Mutations within the programmed cell death 10 gene cause cerebral cavernous malformations

Cerebral cavernous malformations (CCMs) are hamartomatous vascular malformations characterized by abnormally enlarged capillary cavities without intervening brain parenchyma. They cause seizures and cerebral hemorrhages, which can result in focal neurological deficits. Three CCM loci have been mapped, and loss-of-function mutations were identified in the KRIT1 (CCM1) and MGC4607 (CCM2) genes. We report herein the identification of PDCD10 (programmed cell death 10) as the CCM3 gene. The CCM3 locus has been previously mapped to 3q26-27 within a 22-cM interval that is bracketed by D3S1763 and D3S1262. We hypothesized that genomic deletions might occur at the CCM3 locus, as reported previously to occur at the CCM2 locus. Through high-density microsatellite genotyping of 20 families, we identified, in one family, null alleles that resulted from a deletion within a 4-Mb interval flanked by markers D3S3668 and D3S1614. This de novo deletion encompassed D3S1763, which strongly suggests that the CCM3 gene lies within a 970-kb region bracketed by D3S1763 and D3S1614. Six additional distinct deleterious mutations within PDCD10, one of the five known genes mapped within this interval, were identified in seven families. Three of these mutations were nonsense mutations, and two led to an aberrant splicing of exon 9, with a frameshift and a longer open reading frame within exon 10. The last of the six mutations led to an aberrant splicing of exon 5, without frameshift. Three of these mutations occurred de novo. All of them cosegregated with the disease in the families and were not observed in 200 control chromosomes. PDCD10, also called "TFAR15," had been initially identified through a screening for genes differentially expressed during the induction of apoptosis in the TF-1 premyeloid cell line. It is highly conserved in both vertebrates and invertebrates. Its implication in cerebral cavernous malformations strongly suggests that it is a new player in vascular morphogenesis and/or remodeling.

Split atlas in a patient with odontoid fracture

We report the unusual association of a split atlas and an odontoid fracture in a case of a cervical trauma, thus mimicking a complex C1-C2 fracture. The normal embryology of C1 and the literature on this rare malformation are reviewed.

[Rathke's cleft cyst]

Rathke's cleft cyst (RCC) are frequent benign cystic sellar lesions. Most RCC are small, intrasellar and asymptomatic. Larger cysts may compress adjacent structures and rarely become symptomatic. Diagnosis is strongly suggested at MRI by the presence of a midline non-enhancing lesion located exactly between the anterior and posterior lobes of the pituitary gland. Even if its signal is variable and related to intracystic protein concentration, it must be homogeneous with no fluid-fluid level. Once a diagnosis of RCC made, routine MR and clinical follow-up is sufficient for incidental asymptomatic cysts whereas the rare symptomatic lesions are neurosurgically resected.

[Follow-up MRI after trans-sphenoidal surgery]

The authors report their 10 year experience on postsurgical MRI of the sphenoidal region. All patients underwent MRI examination 4 days after surgery, then between 2 and 3 months and one year or more after surgery. The reproducibility of pulse sequences is mandatory to make a diagnosis of recurrent adenoma as early as possible.

Electrochemical generation of the Fenton's reagent: application to atrazine degradation

The degradation of refractory chemicals in water requires chemical oxidation by hydroxyl radicals. Among the systems that may be used to generate OH(o), the Fenton's reagent consists of the mixing of ferrous iron and hydrogen peroxide. Even though this system is very simple, the oxidation of an organic compound is difficult to control and the ferrous iron regeneration is limited. Very recently, electrochemical systems have merged that allow the electrochemical production of ferrous iron and/or hydrogen peroxide, thereby allowing the generation of OH(o). So a simple electro-Fenton system has been used and tested for its efficiency in producing hydroxyl radicals. Atrazine was chosen as a model organic compound as its reaction with OH(o) has been extensively studied. Comparison with the classical Fenton system gives advantage to the electrochemical system, due to a more thorough oxidation of atrazine.

[Pituitary gland imaging in Cushing's disease]

Specific MR techniques are required for optimal detection of adenocorticotropic hormone secreting adenomas responsible for Cushing's disease. Adequate MR sequences, high resolution coronal T1 and T2 - weighted images, dynamic MR imaging, post-gadolinium delayed images, dose of gadolinium adjusted for each sequence can routinely demonstrate pituitary adenomas less than 3 mm in Cushing's disease.

[Intramedullary spread of a cerebral oligodendroglioma. Two case reports]

We report two cases of leptomeningeal metastatic dissemination to the spinal cord of a grade B oligodendroglioma. Diagnosis was suspected on MRI but imaging findings were nonspecific. The pathways by which the intramedullary part of the spinal is reached by metastatic cells remains controversial. In the reported cases, both frontal and cystic primary intracerebral lesions were observed. Chemotherapy after radiotherapy appears to improve outcome. Nevertheless, prognosis remains very poor.

Mapping the functional anatomy of BgK on Kv1.1, Kv1.2, and Kv1.3. Clues to design analogs with enhanced selectivity

BgK is a peptide from the sea anemone Bunodosoma granulifera, which blocks Kv1.1, Kv1.2, and Kv1.3 potassium channels. Using 25 analogs substituted at a single position by an alanine residue, we performed the complete mapping of the BgK binding sites for the three Kv1 channels. These binding sites included three common residues (Ser-23, Lys-25, and Tyr-26) and a variable set of additional residues depending on the particular channel. Shortening the side chain of Lys-25 by taking out the four methylene groups dramatically decreased the BgK affinity to all Kv1 channels tested. However, the analog K25Orn displayed increased potency on Kv1.2, which makes this peptide a selective blocker for Kv1.2 (K(D) 50- and 300-fold lower than for Kv1.1 and Kv1.3, respectively). BgK analogs with enhanced selectivity could also be made by substituting residues that are differentially involved in the binding to some of the three Kv1 channels. For example, the analog F6A was found to be >500-fold more potent for Kv1.1 than for Kv1.2 and Kv1.3. These results provide new information about the mechanisms by which a channel blocker distinguishes individual channels among closely related isoforms and give clues for designing analogs with enhanced selectivity.

Distribution in rat brain of binding sites of kaliotoxin, a blocker of Kv1.1 and Kv1.3 alpha-subunits

The distribution of the binding sites for kaliotoxin (KTX), a blocker of voltage-dependent K(+) channels, was studied with quantitative autoradiography in adult rat brain and during postnatal brain maturation. Iodinated KTX bound specifically to tissue sections with a high affinity (K(d) = 82 pM) and a maximal binding capacity of 13.4 fmol/mg protein. The distribution of KTX binding sites within the central nervous system was heterogeneous. The highest densities were found in the neocortex, hypothalamus, dentate gyrus, bed nucleus of the stria terminalis, and parabrachial nuclei. The lowest level was observed in the white matter. From postnatal day 5 onward, KTX binding sites were detectable only in the hindbrain. The density of KTX binding sites in whole brain drastically increased after postnatal day 15 to achieve adult levels at postnatal day 60 in the whole brain. Bath application of KTX to Xenopus laevis oocytes blocked recombinant Kv1.3 and Kv1.1 channels potently and Kv1.2 channels less potently, with respective K(d) values of 0.1, 1.5, and 25 nM. KTX affinities for each of these channels expressed in mammalian cells were about 10-fold lower. A comparison of the distribution of KTX binding sites with that of Kv1 channel polypeptides, together with the pharmacology of KTX block, suggests that the principal targets for KTX in rat brain are K(+) channels containing Kv1.1 and Kv1.3 alpha-subunits.

[Results of cervical interbody fusion with coral grafts]

OBJECTIVES

We present the long term clinical and radiological results of a retrospective series of 46 cervical interbody fusions using coral grafts performed in 38 patients.

MATERIAL AND METHODS

The patients were treated for prolapsed discs (19 cases) or cervical spondylosis (19 cases) with a clinical presentation of either radiculopathy (31 cases) or myelopathy (7 cases). We have done a post-operative clinical analysis of cervicoscapulalgia and radiculo-medullary symptoms and a radiological comparison of the change of the cervical spine angulation, the loss of height and the fusion rate at the graft site.

RESULTS

The early clinical postoperative outcome showed that 10 out of 20 patients with excellent radiculo-medullary results had cervicoscapulalgia and 13 out of 18 patients with partial improvement had cervicoscapulalgia. No poor results according to our classification were noted. The late clinical outcome (average follow-up of 16 months) showed that 15 patients out of 31 had radiculo-medullary degradation and 24 presented with cervicoscapulalgia. Sixteen out of 20 patients had a loss of lordosis (range 6.2 degrees; SD 1.2) and 17 a loss of height (range 11.3%; SD 1.5). After 2 years, 13 out of 20 grafts were still hyperdense compared to the adjacent bone, and 8 had a hypodense peripheral edge.

CONCLUSIONS

Coral grafts of this series have not been able to keep a physiological sagittal balance of the cervical spine, which is probably one of the essential factors to prevent postoperative cervicoscapulalgia. In the same way, the loss of height of the fused segments, by narrowing of the intervertabral foramen, may explain some further radiculo-medullary deterioration.

Long-term reproducibility optimization of an x-ray process for bone architectural evaluation during osteoporosis

Non-invasive and in vivo assessment of bone architectural changes at high resolution is of considerable interest in osteoporosis. In this note, the use of an x-ray acquisition system in the evaluation of the architectural quality of trabecular bone by radiographic texture analysis is optimized to achieve good long-term reproducibility. First, radiographic and digitization processes are modelled and defined. Procedures to make radiographs and their digital images are fixed. Then, measurements of the modulation transfer function (MTF) of the entire acquisition chain were completed. These measurements provide an MTF in excess of 30% at a spatial frequency of 2.5 lp/mm. Also, results of a fractal texture analysis made on digital images of calcaneus radiographs show a mean coefficient of variation of 2.07%. These data show that good long-term reproducibility can make the x-ray acquisition system efficient for patient follow-up, or evaluation of treatment regimes for osteoporosis. Finally, it is shown that fractal texture parameters are statistically different in an osteoporotic population and in a control group. Therefore, this system should also be of medical interest.

Maurotoxin, a four disulfide bridges scorpion toxin acting on K+ channels

Maurotoxin, a toxin from the venom of the Tunisian chactoid scorpion Scorpio maurus, has been purified to homogeneity by gel filtration/reversed-phase HPLC, and characterized. It is a basic and C-terminal amidated 34-residue polypeptide cross-linked by four disulfide bridges. From Edman sequencing results, only six different pairings between the first six half-cystines were retained whereas a disulfide bridge was predicted between the two half-cystines in positions 31 and 34. Modelling based on the structure of charybdotoxin favored two different pairings, one of which possessed two disulfides in common with the general motif of scorpion toxins. The solid-phase technique was used to obtain synthetic maurotoxin, sMTX. The half-cystine pairings of sMTX were determined by enzymatic cleavage and were found to be Cys3 Cys24, Cys9-Cys29, Cys13-Cys19, and Cys31-34, in agreement with experimental data obtained with natural maurotoxin. Both natural and synthetic maurotoxins were lethal to mice following intracerebroventricular injection (LD50, 80 ng/mouse). They blocked the Kv1.1, Kv1.2, and Kv1.3 channels expressed in Xenopus oocytes with almost identical half-effects (IC50) in the range of 40, 0.8 and 150 nM, respectively. They also competed with 125I-apamin (SKca channel blocker) and 125I-kaliotoxin (Kv channel blocker) for binding to rat brain synaptosomes with IC50 of about 5 and 0.03 nM. As the natural and synthetic maurotoxins exhibit indistinguishable physicochemical and pharmacological properties, they are likely to adopt the same half-cystine pairing pattern which is unique among known scorpion toxins. However, this disulfide organization is different from those reported for Pandinus imperator and Heterometrus spinnifer toxins 1 (Pi1 and HsTx1), two novel four-disulfide bridged K+ channel-acting scorpion toxin sharing about 50-70% sequence identity with maurotoxin.

Biomechanical properties of human os calcanei: relationships with bone density and fractal evaluation of bone microarchitecture

The relationship between bone strength and bone mass is well established. The link between trabecular microarchitecture and biomechanical properties has been less extensively explored. To address this question, we have tested the mechanical behaviour of calcaneus bone samples and investigated the correlations between mechanical properties on the one hand, bone density and fractal analysis of microarchitecture on the other hand. Mechanical properties of 43 human os calcanei were determined by uniaxial compression testing of samples from tuber calcanei. Ash density, bulk density and dual energy X-ray absorptiometry of the samples were measured. Fractal analysis of the trabecular bone on calcaneus radiographs was performed by two estimators derived from the fractional Brownian motion model. The mechanical properties of human os calcis were found to correlate with age and density measurements. Fractal parameters derived from the bone texture analysis showed weaker but significant correlations with bone strength. Fractal analysis of texture could account in part for the variations of bone strength, but in this study cannot explain better than density the mechanical properties of trabecular bone. Nevertheless, it provides a non-invasive means of assessing molecular bone microarchitecture.

Chemical synthesis and characterization of maurotoxin, a short scorpion toxin with four disulfide bridges that acts on K+ channels

Maurotoxin is a toxin isolated from the venom of the Tunisian chactoid scorpion Scorpio maurus. It is a 34-amino-acid peptide cross-linked by four disulfide bridges. Maurotoxin competes with radiolabeled apamin and kaliotoxin for binding to rat-brain synaptosomes. Due to its very low concentration in venom (0.6% of the proteins), maurotoxin was chemically synthesized by means of an optimized solid-phase technique. The synthetic maurotoxin was characterized. It was lethal to mice following intracerebroventricular injection (LD50, 80 ng/mouse). The synthetic maurotoxin competed with 125I-apamin and 125I-kaliotoxin for binding to rat-brain synaptosomes with half-maximal effects at concentrations of 5 nM and 0.2 nM, respectively. Synthetic maurotoxin was tested on K+ channels and was found to block the Kv1.1, Kv1.2, and Kv1.3 currents with half-maximal blockage (IC50) at 37, 0.8 and 150 nM, respectively. Thus, maurotoxin is a scorpion toxin with four disulfide bridges that acts on K+ channels. The half-cystine pairings of synthetic maurotoxin were identified by enzymatic cleavage. The pairings were Cys3-Cys24, Cys9-Cys29, Cys13-Cys19 and Cys31-Cys34. This disulfide organization is unique among known scorpion toxins. The physicochemical and pharmacological properties of synthetic maurotoxin were indistinguishable from those of natural maurotoxin, which suggests that natural maurotoxin adopts the same half-cystine pairing pattern. The conformation of synthetic maurotoxin was investigated by means of circular dichroism spectroscopy and molecular modeling. In spite of its unusual half-cystine pairings, the synthetic-maurotoxin conformation appears to be similar to that of other short scorpion toxins.

Anisotropy measurements obtained by fractal analysis of trabecular bone at the calcaneus and radius

The resistance of bone tissue is influenced not only by bone density parameters but also by bone architecture parameters, such as the microarchitecture and anisotropy of trabecular bone. We have developed and validated a fractal analysis method for studying bone microarchitecture on roentgenograms. This technique provides reproducible measurements of the fractal dimension (D) of bone, which reflects bone texture. The fractal dimension is determined in 36 different directions; the mean of these 36 values is representative of the image. A polar diagram gives the value of D according to the angle of analysis. By decomposing this diagram using polar Fourier Transform analysis, the parameters related to the shape of the polar diagram can be determined. This diagram image analysis technique has been used for other similar diagrams and applied to the results of our fractal analysis method. Diagram shape characterization may provide information on the angular distribution of results and therefore on the anisotropy of the images under study. The purpose of this study was to compare roentgenograms of the calcaneus and radius in the same subjects to determine whether texture and anisotropy parameters discriminated between these two bones. Roentgenograms of the calcaneus and radius were obtained in ten nonosteoporotic subjects. The radius had a smaller fractal dimension than the calcaneus (mean +/- standard deviation: 1.215 +/- 0.025 and 1.285 +/- 0.066, respectively; p = 0.014). Differences in the shape of the polar diagram were found between the two bones. The mean Fourier coefficient ratio C2/C4 was considerably smaller at the calcaneus (0.63 +/- 0.50) than at the radius (4.88 +/- 3.45; p = 0.005). Our method allows quantitative characterization of texture and anisotropy differences between the calcaneus and radius. The smaller fractal dimension of the radius probably reflects the simpler architecture of this non weight-bearing bone. The differences in polar diagram shape allow to evaluate anisotropy differences between the calcaneus and radius.

The kaliotoxin family enlarged. Purification, characterization, and precursor nucleotide sequence of KTX2 from Androctonus australis venom

Kaliotoxin (KTX) has been originally described as an inhibitor of the intermediate conductance Ca(2+)-activated K+ channel (Crest, M., Jacquet, G., Gola, M., Zerrouk, H., Benslimane, A., Rochat, H., Mansuelle, P., and Martin-Eauclaire, M.-F. (1992) J. Biol. Chem. 267, 1640-1647). However, the radioiodinated 125I-KTX-(1-37) was also able to bind to the dendrotoxin sensitive voltage-dependent K+ channel (Romi, R., Crest, M., Gola, M., Sampieri, F., Jacquet, G., Zerrouk, H., Mansuelle, P., Sorokine, O., Van Dorsselaer, A., Rochat, H., Martin-Eauclaire, M.-F., and Van Rietschoten, J. (1993) J. Biol. Chem. 268, 26302-26309). By following the ability to compete with 125I-KTX-(1-37) for binding to its receptor on rat brain synaptosomes, a new kaliotoxin-like peptide, KTX2, was isolated from Androctonus australis scorpion venom. It is a 37-amino acid residue peptide, and its sequence shares 76% identity with KTX. The differences between the two peptides concern the NH2-terminal region and the residues 31 and 34 located in the region involved in the channel recognition. These differences may explain the 5-fold decrease of the molluscan Ca(2+)-activated K+ channel blockage by KTX2 (kd = 135 nM) as well as of its binding affinity to rat brain synaptosomes (IC50 = 50 pM), compared with KTX. Specific antibodies raised against KTX-(1-37) were not able to recognize KTX2. Using degenerate primers, a 370-base pair cDNA encoding the KTX2 precursor was amplified by polymerase chain reaction from a cDNA library of A. australis venom glands. It encoded a presumed signal peptide of 22 residues followed by the sequence of the mature peptide.

Fractal organization of trabecular bone images on calcaneus radiographs

Bone density is not the unique factor conditioning bone strength. Trabecular bone microarchitecture also plays an important role. We have developed a fractal evaluation of trabecular bone microarchitecture on calcaneus radiographs. Fractal models may provide a single numeric evaluation (the fractal dimension) of such complex structures. Our evaluation results from an analysis of images with a varying range of gray levels, without binarization of the image. It is based on the fractional brownian motion model, or more precisely on the analysis of its increment, the fractional gaussian noise (FGN). The use of this model may be considered validated if two conditions are fulfilled: the gaussian repartition and the self-similarity of our data. The gaussian repartition of intermediate lines of these images was tested on a sample of 32,800 lines from 82 images. Following a chi-square goodness-of-fit test, it was checked in 86% of these lines for alpha = 0.01. The self-similarity was tested on 20 images by two estimators, the variance method of Pentland and the spectrum method of Fourier. Self-similarity is defined by lined-up points in a log-log plot of the FGN spectrum or of the variance as a function of the lag. We found two self-similarity areas between scales of analysis ranging from 105 to 420 microns, then above 900 microns, where linear regression produced high mean correlation coefficients (r > or = 0.97). Following this validation, we studied the reproducibility of this new technique. Intra- and interobserver reproducibility, influence of transferring the region of interest, and long-term reproducibility were assessed and given CV of 0.61 +/- 0.15, 0.68 +/- 0.47, 0.53 +/- 0.16, and 2.07 +/- 0.84%, respectively. These data have allowed us to validate the use of this fractal model by checking the fractal organization of our radiographic images analyzed by the model. The good reproducibility of successive x-rays in the same subject allows us to undertake population studies and to envisage longitudinal series.

Intracranial alveolar echinococcosis: CT and MRI

Intracranial alveolar echinococcosis is uncommon. We report a patient with right frontal lobe and palpebral lesions secondary to a primary hepatic focus with secondary lesion in the lung. The intracranial and palpebral cystic masses were totally removed and both proved to be alveolar hydatid cysts. An unusual feature in this case is CT and MRI demonstration of dural and bony extension.

[Torticollis and C1-C2 rotation subluxation. Apropos of a case. The value of a dynamic scanner and of a 3-dimensional scanner]

The authors report the rare and complex case of a girl who had been followed since the age of 3 years for hydrocephalus the cause of which was found only when she was 6-year old. The causative agent was a pilocytic astrocytoma of the cerebellum. On April 10, 1990, she underwent subtotal excision of the tumour, associated with radiotherapy. Four months later she developed an increasingly painful and irreducible torticollis which did not respond to tractions. Dynamic CT scans and 3-dimensional CT scans were performed in the fourth month and provided a diagnosis of right C1-C2 rotatory subluxation. There was no history of injury and no sign of inflammatory process. Rotatory subluxation is a very rare lesion difficult to diagnose, and few cases have been published, although the signs are those of classical torticollis in children. When medical treatment fails, often due to belated diagnosis, the only surgical treatment is uni- or bilateral C1-C2 arthrodesis. If the diagnosis can be made at an early stage, reduction of the rotatory luxation is usually easy and without consequences to the child. It is therefore recommended to perform a dynamic CT scan and a 3D CT scan as soon as possible in all children with lasting painful torticollis.

Synthesis and characterization of kaliotoxin. Is the 26-32 sequence essential for potassium channel recognition?

Kaliotoxin (KTX), a scorpion toxin characterized as a 37-residue inhibitor of the neuronal high conductance Ca(2+)-activated K+ channels (KCa channels), has been chemically synthetized. Differences were observed between natural toxin and the two peptides, KTX(1-37) and KTX(1-37)-amide. Re-examination of the KTX sequence showed that an extra lysine residue was present at the C-terminal end. The 38-residue synthetic peptide was found identical with natural toxin. All three peptides had comparable activities, with LD50 values of 6-9 pmol/mouse after intracerebroventricular injection, and Kd = 2-8 nM for blockage of the whole cell and unitary molluscan KCa currents. Pairing of the disulfide bonds in synthetic KTX corresponded to that in charybdotoxin and iberiotoxin. A competition assay between 125I-KTX(1-37) and different toxins (KTX, dendrotoxin, charybdotoxin, MCD peptide, and iberiotoxin) for binding to rat brain synaptosomal membranes suggested that KTX interacts also with voltage-gated K+ channels. Shorter peptides, KTX(25-35)-amide and KTX(26-32)-amide, expressed no KTX activity, but were able to compete in binding. They were further shown to antagonize KTX in both its toxicity and blocking activity. The (26-32) sequence of KTX, which is a highly conserved region, may contain a low affinity binding subsite essential for potassium channel recognition.

Single-channel and whole-cell recordings from on-neurone glial cells in Helix pomatia ganglia

A procedure is described for performing patch-clamp recordings on satellite glial cells kept in place within the nervous ganglia in the mollusc Helix. Glial cell properties were deduced from whole-cell and cell-attached recordings. The glial membrane was found to contain densely packed inwardly rectifying K+ channels. Activation of the neurones, under either current-clamp or voltage-clamp conditions, depolarized the glial cell layer wrapped around the neurones and induced a delayed persistent increase in the K+ channel opening probability. These results suggest that the glial channels opened in response to a signal emanating from the active neurones. This preparation provides a useful means of detecting and analysing neurone-glial interactions at the cell and unitary channel levels.

Satellite glial cells in situ within mammalian prevertebral ganglia express K+ channels active at rest potential

Patch-clamp experiments were performed on satellite glial cells wrapped around sympathetic neurons in the rabbit coeliac ganglion. With the cleaning method used, the glial cells could be kept in place and were directly accessible to the patch-clamp pipettes. Whole-cell recordings showed that glial cells had almost ohmic properties. Their resting potential (-79.1 +/- 1.2 mV) was found to be very nearly the same as the K+ reversal potential and approximately 20 mV more negative than that of the neurons they encapsulated. Unitary currents from ionic channels present in the glial membrane were recorded in the cell-attached configuration with pipettes filled with various amounts of K+, Na+ and gluconate. Only K(+)-selective channels with slight inwardly rectifying properties (in the presence of 150 mM [K+]o) were detected. These channels were active (Po = 0.7-0.8) at the cell resting potential. The channel conductance, but not its opening probability, was dependent on the [K+] in the pipette. Cl(-)-selective channels (outwardly rectifying and large conductance channels) were detected in excised patches. The properties of the K+ channels (increased inward current with [K+] and detectable outward current at low [K+]) are well suited for siphoning the K+ released by active neurons.

[A rare psychogenic anejaculation. Report of a case of prolactin adenoma]

The authors report a case of prolactinoma discovered during assessment of a case of ejaculation failure attributed for more than eight years to a psychogenic cause. Because of the size of the tumour, surgical resection of the lesion left a persistent hyperprolactinaemia, which only returned to normal after treatment with bromocriptine. The persistence of sexual disorders justified adjuvant treatment with exogenous testosterone. Despite the unusual mode of presentation of hyperprolactinaemia, these data correspond to those reported in the literature. Prolactin assay should therefore be performed in any case of male sexual dysfunction to allow the early diagnosis of prolactinoma and to improve the functional prognosis.

Kaliotoxin, a novel peptidyl inhibitor of neuronal BK-type Ca(2+)-activated K+ channels characterized from Androctonus mauretanicus mauretanicus venom

A peptidyl inhibitor of the high conductance Ca(2+)-activated K+ channels (KCa) has been purified to homogeneity from the venom of the scorpion Androctonus mauretanicus mauretanicus. The peptide has been named kaliotoxin (KTX). It is a single 4-kDa polypeptide chain. Its complete amino acid sequence has been determined. KTX displays sequence homology with other scorpion-derived inhibitors of Ca(2+)-activated or voltage-gated K+ channels: 44% homology with charybdotoxin (CTX), 52% with noxiustoxin (NTX), and 44% with iberiotoxin (IbTX). Electrophysiological experiments performed in identified nerve cells from the mollusc Helix pomatia showed that KTX specifically suppressed the whole cell Ca(2+)-activated K+ current. KTX had no detectable effects on voltage-gated K+ current (delayed rectifier and fast transient A current) or on L-type Ca2+ currents. KTX interacts in a one-to-one way with KCa channels with a Kd of 20 nM. Single channel experiments were performed on high conductance KCa channels excised from the above Helix neurons and from rabbit coeliac ganglia sympathetic neurons. KTX acted exclusively at the outer face of the channel. KTX applied on excised outside-out KCa channels induced a transient period of fast-flicker block followed by a persistent channel blockade. The KTX-induced block was not voltage-dependent which suggests differences in the blockade of KCa channels by KTX and by CTX. Comparison of KTX and CTX sequences leads to the identification of a short amino acid sequence (26-33) which may be implicated in the toxin-channel interaction. KTX therefore appears to be a useful tool for elucidating the molecular pharmacology of the high conductance Ca(2+)-activated K+ channel.

[Hand-Schüller-Christian disease with tumor localization in the posterior fossa]

A 19-year-old girl had been suffering since the age of 4 from Hand-Schüller-Christian disease. The condition was diagnosed by biopsy of a cranial bone lacuna. Later on, she developed diabetes insipidus and bilateral exophthalmos, both being typical signs of Hand-Schüller-Christian disease. At the age of 14, an intracranial tumour in the posterior cerebral fossa was discovered by computerized tomography, but in view of her parent's refusal of surgery, she was operated upon only 4 years later for obstructive hydrocephalus with intracranial hypertension. Two years after this operation, she presented with neurological signs of compression of the medulla oblongata, including tetraparesis and respiratory disorders, and the tumour was resected. Following a brief improvement she died of major hydroelectrolytic disorders due to her irreducible unstable diabetes insipidus. A review of the literature on Hand-Schüller-Christian disease and its rare association with intracranial tumours is analysed. The occurrence of such tumours raise important therapeutic problems and make the prognosis considerably worse.

Degenerative spondylolisthesis, synovial cyst of the zygapophyseal joints, and sciatic syndrome: report of two cases and review of the literature

Two cases of sciatica secondary to nerve root compression by a "synovial cyst" of a zygapophyseal joint are described. In light of these 2 cases and on reviewing the literature, it appears that zygapophyseal joint osteoarthritis with degenerative (or articular) spondylolisthesis can be a predisposing factor to the formation of such synovial expansions and, consequently, the cause of nerve root compression. The coexistence of a lumbar degenerative spondylolisthesis with a radicular syndrome should therefore encourage early investigation by computed tomography scan, so that conservative treatment would not be unnecessarily prolonged.

Lipoma in the cerebellopontine angle

A case of lipoma in the cerebellopontine angle is reported. Intracranial lipomas are very rare, especially in the cerebellopontine angle. To our knowledge, only four cases, including our own, have been operated upon. Until now, total extirpation has not been possible. The singular appearance on computed tomography scanning of this dysembryoplasia is presented together with a bibliography of this subject.

[Intracranial septic aneurysm in an infant. Apropos of a case and review of the literature]

This case report describes a four and a half month old infant with all meningitis symptoms and a sub arachnoidal hemorrhage at the lumbar puncture. Transfontanelle - ultrasonography and computed tomography enables us to diagnose a right intra-cerebral hematoma. Angiography visualises a mycotic aneurysm in a distal portion of the sylvian artery. A success is obtained both by neuro surgery and antibiotics treatment. Regarding this case of intra cranial septic aneurysm and the ones reviewed in the literature, aetiology, frequency, clinical features and management are discussed by the authors.

[Paraplegia with a cauda equina syndrome due to stenosis of the spinal canal caused by tabes arthropathy]

The authors present a case of cauda equina paraparesis due to compression by tabetic osteo-arthropathy. Diagnosis was confirmed by the typical clinical picture of tabes and by the history of a chancre 53 years earlier. Radiography of the spine showed vertibral osteo-arthropathy. Opaque contrast myelography showed compression at the D 11/D 12 and L 4/L 5 levels, with poor contrast filling athe the L 1/L 3 level. Surgical treatment by decompressive laminectomies from D 12 to L 4 led to a satisfactory result with motor recovery and regression of the cauda equina syndrome.

[Metastases of the cervico-occipital junction. The value of tomographic detection of prefracture forms (author's transl)]

The authors stress the frequency of metastases of the cervico-occipital junction unrecognized in medical literature: 30 cases have been diagnosed within four months. They report their different patterns and complications and insist on the prefractured pattern with osteolysis of the body of C-2 which can be shown only by polytomography. The authors propose that a tomographic study of the cervico-occipital junction should be systematically included in every analysis of metastatic extension of osteophilic tumors.

[Intrasellar epidermoid cyst (author's transl)]

The authors present a case of epidermoid cyst in an unusual (intrasellar) situation and with untypical symptomatology (endocrine disorder without ophthalmological manifestations). The treatment was essentially surgical, and the patient's progress has been satisfactory.

[Large partially thrombosed pseudo-tumoral aneurysm of the aqueductal area]

Authors are reporting a case of a giant sylvian aneurism partially thrombosed which had given some tumor like symptoms. The Peumography performed, just before an angiography showed the exact size and the malformation's relations with the lateral ventricle. During the operation, the complete removal of the aneurismatic mass had been done. The follow up was good.