Search PubMed⌕ Search

Biomedical subjects

B Laurent

Publications and source records attributed to B Laurent.

At least 91 records · Page 5Linked to original sources
PubMed1993

Long-term and high-dose piracetam treatment of Alzheimer's disease.

Preclinical research suggests that piracetam (a nootropic drug) may improve cognitive functions, but previous studies have failed to demonstrate a clear benefit for the treatment of Alzheimer's disease (AD). We report a 1-year, double-blind, placebo-controlled, parallel-group study with a high dose of piracetam (8 g/d per os) in 33 ambulant patients with early probable AD. Thirty subjects completed the 1-year study. No improvement occurred in either group, but our results support the hypothesis that long-term administration of high doses of piracetam might slow the progression of cognitive deterioration in patients with AD. The most significant differences concerned the recall of pictures series and recent incident and remote memory. The drug was well-tolerated.

Aged↗
PubMed1992

Ligand-dependent secretion of rat retinol-binding protein expressed in HeLa cells.

A minigene encoding rat retinol-binding protein (RBP) was transfected into HeLa cells, which do not express endogenous RBP, transthyretin, or cellular retinol-binding protein. The HeLa cells manufactured and secreted the transfected gene product, demonstrating that RBP-transthyretin assembly is not a requirement for the secretion of RBP. When HeLa cells were grown under vitamin A-deficient conditions, RBP accumulated in the endoplasmic reticulum. Both serum and retinol stimulated secretion of RBP in a concentration-dependent manner. The retinol-regulated secretion occurred also after protein synthesis had been blocked by cycloheximide. Addition of holo-RBP or retinal, but not retinoic acid, stimulated secretion of RBP. Thus, an in vitro model system that resembles the rat hepatocyte in vivo with regard to the known regulation of RBP secretion has been established in a human cell line of extrahepatic origin. It can be concluded that cellular retinol-binding protein is not required for the transfer of retinol to RBP and that the mechanism whereby retinol controls the intracellular transport of RBP is neither specific for tissues synthesizing RBP nor species-specific. To investigate the structural properties responsible for the endoplasmic reticulum retention of RBP in the absence of its ligand, a cDNA encoding chicken purpurin, a protein that is 50% identical to RBP and that binds retinol, was expressed in HeLa cells. In contrast to RBP, purpurin was not retained in vitamin A-deficient HeLa cells.

Animals↗
PubMed1992

[Unilateral scapulohumeral amyotrophy. Contribution of imaging].

A case of right scapulohumeral muscular atrophy stable after a 6 month progressive course is reported. Cervical metrizamide CT and MRI showed a flattened right cervical spinal cord regarded as a segmental atrophy. The case could belong to the Kaeser type of sporadic chronic spinal amyotrophy, or perhaps corresponds to a benign focal amyotrophy.

Adult↗
PubMed1991

[Traumatic amnesias. Memory disorders consecutive to head injuries].

Traumatic amnesia is a good index predictive of the disablement due sequelae of cranial injuries. The residual memory deficit, correlated with the return to work, mainly affects long-term memory, learning, verbal memory and sensitivity to interferences. The most relevant tests are Rey's 15 words--and particularly their retrieval at 30 minutes--and the verbal fluency test, but the changes in memory observed in the patient's daily life must also be evaluated. Rehabilitation tends to rely on the overall management of intellectual and behavioural disorders, as part of programmes that are specific to subjects with cranial injury.

Amnesia↗
PubMed1991

Pathology of roots, spinal cord and brainstem in syringomyelia-like syndrome of Tangier disease.

We report here a post-mortem examination of a 46-year-old patient who died after a 23-year-long syringomyelia-like syndrome of Tangier disease. The L5 dorsal root and the superficial peroneal nerve showed fiber loss and lipid vacuole accumulation in Schwann cell cytoplasm. The L5 ventral root had moderate fiber loss without lipid vacuoles. In the cervical roots, fiber loss was intense and there were no foamy Schwann cells. Motor neuron loss was severe in the cervical spinal cord and the facial nerve nucleus and slight at the lumbar level. Under electron microscopy, some neurons of the lower spinal cord showed atypical inclusions. These data suggest that an unknown metabolic defect is responsible for a primary neuronopathy. Lipid accumulation in Schwann cells, resulting from fiber degeneration is probably transient, accounting for the absence of foamy cells in regions with longstanding involvement.

Autopsy↗
PubMed1991

[Covering of ischial pressure sores using a fasciocutaneous flap from the posterior surface of thigh (modified Griffith method) after mattressing with the biceps femoris. Apropos of 11 cases].

The ischial region is the commonest site for pressure sores in paraplegics capable of sitting. The choice of treatment must be guided by two imperatives: the need for a thick tissue cover (mattressing) and perfect trophicity, the risk of recurrence which always remains possible. The association of a modified Griffith fasciocutaneous flap from the posterior surface of the thigh and a hamstring muscle flap (preferably biceps femoris) providing mattressing of the ischial region, appears to satisfy these imperatives. The other repair procedures are discussed in order to ensure the best management of the paraplegic patient's cutaneous capital, due to the continual risk of a new pressure sore or a recurrence of the ischial pressure sore.

Adult↗
PubMed1991

[Different clinical types of degenerative aphasia].

The authors report 3 cases of slowly progressive aphasia with different language disturbances: anomia, pure word deafness and Broca's aphasia. All patients were independent in daily life activities. Insight, judgement and overall behaviour were intact. There was no major disturbance of other cognitive functions, but psychometric tests showed mild deficits suggesting widespread involvement. CT scans and magnetic resonance imaging showed focal dilatation of the left sylvian fissure. A positron emission tomographic study showed left perisylvian hypometabolism. A review of the literature yielded an increasing number of cases of this degenerative syndrome affecting dominant hemisphere language areas. Our cases confirm the clinical heterogeneity of degenerative aphasia. Postmortem neuropathological examinations are rare and many causes are found: Pick's disease, Alzheimer's disease or aspecific gliosis.

Aged↗
PubMed1990

[Immunogenetics of primary membranous glomerulonephritis].

In 65 patients with a biopsy-proven diagnosis of membranous glomerulonephritis, the association with HLA class I, class II and class III antigens was studied using classical techniques. We found a highly significant association with the HLA-DR3 (Pc = 8 x 10(-5)) antigen and with the HLA-B8 (Pc = 2 x 10(-4)) antigen in linkage disequilibrium with the former. In addition, there was an excess of null C4 allotypes (C4 AQo or C4 BQo) in patients and a significant decrease of BfS allele. Finally, the most commonly observed phenotype was A1 B8 DR3 BfS C4AQoB1. These results confirm a strong association between major histocompatibility complex and primary membranous glomerulonephritis, raising the possibility of a susceptibility gene being necessary for the development of that disease.

Adult↗
PubMed1990

Pure agraphia after deep left hemisphere haematoma.

Pure agraphia is reported following haematoma in the left centrum semiovale sparing both parietal and frontal cortices. There was total inability to produce graphemes in the absence of limb apraxia. The lesion is assumed to have prevented linguistic and graphemic systems from gaining access to the frontal motor programme.

Adult↗
PubMed1990

[Primarily unilateral herpes encephalitis. Long-term neuropsychological study of 9 cases].

Nine cases of post-herpetic encephalitis with predominant involvement of one temporal lobe at CT scan or MRI (6 on the left and 3 on the right sides) were studied 1 to 6 years after onset with repeated language and memory testing. The neuropsychological findings were well correlated with the lateralization and size of the lesions, as previously observed in unilateral temporal lobectomy. Compared with the usual bilateral form, the sequelae were mild, and all the patients, especially those with right hemisphere involvement, resumed a subnormal family life or social activity. In patients with left predominant lesions the anterograde amnesia concerned verbal information, especially logical and abstract, without visual amnesia. In some cases, the episodic verbal amnesia was associated with a semantic deficit which included the knowledge of some words. In one patient the colour, use and mental imagery of some objects corresponding to forgotten words were involved only for some specific groups (natural objects, whereas man-made objects fared better). Testing of verbal memory is proposed to determine the role of the preserved minor hemisphere in learning the context of word presentation, and words with concrete and visual connections which are better recalled than those with abstract or logical link. Disorders of behaviour or mood are usual in the 2 groups of lesions. Thus, herpes encephalitis in these asymmetrical and benign forms in an attractive model to study the role played by the temporal lobe and lateralization in memory.

Adult↗
PubMed1990

[Cortical pain. Clinical, electrophysiologic and topographic study of 12 cases].

Vascular lesions of the cerebral cortex sparing the thalamus (MRI or CT with reconstructions) may be accompanied by burning or constrictive pain which suggests thalamic pain as it affects one half of the body and is associated with induced pain. Summation hyperpathia is rare; allodynia is more common and sometimes isolated (2 cases). Cortical pain may be paroxysmal, and in 3 of our patients it progressed like a jacksonian seizure. The territory of pain is also the site of global or spinothalamic hypoaesthesia (5 cases). Early SEPs are abolished or of low amplitude (8 cases). The lesion is located in area SI or extends to the thalamo-parietal radiations; in 11 out of 12 patients it was located in the minor hemisphere. Two physiopathological theories are discussed: hyperactivity of the intralaminar thalamus relieved from cortical inhibition, or denervation hyperactivity related to the cortical or subcortical lesion.

Adult↗
PubMed1989

[Lexical agraphia caused by left temporoparietal hematoma].

A patient presented with dysorthographia associated with amnestic aphasia due to a left temporo-parietal hematoma. Reading, copying, graphism of letters were normal. Dictation showed better results for logatomes and regular words, without orthographical difficulty, than for those with orthographical problems (ambiguous and irregular words). The overall features suggested a disorder of the lexical system in which orthography of words known to patients is present. The phonological pathway of phoneme-grapheme conversion was preserved since errors were usually phonologically correct. Initially it was possible to conclude to a disorder of the semantic value of words in their visual form. Oral spelling, auditory reading and written denomination also showed more errors for words of difficult orthography. This patient presented a disorder of visual representation of words. Comparison of this case with the few reported ones showed that the latter often had amnestic aphasia and differed from our case in the associated lexical or phonologic alexia. A common feature of the lesions is involvement of the left angular gyrus is right-handed patients.

Aged↗