardiac thrombus].

The authors report the case of a 57-year-old patient operated for adrenal metastasis from follicular thyroid carcinoma with intracardiac thrombus, who subsequently developed disseminated metastases leading to death 9 months after the operation. Adrenal metastases of thyroid carcinomas are rare and can be treated surgically when they are isolated. These metastases may appear many years after initial thyroid surgery requiring regular surveillance, especially by serum thyroglobulin assay in the case of well differentiated carcinoma.

Adenocarcinoma, Follicular↗
PubMed2003

Birth after intracytoplasmic injection of epididymal sperm from a man with congenital bilateral absence of the vas deferens who had a robertsonian translocation.

OBJECTIVE: To present the first case of an infertile male with azoospermia related to a congenital bilateral absence of the vas deferens (CBAVD), in which mutations within the cystic fibrosis transmembrane conductance regulator (CFTR) gene coexist with a robertsonian translocation. DESIGN: Case report. SETTINGS: A university hospital. PATIENT(S): A 34-year-old male with a 2-year history of primary infertility. INTERVENTION(S): Lymphocytic karyotype, polymerase chain reaction (PCR) and allele oligonucleotide-specific hybridization (ASO), microsurgical epididymal sperm aspiration (MESA), and intracytoplasmic sperm injection (ICSI). MAIN OUTCOME MEASURE(S): Physical examination and semen analysis. RESULT(S): Semen analyses revealed azoospermia and a well-recognized obstructive phenotype. Analysis of the CFTR gene revealed a compound heterozygosity for a 2184 del A + 2183 A --> G mutation on one allele and the 5T variant within the polypyrimidine tract of intron 8 on the other allele. Cytogenetic analyses revealed a t(13;14)(q10;q10) robertsonian translocation in the same patient. Microsurgical epididymal sperm aspiration allowed retrieval of a million mature motile spermatozoa, excluding any spermatogenic impairment secondary to the genetic abnormalities found in this patient. Epididymal sperm was used for an intracytoplasmic sperm injection program, and a normal child was born at term. CONCLUSION(S): This case illustrates that two distinct genetic defects may coexist, with a variable effect on male fertility but with important implications for genetic counseling of the future pregnancy.

Adult↗
PubMed2003

[Xanthrogranulomatous pyelonephritis with nephrocutaneous fistula].

The authors report a case of xanthogranulomatous pyelonephritis presenting with nephrocutaneous fistula. This case illustrates all of the typical features of this disease: late diagnosis, non-functioning affected kidney, staghorn calculi, urinary tract anomaly, perinephritis with fistulization. The authors review the diagnostic and therapeutic modalities of xanthogranulomatous pyelonephritis and discuss the other aetiologies of nephrocutaneous fistula. In view of the severity of this disease and its preoperative resemblance to renal cancer, nephrectomy is often the only available treatment option.

Female↗
PubMed2003

[Management of the emphysematous pyelonephritis].

We report two cases of emphysematous pyelonephritis in diabetic patients. The first suffered from emphysematous pyelonephritis and emergency nephrectomy was performed. The second patient suffered from emphysematous pyelitis and was successfully treated by nephrostomy. We present a comprehensive review of the literature on emphysematous pyelonephritis and discuss the indications and the results of treatments of this rare and severe infection.

Emphysema↗