Accumulation patterns of endogenous ß-aminobutyric acid during plant development and defence in Arabidopsis thaliana.

We recently discovered that ß-aminobutyric acid (BABA), a molecule known for its ability to prime defences in plants, is a natural plant metabolite. However, the role played by endogenous BABA in plants is currently unknown. In this study we investigated the systemic accumulation of BABA during pathogen infection, levels of BABA during plant growth and development and analysed mutants possibly involved in BABA transport or regulation. BABA was quantified by LC-MS using an improved method adapted from a previously published protocol. Systemic accumulation of BABA was determined by analysing non-infected leaves and roots after localised infections with Plectosphaerella cucumerina or Pseudomonas syringae pv. tomato (Pst) DC3000 avrRpt2. The levels of BABA were also quantified in different plant tissues and organs during normal plant growth, and in leaves during senescence. Mutants affecting amino acid transport (aap6, aap3, prot1 and gat1), γ-aminobutyric acid levels (pop2) and senescence/defence (cpr5-2) were analysed. BABA was found to accumulate only locally after bacterial or fungal infection, with no detectable increase in non-infected systemic plant parts. In leaves, BABA content increased during natural and induced senescence. Reproductive organs had the highest levels of BABA, and the mutant cpr5-2 produced constitutively high levels of BABA. Synthetic BABA is highly mobile in the receiving plant, whereas endogenous BABA appears to be produced and accumulated locally in a tissue-specific way. We discuss a possible role for BABA in age-related resistance and propose a comprehensive model for endogenous and synthetic BABA.

[New strategies in pediatric ophthalmic oncology]. / Nouvelles stratégies thérapeutiques en oncologie ophtalmo-pédiatrique.

Retinoblastoma represents 11% of all cancers during the first year of life. New drugs and focal treatments have been developed in order to avoid the side effects of systemic chemotherapy and external radiotherapy. New targeted and local administration strategies such as periocular chemotherapy (topotecan) or direct ophthalmic artery delivery (carboplatin), are already used today in selected resistant cases. Radiotherapy, presently indicated only as a second-line treatment, is also subject to new techniques, targeting tumors more closely to avoid involving healthy tissue and reduce the risk of radio-induced nonocular tumors. Stereotactic conformal radiotherapy and proton therapy may thus be included in the new range of treatment methods in retinoblastoma.

Diagnosis and current management of retinoblastoma.

Retinoblastoma represents the prototypic model for inherited cancers. The RB1 gene was the first tumor suppressor gene to be identified. It represents the most frequent primary eye cancer in children under 15 years old, habitually occurring in infancy, even in utero, but can be observed in older children or young adults. Many other retinal lesions may also simulate retinoblastoma. The two major presenting signs are leukocoria and strabismus, but other ocular or general signs may be observed. A highly malignant tumor, retinoblastoma can nowadays be cured. The heritable form, however, carries a high risk of second nonocular tumors. Treatment in the early stages of disease holds a good prognosis for survival and salvage of visual function. In very late stages, however, the prognosis for ocular function and even survival is jeopardized.

[Centenary of the first radiotherapy treatment of retinoblastoma (Hilgartner, 1903)]. / 100e anniversaire du premier traitement d'un rétinoblastome par irradiation (Hilgartner, 1903).

One hundred years ago, Hilgartner used external radiotherapy for the first time in the treatment of retinoblastoma. This first case was published in the Texas Medical Journal in 1903. Immediate results were reported to be excellent but the long-term outcome was not known. The first documented cure of retinoblastoma over a long period of time was a case initially treated by Verhoeff (Boston) in 1917, with histopathological findings provided 71 years later by Marcus et al. at the patient's death. Henry Louis Hilgartner was born in 1868 in Baltimore and died in 1937 at the age of 69. His revolutionary treatment developed from the discovery of X-rays in 1895 by Wilhelm Conrad Röntgen and the parallel discovery of radioactivity by Henri Bequerel and Marie and Pierre Curie. In the sociopolitical context of 1903, Emile Loubet was president of France and this same year saw the Wright brothers' first motorized flight with the first power-driven heavier-than-air machine. The development of radiotherapy in the treatment of retinoblastoma can be divided into three distinct periods: an initial period of trial and error lasting from 1903 to 1928; a second period from 1929 to 1948 covering the introduction of calibrated radon needles up to the advent of external radiotherapy, and a third period, from 1948 to the present day, which can be considered a time of technical improvement and innovation. One hundred years ago, radiotherapy made a triumphant entry on the scene of retinoblastoma management. With our present knowledge of its side effects, we are now trying to remove it.

Pulverulent cataract with variably associated microcornea and iris coloboma in a MAF mutation family.

AIMS: To report the detailed clinical findings in a three generation pedigree with autosomal dominant cataract, microcornea, and coloboma resulting from mutation of the lens development gene, MAF. METHODS: Five members of a three generation pedigree with progressive cataracts underwent detailed ophthalmic examination to characterise associated ocular phenotypic features. RESULTS: The cataracts present in all affected individuals were cortical, and/or nuclear, pulverulent opacities. Corneal diameters of 10-10.25 mm were present in two family members. Axial lengths were in the normal range. Bilateral iris coloboma in the 6 o'clock position was present in one patient. Uveal melanoma was present in one patient, with uveal naevi in this and one other patient. CONCLUSION: The bZIP transcription factor MAF is a key lens development gene that regulates the expression of the crystallins. Individuals with a mutation in MAF may have pulverulent cataract alone or cataract in association with microcornea or iris coloboma.

[New strategies in the management of retinoblastoma]. / Nouvelles stratégies dans le traitement du rétinoblastome.

It was rare that a child survived retinoblastoma at the beginning of the twentieth century. Today the survival rate is in the order of 95% in reference centers, with new strategies improving prognosis step by step. Systematic enucleation used to be the starting point of any true and structured management, until the advent of radiotherapy made it possible not only to save lives but also to retain some useful vision. Early diagnosis has enabled focal therapies such as photocoagulation, cryocoagulation, and radioactive applicators to open up a new era of targeted tumor treatment. However, the onset of nonocular tumors secondary to radiotherapy, the resistance of certain tumors to irradiation, and unsightly cosmetic consequences all justify research into alternative therapeutic strategies. New types of chemotherapy have shown spectacular results and are currently under study: chemoreduction to make large tumors more manageable and enable less aggressive treatment of tumors located in delicate sites, thermochemotherapy using the effect of heat on plasma membrane permeability to antimitotics, and chemotherapy associated with cyclosporine to reduce the multidrug resistance of certain tumors. The aim is to avoid primary enucleation and external beam radiation as far as possible. The future may lie in local chemotherapy, hyperthermia, and dynamic phototherapy, accelerated proton beam radiotherapy also has promising prospects.

[Diagnosis and treatment of intraocular tumors in the child]. / Diagnostic et traitement des tumeurs intra-oculaires chez l'enfant.

PURPOSE: To remind of the absolute necessity for early diagnosis in the presence of ocular signs in children giving rise to possible intraocular tumours. METHOD: Based on our own experience of intraocular tumours in children, together with findings from the literature, diagnostic criteria and methods of treatment are presented. RESULTS: Retinoblastoma is the predominant cause of intraocular tumours in children, representing over 80% of cases under the age of 15 years. Other diseases may give rise to the same initial signs, usually leukocoria, sometimes strabismus, more rarely other atypical signs. Elements taken into account for diagnosis include age, sex, laterality, heredity, size of the globe, clinical aspect of the tumours, presence of calcifications and vitreous seeding. Full fundus examination under general anaesthetic is usually necessary. Biological examination, ultrasonography, computerized tomography and MRI enable an accurate diagnosis to be made in the majority of doubtful cases. The management of retinoblastoma is adapted for each individual case from the wide range of treatments available. Enucleation, radioactive applicators (...), brachytherapy (...), cryo- and photocoagulation represent classical measures. Primary chemotherapy, combined with other treatments such as thermotherapy, has become the treatment of choice in those cases where external beam radiotherapy has been used up to now, or in some instances before enucleation. Enucleation is usually carried out for medullo-epitheliomas, but brachytherapy may offer an alternative. CONCLUSION: Any unexplained ocular sign in children should be considered as a possible retinoblastoma, making an accurate and certain diagnosis imperative. Early treatment may save not only the life but also the vision of patients carrying this highly malignant lesion.

Further delineation of the facial 13q14 deletion syndrome in 13 retinoblastoma patients.

Thirteen years ago, Motegi and colleagues (J Med Genet 1987;24:696-697) summarized the specific facial phenotype of six Japanese retinoblastoma patients with interstitial 13q14 deletions. Among a series of 228 propositi with retinoblastoma referred to the Lausanne Retinoblastoma Clinic for treatment and genetic counseling between 1986 and 1997, 13 (5.7%) were diagnosed with a cytogenetic de-novo 13q14 deletion. We confirm the presence of the reported facial phenotype in our population of Caucasian patients and describe additional clinical traits, thus extending the facial phenotype associated with the 13q14 deletion. Del(13q14) comprises, among others, cranial anomalies, frontal bossing, deeply grooved and long philtrum, depressed and broad nasal bridge, bulbous tip of the nose, thick lower lip, thin upper lip, broad cheeks, and large ears and lobules. Recognition of this particular facial appearance was instrumental in the genetic diagnosis of 13q deletions and in the presymptomatic diagnosis of retinoblastoma in a significant number of our cases. Identification of this phenotype in a retinoblastoma patient allows for efficient diagnosis of recurrence in his progeny and/or sibship, while its ignorance will compromise genetic counseling due to the possible difficulties in detecting large deletions by standard molecular mutation analysis. Recognition of this syndrome in newborns without known familial risk for retinoblastoma is even more important as it is a clear warning sign that indicates immediate ophthalmic examination.

A progressive autosomal recessive cataract locus maps to chromosome 9q13-q22.

Cataracts are the leading cause of blindness in most countries. Although most hereditary cases appear to follow an autosomal dominant pattern of inheritance, autosomal recessive inheritance has been clearly documented and is probably underrecognized. We studied a large family-from a relatively isolated geographic region-whose members were affected by autosomal recessive adult-onset pulverulent cataracts. We mapped the disease locus to a 14-cM interval at a novel disease locus, 9q13-q22 (between markers D9S1123 and D9S257), with a LOD score of 4.7. The study of this progressive and age-related cataract phenotype may provide insight into the cause of the more common sporadic form of age-related cataracts.

First-line chemotherapy with local treatment can prevent external-beam irradiation and enucleation in low-stage intraocular retinoblastoma.

PURPOSE: To evaluate the efficacy of first-line chemotherapy (CT) in preventing external-beam radiotherapy (EBR) and/or enucleation in patients with retinoblastoma (Rbl). PATIENTS AND METHODS: Twenty-four patients with newly diagnosed unilateral or bilateral Rbl received CT associated with local treatment (LT). Two to five courses of etoposide and carboplatin were administered at 3- to 4-week intervals, depending on tumor response, and were completed each time by LT. RESULTS: Tumor response was observed in all eyes. Twenty-one of 24 patients showed a complete response (CR) that persisted at a median follow-up (FU) of 31 months (range, 4 to 41 months). Among the three patients who relapsed, two were lost to FU and one died of progressive disease. CR was achieved by CT and LT alone in 15 (71.4%) of 21 patients with less advanced disease (groups I to III). Six other patients with advanced disease (groups IV and V) experienced treatment failure and needed salvage treatment by EBR and/or enucleation. The difference between the two patient groups with regard to disease stage was statistically significant (P <.0001). EBR could be avoided in 13 (68.4%) of 19 patients, who presented with groups I to III (15 eyes) and group V (one eye) disease, whereas enucleation could be avoided in only two (40%) of five. CONCLUSION: CT combined with intensive LT is effective in patients with groups I to III Rbl, permitting the avoidance of EBR in the majority of these young children and, thus, reducing the risk of long-term sequelae. This is in contrast with the disappointing results for patients with groups IV and V Rbl, in whom EBR and/or enucleation was needed.

Rhegmatogenous retinal detachment after treatment of retinoblastoma.

PURPOSE: To determine the rate of retinal detachment after treatment of retinoblastoma, to describe the clinical features and management, and to discuss possible pathogenic mechanisms. METHODS: We retrospectively analyzed the charts of 80 patients (83 eyes) with retinoblastoma treated conservatively between 1963 and 1994, looking specifically for cases that developed a retinal detachment after treatment. RESULTS: Five patients (5 eyes, stages IVa to Vb) developed a retinal detachment after treatment. Of these, four had undergone external radiotherapy and one had an episcleral cobalt plaque. Retinal detachment developed within three months after radiotherapy and relentlessly progressed in all four eyes over a period of five months to four years. In the eye that received the episcleral cobalt plaque, the detachment remained localized inferiorly. Even though no retinal break could be detected in four eyes, the clinical features were suggestive of a rhegmatogenous detachment: there was retinal thinning adjacent to the regressed tumors, and the evolution was much longer than that of an exudative retinal detachment. A scleral buckling procedure was performed in two eyes and the retina was successfully reattached. The retinal detachment was not operated on in the three other eyes: the hole was too posterior in one eye; retinal surgery was refused in the second eye; and the retinal detachment remained localized inferiorly in the third eye. CONCLUSION: A retinal detachment developed in 6% of eyes after conservative treatment of retinoblastoma. The possibility of a rhegmatogenous origin should be considered even if no retinal break is detected. In the absence of tumor activity, a scleral buckling repair could be carefully considered if the retinal detachment threatens the macula, and if its evolution is not indicative of an exudative detachment.

[Leukokoria in a child: emergency and challenge]. / Leucocorie chez l'enfant: une urgence et un défi.

PURPOSE: To heighten the awareness of the medical world to the importance of correct and rapid diagnosis in the presence of leukocoria in the child. METHODS: Starting with the presenting symptom, the authors present the guide lines to follow in a practical manner in order to reach a diagnosis in the principal retinal diseases causing leukocoria. RESULTS: A white pupil is due to retinoblastoma in almost half of all cases. Other possible causes, in order of frequency, are: persistent hyperplastic primary vitreous, Coats' disease, ocular toxocariasis, retinopathy of prematurity, retinal hamartomas. Diagnosis can usually readily be made by ophthalmoscopy, but may be problematic when the clinical presentation is atypical or in the presence of late complications. Age, sex, laterality, heredity, and in particular the presence or absence of calcifications and the size of the globe, are the main criteria for diagnosis. Ultrasonography plays a major role in this essential quest for correct diagnosis, quest which may ultimately lead to enucleation. CONCLUSION: Leukocoria in the child is a danger signal demanding certain diagnosis within the shortest possible time.

[Diagnostic imaging of intraocular lesions in the child]. / L'imagerie dans le diagnostic des lésions intraoculaires chez l'enfant.

BACKGROUND: A certain diagnosis, as soon as possible, is indispensable in children with intraocular lesions, the presence of retinoblastoma always being a possibility. PATIENTS: From our casuistic of 418 children since 1970 and from the literature, we currently adopt the following attitude. Where the media are clear, a drawing and fundus photographs are made. Echography is performed in all cases. Ultrasound biomicroscopic examination is carried out in all lesions where involvement of the anterior segment is suspected. RESULTS: Where echography shows no calcifications, computed tomography (CT) is indicated. CT may also enable a possible lesion extension, particularly to the optic nerve, to be studied. CONCLUSIONS: Magnetic resonance imaging (RMI) is the procedure of choice for evaluating secondary retinal detachment, massive extension of retinoblastoma and for detecting any early involvement of the pineal gland (pinealoblastoma), or any other associated lesion. In case of unilateral unifocal sporadic retinoblastoma, however, no CT or MRI is performed, except where there is a suspected extension into the optic nerve or the orbit. Echography remains the most economical, rapid and safest means of diagnosis even in difficult cases.

[Ocular phenotype in a child with chondrodysplasia punctata, rhizomelic form]. / Phénotype oculaire chez un enfant atteint d'une chondrodysplasia punctata, forme rhizomélique.

Chondrodysplasia calcificans punctata (CDP) is a rare congenital syndrome characterized by calcific stippling of the hyaline cartilage. CDP is classified into 4 types: the autosomal dominant Conradi-Hünermann type, the autosomal recessive rhizomelic type, the X-linked dominant form and the X-linked recessive form. We present a child affected with a rhizomelic CDP born from consanguinous parents. The ocular phenotype consisted of microphakia associated with a progressive bilateral "cataracta cortico-zonularis suturata". At 11 years of age, a phacoemulsification and intraocular lens implantation was performed in the left eye.

Prognostic factors associated with loss of heterozygosity at the RB1 locus in retinoblastoma.

The nature of the tumorigenic mutation was analyzed in 30 retinoblastoma (Rb) tumors (16 non-hereditary and 14 hereditary) and categorized into loss of heterozygosity (LOH) or retention of heterozygosity (non-LOH) at the RB1 locus. These genotypic characteristics were compared with the clinicopathological phenotype for possible correlation. The overall frequency of LOH was roughly 55%, in both hereditary and non-hereditary Rb. The presence of LOH was preferentially associated with differentiated tumors and absence of choroidal invasion. LOH was found in 82% of females versus 33% of males. Finally, LOH-initiated tumors were associated with a significantly younger age at diagnosis in hereditary Rb. In conclusion, the preferential association of LOH with absence of choroidal invasion, tumoral differentiation, and younger age at diagnosis may establish LOH as a prognostic marker in Rb patients.

[Retinoblastoma: clinical and molecular diagnostic aspects]. / Le rétinoblastome: aspects cliniques et diagnostic moléculaire.

Retinoblastoma, a tumor of the immature retina concerns babies and young infants in particular. They make up for 14% of malignomas in the first years of life. There are two types of retinoblastoma: In the first two alleles of the gene Rb1 must be inactivated sequentially in the same retinoblast cell until this may escape control. In this case the retinoblastoma is always unilateral and unifocal. This is explained by the lower frequency of two mutations in one retinoblast. The other type, however, is inherited: One allele Rb1 is inactivated in all cells of the organism by mutation. The probability that a second mutation arrives in different retinoblasts is thus high. In this case bilateral multifocal tumors develop. Characterization of the Rb1 gene has permitted identification or at least determination of a haplotype in persons at risk. This knowledge is decisive for early recognition of babies at risk and for genetic counselling.