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Biomedical subjects

B Vallée

Publications and source records attributed to B Vallée.

At least 19 recordsLinked to original sources
PubMed2001

Lag1p and Lac1p are essential for the Acyl-CoA-dependent ceramide synthase reaction in Saccharomyces cerevisae.

Lag1p and Lac1p are two homologous transmembrane proteins of the endoplasmic reticulum in Saccharomyces cerevisiae. Homologous genes have been found in a wide variety of eukaryotes. In yeast, both genes, LAC1 and LAG1, are required for efficient endoplasmic reticulum-to-Golgi transport of glycosylphosphatidylinositol-anchored proteins. In this study, we show that lag1 Delta lac1 Delta cells have reduced sphingolipid levels due to a block of the fumonisin B1-sensitive and acyl-CoA-dependent ceramide synthase reaction. The sphingolipid synthesis defect in lag1 Delta lac1 Delta cells can be partially corrected by overexpression of YPC1 or YDC1, encoding ceramidases that have been reported to have acyl-CoA-independent ceramide synthesis activity. Quadruple mutant cells (lag1 Delta lac1 Delta ypc1 Delta ydc1 Delta) do not make any sphingolipids, but are still viable probably because they produce novel lipids. Moreover, lag1 Delta lac1 Delta cells are resistant to aureobasidin A, an inhibitor of the inositolphosphorylceramide synthase, suggesting that aureobasidin A may be toxic because it leads to increased ceramide levels. Based on these data, LAG1 and LAC1 are the first genes to be identified that are required for the fumonisin B1-sensitive and acyl-CoA-dependent ceramide synthase reaction.

Acyl Coenzyme A↗
PubMed2000

Sexual dimorphism of pancreatic gene expression in normal mice.

A differential pancreatic behavior observed between male and female mice in diabetes and pancreatitis led us to study the gene and protein expressions of endocrine and exocrine pancreatic proteins in normal mice. We compared the levels of expression of six pancreatic genes and of four of the corresponding proteins in male and female mice OF1. Amylase gene expression was found to be significantly higher in females than in males, whereas trypsinogen and lipase gene expression were significantly lower. For chymotrypsinogen, reg, and insulin the differences were not significant. This sexual dimorphism did not exist in rat pancreas, where no gender difference was observed. After characterization of mice enzymes by sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and antibodies directed to the closely related human pancreatic enzymes, we have compared the levels of these proteins in mice pancreatic homogenates. No significant difference was observed between males and females at the level of protein expression. These data suggest a hormonal sexual difference in the regulation of pancreatic protein synthesis at the pre- and posttranscriptional levels in normal mice, which may play a role in the development of mice pancreatic diseases.

Amylases↗
PubMed1999

The left retro-aortic brachiocephalic vein: morphologic data and diagnostic ultrasound in 27 cases.

A left retro-aortic brachiocephalic vein is a rare anatomic entity. A retrospective study was made of 5218 congenital cardiopathies treated between 1982 and 1998 in a medico-surgical department of paediatric cardiology. A left retro-aortic brachiocephalic vein was demonstrated in 27 patients, i.e. an incidence of 0.5%. The chief cardiopathy in these patients was a tetralogy of Fallot in 25 cases (93%). Among these 25 cases of Fallot's tetralogy the aortic arch was rightsided in 19 cases (70%). The paraclinical diagnosis of this anomaly was facilitated by ultrasonography, provided it was sought for. In this series 6 cases (22%) were discovered during surgery without previous ultrasound diagnosis. The embryological origin of the left retro-aortic brachiocephalic v. differs from that of the venous trunk in its classical anatomic form. It derives from the inferior (but not superior) transverse plexuses, connecting the two anterior cardinal veins. One of the main consequences of this anomaly is its possible confusion with other vascular structures, particularly the right pulmonary artery. Such confusion may give rise to inappropriate surgical procedures. The differential diagnosis is facilitated by the use of the Doppler: the venous flow is biphasic and regulated by respiration, whereas the Doppler recording from a pulmonary artery is that of a characteristic systolic arterial flow.

Adolescent↗
PubMed1999

Anatomic basis of vascularised nerve grafts: the blood supply of peripheral nerves.

The present study was carried out on 30 cadavers (5 fresh, 20 preserved adult and 5 fresh stillborn) following injection of red latex through the subclavian and common iliac arteries. The blood supply to the peripheral nerves was studied in general, together with the vascular pedicles to the ulnar, saphenous, sural, deep and superficial peroneal nerves, and the superficial branch of the radial nerve. The nutrient arteries supplying the peripheral nerves came from either the adjacent axial artery or the fasciocutaneous or muscular arteries. They formed anastomotic channels in the epineurium and penetrated it to form a continuous longitudinal artery. Based on the presence of absence of dominant arterial pedicles, five patterns of blood-supply to the nerves could be identified. I: no dominant arterial pedicle; II: only one dominant artery (e.g. artery with a diameter more than 0.8 mm and accompanying the nerve for most of its length); III: only one dominant vessel that divided into ascending and descending branches to supply the nerve; IV: multiple dominant pedicles; V: multiple dominant arterial pedicles forming a continuous artery that accompanied the nerve. The arterial pedicles to the ulnar, saphenous and deep peroneal nerves and the superficial branch of the radial n. had mean diameters of over 0.8 mm, thus being suitable for microvascular anastomosis. Those to the sural nerve were not present in two thirds of the dissected cadavers. In 10% of the cadavers the superficial peroneal nerve had an arterial pedicle that accompanied the nerve for less than two cm with a mean diameter less than 0.8 mm. The ulnar nerve could be very suitable as a donor vascularized nerve graft as it had a dominant vascular pedicle in all the cases studied; however, its use should be restricted to C8 and T1 root damage of the brachial plexus. The superficial branch of the radial n. might be suitable for vascularized nerve grafting, but this is difficult in practice since the radial artery is a major limb artery. The saphenous nerve had a dominant arterial pedicles in all the cadavers dissected and could be the most suitable as a donor vascularized nerve graft, unlike the sural nerve which did not have a dominant arterial pedicle in two-thirds of the specimens. The deep and superficial peroneal nerves may also be unsuitable since the former is accompanied by a major limb vessel while the latter had a dominant vascular pedicle that accompanied the nerve for only a short distance in 10% of the dissected cadavers.

Aged↗
PubMed1999

Ventral transdural herniation of the thoracic spinal cord: surgical treatment in four cases and review of literature.

BACKGROUND: A specific cause of progressive Brown-Sequard syndrome has been identified: a ventral herniation of the thoracic spinal cord through the dural sleeve on one side. METHOD: Four female patients who were affected by a progressive Brown Sequard syndrome related to a transdural spinal cord herniation have been investigated and were submitted to surgery and postoperative evaluation. FINDINGS: The MRI scan showed atrophy and forward displacement of the spinal cord on one side and adhesion of the spinal cord to the dura mater. CT myelography demonstrated the disappearance of the premedullar rim at the level of the herniation and the shadow of the extradural herniation. Surgical treatment consisted in the excision of the arachnoid cyst when there was one, section of the dentate ligament, release of the adhesions, detachment of the spinal cord from the hernial orifice, and lastly suture of the dural tear or placement by a patch. Follow-up examination showed motor improvement with persistent sensory deficit in two cases and stabilisation in two cases. INTERPRETATION: The cause of the dural tear, either traumatic or congenital could not be confirmed in the four cases. Symptoms probably occur when herniation fills the orifice and strangulation happens which explains the late appearance and progressive evolution of this myelopathy. Mobilisation of the herniated spinal cord back into the intradural space can be achieved by surgery and may stop the evolution of the symptoms and signs.

Adult↗
PubMed1999

Stability and physicochemical properties of the bovine brain phosphatidylethanolamine-binding protein.

The equilibrium behaviour of the bovine phosphatidylethanolamine-binding protein (PEBP) has been studied under various conditions of pH, temperature and urea concentration. Far-UV and near-UV CD, fluorescence and Fourier transform infrared spectroscopies indicate that, in its native state, PEBP is mainly composed of beta-sheets, with Trp residues mostly localized in a hydrophobic environment; these results suggest that the conformation of PEBP in solution is similar to the three-dimensional structure determined by X-ray crystallography. The pH-induced conformational changes show a transition midpoint at pH 3.0, implying nine protons in the transition. At neutral pH, the thermal denaturation is irreversible due to protein precipitation, whereas at acidic pH values the protein exhibits a reversible denaturation. The thermal denaturation curves, as monitored by CD, fluorescence and differential scanning calorimetry, support a two-state model for the equilibrium and display coincident values with a melting temperature Tm = 54 degrees C, an enthalpy change DeltaH = 119 kcal.mol-1 and a free energy change DeltaG(H2O, 25 degrees C) = 5 kcal.mol-1. The urea-induced unfolding profiles of PEBP show a midpoint of the two-state unfolding transition at 4.8 M denaturant, and the stability of PEBP is 4.5 kcal.mol-1 at 25 degrees C. Moreover, the surface active properties indicate that PEBP is essentially a hydrophilic protein which progressively unfolds at the air/water interface over the course of time. Together, these results suggest that PEBP is well-structured in solution but that its conformation is weakly stable and sensitive to hydrophobic conditions: the PEBP structure seems to be flexible and adaptable to its environment.

Air↗
PubMed1999

[Intracranial cavernoma. Surgical results of 47 cases].

We report the surgical results in a series of 47 patients with cerebral cavernous malformation who had undergone surgery between 1973 and 1994, with a follow up ranging from 12 months to 24 years (mean: 4 years). They were divided in there groups according to their initial clinical presentation: epilepsy (31 cases), hemorrhage (11 cases) and neurological deficit (5 cases). Surgery consisted of cavernoma resection only (11 cases) or its extension to surrounding gliotic tissue (36 cases). Results are satisfactory: no surgical mortality, low morbidity (4 cases), no recurrent hemorrhage, seizures disappearance with anticonvulsant therapy stop (4 cases) or alleviation (20 cases). Only one patient died far from surgery (6 months) consequently to his initial bleeding, while all the others lead a normal active life. The therapeutic management, compared to the literature, pleads in favour of intentionally surgical attitude and gliotic tissue removal as often as reasonably possible.

Adolescent↗
PubMed1999

[Epidermoid cyst of the lateral ventricles].

A case of epidermoid cyst of the lateral ventricles is reported. The patient presented with a weakness of the left lower limb and neuropsychological disorders. The diagnosis was assessed by CT scan and MRI, and confirmed at the operation. The lesion has been largely removed through a transcallosal approach though incompletely. However the long term follow-up was uneventful. Twenty-nine cases of the literature have been reviewed.

Adult↗
PubMed1998

Crystal structure of the phosphatidylethanolamine-binding protein from bovine brain: a novel structural class of phospholipid-binding proteins.

BACKGROUND: Phosphatidylethanolamine-binding protein (PEBP) is a basic protein found in numerous tissues from a wide range of species. The screening of gene and protein data banks defines a family of PEBP-related proteins that are present in a variety of organisms, including Drosophila and inferior eukaryotes. PEBP binds to phosphatidylethanolamine and nucleotides in vitro, but its biological function in vivo is not yet known. The expression of PEBP and related proteins seems to be correlated with development and cell morphogenesis, however. To obtain new insights into the PEBP family and its potential functions, we initiated a crystallographic study of bovine brain PEPB. RESULTS: The X-ray crystal structure of bovine brain PEBP has been solved using multiple isomorphous replacement methods, and refined to 1.84 A resolution. The structure displays a beta fold and exhibits one nonprolyl cis peptide bond. Analysis of cavities within the structure and sequence alignments were used to identify a putative ligand-binding site. This binding site is defined by residues of the C-terminal helix and the residues His85, Asp69, Gly109 and Tyr119. This site also corresponds to the binding site of phosphorylethanolamine, the polar head group of phosphatidylethanolamine. CONCLUSIONS: This study shows that PEBP is not related to the G-protein family nor to known lipid-binding proteins, and therefore defines a novel structural family of phospholipid-binding proteins. The PEBP structure contains no internal hydrophobic pocket, as described for lipocalins or small phospholipid-transfer proteins. Nevertheless, in PEBP, a small cavity close to the protein surface has a high affinity for anions, such as phosphate and acetate, and also phosphorylethanolamine. We suggest that this cavity corresponds to the binding site of the polar head group of phosphatidylethanolamine.

Amino Acid Sequence↗
PubMed1998

Arterial and neural relations at the posterior and lateral aspects of the medullo-spinal junction.

The authors report the results of a series of 59 microdissections of the region of the foramen magnum. These dissections were made under the strict conditions of a surgical approach using an operating microscope. The major anatomic structures of the medullo-spinal junction are arranged mainly at its lateral aspect. The customary surgical approaches to the posterior cranial fossa give ready access to the cerebello- and latero-medullary cisterns. The description of the neurovascular structures contained therein assumes a particular importance because of the relative frequency of lesions developing at this level. This study deals particularly with the vertebral a. (VA), the inferior posterior cerebellar a. (IPCA), the cranial nn. IX (glossopharyngeal n.), X (vagus n.), XIc and XIs (cranial and spinal accessory n.) and XII (hypoglossal n.). The anatomy of this posterior and lateral region is characterised by the contrast between the relatively uniform course of the VA and the variable course of the IPCA, a true guideline whose very irregular arrangement accounts for the diversity of its relations with the last four cranial nn.

Cadaver↗
PubMed1998

[Subarachnoid hemorrhage syndrome and its aneurysmal etiology. From Morgagni to Moniz, Dott and Dandy. A historical overview].

Although obvious today, the concept of subarachnoid hemorrhage due to ruptured intracranial aneurysms emerged slowly in medical knowledge with the clinical and pathological observations of many perspicacious authors beginning with Morgagni in the middle of the eighteenth century. This body of clinical material made it possible for Symonds in 1924 to affirm this concept on clinical and pathological grounds just a few years before Egas Moniz performed the first cerebral angiograms and such pioneers as Norman Dott and Walter Dandy the first direct attacks on cerebral aneurysms.

Aneurysm, Ruptured↗
PubMed1997

[Focalized multiple beam radiotherapy: an alternative in the treatment of deep cerebral arteriovenous malformations].

BACKGROUND: Cerebral arteriovenous malformations are usually treated by excision or selective embolization. Some untreatable malformations may be presently cured by radiosurgery. CASE REPORT: A 10-year-old girl without previous illness suffered from a sudden quadriventricular hemorrhage due to arteriovenous malformation. Initially the child recovered with symptomatic treatment. Neurosurgery and arterial embolization being impossible, Gamma-Unit treatment was performed. Treatment was first well tolerated but 8 months later, left hemiparesis and language disorders occurred, due to radionecrosis. These complications were dramatically improved by corticosteroids. CONCLUSION: Gamma-Unit treatment can be successfully proposed for treating those malformations that are inaccessible to surgery or embolization.

Anti-Inflammatory Agents↗
PubMed1997

[Benign glial cysts of the pineal region].

A review of the pertinent literature regarding glial cysts of the pineal region is presented. Various pathogenic factors have been advocated such as the physiological involution of the pineal gland, a sequestration of the embryonic cavum pineale or the degenerative evolution of glial inclusions within the pineal gland. The pathological description is classical with three layers: an external fibrous capsule, an intermediate layer of pineal tissue and an internal glial wall. Imaging of these lesions is typical, namely the thin rim of peripheral contrast enhancement and the presence of calcifications. These cysts are more frequent in women in their third decade of life. They are almost always latent and their fortuitous disclosure at NMR examinations is common. Some of them will nevertheless cause intracranial hypertension due to hydrocephalus and hemorrhage. Those symptomatic cysts should be treated. Surgical excision has been the method of choice and the results are good. More recently a mere stereotactic needle aspiration has been performed with satisfactory long-term results.

Adult↗
PubMed1997

[Benign hemorrhagic cyst of the pineal region. Treatment by stereotactic puncture. 4-year follow-up].

We report the case of a 27 year-old male patient in whom acute intracranial hypertension led to the diagnosis of a pineal hemorrhagic cyst as demonstrated by CT-scan and MRI examinations. Treatment consisted in stereotactic needle-aspiration following insertion of a ventriculo-peritoneal shunt. Pathological examination confirmed a benign glial lesion. The outcome was good as complete shrinkage of the cyst and complete relief of the signs and symptoms were achieved. These clinical and radiological results persisted over four years. Approximately 70 cases of symptomatic benign pineal cysts have been reported to-date. Surgical excision has been the method of choice. The present case and twelve other cases of stereotactic management of the condition in the literature suggest the interest of a mere stereotactic needle aspiration of these lesions.

Adult↗
PubMed1994

The "anatomic" view of the suprarenals in medical imaging.

Based on coordinates derived from three series of anatomic sections, the authors propose a view for tomographic investigation, applicable in MRI and ultrasound, which reconstructs the ideal image of the suprarenal gland in its quadrilateral as described by Testut. This "anatomic" view is 45 degrees vertical and oblique, intermediate between the sagittal and frontal views, which it can advantageously replace. A new aspect of suprarenal tomography, recalling the image of a triskele, is described in the context of this view.

Adrenal Glands↗