Biomedical subjects
Publications and source records attributed to D Michel.
A case of post-traumatic cervico-thoracic syringomyelia was complicated, 3 years after the injury, by a bulbar extension manifested by a downbeat vertical nystagmus which became a source of disabling oscillopsia. The syringobulbia was visualized at MRI. The usefulness of syringostomy in such a case is discussed.
Quail neuroretinal cells (QNR cells) from 7-day-old embryos do not proliferate even in the presence of 8% fetal calf serum. After infection by the Rous sarcoma virus (RSV) they proliferate actively and exhibit a transformed phenotype; this effect is mediated by the oncoprotein pp60v-src. Secondary cultures infected by the thermosensitive strain tsNY68 of RSV are blocked in G0 either by thermal inactivation of pp60v-src at 41.5 degrees C or by serum deprivation at the permissive temperature (36.5 degrees C). Cell division is reinduced either by pp60v-src thermal renaturation or by subsequent serum addition. Our results indicate that v-src and serum control two synergic pathways leading to G0/G1 transition in QNR cells. In order to characterize genes related to the mitogenic and transforming effects of v-src in nerve cells, we have constructed a cDNA library from QNR cells transformed by tsNY68. We report the properties of five molecular clones isolated by differential screening of this library. Unlike immediate-early genes like c-fos, they are induced in mid and late G1. Four of them correspond to unknown mRNAs and the last one codes for nucleolin. This set of v-src-regulated genes is likely to code for functions deficient in terminally differentiated QNR cells and necessary for the progression in G1.
We have isolated the avian gene T64 corresponding to the mammalian clusterin, on the basis of high accumulation of its template mRNA in cells infected with oncogenic retroviruses. Since the clusterin was shown to have a protective effect against the immune system, its induction by oncogenic viruses is of major biological importance. The unique, short 5 kb-long T64 genomic locus is inactive in normal quail embryo fibroblasts in primary culture whereas it shows a high transcriptional activity after transformation by the Rous sarcoma virus. The 963 bp-long 5' flanking region is sufficient to drive the transcription of the chloramphenicol acetyltransferase reporter gene in a thermodependent manner when a thermosensitive version of pp60v-src is used. Deletion and point mutation analyses of the promoter show that the v-src response requires at least two separate elements: PUR and AP-1, located respectively at positions -167 to -152 and -25 to -19 relative to the single transcription initiation site. In addition, the binding of specific nuclear factors to these responsive elements correlates with the T64 promoter activation.
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Polypurine/polypyrimidine repetitive sequences occur with high frequency in eucaryotic genomes, particularly around transcription units. Since such sequences are known to adopt triple stranded-structures under appropriate conditions in vitro, it is of major interest to know if they occur in vivo, and thus if they can have some biological importance by inducing structural constraints in the genomic DNA. To this end, we have isolated a (TTCCC)48 sequence, present in the promoter of an avian gene, and tested its ability to form PU-PY-PY and PU-PU-PY triple helices in vitro, through the oligonucleotide gel shift technique and single strand-specific nuclease footprinting. We have then developed an oligonucleotide protection assay, which can be adapted to in vivo investigations. This strategy leads us to conclude that in vivo conditions allow preponderant formation of triplex of the PU-PU-PY class.
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Azosemide, a novel loop diuretic that has been available for the past few years, acts qualitatively like thiazide, viz by prolonging the diuretic effect with, however, only a slight delay in the onset of diuresis, in combination with the quantitative effect of previous loop diuretics, i.e. large excretion volumes. On the basis of experience gained to date, specific indications will presumably be cardiac and renal edema and ascites, also as long-term treatment. Provided that no NaCl or volume deficiency presents, side effects are insignificant.
The resurrection plant Craterostigma plantagineum tolerates an extreme loss of cellular water. Therefore this plant is being studied as model system to analyse desiccation tolerance at the molecular level. Upon dehydration, new transcripts are abundantly expressed in different tissues of the plant. One such desiccation-related nuclear gene (dsp-22 for desiccation stress protein) encodes a mature 21 kDa protein which accumulates in the chloroplasts. Sequence analysis indicates that dsp-22 is closely related to early light inducible genes (Elip) of higher plants and to a carotene biosynthesis related gene (cbr) isolated from the green alga Dunaliella bardawil. In contrast to other desiccation-related genes, light is an essential positive factor regulating the expression of dsp-22: ABA-mediated gene activation leads to the accumulation of the transcript only in the presence of light. During the desiccation process, light acts at the transcriptional and post-transcriptional levels. The implications of these different controls and the possible role of the dsp-22 protein in the desiccation/rehydration process are discussed.
This brief review discusses the recent characterization in the brain of a gene coding for a protein that may be involved in programmed cell death and/or brain plasticity. We will term it sulfated glycoprotein-2 (SGP-2), the name corresponding to the first cDNA characterized. Recent studies have demonstrated the overexpression of this sulfated glycoprotein in various CNS disorders, such as certain gliomas, Alzheimer's disease and epilepsy, as well as after experimental brain injury in animals where different cell types were undergoing tissue remodelling or cell death. In peripheral tissues, SGP-2 gene expression has been found to be strikingly increased following experimental manipulations in which cells of injured tissues were undergoing programmed cell death or apoptosis. The results reported thus far are intriguing and suggest the possible involvement of SGP-2 in apoptotic mechanisms as well as its interaction with components of the immune system possibly associated with cell death in neurodegenerative disorders.
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Antibodies directed against the central nervous system were looked for by indirect immunohistochemistry in the sera of 8 patients with paraneoplastic neurological syndrome (group 1), 21 cancer patients without neurological signs, 23 patients with miscellaneous neurological diseases and 63 normal subjects (groups 2 to 4). Four patients in group 1 had very high titres of antibodies. In 2 patients with small-cell lung carcinoma associated with sensory neuropathy the antibody recognized the cytoplasm and nucleus of all neurons. A 37 Kd protein was recognized by Western blot. A woman with cancer of the ovary and cerebellar syndrome exhibited an antibody against Purkinje's cell cytoplasm with a band of about 50-55 Kd at Western blot. In a woman with chronic uveitis and cerebellar atrophy with disappearance of Purkinje's cells the antibody (in blood and CSF) recognized certain layers of the retina as well as glial cells and cells present in the subependymal areas of the brain. Two bands of 46 and 59 Kd were revealed by Western blot. Immunoglobulins were detected in the cytoplasm of white matter cells in the cerebellum and brain stem. Among the other groups, one patient with lung cancer had a moderate titre of neuronal antinuclear antibody. The Western blot test was negative. The relevance of these antibodies for the diagnosis and treatment is discussed.
In a 41-year old woman complaining of episodic bilateral sciatic pain, MRI showed large sacral cysts developed in the pelvis. The fact that these cysts communicated with the subarachnoidal spaces was not clearly demonstrated by CT. The mechanism underlying the development of this perineural variety of extradural cysts is discussed.
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.
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In the treatment of heart failure-also in the aged-digitalis preparations remain indispensable. At the present time, in particular in combination with diuretics and ACE inhibitors, they are experiencing a revival in the treatment of severe stages (NYHA stages III and IV). In addition, a spectrum of newly developed positive inotropic substances of various classes is now available. Among the catecholamines, apart from dopamine, dobutamine and their derivatives, new drugs with a beta-adrenergic agonistic effect are presently undergoing clinical testing. Another heterogeneous group of substances combine positive inotropic with vasodilatory properties. In this connection, mention might be made of the phosphodiesterase inhibitors, the H2 receptor antagonists, and certain catecholamine derivatives. However, digitalis remains the only substance that can be given orally over the long-term without tolerance developing. Particular aspects of the use of digitalis in geriatric patients are discussed.
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