PubMed Health⌕ Search

Biomedical subjects

J Valat

Publications and source records attributed to J Valat.

7 recordsLinked to original sources
PubMed1991

Motile responses of isolated guinea pig vestibular hair cells.

Vestibular hair cells were isolated from the guinea pig vestibule by a micromechanical non-enzymatic procedure. Perfusion with 125 mM K+ solution induced irreversible slow shortening of the necks in 42.8% of the hair cells tested. Mechanical stimulation, creating a displacement of the hair bundle towards the kinocilium, induced either irreversible coiling or tilting of the neck of the cells, or reversible fast tilting of the cuticular plate (44.5% of tested cells). The response to the Ca2+ antagonist, Flunarizine, suggested that these movements were calcium-dependent. We propose several explanations of the physiological role of these mechanisms and discuss the possibility that fast tilting of the cuticular plate is a physiological movement involving the hair cells at the periphery of the vestibular receptors. The regulation of the vestibular message at the apex of type I hair cells is also considered.

Animals↗
PubMed1978

[Analytical study and processing of information from a primary intervention report].

Analytical study of treatment of information from a primary intervention by the S.A.M.U. were brought about with the aim of performing a "statistical" study of enumeration of the various possibilities, using three "standard" programmes. After exploitation of the statistical data, the card index is stocked on conventional magnetic tape and verified by different parameters permitting its identification. In addition, the concatenation of different card indices is easy to obtain, which makes it possible to carry out research into all existing file cards regardless of the month or year.

Electronic Data Processing↗
PubMed1978

[Postnatal cellular reactivity of the optic nerve after enucleation in the rat. Quantitative aspects in relation to myelinization].

The use of an experimental procedure based upon progressive postoperative delays allowed the quantification of the effects of enucleation performed at the ages of 2, 8 and 20 days, corresponding to key stages of the postnatal maturation of the optic nerve, namely premyelination, myelination and postmyelination. Two main events were noteworthy regarding cell reactivity. The higher the age of the animals at operation, the lower was the proliferation, and the larger was the time lapse between operation and the peak of proliferation. The interferences between reaction gliosis and myelination gliosis depended upon the developmental stage of the optic nerve. This reflects a progressive loss of plasticity.

Age Factors↗
PubMed1975

NMR investigations of proline and its derivatives. 4-Proton magnetic resonance parameters and structure of acetyl-proline amide.

The proton magnetic resonance (PMR) spectrum of acetyl-proline amide in D2O solution has been analysed by computer simulation. The spectra of the cis and the trans isomers have been separated and their PMR parameters (chemical shift and coupling constants) are given. Vicinal coupling constants of the pyrrolidine ring are interpreted by means of a Karplus zone relation. The chemical shift effect of the anisotropy of both peptide planes is considered. It follows that both isomers are puckered with Cgamma in an endo position, but the cis isomer is more rigid than the trans isomer, which moreover undergoes a small interconversion of the Cgamma and Cdelta atoms between two extreme spatial positions. The dihedral angle phi has different values in both isomers. Thus, the dihedral angle between the two peptide planes is smaller in the trans isomer than in the cis isomer.

Chemical Phenomena↗
PubMed1975

[The setting up of a computer system for records of first entries at the emergency medical assistance service in Montpellier].

The setting up of a computing device to exploit the files of first transports at the MONTPELLIER SAMU was started essentially in order to constitute a document both accurate and of easy access, able to memorize the physical and mental behaviour of a patient in a transient state. The results thus obtained include: 1 -- An analytical study with a part devoted to general data such as the number of injured people or of patients, the number of calls from various sources, the means of intervention etc. and a more specific part dealing with type of accident the determination of the traumatic impacts, the first therapy etc.; 2 -- A synthetical study that constitutes the second phase of the dealing with information thanks to the drawing up of graphs indicating the number of calls per accident according to the time, the age, the number of serious cases etc.

Computers↗