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Biomedical subjects

P Dureau

Publications and source records attributed to P Dureau.

At least 19 recordsLinked to original sources

[Congenital glaucoma and trabeculodysgenesis. Clinical and genetic aspects].

Congenital glaucoma is generally related to an iridocorneal angle malformation, with an obstacle to aqueous humor outflow. This spectrum of diseases can involve the angle, the iris and the cornea. The diagnosis relies on characteristic signs and is confirmed by an examination under general anaesthesia and paraclinical examinations (especially echography). An early diagnosis is essential for beginning surgical treatment. Several filtering surgery techniques with equivalent intraocular pressure results are available, but visual function must be protected in all cases. In many cases, genetic counseling relies on a careful clinical analysis and sometimes on a molecular analysis. A number of ocular and/or general abnormalities can be accompanied by glaucoma in infants and children. They must be screened in case of associated signs, but the existence of these abnormalities leads to suspicion of associated glaucoma.

Abnormalities, Multiple↗

[Iris mammillations: three case reports].

INTRODUCTION: Iris mammillations are congenital abnormalities characterized by vitiliform protuberances regularly spaced on the surface of a velvety iris. They can be either isolated or associated with melanocytosis involving iris, sclera or periocular tissues, resulting in a risk for uveal melanoma. They can be complicated by ocular hypertension. We report three cases of iris mammillations in three children. CASES REPORT: For each patient, age, circumstances of revelation, anterior and posterior segment examination, intraocular pressure, associated anomalies, and progression were noted. Patient no. 1: In a 13-month-old boy examined for a squint, bilateral iris mammillations were fortuitously discovered. Intraocular pressure remained normal over 22 months of follow-up. Patient no. 2: In an eight-year-old boy, bilateral iris mammillations with papillary excavation were fortuitously discovered. Intraocular pressure was normal and the excavation did not change over 20 months of follow-up. Patient no. 3: A five-year-old boy was examined for a scleral pigmentation in the right eye. The examination found unilateral iris mammillations and ipsilateral ocular melanocytosis. Intraocular pressure and fundus were normal and remained normal over 13 months of follow-up. DISCUSSION: and conclusion: Iris mammillations are congenital abnormalities, generally unilateral, sometimes hereditary. The differential diagnosis includes Lisch nodules of neurofibromatosis and iris melanoma. The etiology of iris mammillations is unknown; these lesions can be complicated by ocular hypertony and, in case of associated melanocytosis of the iris, sclera or periocular tissues, by uveal melanoma. These potential complications warrant a regular clinical follow-up.

Child↗

Sevoflurane effects on retrobulbar arteries blood flow in children.

BACKGROUND: Measure of blood flow velocity in retrobulbar vessels is performed to determine the severity of ophthalmic pathologies as glaucoma. In children, this measure is usually performed under general anaesthesia. Sevoflurane is known to not modify cerebral blow flow velocities. However, its effect on retrobulbar circulation is not known. This study was designed to evaluate the effect of sevoflurane on retrobulbar circulation flow velocity in children undergoing examination for ocular disorders under general anaesthesia. METHODS: Thirteen mechanically ventilated children (Fi(O2))=1) were included. Blood flow velocities of central retinal artery, ophthalmic artery, and middle cerebral artery were measured by Doppler ultrasound during 1 and 2 age-adjusted minimal alveolar concentration (MAC) sevoflurane anaesthesia. Intra-ocular pressure and non-invasive haemodynamic parameters were also measured. End-tidal carbon dioxide tension was controlled during all the study period. RESULTS: Mean arterial pressure decreased from 1 to 2 age-adjusted MAC sevoflurane (58 [12] vs 54 [12] mm Hg, P=0.01). In the ophthalmic artery, end diastolic velocity (EDV) decreased significantly at 2 MAC (1 MAC: 4.4 [4] cm s(-1) vs 2 MAC: 1.4 [2.4] cm s(-1); P=0.04) and resistivity index (RI) increased significantly (1 MAC: 0.83 [0.11] vs 2 MAC: 0.93 [0.09]; P=0.007). Systolic velocity, EDV, and RI remained constant in the central retinal artery and in the middle cerebral artery. CONCLUSION: High alveolar concentration of sevoflurane decreased blood flow velocity in the ophthalmic artery, but not in the central retinal and the middle cerebral arteries in children ventilated in hyperoxic condition. This effect was related to a decrease in mean arterial pressure. This vessel-dependent effect may be explained by the different autoregulatory mechanisms of these arteries. In the present hyperoxic conditions, the vascular effect of sevoflurane may have been limited in the central retinal artery and not in the ophthalmic artery.

Anesthesia, General↗

[Computer-assisted diagnosis and therapy for glaucoma].

Boolean algebra, or combinatory analysis and their related computer routines, can provide invaluable help in resolving classic diagnostic problems. However complex each case may be, the diagnosis is always made from a finite set of data, and the fundamental problem is thus how to exploit this data. Invention no longer has a place in ascertaining a diagnosis. Traditional ways of reasoning are numerous, personal, and fragile, but fortunately redundant. They may give rise to four types of error: omission or mistake (an error of judgment), either during the semiotic or the dialectic stages. Whereas the physiological capacity of the human brain and memory only enables it to make a limited number of hypotheses concerning certain aspects of glaucoma, computer programs can take the total number of hypotheses into account, i.e., 3000. For every input the program explores each of the 3,000 items, thus eliminating the four types of error. The probabilistic nature of data, which compromises the confidence one can have in conclusions resulting from such complex reasoning, is treated by the adjusted probabilities. The use of such diagnostic aids, whose thesaurus is updated regularly, is reserved for ophthalmologists, the only authority capable of assessing the pertinence of the computer responses. Consequently, the specialist can rest assured that the patient has benefited from the most comprehensive and updated knowledge in medical science.

Glaucoma↗

[Ocular injuries and childbirth].

INTRODUCTION: Severe ocular traumatisms related to childbirth are rare and often subordinate to maneuvers with instruments. The aim of this study was to report on the different severe ocular injuries that might occur during childbirth and their possible consequences. There can be several of these ocular injuries. PATIENTS AND METHODS: Since 1984, we have examined 11 cases of this type of traumatism. For each case, the childbirth circumstances, the affected side, the different injuries observed such as ocular, orbital, cranial and even cerebral lesions, and the results of the ophthalmological follow-up examinations were recorded. RESULTS: In most cases, lesions resulted from forceps traumatisms, and the injuries were corneal (vertical tears in the Descemet's membrane), retinal (hemorrhages), and orbital (e.g., the optical nerve and oculomotor nerve). CONCLUSION: These injuries, sometimes severe, must benefit from early and complete examination, possibly with general anesthesia, and long-term follow-up. Furthermore, a radiographic and clinical neurological examination is recommended to prevent any cerebral complication.

Birth Injuries↗

Early prognostic factors for intellectual outcome in CHARGE syndrome.

CHARGE syndrome (coloboma, heart disease, atresia of the choanae, retarded growth and mental development, genital anomalies, and ear malformations and hearing loss) is a heterogeneous condition for which early prediction of intellectual outcome is important but difficult. The psychomotor milestones and intellectual outcome of a consecutive series of children with CHARGE syndrome who were observed by the same team from the neonatal period to the time of study were analyzed retrospectively. Twenty-one children (11 males and 10 females, aged from 5 to 12 years, mean 8 years 7 months, SD 2 years 5 months) were included. The influence of 19 early identifiable parameters that could be considered as deleterious for intellectual outcome was recorded. Generally, the main psychomotor milestones (0 to 4 years) were severely delayed, although intellectual outcome (at primary-school age) was satisfactory for half the children in this series. We show that extensive bilateral coloboma resulting in low vision, microcephaly, and brain malformation were the only three parameters that were predictive of poor intellectual outcome. Conversely, severe neonatal medical conditions, such as tracheotomy, conditions requiring long stays in hospital, or cardiac surgery were not predictive of poor intellectual outcome. Severe hearing loss was not found to be negatively correlated with intellectual outcome once coloboma had been taken into account.

Abnormalities, Multiple↗

Use of denaturing HPLC and automated sequencing to screen the VMD2 gene for mutations associated with Best's vitelliform macular dystrophy.

We identified three novel VMD2 mutations in patients with Best's macular dystrophy. DHPLC analysis of the 11 VMD2 exons revealed abnormal profiles in exon 8. Direct sequencing showed that these abnormal profiles were due to monoallelic transitions and transversions. We also found three polymorphic sequence changes that have been reported previously and annotated to an online database (http://www.uni-wuerzburg.de/humangenetics/vmd2.html).

Bestrophins↗

[Congenital megalocornea].

Congenital megalocornea is a bilateral enlargement of the cornea's diameter that can be associated with trabecula and/or iris dysgenesis. This condition predisposes the patient to glaucoma. The physiopathology is poorly understood and may be related to lens induction during embryological development of the anterior of the eye. X-linked genetic transmission is found in 50% of cases, autosomal transmission in 40%, and sporadic transmission in the remaining 10%. Diagnosis is based on a thorough examination of the child's eye, often with general anesthesia. Different clinical aspects can be observed: simple megalocornea without ocular or systemic anomalies, megalocornea with ocular and/or systemic anomalies as well as multiple malformation syndromes, dermatological diseases, skeletal diseases, and genetic or chromosomic diseases. A systematic general pediatric examination is therefore necessary. Congenital megalocornea must be considered, first of all, as a differential diagnosis of primary congenital glaucoma and all of its etiologies. Treatment of associated ocular diseases, the search for an association with systemic diseases, and follow-up for the rest of the patient's life are indispensable.

Child, Preschool↗

Identification of novel VMD2 gene mutations in patients with best vitelliform macular dystrophy.

ABSTRACT We report five novel VMD2 mutations in Best's macular dystrophy patients (S16F, I73N, R92H, V235L, and N296S). An SSCP analysis of the VMD2 11 exons revealed electrophoretic mobility shifts exclusively in exons 2, 3, 4, 6 and 8. Direct sequencing indicated that these shifts are caused by mono-allelic transition in exons 2, 4, 6, 8 and transversion in exons 3 and 6. Five novel "silent" polymorphisms are also reported: 213T>C, 323C>A, 1514A>G, 1661C>T, and 1712T>C. Hum Mutat 17:235, 2001.

Base Sequence↗

Renal coloboma syndrome.

OBJECTIVE: To characterize the ocular features of renal coloboma syndrome. DESIGN: Prospective, observational case series. PARTICIPANTS: Twelve patients referred by the pediatric nephrology clinic and the ophthalmic records of five additional patients. METHODS: For each patient, age at the time of examination, gender, renal function, and presence of a mutation in the PAX2 gene were noted. All patients underwent measurement of visual acuity and anterior and posterior segment examination with fundus photography. Goldmann visual fields were tested in four cases. MAIN OUTCOME MEASURES: Visual acuity, optic disc abnormalities, and mutation in the PAX2 gene. RESULTS: Mean age was 21.5 years. Renal failure was mild in 6 patients and severe in 11 patients. A mutation in the PAX2 gene was identified in nine patients, without correlation to the ocular phenotype. Ocular features could be divided into five groups: optic disc dysplasia limited to an unusual pattern of retinal vessels without functional consequence; optic disc pit with normal visual acuity and blind spot enlargement; large optic disc coloboma; large coloboma of the optic disc and adjacent retina; morning glory anomaly (these last three conditions were accompanied by poor visual acuity). Fundus abnormalities were symmetrical in most cases and unrelated to renal status. CONCLUSIONS: Ophthalmic and renal characteristics of the renal coloboma syndrome are highly variable. The need for dialysis or renal transplantation can occur early in life or several years later. A wide range of ocular abnormalities located in the posterior segment can be observed. Mild optic disc dysplasia or pit have no functional consequence and can be underdiagnosed. More severe colobomas or related abnormalities, such as morning glory anomaly, often lead to poor visual acuity. Molecular biology allows detection of the mutations in the PAX2 gene, but can be negative in approximately 50% of cases. The observation of an optic disc coloboma or related abnormality stimulates the ophthalmologist to propose simple nephrologic investigations to check for renal hypoplasia, a potentially life-threatening disease. Conversely, renal hypoplasia stimulates the nephrologist to ask for a fundus examination to confirm the diagnosis and check for complications such as retinal detachment.

Abnormalities, Multiple↗

PAX2 mutations in oligomeganephronia.

BACKGROUND: Oligomeganephronia (OMN) is a rare congenital and usually sporadic anomaly. It is characterized by bilateral renal hypoplasia, with a reduced number of enlarged nephrons. The mechanisms involved in this deficient nephrogenesis are unknown. The paired box transcription factor PAX2 plays a fundamental role in renal development. Heterozygous Pax2 mutants in mice are characterized by renal hypoplasia and retinal defects, and in humans, PAX2 mutations have been described in the renal-coloboma syndrome. METHODS: To assess whether OMN could be related to PAX2, we searched for PAX2 mutations in nine patients presenting with sporadic and apparently isolated OMN. RESULTS: Heterozygous PAX2 mutations were found in three patients. A limited optic nerve coloboma was secondarily detected in two cases and a very mild optic disk dysplasia in one patient. None of these patients had visual impairment. CONCLUSIONS: Ocular anomaly and PAX2 mutations should be sought in all patients with OMN.

Adolescent↗

Quantitative analysis of intravitreal injections in the rat.

Intravitreal injections are currently used in the rat to introduce a therapeutic factor in the eye, especially for experimental treatments of retinal degenerations. The injected volume and its location can influence the quantification of results. We have investigated the quantitative effect of a single intravitreal injection in rats at different ages and for different volumes. Albinos rats aged three weeks or two months received intravitreal injections of 1, 3, 5 or 10 microl China ink. Animals were sacrificed immediately after injection, eyes were enucleated, fixated, embedded in paraffin and microtomy was performed in a sagittal plane. Regularly spaced sections were analyzed to reconstruct the vitreous and injected dye volumes. The measured vitreous volume was 6.76 +/- 0.37 mm(3) in three weeks old rats and 13.36 +/- 0.64 mm(3) in two months old rats. Mean intravitreal ink volumes immediately after injection were 0.8 mm(3) for 1 ml injections, 2 mm( 3) for 3 ml, 2.3 to 2.6 mm(3) for 5 microl and 3.2 mm(3 ) for 10 microl. The percentage of vitreous volume involved by the injection ranged from 4.4% to 33.2%. The injected volume is limited by the large lens size of the rat. Extraocular loss of injected solution increases for higher injected volumes, with larger standard deviations. In this model, the dye tends to localize behind the lens. A 3 or 5 microl volume appears to have the best reproducibility with minimum loss of solution.

Aging↗

Prominent beta-5 gene expression in the cardiovascular system and in the cartilaginous primordiae of the skeleton during mouse development.

The alpha v beta (alpha(v)beta5) heterodimer has been implicated in many biological functions, including angiogenesis. We report the beta5 gene expression pattern in embryonic and foetal mouse tissues as determined by Northern blotting and in situ hybridization. During the earliest stages, beta5 mRNA is widespread in the mesoderm. During later developmental stages, it remains mostly confined to tissues of mesodermal origin, although probable inductive effects trigger shifts of beta5 gene expression from some mesenchymatous to epithelial structures. This was observed in the teeth, skin, kidneys, and gut. Of physiological importance is the beta5 labeling in the developing cardiovascular and respiratory systems and cartilages. Furthermore, early beta5 gene expression was observed within the intra- and extraembryonic sites of hematopoiesis. This suggests a major role for beta5 in the hematopoietic and angiogenic stem cells and thus in the development of the vascular system. Later, the beta5 gene was expressed in endothelial cells of the vessels developing both by angiogenesis and vasculogenesis in the lung, heart, and kidneys. Moreover, the beta5 hybridization signal was detected in developing cartilages but not in ossified or ossifying bones. beta5-Integrin is a key integrin involved in angiogenesis, vasculogenesis, hematopoiesis, and bone formation.

Animals↗

[Benign childhood intracranial hypertension].

INTRODUCTION: Infrequent in children, benign intracranial hypertension (or pseudotumor cerebri) is most often observed in adults. Careful diagnosis requires eliminating all the other etiologies of intracranial hypertension. Most often medical, its treatment must be rapid to avoid permanent visual loss. However, a surgical procedure is necessary when vision is threatened. We present our experience with this pathology and discuss its clinical aspects, its etiologies, and the physiopathological mechanisms. PATIENTS AND METHODS: We conducted a retrospective study on children who presented benign intracranial hypertension confirmed by neuroradiological and neurosurgical examinations. These examinations also served to specify the responsible etiologies. The ophthalmologic examinations, adapted to the child's age and clinical status, included visual acuity testing, optic disc evaluation, ocular motility testing, and visual field evaluation. Progression of visual acuity and the topic disc was analyzed after treatment. RESULTS: The diagnosis of benign intracranial hypertension was confirmed in 22 children (12 boys and 10 girls). Clinical presentation included headache and visual disturbance such as visual loss and oculomotor nerve palsy. Papilledema was present in nearly all cases. Medical treatment was successful in 7 children; however, the remaining 15 patients required a lumboperitoneal shunt because of elevated intracranial pressure, no response to the medical therapy, or threatened vision. DISCUSSION: The physiopathological mechanisms of benign intracranial hypertension, an uncommon condition in children, are still unclear. It can be associated with severe visual loss. All other intracranial or medullary expansive lesions should be eliminated before diagnosis. The causes of this syndrome are not the same for pediatric and adult patients. Although medical therapy is usually sufficient to normalize the intracranial pressure, a lumboperitoneal shunt is at times required. The role of the ophthalmologist is important in detecting a possible visual loss or papilla abnormality and in ensuring proper treatment follow-up. CONCLUSION: Ophtalmologists are involved in the detection of pseudotumor cerebri and the monitoring of visual function, an important element in evaluating treatment efficacy.

Adolescent↗