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Biomedical subjects

M Brun

Publications and source records attributed to M Brun.

At least 19 recordsLinked to original sources
PubMed2006

Surface plasmon mediated near-field imaging and optical addressing in nanoscience.

We present an overview of recent progress in "plasmonics". We focus our study on the observation and excitation of surface plasmon polaritons (SPPs) with optical near-field microscopy. We discuss in particular recent applications of photon scanning tunnelling microscope (PSTM) for imaging of SPP propagating in metal and dielectric wave guides. We show how near-field scanning optical microscopy (NSOM) can be used to optically and actively address remote nano objects such as quantum dots. Additionally we compare results obtained with near-field microcopy to those obtained with other optical far-field methods of analysis such as leakage radiation microscopy (LRM).

Journal Article↗
PubMed2006

Differential diagnosis of fetal hyperechogenic cystic kidneys unrelated to renal tract anomalies: A multicenter study.

OBJECTIVES: To identify important factors in the differential diagnosis of renal cysts associated with hyperechogenic kidneys. METHODS: This was a retrospective multicenter study. We identified 93 fetuses presenting between 1990 and 2002 with hyperechogenic kidneys and which had a diagnosis of nephropathy confirmed later. We analyzed retrospectively the prenatal ultrasound findings of those fetuses which were found sonographically to have renal cysts. RESULTS: Of the 93 fetuses presenting with hyperechogenic kidneys and with a later diagnosis of nephropathy, there were 28 with autosomal dominant polycystic kidney disease (ADPKD), 31 with autosomal recessive polycystic kidney disease (ARPKD), 11 with Bardet-Biedl syndrome, nine with Meckel-Gruber syndrome, six with Ivemark II syndrome, one with Jarcho-Levin syndrome, one with Beemer syndrome and one with Meckel-like syndrome. One third of the fetuses (30/93) had renal cysts. Cystic characteristics (size, location, number) were not very useful for diagnosis; more useful was diagnosis of an associated malformation. Three (11%) of the fetuses with ADPKD had cysts, as did nine (29%) of those with ARPKD, three (27%) of those with Bardet-Biedl syndrome, all (100%) of those with Meckel-Gruber syndrome, three (50%) of those with Ivemark II syndrome, and each of the three cases with other syndromes (Jarcho-Levin, Beemer and Meckel-like syndromes). None of the cases with trisomy 13 had cysts. There were no associated malformations in the 12 cases with renal cysts and polycystic kidney disease; the other 18 cases with renal cysts were associated with malformations that were often specific, such as polydactyly in Bardet-Biedl and Beemer syndromes, occipital defect and Dandy-Walker malformation in Meckel-Gruber or Meckel-Gruber-like syndromes, and thoracic and/or vertebral abnormalities in Jarcho-Levin and Beemer syndromes. CONCLUSION: Renal cysts associated with hyperechogenic kidneys are not rare. The clue to diagnosis is the demonstration of an associated malformation. If no malformation is found, the main diagnosis remains polycystic kidney disease, i.e. ARPKD or ADPKD.

Bardet-Biedl Syndrome↗
PubMed2006

A variant chronic B-cell lymphoma characterized by villous cells with novel immunophenotypic and cytogenetic profiles.

The less common chronic B-cell lymphomas include hairy cell leukemia, hairy cell leukemia variant and splenic lymphoma with villous lymphocytes. These disease entities can sometimes cause a diagnostic dilemma; however, immunophenotypic markers have been identified as disease specific and scoring systems have been proposed to assist the process. This study reports a case of a chronic B-cell lymphoma with long cytoplasmic projections which does not fit into any of the published disease categories based upon a combination of clinical and morphological features and immunophenotyping. Furthermore, this case featured a combination of cytogenetic abnormalities not previously described in the published literature in association with a B-cell lymphoproliferative disorder.

Cell Surface Extensions↗
PubMed2006

Effects of hydroxyurea on malaria, parasite growth and adhesion in experimental models.

We recently raised concern over using hydroxyurea (HU) in the treatment of sickle cell disease in areas endemic for malaria, becauseit up-regulates the endothelial surface expression of ICAM-1, a major receptor for Plasmodium falciparum-infected erythrocytes in the brain. Using human in vitro models of cerebral malaria, we evaluated the interaction of HU with parasites and demonstrated that HU pretreatment increased the number of infected red blood cells adhering to the endothelium, but did not increase endothelial apoptosis. Moreover, using an experimental cerebral malaria model, HU pretreatment was found to prevent significantly mice from developing neurological syndrome by inhibiting parasite growth, opening potential therapeutic avenues.

Anemia, Sickle Cell↗
PubMed2004

Prenatal sonographic patterns in autosomal dominant polycystic kidney disease: a multicenter study.

OBJECTIVE: To determine whether a specific prenatal sonographic pattern can be identified for autosomal dominant polycystic kidney disease (ADPKD) and if so whether it would be helpful in orienting complementary analysis, properly counseling parents and adapting pregnancy management. METHODS: A retrospective multicenter study was conducted in four prenatal diagnostic centers. The records of fetuses with a prenatal ultrasound examination revealing abnormal kidneys and with a final diagnosis of ADPKD were analyzed. Ultrasound analysis included: amount of amniotic fluid, bladder size, renal length, presence or absence of renal cysts and size of renal pelves, and was focused on parenchyma echogenicity and status of corticomedullary differentiation. Postnatal follow-up was reviewed. RESULTS: Of the 27 patients included in the study, 25 had hyperechogenic renal cortex and 20 had hypoechogenic medulla resulting in increased corticomedullary differentiation (CMD). In six cases, the medulla was hyperechogenic leading to absent or decreased CMD. One patient had normal cortical echogenicity and CMD. Renal cysts were present during the prenatal period in four patients (at 22 weeks in one case and after 30 weeks in three cases). In 12 patients, the cysts appeared after birth (within the first 6 months of postnatal life in 10 cases and by the age of 1 year in two cases). Elevated blood pressure was observed in only two cases and moderate chronic renal failure in one case. CONCLUSION: We have described the sonographic presentation in fetuses with ADPKD: moderately enlarged hyperechogenic kidneys with increased CMD. Although not specific to ADPKD, these findings should prompt familial screening. Other prenatal sonographic features (absent or decreased CMD and cortical cysts) are less frequent.

Amniotic Fluid↗
PubMed2004

[Practical measurement of radiation dose in pediatric radiology: use of the dose surface product in digital fluoroscopy and for neonatal chest radiographs].

PURPOSE: Control of radiation dose in pediatric radiology requires knowledge of the reference levels for all examinations. These data are useful for daily quality assessment, but are not perfectly known for some radiographic examinations. The purpose of our study was to evaluate the dose related to voiding cystourethrograms (VCUG), upper GI (UGI) and intravenous urography (IVU). Neonatal chest radiographs in the intensive care unit were also evaluated. MATERIAL AND METHODS: For examinations with contrast material (478VCUG, 220UGI, 80IVU), the children were divided in groups based on their weight, from 5 to 30 Kg. Measurements were performed using an ionization chamber and expressed with the dose-area product (DAP). For chest radiographs, a direct measurement of the entrance-skin dose was performed, with secondary calculation of the DAP. RESULTS: For VCUGs, the DAP ranged between 42.89cGy.cm2 and 125.41cGy.cm2. The range was between 76.43 and 150.62cGy.cm2 for UGIs and between 49.06 and 83.33cGy.cm2 for IVUs. For neonate chest radiographs, DAP calculations were between 0.29 and 0.99cGy.cm2. CONCLUSION: These values represent our reference doses. They allow continuous monitoring of our radiographic technical parameters and radiographic equipment and help to correct and improve them if necessary.

Body Weight↗
PubMed2003

Hydroxyurea downregulates endothelin-1 gene expression and upregulates ICAM-1 gene expression in cultured human endothelial cells.

The clinical efficacy of oral hydroxyurea (HU) in adults and children with sickle cell anemia (SCA) cannot solely be explained by its ability to enhance fetal hemoglobin (HbF) expression. Since increased adherence of sickle red blood cells to vascular endothelium is a possible contributing factor to vaso-occlusive crisis (VOC), we explored the effect of HU on human endothelial cell (EC) lines (TrHBMEC and EA-hy 926). We demonstrated that HU, in a dose-dependent and reversible manner, significantly decreased (up to three-fold) the release of endothelin-1 (ET-1), a vasoconstrictor peptide through downregulation (up to three-fold) of ET-1 gene expression. This finding is of therapeutic relevance as SCA patients exhibit elevated serum levels of ET-1 during episodes of VOC and levels correlate with disease severity. Unexpectedly, HU upregulated (up to three-fold) the expression of membrane-bound intercellular cell adhesion molecule 1 (mbICAM-1) and its soluble form (sICAM-1) with a parallel increase in ICAM-1 mRNA expression. Although ICAM-1 does not appear to be involved in the sickle cell adhesion to vascular endothelium, it may exacerbate vaso-occlusion by promoting leukocyte adhesion. The HU-induced increase in mbICAM-1 may appear inconsistent with the clinical benefits confered by HU. However, both the increase in sICAM-1- and HU-induced leukocyte reduction in patients, may counteract the potentially detrimental effect of elevated mbICAM-1 expression. Also HU reduces the expression of vascular cell adhesion molecule (VCAM-1) on EC. Since HU reduces the very late antigen 4-positive reticulocytes in SCA patients, a ligand for VCAM-1, HU-induced downregulation of VCAM-1 on EC will very likely decrease the reticulocyte-endothelium adhesion. Thus, HU, apart from inducing HbF expression in the red cell, also affects the expression profile of EC compartment.

Anemia, Sickle Cell↗
PubMed2003

Intra-rachidian disorders: two unusual cases of recurrent abdominal pain in children.

UNLABELLED: Recurrent abdominal pain (RAP) is generally thought to be of psychological origin but organic aetiologies are increasingly being identified. The cases of two children with vertebral disorders revealed by recurrent abdominal pain are reported. A 14-y-old girl presented with RAP associated with scoliosis, due to a T8-T9 intra-dural extra-medullary tumour. A 7-y-old girl who suffered from nocturnal RAP located in the right iliac fossa for 1 y had decreased muscular strength, pyramidal signs, and a 10 degree Lassègue sign in the right lower limb, revealing a vascular malformation extending from T12 to L2. CONCLUSION: Atypical pain and associated neurological signs or scoliosis must raise the possibility of intra-rachidian disorders. Magnetic resonance examination will then precisely state the location and nature of the pathological process, avoiding excessive delay in therapeutic management.

Abdominal Pain↗
PubMed2002

Abdominal cystic lymphangiomas in children: presurgical evaluation with imaging.

Cystic lymphangiomas are benign vascular tumors which are most often seen in young children. They are considered to be congenital malformations stemming from sequestration of lymphatic tissue. The authors report 15 cases of abdominal location and detail the findings of imaging in the etiologic and topographic diagnosis of these lesions. The initial incidents were essentially the discovery of a palpable abdominal mass, and more rarely, an acute gastrointestinal complication. There was also one case of prenatal diagnosis. Plain films provide only indirect signs related to the displacement of neighboring organs. Ultrasonography permits the etiologic diagnosis by showing an often voluminous, septated cyst. The intra- or retroperitoneal location of the lesion is sometimes difficult to determine by sonography, in which case CT scanning is usually adequate. For abdominal locations, percutaneous sclerosis is not available, and surgical removal is the only treatment for this disorder. The topography of the lesion and the involvement of retroperitoneal structures is important to determine.

Abdominal Neoplasms↗
PubMed2001

Low-temperature near-field spectroscopy of CdTe quantum dots.

A near-field optical microscope has been developed for operation at low temperature. This microscope is used to study the photoluminescence of CdTe-based quantum dots. Spectra collected upon approaching the optical tip into the near-field region of the sample reveal the evolution from a broad far-field luminescence band - that is typical for a large ensemble of dots - to a near-field structure made up of a few sharp peaks originating from individual dots. Experiments carried out in the excitation-collection mode through the optical tip allow study of the effect of an increase in excitation power on the near-field spectra. It is found that upon increasing the excitation by two orders of magnitude, a spatially resolved spectrum progressively transforms back into a broad 'far-field-like' spectrum. Photoluminescence images taken by scanning the sample under the tip are used to discriminate various contributions coming from individual dots.

Journal Article↗
PubMed2001

MRI and clinical differences between optic pathway tumours in children with and without neurofibromatosis.

The purpose of this study was to evaluate the value of MRI in studying optic pathway tumours associated with neurofibromatosis, and to look for potentially helpful criteria for the management of such lesions. This retrospective study included 14 children with neurofibromatosis type 1 (NF-1) as well as a lesion of the optic pathway. Clinical data and MRI findings were analysed with regard to location, structure and course of the tumours, and were compared with 13 optic pathway tumours in patients without NF-1. The median age of onset was 4.1 years. 11 patients with NF-1 were asymptomatic. In the NF-1 group, the optic nerves were involved in 10 cases without a cystic component at the time of diagnosis. In the non-NF-1 group, the tumour was located in the chiasma in 11 cases; 12 cases had a cystic component. 10 of the NF-1 group had no tumour progression over an average follow-up of 3.2 years without treatment. These findings suggest that optic astrocytomas in association with NF-1 are distinct lesions from isolated optic gliomas. In NF-1, most such tumours show only slight progression, and may correspond to perineural gliomatosis rather than a true pilocytic astrocytoma. Among NF-1 patients, initial MRI provides no prognostic criteria in children who subsequently show tumour progression. Nevertheless, MRI can be useful in establishing the diagnosis of NF-1 and can serve as a baseline study.

Age of Onset↗
PubMed2000

Capillary haemangioma of the greater omentum in a 5-month-old female infant: a case report.

Capillary haemangiomas are frequent benign tumours in infancy. The authors report a case of capillary haemangioma of the greater omentum, discovered in a child of 5 months of age and studied with US, CT and MRI. The localization of such a lesion in the greater omentum is exceptional. Abdominal US revealed a heterogeneous, multinodular intraperitoneal mass. Doppler study demonstrated hypervascularity of the lesion. CT localized the mass to the greater omentum. The mass was hypodense on the unenhanced scan and enhanced massively after injection. The infant suffered a reaction to contrast medium during the CT. MRI demonstrated a mass which was hypointense on T1-weighted images and hyperintense on T2-weighted images. Laparotomy confirmed the location of the mass within the greater omentum and allowed resection of the tumour.

Female↗
PubMed2000

[Concomitant chemoradiotherapy and preoperative radiotherapy in exocrine pancreatic adenocarcinoma].

The prognosis of pancreatic adenocarcinoma remains poor, with a 5-year survival rate lower than 5%. Resection, the gold standard treatment, can be performed in less than 10% of patients. Following surgery, the median survival is 12 months. Concomitant chemoradiation, as an adjuvant treatment could be superior to surgery alone, in terms of survival; controlled trials are currently performed. Neoadjuvant chemoradiation is a new approach, potentially able to increase survival and resection rate. Finally, current data regarding intraoperative irradiation are exposed.

Adenocarcinoma↗
PubMed2000

Schizencephaly: clinical and imaging features in 30 infantile cases.

Schizencephaly is an uncommon structural disorder of cerebral cortical development, characterized by congenital clefts spanning the cerebral hemispheres from the pial surface to the lateral ventricles and lined by cortical gray matter. Either an antenatal environmental incident or a genetic origin could be responsible for this lesion which occurs between the third and fourth month of gestation. We report the clinical and cranial imaging features of 30 children, of whom 15 had unilateral and 15 had bilateral lesions. Their ages at the time of the first presentation ranged from 1 month to 10 years. They were thoroughly studied from clinical, epileptical, imaging and electroencephalographic (EEG) viewpoints. Five patients were investigated by cranial computed tomography (CT), eight by cranial magnetic resonance (MR) imaging, and 17 by both methods. The clinical features consisted of mild hemiparesis in 17 cases (57%), 12/17 were related to a unilateral phenotype (80% of all unilateral forms) and 5/17 to a bilateral phenotype. A tetraparesis was present in nine cases, all of which were due to a bilateral cleft. Bilateral forms were significantly associated with tetraparesis, whereas unilateral forms were associated with hemiparesis. Mental retardation was observed in 17 cases (57%), and was observed significantly more often in bilateral clefts (80%). When both hemispheres are involved, an absence of reorganization of the brain function between the two hemispheres leads to severe mental deficits, in addition to the cerebral anomaly itself. Eleven patients had seizures (seven from unilateral and three from bilateral forms). The degree of malformation was not related to the severity of epilepsy. Migration disorders, such as dysplasia or heterotopia, were observed in 30% of cases and are also important etiopathogenetic factors. The septum pellucidum was absent in 13 cases (43%), with septo-optical dysplasia in two cases. Corpus callosum dysgenesis was noted in 30% of cases. Four cases of mega cisterna magna were noted. Although familial cases and environmental factors have been previously reported, schizencephaly appears to be, in the majority of cases, sporadic.

Adolescent↗
PubMed2000

Acute basophilic leukemia presenting with abnormal liver function tests and the absence of blast cells in the peripheral blood.

Acute basophilic leukemia is an uncommon form of acute leukemia, rarely occurring as a de novo disease. We describe a case of de novo acute basophilic leukemia occurring in a 47-year-old man who presented with abnormal liver function tests in the absence of leukemic infiltration of the liver. We postulate that this presentation occurred as a consequence of pathophysiological features of the malignant basophilic blast cells.

Antineoplastic Combined Chemotherapy Protocols↗