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Biomedical subjects

J Cambier

Publications and source records attributed to J Cambier.

At least 19 recordsLinked to original sources
PubMed2000

Positive regulation of interleukin-4-mediated proliferation by the SH2-containing inositol-5'-phosphatase.

The SH2-containing inositol 5'-phosphatase (SHIP) is tyrosine-phosphorylated in response to cytokines such as interleukin (IL)-3, granulocyte-macrophage colony-stimulating factor, and macrophage colony-stimulating factor. SHIP has been shown to modulate negatively these cytokine signalings; however, a potential role in IL-4 signaling remains uncharacterized. It has been recently shown that IL-4 induces tyrosine phosphorylation of SHIP, implicating the phosphatase in IL-4 processes. Tyrosine kinases, Jak1 and Jak3, involved in IL-4 signaling can associate with SHIP, yet only Jak1 can tyrosine-phosphorylate SHIP when co-expressed. In functional studies, cells overexpressing wild type SHIP are found to be hyperproliferative in response to IL-4 in comparison to parental cells. In contrast, cells expressing catalytically inactive form, SHIP(D672A), show reduced proliferation in response to IL-4. These changes in IL-4-induced proliferation correlate with alterations in phosphatidylinositol 3,4,5-triphosphate levels. However, no differential activation of STAT6, Akt, IRS-2, or p70(S6k), in response to IL-4, was observed in these cells. These data suggest that the catalytic activity of SHIP acts in a novel manner to influence IL-4 signaling. In addition, these data support recent findings that suggest there are uncharacterized signaling pathways downstream of phosphatidylinositol 3,4,5-triphosphate.

Cell Division↗
PubMed2000

[Time rediscovered].

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Chronobiology Disorders↗
PubMed1999

[The loss of human autonomy: utilization and imitative behaviors].

In 1981, when François Lhermitte described utilisation behaviour, his experience was based on 40 patients with bilateral frontal lesions and 5 cases of unilateral lesions. This behaviour was never observed in normal subjects or in patients whose lesions spared the frontal lobes. The description of imitation behaviour followed shortly after. In 1986, of the 125 patients studied, 40 presented an imitation behaviour without utilisation behaviour, 35 had both types of abnormal behaviour and 50 had neither. Continuing his study of patients presenting a frontal syndrome, Lhermitte showed that dependence on objects and dependence on individuals can be prolonged in the form of a dependence on social context which ultimately characterises the loss of autonomy. Lastly, in 1993, he noticed that certain major depressive states gave rise to an utilisation and imitation behaviour similar to the type of behaviour resulting from a frontal syndrome of organic origin. The concept of loss of autonomy must be discussed in relation to the notion of intentionality of the various manifestations of loss of autonomy. Pathological prehension and the grasping reflex no longer provide a satisfactory explanation. Electrophysiology and the study of regional activity in the cerebral cortex associated with the preparation and execution of the movement have led to these phenomena being viewed in a new light. With the concept of loss of autonomy, the distinction between the mechanisms underlying intention and those which modulate actions in response to external demands is now seen to be well-founded. François Lhermitte opened the way.

Behavior↗
PubMed1997

[Letter-by-letter alexia after left hemispheral lesion without hemianopsia nor callosal involvement. 2 cases].

We describe two patients suffering from a letter-by-letter reading following an infarct in the left posterior cerebral artery's territory. Unlike most of the verbal alexics, this strategy was particularly fast and effective. Two other features distinguished these patients from verbal alexics: the absence of hemianopia and the sparing of the corpus callosum. A study of the reading of letters and words by each hemisphere was performed. In the first case, the left hemisphere was unable to identify any letter or word. The visual stimuli did not activate the visual word form, not the system which normally recognize letters. However, this latter could be activated by the information transmitted by the right hemisphere via the corpus callosum. In the second case, the left hemisphere could, as well as the right one, identify all the letters. On the other hand, identification of words was impaired, and did not improve when the duration of the visual presentation increased. The left hemisphere, unable to access to the visual word form, could not decipher letter-by-letter. One hypothesis is that the left visual working memory was reduced, and could not store more than one letter. The right hemisphere deciphered the words sequentially, and transmitted the information to the left systems which recognize the letter. These two observations confirm that letter-by-letter alexia could result exclusively from the destruction, of the inaccessibility of the visual word-form. A lesion of the left ventral occipito-temporal structures is sufficient, and a left hemianopia, or a splenial lesion is not absolutely necessary. The sparing of the corpus callosum allows a fast transmission to the left phonological processing, if the left systems recognizing letters are efficient.

Aged↗
PubMed1996

[Gustave Flaubert and his double, or the dialectic of the hemispheres in artistic creation].

Paul Girard was intrigued by Gustave Flaubert, author of the famous French novel Madame Bovary, because of the relationship between the author's style and his left temporal epilepsy. Gustave Flaubert led a double life; a highly appreciated guest at the best of Parisian soirées, he spent much of his life at Croisset as a hermit. He spoke little, yet he wrote in an extremely elaborate literary style. These contrasts cannot be explained solely on the grounds of an intercritical behaviour syndrome due to temporal epilepsy. For Flaubert, writing was a mean of compensating for an unbalanced hemispheric activation, his rigorous attention to style taming his overabundant imagination.

Epilepsy, Temporal Lobe↗
PubMed1995

[Downbeat nystagmus and vertebrobasilar arterial dolichoectasia].

A 66-year-old man presented with a downbeat nystagmus. The underlying cause was unknown. A dolichoectasia of the vertebrobasilar artery was the only identifiable abnormality at Magnetic Resonance Image which also disclosed distortion of the anterolateral aspect of the medulla. Compression of the caudal brain-stem by an enlarged and tortuous vertebrobasilar arterial system may be the cause of downbeat nystagmus in cases unassociated with the more commonly recognized causes.

Aged↗
PubMed1994

[Apraxia and autotopoagnosia without aphasia or agraphia with compulsive language activity in right hemispheric lesion].

A 75 year-old woman was admitted with a left hemiplegia resulting from an infarct in the right middle artery's territory. Her manual preference was ambiguous from early childhood. She presented with severe bilateral apraxia, autotopoagnosia, finger agnosia, and left spatial neglect. There was, however, no aphasia nor agraphia. When the patient attempted to perform gestures on order, she compulsively produced oral or written language. In this very unusual case, dominance for gesture and dominance for language were strictly independent, each ensured by one hemisphere. The patient's performances in gestual activities, especially dissociation between automatic and voluntary movements, and compulsive linguistic productions, are discussed in relation to this functional lateralization. We suggest that the propositional nature of the responses required in test conditions could activate either voluntary language in the left cerebral hemisphere, or voluntary gestures in the right. A competition between the two hemispheres could explain the patient's linguistic apraxic or behavior in response to orders. Autotopoagnosia, an uncommon symptom, could interfere with apraxia, but is not directly responsible.

Aged↗
PubMed1994

[Hippocampothalamic infarction. A limited form of infarction in the posterior cerebral artery area].

Infarction of the hippocampus and the right ventroposterolateral thalamus was observed. Angiography revealed a posterior cerebral artery occluded near its origin, immediately upstream from the posterior communicating artery. The infarction was limited to the areas irrigated by the branches originating in the proximal part of the artery. More distal branches for the calcarine scissure and the temporooccipital gyruses were not involved.

Adult↗
PubMed1993

[Lhermitte's sign].

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Demyelinating Diseases↗