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Biomedical subjects

C Gros

Publications and source records attributed to C Gros.

At least 145 records · Page 8Linked to original sources
PubMed1976

Limited proteolysis of tryptophanyl-tRNA synthetase from beef pancreas.

Treatment of purified tryptophanyl-tRNA synthetase with either chymotrypsin, papain, subtilisin or elastase converts all the enzyme into a high-molecular-weight intermediate. This protease-resistant core molecule has the same dimeric structure as the native protein and possesses the ability to bind substrates (tryptophan, ATP and tRNATrp) but is catalytically inactive. The monomer molecular weight of the protease-treated enzyme is 39000 compared to 54000 for the intact molecule. Chemical studies indicate that proteases excise the amino-terminal part of the polypeptide chain. It has been demonstrated previously that removal of a 13000-dalton fragment from the amino-terminal region of the tryptophanyl-tRNA synthetase converts the native enzyme to another active form. Cleavage of 20 additional amino acids produces the inactive protease-resistant core.

Amino Acids↗
PubMed1976

Sectorial posterior rhizotomy, a new technique of surgical treatment for spasticity.

After their experience of Foerster's operation and its technical modifications in 80 cases the authors report a new concept of analysis and treatment of spasticity in lower limbs. Spasticity of the different muscle groups is classified either as "useful spasticity" or "handicapping spasticity". The first has to be preserved, the second must be reduced. In order to achieve this purpose a new technique is presented, based on operative sectorial identification of the posterior rootlets subserving the "handicapping spasticity" by electrophysiological stimulation, muscle testing, and E.M.G. studies. The conus medullaris and cauda equina are exposed by T 11-L 1 laminectomy, performed in the lateral position. The clinical and E.M.G. evaluation of responses to stimulation enables the surgeon to establish a map of rootlet groups which are marked with coloured threads. Selective resection of "handicapping posterior rootlets" is then performed after several tests of the mapping. The rootlets subserving useful spasticity are carefully preserved. Ten cases are reported, comprising five cases of cerebral palsy operated upon since 1974 and five cases of posttraumatic spastic paraplegia from the same period. Pre and postoperative findings are summarized. The technical features of this procedure are discussed and compared with other surgical procedures. The problem of the rootlet reflex arch is considered in the light of the effects of stimulation of anterior and posterior rootlets at the same level.

Adolescent↗
PubMed1976

Long term results of stereotaxic surgery for infantile dystonia and dyskinesia.

Our experience is based on a series of 25 patients suffering from infantile dyskinesias and dystonias who underwent stereotaxic surgery of basal ganglia. We first note the immediate good results (77%) obtained by thalamo-sub-thalamotomy. Concerning dyskinesia this type of surgery enjoys in an opinion a place of choice. Secondly we have been able to estimate secondary deterioration on long term results in patients examined 2 to 15 years post-operatively. In contrast to various results reported in the literature good long term results are not superior to 50%. Some deterioration is noted in patients operated on for choreo-athetosis over the age of 20. A pallido-subthalamic lesion is efficient at the beginning of the disease course since it improves motor performance and thereby helps possibilities of intellectual acquirement. Bilateral lesions have after improved I.Q. Effects of this treatment specially on spasticity must be discussed among other types of surgery.

Adolescent↗
PubMed1975

Molecular aspects of the inactivation of tryptophanyl transfer ribonucleic acid synthetase by N-ethylmaleimide.

The tryptic maps of tryptophanyl-tRNA synthetase from beef pancreas show that the 8 cysteinyl residues of the enzyme subunit are located, 2 by 2, on four different peptides. The kinetics of the incorporation of radioactivity from N-[ethyl-14C]ethylmaleimide into these peptides are compared in this paper with the kinetics of the changes of the catalytic properties of the enzyme occurring during alkylation. This comparison allows the identification of (a) the peptide carrying the cysteinyl residues located on the surface of the molecule, (b) the peptide carrying the deeply buried residues unmasked by the dissociation of the subunits, and (c) the peptide carrying the --SH group located in the vicinity of the binding site of tryptophan. The fourth peptide is shown to have a great sensitivity to pH with respect to the reactivity of its cysteinyl residues toward N-ethylmaleimide. The same unusual pH dependence is found for the rate of quenching of the intrinsic fluorescence of the protein during the alkylation, suggesting a strong sensitivity of the conformation of tryptophanyl-tRNA synthetase to pH in the range of 7 to 9.

Amino Acid Sequence↗
PubMed1975

Multiple forms of tryptophanyl-tRNA synthetase from beef pancreas.

Three different forms of tryptophanyl-tRNA synthetase can be isolated from pancreatic extracts. Structural, immunological and catalytic properties of these various forms have been compared. The native enzyme is a dimeric molecule of molecular weight 108000. Two other forms, of molecular weight 85000 and 82000, are composed of two polypeptide chains identical with the carboxyl terminal region of the native subunits. These molecules are supposed to derive from the original protein by removal, from the amino-terminal part of each subunit, of a fragment of 11000 to 13000 molecular weight. Such removal modifies the shape and the stability of the molecule and decreases its specific acitvity. The origin of the derived forms is attributed to proteolysis. In fact, limited proteolysis of purified tryptophanyl-tRNA synthetase, in its native form, by elastase, results in the formation of an active compound, similar to one of the tryptophanyl-tRNA synthetase derived forms. Furthermore, incubation with "elastolytic fractions" prepared from pancreatic extracts presenting a particularly high level of proteolytic activity produces the same cleavage in tryptophanyl-tRNA synthetase polypeptide chain.

Amino Acids↗
PubMed1975

Prognosis and post-therapeutic follow-up of breast cancers by thermography.

Statistical analysis of approximately 800 cases of breast cancer followed up for at least 3-5 years with careful correlation between mammography, thermography and clinical data has confirmed the accuracy and indispensable use of thermography for prognosis and follow-up. Pre-therapeutic prognosis. Strong correlations exist between the thermographic class and survival for T1, T2 and T3 cancers, confirming the contribution of thermography in therapeutic decision. Thus, a T1 cancer should be treated differently depending on the thermographic findings. Post-irradiation follow-up. Correlations exist between the development of thermic anomalies and the effect of irradiation on the cancer, showing the possibility of confirming sterilization or early detection of a recurrence. This is valid only if the thermic effects of radiation on the skin and gland are recognized and discounted.

Breast Neoplasms↗
PubMed1975

[Thermogenesis of breast cancers. V. The effects of 60Co radiotherapy and the correlations with expectations of a cure].

The action of ionizing radiation on the metabolic heat production by cancers has been investigated on a group of 24 small breast carcinomas (T1 and T2), all treated exclusively by radiotherapy under equivalent conditions (60Co) and then followed up regularly (mean recall period of five years). Following techniques have been used: intratumoral thermometry and fluvography for computing the specific heat power of the tumour, infrared thermography for analysing the skin thermal pattern quantitatively. Comparison between clinical, radiographical and thermal findings has more especially shown; a) the constant agreement between the final loco-regional results of radiotherapy and the evolution of both the heat production by the tumour and the related hyperthermia on the skin; b) the early appearance of the thermal signs of either a regression or a recurrence of the tumour, compared with the corresponding morphological signs. The fundamental and practical consequences can be summarized as follows: 1 degree distinction between radiosensitive and radioresistant carcinomas accroding as the specific heat power of the tumour is reduced or not after irradiation; 2 degrees definition of three types of thermal evolution by normalization, regression followed by re-increase, and continuance of both tumour heat production and malignant skin hyperthemia, and corresponding to the clinical concepts of sterilization, recurrence and nonsterilization respectively; 3 degrees justification of the systematic use of thermal methods for post-irradiation follow-up, especially to detect a local recurrence earlier and to specify the nature of a doubtful remaining opacity; 4 degrees description of objective thermal criteria allowing to decide a repairing mastectomy within shorter delays.

Adult↗
PubMed1975

[Heat production by breast neoplasms. IV. Influence of growth rate and probability of lymphatic dissemination during spontaneous development].

Growth rate and heat production of breast carcinomas have been investigated during the natural evolution of 21 untreated cancers, all with small tumour size (greater than or equal to 3 cm) and most of them were treated by surgery (excision of growth, mastectomy). Three original facts have thus been discovered : a) the specific heat power 1 (i.e. the heat quantity generated by the tumour per untis of volume and time, computed from from intramammary temperature and thermal conductivity measurements made using of fluvographic needle probes), is typical of each cancer and re7ains remarkably constant during the growth in spite of themorphological and of the morphological and circulatory changes; b) the tumour doubling time tau2v (calculated from measurements of the tumour size effected at various stages of the evolution by assuming an exponential growth), is univocally related to 1 by a hyperbolic law so that the faster the tumour is growing themore heat generates; c) q is significanty higher and tau2v shorter in all cases where the histological examination has revealed signs of lymphatic dissemination (carcinomatous lymphangitis, lymph node metastases,...). Practically q represents a quantitative criteria useful for setting with objectivity the pre-therapeutical prognosis of cancers clinically classified T1 or T2 and of circumscribed no palpable cancers. Similar but less accurate prognostic information may also be obtained by cutaneous thermography (infrared, liquid crystals) considering the intensity, extent and topography of the skin hyperthermia frequently elicited by the cancer. Thid aid to prognosis of the thermal methods is all the more valuable as the tumour doubling time cannot be evaluated under the customary clinical conditions.

Adult↗