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Biomedical subjects

B Laurent

Publications and source records attributed to B Laurent.

At least 163 records · Page 9Linked to original sources
PubMedDate not supplied

Functional imaging and neurophysiological assessment of spinal and brain therapeutic modulation in humans.

We summarize here our experience in the neurophysiological and neuroimaging assessment of spinal and brain neuromodulation for pain relief. Techniques reviewed include somatosensory evoked potentials (SEPs), nociceptive spinal (RIII) reflexes, and positron emission tomography (PET), which have been applied both to investigate the mechanisms and to optimize the application of neurostimulation procedures. SEPs are especially useful in the preoperative assessment of patients with neuropathic pain, as they allow the establishment of the functional state of the dorsal column system. Patients with strongly abnormal SEPs due to ganglionic or preganglionic pathology are not likely to benefit from spinal (SCS) or peripheral (TENS) neurostimulation, because ascending fibers disconnected from their soma will undergo rapid degeneration and not be excitable. In the postoperative period, nociceptive spinal reflexes yield objective data concerning the effects of neurostimulation on spinal circuitry. In our experience, the best clinical results are achieved in patients with preserved preoperative SEPs, in whom neurostimulation entails profound attenuation of nociceptive reflexes.PET-scan imaging techniques have recently been used to demonstrate changes in cerebral blood flow during new neuromodulation schemes such as motor cortex stimulation for pain control (MCS). PET studies highlight the thalamus as the key structure mediating functional MCS effects. Thalamic activation would trigger a cascade of synaptic events influencing activity in other pain-related structures including the anterior cingulate gyrus, insula, and upper brainstem. The combination of clinical electrophysiology and functional neuroimaging provides insight into the mechanisms of action of neuromodulation procedures, guides clinical decision, and contributes to optimize patient selection.

Central Nervous System Diseases↗
PubMedDate not supplied

[Salmonella possessing the 6,7:c:1,5 antigenic factors].

A total of 358 Salmonella strains belonging to subspecies I (other than "S. typhisuis") and possessing the 6,7:c:1,5 antigenic factors were studied on the basis of their classical biochemical characters and their subfactors of the H:c antigen. They were classified into 4 homogeneous taxa which can be differentiated by the use of three characters: production of acid from dulcitol and mucate and H2S production. Production of acid from arabinose and trehalose are not reliable markers. The taxonomic level of these four taxa founded on their biochemical characters is that of biovars within one serovar. For practical purposes, we propose to refer to these biovars as Paratyphi C, Choleraesuis sensu stricto, Choleraesuis var. Kunzendorf and Choleraesuis var. Decatur.

Animals↗
PubMedDate not supplied

Differential mechanisms of impairment of remote memory in Alzheimer's and frontotemporal dementia.

This paper describes retrograde memory performances of 12 Alzheimer's disease (AD) patients and 12 frontotemporal dementia (FTD) patients. First of all, we observed that FTD and AD patients did not differ for language tests (verbal fluency tests and oral denomination 80), for semantic memory tests, for logical memory test and Benton visual memory test and differed for anterograde verbal memory and frontal tests. Concerning retrograde memory, there was no difference between AD and FTD patients in retrograde memory scores (autobiographical memory interview, Crovitz's task, French public events interview battery) and both FTD and AD patients exhibited a retrieval deficit in their remote memory. We observed that the mechanisms of remote memory deficit was different in FTD and in AD patients. We observed no classical paradigm of Ribot for FTD patient's remote informations, and they appeared to have lost of access to memories and executive difficulties. In AD, the results indicated these patients' ability to learn new information and to search semantic memory failed.

Aged↗
PubMedDate not supplied

A new method for the identification of cerebrospinal fluid leakage.

Apart from the use of anamnestic data the most common techniques for the diagnosis of CSF leakage have included X-ray studies, and chemical analysis of glucose, protein, and electrolytes of the fluid obtained from the nose or ear, intrathecal staining, and radioactive cisternography. These studies, although useful, have not always succeeded in demonstrating the CSF leakage, especially when the leak is delayed, small, or contaminated. A new immunochemical technique for the identification of the CSF leakage is described. It is based on demonstration of an extra band of transferrin located in the beta 2-fraction of protein electrophoresis of CSF. This beta 2-transferrin is pathognomonic for liquor and could not be demonstrated in serum, nasal secretions, saliva, tears, or peri- and endolymph. After routine protein electrophoresis on cellulose acetate membranes, the transferrins are identified by application of anti-transferrin on beta-regions. Stained precipitates in both beta-regions demonstrate clearly the presence of CSF. Compared with other methods, the new technique offers many advantages. The amount of sample needed for the procedure is small, moderate contamination does not invalidate it, it makes it possible to localize the leak by differential suction, and it is absolutely safe for the patient.

Blood Protein Electrophoresis↗
PubMedDate not supplied

[Amnesic presentations of the compulsive obsessional confusions (about 3 patients appearing in a consultation of memory)].

Disorders or complaints of memory are a frequent cause of consultation in depression, major anxiety and psychiatry disease with personality disorders. We report 3 patients with obsessive compulsive disorder (OCD), without diagnosis and treatment, examined in a specialized memory consultation. They always had OCD with cognitive checking. Diagnosis of transient global amnesia and temporal complex seizure were discussed in 2 cases. Psychometric impairment only was observed in first free recall of a verbal memory task and was no specific. Behavioural during testing seemed to be very important to analyse. First, a 49-year-old man consulted because he had stereotyped transient amnesia lasted one minute, 2 or 3 times a week, since 6 months. He was a teacher. Transient amnesia always occurred during lessons. Suddenly he didn't know where he was or what he was speaking about. Episodes lasted one minute. After them, he had no confusion and no difficulty in concentration but intense anxiety. In an another hand, when he was in his car, after lessons, he could forget where he was during some minutes. CT scan and EEG were normal. Neuropsychological tests only objectived impairment in first free recall of Grober and Buschke's words. Patient explained that he could not prevent to check responses. He told us checking obsessive compulsive disorder during since long time ago. We discussed clear differences which existed between seizure and ruminations or preoccupations. Secondly, a 55-year-old woman was afraid of her memory performances. She was medical secretary and had no problem in her work but she would like a memory consultation to reassure herself. She was neither depressed nor anxious. She presented curious production in fluency task. She had to produce as many animals's names as possible: she could say 35 names which was an excellent performance but only in alphabetic order! Neuropsychological tests objectived impairment in her first free recall of Grober and Buschke's words. She tried in her first free recall to remember words in alphabetic order. She explained how she was bound to range everything in alphabetic order! She had a lot of rituals. She thought that she had an obsessive compulsive disorder but never consulted about this. The observation illustrated suspiscions about memory operations which could be observed in patients group with obsessive compulsive disorders. Finally, a 62-year-old man told us that he had presented a transient global amnesia during 4 hours. He had an important appointment and was upset about that. He didn't go to it and wandered in his flat. He always asked the same questions and forgot everything. He had no neurological deficit. He was anxious, sad and cried several times. He perfectly remembered the episod and thought that he had a panic attack! Verbal memory tests only objectived difficulties in his first free recall of Grober and Buschke words as the two others patients. He had a story of obsessive compulsive disorder with checking and rituals. In this observation, we discussed clear differences which existed between panic attacks and global transient amnesia. We analyzed patterns of neuropsychological performances which illustrated clinical features of obsessive compulsive disorder. These three patients impaired in their first free recall of verbal memory task. It is not a specific result. We observed during psychometric evaluation, strategic processing which impaired episodic memory: patients tried to check their performances. Memory complaints only were observed in checking obsessive compulsive disorder. It is a difficulty or a doubt about memory capacities. Difficulties could be due to particular cognitive processes who pertubate normal memory capacities.

Female↗
PubMedDate not supplied

[Bucco-linquo-facial and choriform hyperkinesies (author's transl)].

These bucco-linguo-facial and choriform hyperkinesies still remain all too frequent in many neurological diseases. The authors study exclusively the dyskinesies of essential origin or iatrogenous including the post neuroleptic and post dopatherapy dyskinesies. All the neuroleptics can be involved at different stages of the treatment, giving rise to difficulties in the diagnosis. Dopatherapy in the Parkinson disease is also responsable of many dyskinesias. Time of appearance after the drug's taking, significance and treatment are discussed. The idiopathic dyskinesis are more unusual either with the some only facial involvement, or in association with another abnormal movements. The physiopathology is doubtful, so the treatment is often very difficult.

Antipsychotic Agents↗
PubMedDate not supplied

[Complications of diverticular disease of the colon. Apropos of 247 cases].

In the last five years, 7 teams, members of a surgical club of lower Normandy, have performed 1,136 colon procedures, including 247 for severe diverticular disease. The patients were grouped in two categories according to the severity of the complications presented: 159 sub-acute complications including 137 acute cases of sigmoiditis (diverticulitis, peri-colic micro abscesses, pseudo-tumoral forms) and 22 fistulae, 88 severe acute complications including 60 generalized peritonites, 12 huge abscesses, 9 occlusions and 7 hemorrhages. The total post-operative mortality is 6 p. cent. It is quite different in the surgery of sub-acute complications (0.6%) and the surgery of acute severe complications (16%). The total morbidity reaches 14.8 p. cent. Complications are more frequent and more severe in acute forms (18.5%) than in subacute forms (10.5%). At long term, 10.8 p. cent of the patients operated upon, kept a permanent colostomy (25 p. cent in acute forms vs 2.3 p. cent in subacute forms). 89.2 p. cent have a normal digestive tract following treatment (97.7 p. cent in subacute forms and 53 p. cent in acute forms).

Abscess↗
PubMedDate not supplied

[Characterization of a 7th subspecies of Salmonella: S. choleraesuis subsp. indica subsp. nov].

A new Salmonella subspecies designated as S. choleraesuis subsp. indica (shortly, subspecies VI) was delineated on the basis of biochemical characters and genomic relatedness. Eight serovars were assigned to this subspecies: one of these was previously classified in subspecies I (serovar Ferlac) and seven in subspecies II. This subspecies can be identified by five biochemical characters: gelatinase+, malonate-, L(+)tartrate-, salicin- and sorbitol-. The type strain is CIP 102501 (serovar 1,6,14,25:a:e,n,x formerly called Ferlac).

DNA, Bacterial↗
PubMedDate not supplied

[Selective study of sulfate and glucuronide conjugates of urinary MHPG in nervous depression. Peripheral and central influences].

The determination of urinary MHPG (3-methoxy-4-hydroxyphenyl glycol) has been extensively performed to confirm the noradrenergic hypothesis of some depressions. However, owing to the double origin, central and peripheral, of this norepinephrine metabolite, the validity of total MHPG assay as an index of central noradrenergic activity may be challenged. MHPG exists in human urine in two conjugated forms, at equal amounts: sulfate and glucuronide. A number of arguments suggest that MHPG sulfate and MHPG glucuronide respectively reflect central and peripheral norepinephrine metabolism. In this work, we have selectively estimated both MHPG conjugates in 24 h-urine samples of 36 severely depressed women in view to assess the extent and frequency of central or/and peripheral norepinephrine dysfunction. On the basis of MHPG sulfate and glucuronide values, we conclude that in the examined population (6 endogenous, 19 neurotic, 11 reactive depressions) about 80% of patients exhibited a central NE functional deficit, and many of them had also a diminished sympathetic activity. Clinical symptoms related to psychic factors (melancholia) or associated to sympathetic activity changes (anxiety, retardation) respectively alter sulfate or glucuronide MHPG excretion. These data altogether validate the concept of the independent origin of the two MHPG conjugated and show that their selective assay is able to provide a more satisfactory reflection of the psychobiological state in depressed patients than total MHPG determination.

Adult↗