Family with recurrent cases of neural tube defects in Niamey (Niger)

A series of patients affected by neural tube defects have been studied in Niamey (Niger). This population is highly consanguineous and we try estimating the number of cases in which a previous identical malformation has been reported in the family. We found only 4 families indicating that the percentage of such families is not increased in our population. However, we think that studying genetic factors in this specific population could allow to demonstrate susceptibility genes that can act on this pathology.

Polymicrogyria, aventriculy, polydactyly, encephalocele, callosal agenesis (PAPEC): a new syndrome?

INTRODUCTION

Aventriculy is a very rare observation and is generally associated with holoprosencephaly. We report here a case of polymalformation affecting the brain, hands, and feet observed in a highly consanguineous family in Niger.

CASE REPORT

A boy was born from a highly consanguineous family presenting multiple malformations (aventriculy, extreme microcephaly, polydactyly, polymicrogyria, callosal agenesis, and parietal encephalocele). To the best of our knowledge, such association has never been reported so far.

DISCUSSION

We propose to name this association PAPEC (for polymicrogyria, aventriculy, polydactyly, encephalocele, and callosal agenesis). The occurrence of this disease in a highly consanguineous family suggests a genetic origin. Furthermore, we propose hypotheses that could explain pathophysiology of this defect.

Hepatitis C Virus positivity prediction from serum samples using NIRS and L1-penalized classification

AIMS

The hepatitis C virus (HCV) has developed a strategy to coexist with its host resulting in varying degrees of tissue and cell damage, which generate different pathological phenotypes, such as varying degrees of fibrosis, cirrhosis, and hepatocellular carcinoma (HCC). However, there is no integrated information that can predict the evolutionary course of the infection. We propose to combine Near-infrared spectroscopy (NIRS) and machine learning techniques to provide a predictive model. In this work, we propose to discriminate HCV positivity in biobank patient serum samples.

METHODS

126 serum samples from 38 HCV patients in different stages of the disease were obtained from the Biobank of Hospital Universitario Fundación Alcorcon. NIRS spectrum was captured by a FT-NIRS Spectrum 100 (Perkin Elmer) device in reflectance mode. For each patient, the HCV positivity was identified (PCR) and labeled as detectable =1 and undetectable =0. We propose an L1-penalized logistic regression model to classify each spectrum as positive (1) or negative (0) for HCV presence (x). The regularization parameter is selected using 5- fold cross-validation. The penalized model will induce sparsity in the solution so that only a few relevant wavelengths will be different from zero.

RESULTS

L1-penalized logistic regression model provided 167 wavelengths different from zero. The accuracy on an independent test set was 0.78.

CONCLUSIONS

We present a straightforward promising approach to detect HCV positivity from patient serum samples combining NIRS and machine learning techniques. This result is encouraging to predict HCV progression, among other applications. Clinical relevance- We presented a simple while promising approach to use machine learning and NIRS to analyze viral presence on sample serums.

[Development and growth of the vault of the skull]

The vault of the skull is a region of the neurocranium formed by a process of membranous ossification. It consists of several bones: frontal bone, parietal bone, squamous part of the temporal bone, lamina ascendens of the sphenoid, and interparietal bone. The embryological origin of the bones of the skull vault is still the subject of controversy. This can be explained by the different animal models used for these purposes, but also by the various techniques applied to this problem. At all events, it seems that the cells of the neural crest generate some of the bones of the vault and that the others are derived from the mesoderm. This uncertainty should lead readers to be extremely cautious before using the presumptive maps published in the literature. Several tissues interact with osteo-progenitor cells: neural tube, surface ectoderm and dura mater. Analysis of genes in which mutations lead to abnormalities of the skull vault has partly revealed the molecular interactions. These are very complex and are the field of very numerous experimental investigations. In the relatively near future, we can hope to discover some of the molecular networks leading to the formation of these bony structures.

[Development and growth of the skull base]

The skull base is a part of the neuro-cranium formed by endochondral ossification. The embryological origin of the skull base is not perfectly known, but there seems to be an anterior region derived from the neural crest and a posterior part derived from the mesoderm. Further studies are needed to define reliable presumptive maps. The origin of the different components of the occipital bone is just as poorly known. Much fundamental work remains to be done to suggest any solution to these problems in humans.

GJA1 Variants Cause Spastic Paraplegia Associated with Cerebral Hypomyelination

Oculodentodigital dysplasia is an autosomal dominant disorder due to GJA1 variants characterized by dysmorphic features. Neurologic symptoms have been described in some patients but without a clear neuroimaging pattern. To understand the pathophysiology underlying neurologic deficits in oculodentodigital dysplasia, we studied 8 consecutive patients presenting with hereditary spastic paraplegia due to GJA1 variants. Clinical disease severity was highly variable. Cerebral MR imaging revealed variable white matter abnormalities, consistent with a hypomyelination pattern, and bilateral hypointense signal of the basal ganglia on T2-weighted images and/or magnetic susceptibility sequences, as seen in neurodegeneration with brain iron accumulation diseases. Patients with the more prominent basal ganglia abnormalities were the most disabled ones. This study suggests that GJA1-related hereditary spastic paraplegia is a complex neurodegenerative disease affecting both the myelin and the basal ganglia. GJA1 variants should be considered in patients with hereditary spastic paraplegia presenting with brain hypomyelination, especially if associated with neurodegeneration and a brain iron accumulation pattern.

Notomelia and related neural tube defects in a baby born in Niger: case report and literature review

INTRODUCTION

Notomelia associated with neural tube defects are rare diseases.

CASE REPORT

A baby was born in Niger with multiple congenital embryonic malformations on the posterior midline. The most rostral malformation was an accessory limb (polymelia) at the level of the lumbar vertebrae composed of two long bones, a foot and three toes. Accessory male genitalia were present at the base of this malformed accessory limb which had no apparent motor or sensory innervation. The second malformation was a sacral vestigial appendage with an adjacent dermal sinus opening onto the posterior midline and extending internally to the dura through a defect of the vertebral arches. From the published literature and this particular case, we conclude that notomelia is a rare clinical sequela of a neural tube defect (NTD) and is correctly classified as a dysraphic appendage.

CONCLUSION

The recent occurrence of three similar cases in the same ethnic group from Niger, three from consanguineous parents, suggests that genetic factors are likely to contribute significantly to the genesis of this syndrome, consistent with a recent report that mutation of the bovine NHLRC2 gene resulting in a V311A substitution at a highly conserved locus in the NHLRC2 protein is, when homozygous, causally associated with several forms of polymelia including notomelia, with heteropagus conjoined twinning and with other NTD-related embryonic malformations. Detailed genome-wide studies of children with dysraphic appendages are indicated.

A case of cephalomelia discovered in a baby born in Niger

INTRODUCTION

Subcutaneous tumors with extra limbs are very rare, and they are considered either as fetus in fetu or fetiform teratoma.

CASE REPORT

We report here the case of a 6-day-old presenting a mass extending at the level of the occipital bone. This mass is developed in the extracranial region and contains two forelimbs including hands with digits. CT shows that the squamous part of the occipital bone is involved with several defects through which a part of the cerebellum herniates. The boy was operated on and the tumor was removed. The herniated region of the cerebellum has also been removed. After surgery, the boy develops normally.

CONCLUSION

This type of tumor is extremely rare and is only the second case that has been reported at this exact location. This could be the so-called céphalomélie described by Isidore Geoffroy Saint-Hilaire in a duck in his famous Treatise of Teratology (1836). The cause of this malformation is still a matter for debate.

Monitoring of reversible boronic acid–diol interactions by fluorine NMR spectroscopy in aqueous media

A new convenient method for monitoring boronic acid–diol interactions in aqueous media based on ¹⁹F NMR spectroscopy with fluorinated boronic acid probes is described.

["The first stages of the human egg" by Auguste d'Eternod published one hundred years ago in the Comptes Rendus de l'Association des Anatomistes]

The development of the embryo and foetus fascinates, but its study in humans is difficult because of both technical and ethical problems. Auguste d'Eternod, Swiss embryologist, published in 1913 an article entitled "The early stages of the human egg" in the Comptes Rendus de l'Association des Anatomistes, the ancestor of the journal Morphologie. This work is focused not only on the early stages of development: fertilization, cleavage of the egg, blastocyst formation, gastrulation, but also on the extra-embryonic processes characteristic of mammals. On the occasion of the centenary of the publication of this work, I propose a critical review by placing the data published in the literature and historical context of the time. Finally, I try to extract from these observations the concepts that are still used today by embryologists.

Georges Marinesco (1863-1938): neurologist, neurohistologist and neuropathologist

Gheorghe Marinescu (Georges Marinesco, in French) is a Romanian physician, founder of the School of Neurology in that country. He begins his medical studies in Bucharest, then has the opportunity to reach Paris and join the School of Neurology in La Salpêtrière Hospital, lead by Jean-Martin Charcot. This trip will forever imprint the mind of Marinescu, a great friend of France, a respectful student of Charcot and a friendly colleague of many Parisian neurologists. Marinescu's works are multiple and very important. He describes the succulent hand in syringomyelia and the palmar-jaw reflex. Marinescu is also one of the first to use the cinema for medical purposes. His work as an anatomo-clinician, a method developed by Charcot, is important. We denote the description of the locus niger affected by tuberculosis in a case of parkinsonism (this description paving Etienne Brissaud's way to highlight the anatomical origin of Parkinson's disease), the original clinical description of Marinesco-Sjögren syndrome, and that of medullomyoblastoma. Marinescu is also a famous neurocytologist as evidenced by his work, La Cellule Nerveuse, published in 1909. The first volume of the book is devoted to the aspects of the normal nervous tissue: the neurofibrillar network, the chromatophilic elements, and the paranucleolar corpuscles (now known as Marinescu's bodies). The second volume of the book is almost related to features revealed by experimental lesions: chromatolysis and neuronophagia. Furthermore, Marinescu describes with Oscar Blocq, small nodules than are now regarded as the first description of senile plaques.

366 SEXING OF GOAT BLASTOCYSTS PRODUCED IN VITRO BY FISH USING CHROMOSOME X AND Y OVINE SPECIFIC PROBES

The aim of this study was to test a FISH approach using ovine-painted probes specific for the chromosomes X and Y, on goat interphase and metaphase nuclei of blastocyst cells. Oocytes of prepubertal goats were recovered at a slaughterhouse and selected by morphological criteria. Oocytes were matured in TCM-199 supplemented with hormones, serum and cysteine at 38.5°C for 27 h. IVM-oocytes were fertilized in vitro and the presumptive zygotes were cultured for 10 days in SOF with 10% FCS at 38.5°C, 5% CO2 and 5% O2. The blastocyst nuclei were spread using a modified Tarkowski method (1966). Briefly, individual embryos were immersed into hypotonic solution for 5 min, followed by fixative solution of methanol/acetic acid (Carnoy’s solution) until the embryos acquired a transparent appearance. Next, the embryos were transferred to a Superfrost plus Slide (Menzel Gläser, Braunschweig, Germany) in a small droplet mixture of distilled water and Carnoy The zona pellucida and the blastomere cytoplasm dissolved gradually and Carnoy solution was added dropwise to the slide before the nuclei dried out. The morphology and total number of nuclei in each embryo were analyzed under phase contrast microscope and stored at -18°C. Embryos with appropriate fixation were then subjected to hybridization with ovine-painted probes specific to chromosomes X (Fluorocrom green-FITC) and Y (Fluorocrom orange-TAMRA) (Chrombios-Molecular Cytogenetics GmbH, Raubling, Germany) according to the manufacturers protocol and adjusted for the caprine species. Briefly, slides were then incubated at 60°C for 1 h. The chromosomal DNA was then denatured by immersing slides in 70% formamide/30% 2 × SSC at 70°C for 1.5 min, and immediately dehydrated in an ethanol series (70%, 90%, and 100%), 4 min duration per solution and air dried. In parallel, X- and Y-probes were added to the hybridization solution (50% deionized formamide, 10% dextran sulfate, 2 × SSC) and denatured at 75°C for 10 min. Aliquots (0.5 to 1.5 μL) of this solution were placed on each slide and sealed with a coverslip and glue prior to incubation at 37°C (Hybrite; Vysis Inc, Dowers Grove, IL, USA). After 22 to 24 h the coverslip was removed and the slides were washed three times. The first and third washes were performed with 2 × SSC at room temperature while the second wash was in a 0.4 × SSC/0.1% Tween at 73°C for 3 min. Nuclear DNA was counterstained with diamino-phenyl-indole solution (DAPI) and examined with a fluorescence microscope (Olympus BX61, Olympus America Inc., Melville, NY, USA) equipped with appropriate filters. From a total of 69 blastocysts, 11 355 blastomeres were analyzed and 7,825 were correctly hybridized (68.9%). The results of the embryo sexing were: 24 embryos XX, 11 XY, 22 polyploid embryos (of which 13 presented more than 80% of cells XX), 3 haploid embryos (X0), 2 tetraploid embryos, and 5 no result. In summary, goat blastocysts were successfully sexed using FISH with painted ovine X- and Y-specific probes. Grant sponsor Spanish Ministery of Science and Innovation.Code: AGL2007-60227-CO2-01.

The Pediatric Posterior Fossa: an Embryologist's View

The paediatric posterior fossa is a complex structure made up of both neural elements and skeletal pieces. The first structures to be formed are the neural elements followed later by bones moulded around the already patterned neural elements. The nervous structures derive from the neural tube at the exact level of the rhombencephalon (also called the hindbrain). This neural tube is segmented into neuromeres called the rhombomeres. These structures form compartments in which cell migration is restricted. Furthermore, these compartments display specific gene expression and if the expression of a gene is forced into an aberrant rhombomere, a severe defect is determined in its own development. The cerebellum, that is one of the major neural components at this level, derives from rhombomere 1. It grows in a rostral to caudal direction like a curtain because its rostral progression is prevented by the cerebellar tentorium. The cerebellum arises as two distinct primordia that unite on the midline thanks to migration of the primordium of this structure. An impairment of this structure will generate a defective fusion at the midline. It is important to note that the different anatomical parts of the cerebellum are not regulated by the same molecular processes leading to a heterogeneity of this organ. Lastly, the bony structures of the posterior fossa derive from the mesoderm. We will review the exact contribution of both the somites and the cephalic mesoderm in such a context.

Procedure for Maximizing Oocyte Harvest for In Vitro Embryo Production in Small Ruminants

Possible effects of repeated hormonal treatments and laparoscopic ovum pick-up (LOPU) on the efficiency of oocyte recovery rate and quality were determined in sheep and goats. In six adult Merino sheep and five Criolla goats, ovarian status was synchronized by a prostaglandin F(2 alpha) analogue and the insertion of an intravaginal sponge 48 h later. Follicle development was stimulated by a single dose of FSH (60 mg NIH-FSH-P1) plus a single dose of equine chorionic gonadotrophin (eCG; 300 UI). The first FSH/eCG doses were administered 48 h after the sponge insertion, being repeated every 4 days to complete a total of four treatments in sheep and three in goats. Follicles in both ovaries were categorized according to their diameter and follicular fluid was aspirated under laparoscopic observation without a vacuum pump. In sheep, during a 12-day-period, a total of 347 follicles were aspirated with a recovery rate of 46.9%. In goats, during an 8-day-period, 219 follicles were aspirated with a recovery rate of 45.6%. In both species, there were no significant differences in the number of aspirated follicles, oocyte recovery rate and good quality oocyte recovery rate. However, in sheep the oocyte recovery rate was higher for large follicles, whereas in goats no such effect was detected. In summary, current results indicate that retrieval of oocytes can be maximized, without affecting oocyte quality, by repeating 'oneshot' FSH/eCG regimes and LOPUs at intervals as short as 4 days.

70 NON-PLATED GRANULOSA AND CUMULUS CELLS AND FIRST PASSAGE FIBROBLASTS AS NUCLEUS DONOR FOR GOAT CLONING

Different types of somatic cells have been used as nucleus donors for cloning. Most of them were previously cultured in vitro as a monolayer through several plate passages. The experiment reported here was conducted to study the potential usages of granulosa and cumulus cells for cloning without previous culture as a monolayer. A first-plate-passage fibroblast was also used. Oocytes were aspirated by laparoscopy from Criolla goats and matured in TCM-199 + 5% FCS at 39°C for 24 h. Matured oocytes were denuded by vortexing for 3 min in TL HEPES with 1 mg/mL bovine testis hyaluronidase. Metaphases were assessed and oocytes were enucleated by visualization with Hoechst 33342 (5 μg/mL) under UV light (<6 s). Granulosa and cumulus cells were also recovered by laparoscopy and maintained in maturation medium in cryotube for 20 h at room temperature or 39°C, respectively. Goat adult ear fibroblasts were cultured for 1 or 2 weeks and used 2 days after confluence. All types of donor cells were transferred to the perivitlline space of enucleated oocytes and fused by an electrical pulse. After 2 h, activation was induced by incubation in TL-HEPES with 5 µM ionomycin for 4 min and 2 mM 6-DMAP for 3 h. The oocytes were then washed with TL-HEPES and cultured in SOF medium and atmosphere of 5% CO2 + 5% O2 + 90% N2. Cleavage (Day 2) and development to blastocysts (Day 6) were recorded and analyzed by chi-square test. The cleavage rate for non-plated granulosa cells was higher than for the other treatment goups; cumulus cells had a lower rate of development to blastocysts (Table 1). These results suggest that granulosa cells collected and maintained for 24 h at room temperature could be used to produce cloned blastocysts. Table 1. Effect of non-plated granulosa and cumulus cells and first passage fibroblasts as donor nucleus oocytes in goat cloning

274 LAPAROSCOPIC OVUM PICK-UP IN SHEEP AND GOATS: EFFECTS OF REPEATED RECOVERIES AND FOLLICULAR DIAMETER

Laparoscopic ovum pickup (LOPU) is a modern technique that may be used in programs of sheep and goat in vitro embryo production. The effects of repeated recoveries and follicular diameter on the efficiency of LOPU were evaluated in these species. In six Merino donor sheep and five Criolla goats, ovarian stimulation for follicular development was performed by administering a single dose of 60 mg NIH-FSH-P1 (Folltropin®; Bioniche, Canada) and 300 UI of eCG (Novoromon 5000®; Syntex, Argentina). Every four days, a total of 4 LOPU in sheep and 3 in goats were performed 24 h after each ovarian stimulation treatment. The intravaginal sponge with 60 mg of medroxyprogesterone (Esponjas Vaginales Syntex®; Syntex, Argentina) were removed after the last LOPU. Follicular fluid was aspirated under laparoscopic observation according to the follicle diameter with a cannula for intrauterine artificial insemination without a vacuum pump. The number and size of follicles, oocyte quantity and quality and recovery rate were evaluated. A total of 566 follicles were aspirated (14.4 ± 2.4 follicles/sheep and 14.6 ± 7.5 follicles/goat), yielding a total of 263 oocytes (6.8 ± 1.5 oocytes/sheep and 6.6 ± 2.9 oocytes/goat) and a recovery rate of 47% in sheep and 46% in goats (Table 1). In both species, there were no significant differences in the number of aspirated follicles, recovered oocytes, overall recovery rate, and the recovery rate of good quality oocytes in the repeated LOPU. The oocyte recovery rates in sheep differed significantly according to the follicular size (55% in large follicles, 36% in small follicles; P < 0.05), whereas in goats recovery rates of oocytes related to follicular size showed no significant differences (42 and 54% for large and small follicles, respectively). Follicular sizes from which oocytes were obtained was not a determining factor in the recovery rate of good quality oocytes. The technique used would allow effective and repeated oocyte recoveries for in vitro embryo production in sheep and goats. Table 1. Repeated recoveries by laparoscopic ovum pickup (LOPU) in sheep and goats

[To live or to die, an embryonic dilemma]

The development and formation of an organ needs both cell proliferation and cell death. It is commonly possible to decipher three types of basic cell death: 1) the so-called morphogenetic cell death (an example is the formation of the digits); 2) the histogenetic cell death like the apoptotic processes taking place in the spinal cord and allowing to regulate the number of motoneurons according to their targets; and 3) the phylogenetic cell death in which vestigial structures are selectively removed (e.g. destruction of the pronephros or removal of the tail in the anuran larva).

[Spontaneous cholecystocutaneous fistula]

INTRODUCTION

Spontaneous cholecystocutaneous fistula is now a rare entity due to the advent of antibiotics, ultrasonography, and safe and early surgical treatment of biliary tract diseases. Such a case is reporting here, revealed by the systematic histological examination of the skin biopsy.

OBSERVATION

A 65 year-old male presented with an inflammatory and ulcerated lesion located on his right flank, with a long-standing but asymptomatic course. Biological tests and biliary tract ultrasonography were not very contributive. Histopathological findings consisted in a granulomatous dermal reaction enclosing biliary fragments. Per-operative data were in favour of a compound biliocutaneous fistula complicating an inflammatory process of the gall-bladder.

DISCUSSION

Spontaneous cholecystocutaneous fistula is unusual. Diagnosis might be difficult because of the lack of clinical specificity and a occasionally insidious evolution. Consequently, systemic histological examination is fundamental.

[Where have the neuronal stem cells of the subependymal zone gone in human beings?]

Stem cells are characterized by their ability for self-renewal (allowing them to be present throughout the entire life of the organism) and their ability to give rise to differentiated cells belong to one or more lineages. The strict definition of these cells is however still a matter of debate. There is new experimental evidence (including in human beings) that stem cells are present within the brain and may give rise to neurons. Ependymal cells have been proposed to play such a role. In fact, subependymal cells expressing GFAP would be more likely candidates. Such cells are observed in the brain of human beings. They are able to differentiate into neurons in vitro but such potential appears to be repressed in vivo.

The INSERM expert review on glycol ethers: findings and recommendations

The use of glycol ethers and their effects on health have recently attracted the attention of the French health authorities. At their request, INSERM, the French Institute of Health and Medical Research, conducted a collective expertise review on glycol ethers in 1999. INSERM Expertise Reviews are independent procedures performed by experts from several disciplines, to guarantee the objectivity and the relevance of the report. During several work sessions, the experts carried out a critical analysis of and reviewed studies concerning the toxicity of glycol ethers. This process resulted in a series of recommendations and conclusions. All these data have been published in the form of a report and have been used to help the public authorities to make decisions on how to prevent risks for professionals and consumers.

[Neurosurgical embryology. Part 7: Development of the spinal cord, the spine and the posterior fossa]

The spinal cord arises from the most caudal domain of the neural tube whereas the vertebrae develop from the para-axial mesoderm (namely the somites). The development of the spinal cord and the vertebrae is so intimately linked that it is more convenient to present it in the same chapter. The neural tube is formed from the neural plate during neurulation. This tube is submitted to a double gradient of diffusible molecules that lead to the ventro-dorsal polarization of the tube. This polarization is figured as the emergence of sub-domains that contain progenitors engaged in a specific lineage. Axial organs induce the dissociation of the somites, giving rise to the dermatome, myotome and sclerotome. Vertebrae derive from the sclerotome after the so-called resegmentation of the somites. During this process, a caudal hemi-somite is associated with the rostral hemi-somite of the next caudal somite to differentiate into the vertebra. The occipital bone forms the major part of the walls of the posterior fossa. This bone develops from the para-axial mesoderm for its sub-tentorial part whereas its sus-tentorial derives from neural crest cells.

[Neurosurgical embryology. Part 5: Temporal landmarks of the development of the central nervous system in humans]

The establishment of temporal landmarks of the development of the central nervous system was the primary goal of early human embryologists. The description of these landmarks has lost much of its interest since it is now largely accepted that the temporal profile of development is at best a poor indicator of the origin of malformative syndromes. However, we propose here a rapid review describing the principal data available. One of our goals is to present here the original data that are needed to understand the morphological aspect of the development of the central nervous system. The most important results are the presence of a developmental gradient within each anatomical area. This means that all the neurons of a specific anatomical region are not generated at the same time. There is also another gradient that could be described. This gradient is the rostro-caudal gradient: the spinal cord develops first, then the brain stem, and finally the encephalon. This rule is only a general rule with many exceptions like, for instance, the cerebellum that is a late derivative of the neural tube.

[Neurosurgical embryology. Part 6: The principal models that can be used in developmental biology]

To study the mechanisms controlling embryonic development, experimental analyses must be performed on animal models. There are different species that are currently used as models in developmental biology. In invertebrates, drosophila remains a very useful model thanks to its rapid development and to the extensive study of genes involved in the control of its development. C. elegans has been extensively used because of its simplicity due to the total restricted number of adult cells in this species. In vertebrates, amphibians remain a very useful model with the extensive analysis of Xenopus laevis. The zebrafish is now a widely used model because of its genetic analysis. Birds are still used for the accessibility of their embryo allowing experimental procedures to be performed in ovo. The mouse is now very widely used because it is possible to obtain transgenic mice to study both loss or gain of gene function.

[Neurosurgical embryology. Part 1: Cell differentiation]

In pluricellular organisms, cell differentiation helps to decrease the total amount of energy needed for life. These differentiations can be evidenced at the tissular, the cellular or the molecular levels. Cell differentiation is a progressive process achieved during embryogenesis; different steps in the program can be described. One of the explanations to account for cell differentiation is the specific expression of proteins, called transcription factors, that can control the expression of selected genes. These factors are classified according to their biochemical pattern allowing description of several families of transcription factors. One of the salient questions during embryogenesis is to understand the mechanisms involved in cell differentiation. The first event is due to asymmetry of mitosis leading to the generation of two cell lineages. This is favored by the initial ovocyte polarization. The second event is due to cell interactions (namely inductions). These inductions may be explained either by cell-cell contact (favored by cell adhesion molecules) or by secreting factors that can be either hydrophilic or lipophilic.

[Neurosurgical Embryology. Part 2: Recent data on normal and pathological development of the cortex]

Understanding how the cortex develops has gained very important new data thanks to both experimental and clinical studies. Experimental studies have shown that: --neurons are generated in the ventricular zone by asymmetric mitoses; --the first cortical region to differentiate is the so-called pre-plate that plays a major role in the control of neuroblasts migration; --neuroblasts arise according to an inside-outside gradient; they migrate either along the processes of radial cells or according to a new type of non radial migration; --all the cortical neurons are not generated by the dorsal telencephalon; some of these neurons derive from the basal telencephalon; --neuroblasts acquire their specificity during their way to the cortical plate. There are several genetic syndromes leading to a malformation of the cortex. Classic lissencephaly is essentially due to mutations of the LIS1 or the DCX genes. These genes code for proteins that are involved in cytoskeleton functions. Reelin is responsible for a human syndrome associating pachygyria and cerebellar hypotrophy. Subventricular heterotopia can be X- inherited and are due to a mutation of the gene coding for filamin 1.

[Neurosurgical embryology. Part 4: What are stem-cells?]

Stem-cells have been identified in the adult human brain in two zones which are the subventricular zone and the gyrus dentatus of the hippocampus. Improvement of techniques aimed to identify, to localize and to follow the lineage of these cells have been crucial to the understanding of the following processes: a) identification of cellular proliferation, b) specific immunostaining of differentiated glial and neuronal cells, c) transplantations to decipher between intrinsic stem-cell properties and influence of the environment on the fate of the cell. Furthermore, it seems that stem-cells from other sources than the brain can differentiate into neurons both in vitro and in vivo. The aim of this review is to sum up what is known about cerebral stem-cells and the challenging tools they mean for the future.

[Neurosurgical Embryology. Part 3: Molecular control of corpus callosum development]

The corpus callosum is the most important cerebral commissure allowing axonal fibres to cross the midline. Corpus callosum agenesis is an important condition in man that can reveal numerous genetic syndromes. The corpus callosum develops from the commissural plate, a dorsal region of the telencephalon. Then, axons growing from pyramidal neurons of cortical layer III extend and cross the midline. In experimental models, it is possible to decipher two conditions in which the development of the corpus callosum is impaired. The first condition is characterized by an impairment of the formation of the roof of the telencephalon (the primordium of the commissural plate). This condition can be explained by an abortive induction of this region by an impairment of BMP signaling. This can generate all the forms of holoprosencephaly. Other forms are due to a defective gene coding Hesx1, a transcription factor involved in the control of telencephalic morphogenesis. Such a genetic defect can be observed in human dominant forms of septo-optic dysplasia. The second condition is explained by an impairment of the molecular control of axon growth: such is the case for the couple netrin 1 and DCC or for the adhesion molecule L1.

[Embryology of the sphenoid bone]

The sphenoid bone represents a complex structure in terms of anatomy and embryology. Indeed, it is formed by the fusion of different primordia whose embryonic origins are different. In mammals, it is possible to distinguish two components of this bone: the orbitosphenoid and the basi-post-sphenoid derive from the cephalic mesoderm whereas the alisphenoid and the basi-pre-sphenoid are from neural crest cell origin. The genetic control of the development of these two components is different further increasing the heterogeneity of these components. The sphenoid bone has been linked with several developmental diseases: chordomas, tumors arising from notochordal remnants; persistence of the craniopharyngeal canal may result in the occurrence of trans-sphenoidal encephaloceles.

[Development and maturation of the pyramidal tract]

The pyramidal tract contains axons that originate from neurons located in layer 5 of the neocortex of the frontal areas 4 and 6 and of the parietal lobe. These neurons are generated during the first half of gestation in humans. The growth of these axons is highly regulated and the mechanisms that control this growth begin to be unravelled. For example, netrins could serve as chemattractants, the adhesion molecule L1 plays a crucial role in the control of axonal decussation at the level of the medulla, the ephrin B3-Eph A4 couple prevents the axons from crossing the midline. During development, the total number of pyramidal axons increases progressively and then decreases by regression of exuberant collaterals. The pyramidal tract is the sole unmyelinated tract in the human spinal cord at birth. This accounts for the protracted central conduction time in newborns. This immaturity of the pyramidal system could explain the existence of specific motor reflexes in newborns (the so-called primary reflexes) that disappear as the pyramidal system matures.

[The formation of neurons in the bone marrow, the dream of alchemy in the new millenium]

In rodents, bone marrow contains stem cells that have the potentiality to differentiate into mesodermal and non-mesodermal cells, both in vitro and in vivo. These cells can populate a wide panel of organs such as the liver, the brain, the lungs, the heart.... They appropriately differentiate according to the environment in which they migrate and are known to assume specific functions. Even in adult animals, these cells can migrate and differentiate. Such a potentiality suggests exciting therapeutic outcomes. Brain lesions could benefit of such techniques. These experimental protocols should be precisely controlled before their use in medicine in order to solve problems that still remain such as the permeability of the hemato-encephalic barrier, the integration of differentiated grafted cells into local functional neural networks.

Epidermal growth factor-based cancer vaccine for non-small-cell lung cancer therapy

BACKGROUND

The role that growth factors and their receptors play in human cancer growth and progression makes them interesting targets for novel treatment modalities. Our approach consisted of active immunotherapy with the epidermal growth factor (EGF). Two pilot clinical trials were conducted to examine the safety and immunogenicity of a five-dose immunization protocol and to compare different adjuvants and treatment designs.

PATIENTS AND METHODS

Forty patients with advanced non-small-cell lung cancer were enrolled in both trials. They were randomized to be treated with aluminum hydroxide or montanide ISA 51 as adjuvants in the EGF vaccine preparation. The use of cyclophosphamide prevaccination treatment was evaluated in the second trial.

RESULTS

Pooled data from both trials showed that the use of montanide as adjuvant increased the percentage of good antibody responders (GAR). Cyclophosphamide prevaccination treatment did not provoke improvements in antibody response. GAR had a significant increase in survival as compared with poor antibody responders. Response duration was also related to a significant improvement in survival rates.

CONCLUSIONS

Vaccination with five doses of EGF vaccine is safe and immunogenic. Montanide ISA 51 increased the percentage of GAR. There is a direct relationship between anti-EGF antibody titers and immune response duration with survival time.

[Recent contributions to the establishment of the axes of the mammalian embryo]

The study of the establishment of embryonic axes during early development has shown that this process is a very early event (occurRing either during ovogenesis or during fertilization) for invertebrates and for lower vertebrates. In mammals, it was considered that this establishment appears late during development because of the great plasticity of blastomeres. Recent data in the mouse embryon show that the mammalian ovocyte is a polarized cell, the polar body corresponding to the animal pole of this cell. The blastomeres that are generated by the zygote divide asynchronously. The first that divides is the one which inherits the plasma cell membrane where fertilization takes place. This blastomere will preferentially give rise to the cells of the embryonic pole of the blastocyst whereas the other yields the cells of the abembryonic pole. The mammalian ovocyte is thus a polarized cell with an already established animal-vegetal axis. The point of sperm entry will determine the embryonic-abembryonic axis.

Genetic control of caudal development

Several lines of evidence suggest that caudal development involves a distinct programme. This is illustrated by the fact that a specific pattern of malformations affects the caudal end of the human embryo. In addition, neurulation, the process leading to the formation of the neural tube, proceeds through different morphogenetic movements caudally. In mammals, as in birds, the caudal neural tube arises from cavitation and not from folding of the neural plate as in more rostral levels. However, recent fate mapping studies have suggested that the two modes of neurulation represent a continuous programme, possibly involving similar cellular or molecular mechanisms. Finally, analyses of mutant mice have shown that T-box transcription factors and components of the Wnt signalling pathway control cellular migration and the promotion of mesoderm formation in the caudal embryo. In humans, mutation in the HLXB9 transcription factor causes an autosomal dominant form of sacral agenesis. Thus, the combination of classical embryological and molecular genetics approaches has provided critical reference points for the delineation of the developmental programme of the caudal embryo.

Primary triple teeth: histological and CT morphological study of two case reports

The macromorphology and micromorphology of two specimens of primary triple teeth using histological and CT analysis approach is analyzed. A single morphological pattern of triple teeth has been found and described: three nearly separate crowns with three separate pulp chambers, and three joined roots with three connected root canals. The characteristic triple teeth appearance occurred because a labial supernumerary tooth is the junction element between two teeth of normal series: the central incisor on the mesial side and the lateral incisor on the distal side. Primary triple teeth suggest an idiopathic abnormality in the distribution of the dental material originated very soon in the dental development. They can be considered as an early double fusion between three tooth germs, initially separate but in close proximity and developing synchronically.

A case of antenatal cerebral haemorrhage resulting from maternal alloimmunisation against fetal platelets

Prenatal thrombocytopenia is a rare event and is generally due to fetal infection. In very rare cases, fetal thrombocytopenia is induced by maternal IgG directed against the fetal platelets. This alloimmunisation could lead to in utero bleeding. We now report such a case, in which fetal thrombocytopenia was complicated by a huge temporal lobe haematoma. Such a prenatal event is rare: only eight cases have been published, with only one pathologically confirmed case. Our patient is the second one in which neuropathological examination demonstrated prenatal intracerebral bleeding.

Human and monkey fetal brain development of the supramammillary-hippocampal projections: a system involved in the regulation of theta activity

The supramammillary (SUM)-hippocampal pathway plays a central role in the regulation of theta rhythm frequency. We followed its prenatal development in eight Cynomolgus monkeys (Macaca fascicularis) from embryonic day E88 to postnatal day 12 (term 165 days) and in eight human fetuses from 17.5 to 40 gestational weeks, relying on neurochemical criteria established in the adult (Nitsch and Leranth [1993] Neuroscience 55:797-812). We found that 1) SUM afferents reached the dentate juxtagranular and CA2 pyramidal cell layers at midgestation in human fetuses, earlier than in monkeys (two-thirds of gestation [E109]). They co-expressed calretinin, substance P, and acetylcholinesterase but not gamma-aminobutyric acid (GABA) or glutamic acid decarboxylase (GAD); 2) the presumed parent neurons in the monkey SUM expressed calretinin or both calretinin and substance P; 3) most of them were surrounded by GAD-containing terminals that might correspond to the septo-SUM feedback pathway (Leranth et al. [1999] Neuroscience 88:701); and 4) in addition, a large band of calretinin-labeled terminals that did not co-express substance P, GAD, or acetylcholinesterase was present in the deepest one-third of the dentate molecular layer in both the Cynomolgus monkey and human fetuses. It persisted in the adult monkey but not in adult human hippocampus; it remains questionable whether it originates in the SUM. In conclusion, the early ingrowth of the excitatory SUM-hippocampal system in human and non-human primates may contribute to the prenatal activity-dependent development of the hippocampal formation. The possibility and the functional importance of an in utero generation of hippocampal theta-like activity should also be considered.

A destructive hemispheric cleft discovered in a female fetus

The case of a female fetus who died at the 38th week of gestation is reported. Neuropathological examination disclosed a hemispheric cleft located in the medial part of the left frontal lobe. The cleft did not extend to the ventricle and was not a true schizencephaly. Furthermore, a focus of gliosis was evidenced by GFAP staining located in the superior bank of the cleft suggesting a destructive origin of the process. Maternal psychological stress occurring during the middle of the pregnancy could have favored hemodynamic disturbances acting on the fetal circulation.