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Biomedical subjects

B Vallee

Publications and source records attributed to B Vallee.

At least 19 recordsLinked to original sources
PubMed2006

Vestibular integration in human cerebral cortex contributes to spatial remapping.

The process of visuo-spatial updating is crucial in guiding human behaviour. While the parietal cortex has long been considered a principal candidate for performing spatial transformations, the exact underlying mechanisms are still unclear. In this study, we investigated in a patient with a right occipito-parietal lesion the ability to update the visual space during vestibularly guided saccades. To quantify the possible deficits in visual and vestibular memory processes, we studied the subject's performance in two separate memory tasks, visual (VIS) and vestibular (VES). In the VIS task, a saccade was elicited from a central fixation point to the location of a visual memorized target and in the VEST task, the saccade was elicited after whole-body rotation to the starting position thus compensating for the rotation. Finally, in an updating task (UPD), the subject had to memorize the position of a visual target then after a whole-body rotation he had to produce a saccade to the remembered visual target location in space. Our main findings was a significant hypometria in the final eye position of both VEST and UPD saccades induced during rotation to the left (contralesional) hemispace as compared to saccades induced after right (ipsilesional) rotation. Moreover, these deficits in vestibularly guided saccades correlated with deficits in vestibulo-ocular time constant, reflecting disorders in the inertial vestibular integration path. We conclude that the occipito-parietal cortex in man can provide a first stage in visuo-spatial remapping by encoding inertial head position signals during gaze orientation.

Adult↗
PubMed2005

[Correlation between cranial vault size and brain size over time: preliminary MRI evaluation].

OBJECTIVES: To correlate changes of cranial vault measurements of an adult population during the aging process with brain size using the maximum width of the third ventricle in the axial AC-PC plane. MATERIALS AND METHODS: Prospective study of 126 adult subjects (range: 20 to 80 years) with normal brain MRI and without history of neuropsychiatric disorder. MEASUREMENTS INCLUDED: Cranial vault (Maximum length: Glabella-Opisthocranion, Maximum width: euryon-euryon, and maximum height: Basion-Vertex) measurements and maximum width of the third ventricle in the A C-PC plane. RESULTS: Vault measurements (length, width, high) were similar for every age group, irrespective of gender. The variability of cranial vault measurements between individuals was low (<1 cm). Cranial vault measurements were larger for men, but this was not significant when adjusted for body height Comparatively, a gradual widening of the third ventricle, with an exponential behavior, was observed with advancing age. CONCLUSION: Our results indicate that cranial vault measurements are stable over time (between 20-80 years) comparatively to brain atrophy with advancing age. The low variability of cranial vault measurements and their stability over time should be taken into account during segmentation and normalization of brain parenchymal structures.

Adult↗
PubMed1997

Class 2 aldehyde dehydrogenase. Characterization of the hamster enzyme, sensitive to daidzin and conserved within the family of multiple forms.

Mitochondrial (class 2) hamster aldehyde dehydrogenase has been purified and characterized. Its primary structure has been determined and correlated with the tertiary structure recently established for this class from another species. The protein is found to represent a constant class within a complex family of multiple forms. Variable segments that occur in different species correlate with non-functional segments, in the same manner as in the case of the constant class of alcohol dehydrogenases (class III type) of another protein family, but distinct from the pattern of the corresponding variable enzymes. Hence, in both these protein families, overall variability and segment architectures behave similarly, with at least one 'constant' form in each case, class III in the case of alcohol dehydrogenases, and at least class 2 in the case of aldehyde dehydrogenases.

Aldehyde Dehydrogenase↗
PubMed1994

[Treatment of chronic lumbago and radicular pain by spinal cord stimulation. Long-term results].

Seventy-seven patients with chronic, refractory, low back and radicular pain underwent implantation of a spinal cord stimulator between 1984 and 1992. Most patients had failed back surgery syndrome. In every case, an epidural quadripolar "Resume" electrode was implanted surgically. Results were evaluated after three months then after six to 98 months (mean follow-up 42 months). Long-term efficacy was good in 63.6% of cases, fair in 22%, and poor in 6.5%; treatment failure occurred in 7.9% of cases. Adverse events included one case of meningitis, two cases of local infection, and one case each of cerebrospinal fluid fistula and necrosis of the skin overlying the stimulator. The main causes of treatment failure were complications, inappropriate patient selection, and the escape phenomenon. The results of this study demonstrate that spinal cord stimulation is effective for the treatment of chronic low back and radicular pain in carefully selected patients; scrupulous application of restrictive selection criteria is essential to the success of the method.

Adult↗
PubMed1990

Fast atom bombardment mass spectrometry and chemical analysis in determinations of acyl-blocked protein structures.

Peptide generation and fast atom bombardment mass spectrometry in combination with conventional chemical analysis was used to identify the blocking group and establish the N-terminal structure of six different proteins at the nanomole level. In this manner, the first terminal structures of three non-mammalian alcohol dehydrogenases were determined, demonstrating the presence of N-terminal acetylation in these piscine, amphibian, and avian enzymes. Similarly, two different yeast glucose-6-phosphate dehydrogenases and a minor variant of a human alcohol dehydrogenase were found to be acetylated. The exact end location of C-terminal structures was also established. Together, the analyses permit the definition of terminal regions and blocking groups, thus facilitating the delineation of remaining structures.

Acetylation↗
PubMed1989

[Confluent tuberculomas of the vermis cerebelli associated with an occipital localization. Report of a case and review of the literature].

An unusual case of multiple cerebral tuberculomas is reported. The patient, a 19-year-old woman, presented with a 6-month history of raised intracranial pressure and cerebellar symptoms. CT scan disclosed a conglomerate of several ring-enhancing lesions within the cerebellar vermis and another homogeneously enhancing mass against the right occipital horn. Solid and ring-enhancing lesions are the main mode of presentation of cerebral tuberculomas. Although the patient had no history of systemic tuberculosis, this diagnosis was considered highly probable in this geographic area and was confirmed by pathological examination of the cerebellar mass, the excision of which was considered necessary. Antitubercular medications led to complete regression of the associated occipital lesion, as demonstrated by sequential CT scan examinations.

Adult↗
PubMed1987

Structures of human alcohol and aldehyde dehydrogenases.

Human alcohol dehydrogenase is a dimeric zinc metalloenzyme for which forms of three classes, I, II and III, have been distinguished. Subunits hybridize within but not between classes. There are three types of subunit, alpha, beta, and gamma, in class I. The primary structures of all three forms have been established, as well as the overall properties and the effects of the amino acid substitutions between the various forms. Each subunit has 374 residues, of which 35 exhibit differences among the alpha, beta and gamma chains. Corresponding cDNA structures are also known, as are the genetic organization and details of the gene structures. Allelic variants occur at the beta and gamma loci. Corresponding amino acid substitutions have been characterized, and enzymatic differences between the allelic forms are explained by defined residue exchanges. The results also illustrate recent and repeated isozyme evolution, a subject where alcohol dehydrogenases exceptionally well offer detailed examples. Human aldehyde dehydrogenase occurs of two types, a mitochondrial and a cytosolic form. The enzymes are tetramers, do not contain functional metals, and have subunits which do not form inter-type hybrids. The primary structures have been determined, revealing a positional identity of 68% (in 500 residues) between the mitochondrial and cytosolic forms. The N-terminus is heterogeneous and is not blocked in the subunit of the mitochondrial enzyme, in contrast to that of the cytosolic enzyme or those of all the alcohol dehydrogenases (also cytosolic). A reactive cysteine residue at position 302 has been ascribed functional importance at or close to the active site, is conserved in the two aldehyde dehydrogenases, and is associated with the action of disulfiram on the enzyme. In Oriental populations, a mutant allelic variant of the mitochondrial protein with impaired enzyme function has also been characterized.

Alcohol Dehydrogenase↗
PubMed1985

The lateral spinal artery of the upper cervical spinal cord. Anatomy, normal variations, and angiographic aspects.

The lateral spinal artery corresponds to the most rostral extent of the posterolateral arterial axis of the spinal cord. It supplies the posterior and lateral aspects of the spinal cord, and courses anterior to the posterior roots of the upper cervical spinal nerves (C-1 to C-4), and posterior to the dentate ligament. The lateral spinal artery anastomoses rostrally with the branches of the posterior inferior cerebellar artery (PICA) at the restiform body and laterally with the extraspinal arteries at the emergence of each nerve. It may originate either from the vertebral artery or from the PICA lateral to the medulla. Certain variations will cause an unusual but normal enlargement of the vessel in a specific portion of its course; these variations include vertebral artery duplication, a C-1 or C-2 vertebral origin of the PICA, a C-1 or C-2 occipital origin of the PICA, and an intradural course of the vertebral artery at C-2. Knowledge of these variations in the arterial supply to the area allows for an understanding of the different anatomic peculiarities present and their angiographic importance.

Angiography↗
PubMed1984

Human liver alcohol dehydrogenase. 1. The primary structure of the beta 1 beta 1 isoenzyme.

Determination of the amino acid sequence of the beta 1 subunit from the class I (pyrazole-sensitive) human liver alcohol dehydrogenase isoenzyme beta 1 beta 1 revealed a 373-residue structure differing at 48 positions (including a gap) from that of the subunit of the well studied horse liver alcohol dehydrogenase EE isoenzyme. The structure deduced is compatible with known differences in composition, ultraviolet absorbance, electrophoretic mobility and catalytic properties between the horse and human enzymes. All zinc-liganding residues of the horse E subunit are strictly conserved in the human beta 1 subunit, despite an earlier report of a mutation involving Cys-46. This residue therefore remains conserved in all known alcohol dehydrogenase structures. However, the total cysteine content of the beta 1 structure is raised from 14 in the subunit of the horse enzyme to 15 by a Tyr----Cys exchange. Most exchanges are on the surface of the molecule and of a well conserved nature. Substitutions close to the catalytic centre are of interest to explain the altered substrate specificity and different catalytic activity of the beta 1 homodimer. Functionally, a Ser----Thr exchange at position 48 appears to be of special importance, since Thr-48 in beta 1 instead of Ser-48 in the horse enzyme can restrict available space. Four other substitutions also line the active-site pocket, and appear to constitute partly compensated exchanges.

Alcohol Dehydrogenase↗
PubMed1984

Delayed cerebral pseudo-tumoral radionecrosis following scalp-tumour irradiation. Case report and review of literature.

A case of delayed radionecrosis of the brain is reported, following irradiation of a scalp dermatofibrosarcoma. Signs and symptoms were those of an intracranial neoplasm and appeared 5 years after an irradiation dosage of 1890 rets. Twenty-seven similar cases were gathered from a survey of the literature. Surgical excision was the treatment of choice and led to cure or improvement in 20 cases. Analysis of doses and fractionation revealed excessive irradiation in all but one of the cases.

Adult↗
PubMed1983

Salmonella-infected subdural haematoma.

Post-traumatic chronic subdural haematoma infected by Salmonella sandiego is reported in a 55-year-old alcoholic man. Treatment involved a four-weeks' course of chloramphenicol and also subdural drainage. The patient ultimately recovered. Only four such cases have been reported in the literature. The mode of infection of the subdural haematoma is presumed to have been haematogenous in the absence of an otorhinological focus, meningitis or previous neurosurgery.

Chloramphenicol↗
PubMed1983

[Anatomical basis for the surgical use of the cephalic vein (V. Cephalica). 74 anatomical dissections. 189 surgical dissections].

The delto-pectoral portion of V. Cephalica was dissected 189 times during surgery and 74 times on cadavers. In 8 out of 10 cases the disposition was of the classical type and the diameter was wide enough to allow catheterization with a 3,4 mm catheter. In 2 out of 10 cases the vein was absent or toothin. This anomaly was most often unilateral with a normal disposition on the other side in 2/3 of cases.

Arm↗
PubMed1982

Persisting recessus infundibuli and empty sella. Case report.

In a patient with thrombosis of the central retinal artery, plain skull radiographs showed an enlarged sella turcica and computerized tomography revealed ventricular dilatation. Neuroradiological examination demonstrated stenosis of the Sylvian aqueduct and an unusual type of empty sella due to intrasellar persistence of the recessus infundibuli and the presence of an intrasellar arachnoidocele. The former anomaly has been reported in only three cases; in none of them was it associated with the latter abnormality.

Arachnoid↗
PubMed1982

[The muscular atrioventricular septum].

On the left ventricle septal wall, the tricuspid valve ring attachment is displaced forward, towards the cardiac apex. To this trapezoïdal area between the two atrio-ventricular annuli, the medial wall of the right atrium is attached (laminar attachment), resulting in a atrio-ventricular septum which is: --membranous at its superior extremity (membranous atrio-ventricular septum well described in all classical anatomy textbooks); --and muscular at its inferior extremity. Located in the inferior anterior portion of the Koch triangle, the muscular atrio-ventricular septum is roughly triangular in shape. Its superior and anterior borders are well delineated and represented by: --the pars muscularis crest, at its junction with the membranous atrio-ventricular septum; --and the insertion of the tricuspid septal leaflet on this pars muscularis of the inter-ventricular septum. On the contrary, its third border, the posterior inferior left, is not well defined and varies greatly with the amount of fat filling the crux of the heart. The atrio-ventricular septum separates the right atrium from the base of the left ventricle outflow tract. It shares the important relationship of the "carrefour" of the four cardiac chambers (7 - 8) and first of all the conduction system and its vascular supply. The concept of an atrio-ventricular septum, both muscular and membranous, is to be kept in mind for the good understanding and the surgical correction of different types of "common atrio-ventricular canal" (2 - 10).

Heart Septum↗
PubMed1980

[Lateral interscalenic approach for tumors of the cervical intervertebral foramina (author's transl)].

The authors report six cases of tumours limited to the cervical inter-vertebral foramen. The patients presented with cervico-brachial neuralgias occasionally accompanied by radicular sensitivo-motor impairment. Radiographs and tomographs of the cervical spine demonstrated enlargement of the intervertebral foramen with bone proliferation depending on the etiology and provided in easy diagnosis in all the cases. A myelogram showed the absence of extension into the spinal canal thus allowing distinction from the group of dumbell tumors. In the six cases vertebral angiography gave information regarding the vascularisation and relationships of the tumour. The histological diagnosis was different in each case : neurofibroma, chordoma, osteochondroma, osteoma, osteoblastoma and an aneurysmal bone cyst. The same surgical approach was used in the six cases. Neither a laminectomy with facettectomy, nor a classical antero-lateral approach allow for a satisfactory exposition of the tumor. On the contrary a lateral interscalenic approach including dissection of the brachial plexus lead to a trouble free excision. This approach was precised by anatomical dissections.

Adolescent↗