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C Redon

Publications and source records attributed to C Redon.

12 recordsLinked to original sources
PubMed2002

[Unsuccessful surgery of Cushing's disease. Role and efficacy of fractionated stereotactic radiotherapy].

BACKGROUND AND PURPOSE: To optimize and reduce the toxicity of pituitary adenoma irradiation, we evaluated the feasibility and effectiveness of fractionated stereotactic radiotherapy (FSR) in 51 patients with functional adenoma; 12 of them had Cushing's disease. PATIENTS AND METHODS: Eleven females and one male, median age: 49 years, 8 of them relapsed and 4 had persistent hormonal secretion after surgery. The delivered dose was 50 grays (Gy) (5 x 1.8 Gy/week) using 5 convergent micro-beams scanning in arc therapy mode. The median planned target volume (PTV) receiving 90 to 100% of the total dose was 2,1 cm(3). We used relocatable non-invasive stereotactic device Brain Lab, and adapted Linac for stereotactic radiotherapy. RESULTS: Nine out of twelve patients (75%) presented with complete remission after a median time of 29 months, 3/12 patients with partial remission. Actuarial probability to have hormonal persistent secretion was 88% at on year, 44% from 3 to 5 years, 22% at 7 years, and 11% to 0% after 7 years. The 12-corticotroph adenomas were significantly (p=0.007) more radiosensitive than 39 non-corticotroph adenomas. Toxicity was significantly lower for corticotrope adenoma, with no radio-induced pituitary deficiency and no neurological or optic injury. CONCLUSIONS: Combined surgery and FSR appears to be safe and effective for treatment of pituitary adenomas. However, long-term follow-up is required to determine the impact in terms of tumor response and hormone deficiency. The focused treated volume obtained by FSR seems more suitable for these benign tumours than standard radiotherapy. In addition to this conformal approach, the use of standard fractionation reduced the risk of severe damage to the optic chiasma, which is sometimes observed after radiosurgery and is inherent in single fraction radiotherapy.

Adenoma↗
PubMed2001

Development of postural adaptation to arm raising.

We studied the development of the coordination between posture and movement by analyzing the shifts of the center of pressure (CoP) associated with arm raising. Three groups of children aged 3-5 years, 6-8 years, and 9-10 years and an adult group were tested. The subjects were required to raise their arms to the horizontal position while standing still, with their hands free or loaded (5% of the body weight). The arm movements were recorded by a TV-image processor, and the changes in position of the CoP were measured by a force platform and analyzed before, during, and after the arm movement. The data show that the CoP moved forward during arm raising, that additional load induced a greater shift in all age groups, and that the relative amplitude of the shift decreased with age. The greatest changes occurred between ages 3-5 years and 6-8 years. The pre- and postmovement CoP shift suggests qualitative changes in the postural adaptation to movement between these two age groups: the anticipatory postural adjustments moved from a supporting function to a compensatory function, yielding an increasing functional convergence between the feedforward and the feedback modes of postural control, and an increasing rapidness in recovering postural stability after arm movement. The postural behavior shown by the 9- to 10-year-old children and by the adults in the arms-free condition suggests an increased tolerance to unbalance when postural oscillations do not jeopardize static equilibrium.

Adaptation, Physiological↗
PubMed1999

Megabase chromatin domains involved in DNA double-strand breaks in vivo.

The loss of chromosomal integrity from DNA double-strand breaks introduced into mammalian cells by ionizing radiation results in the specific phosphorylation of histone H2AX on serine residue 139, yielding a specific modified form named gamma-H2AX. An antibody prepared to the unique region of human gamma-H2AX shows that H2AX homologues are phosphorylated not only in irradiated mammalian cells but also in irradiated cells from other species, including Xenopus laevis, Drosophila melanogaster, and Saccharomyces cerevisiae. The antibody reveals that gamma-H2AX appears as discrete nuclear foci within 1 min after exposure of cells to ionizing radiation. The numbers of these foci are comparable to the numbers of induced DNA double-strand breaks. When DNA double-strand breaks are introduced into specific partial nuclear volumes of cells by means of a pulsed microbeam laser, gamma-H2AX foci form at these sites. In mitotic cells from cultures exposed to nonlethal amounts of ionizing radiation, gamma-H2AX foci form band-like structures on chromosome arms and on the end of broken arms. These results offer direct visual confirmation that gamma-H2AX forms en masse at chromosomal sites of DNA double-strand breaks. The results further suggest the possible existence of units of higher order chromatin structure involved in monitoring DNA integrity.

Animals↗
PubMed1999

Feedforward versus feedback control in children and adults subjected to a postural disturbance.

Any action performed by standing subjects is generally accompanied by compensatory postural activities, which reduce or abolish the postural disturbance generated by the movements and keep the subjects' center of gravity within the supporting base. These postural activities are triggered by either anticipatory and/or feedback-based control processes, depending on the information available and on the behavioral context. To investigate the respective involvement of these two components in postural control during development, we studied the extent to which the postural equilibrium of children (3-to 10-year-olds) and adults was disturbed by the same physical event, an unloading, depending on whether it was initiated by the subject or externally imposed. The subjects were standing on a force platform with their eyes closed, holding a load (5% of their own body weight) in their hands, with arms vertical and forearms horizontal. Two conditions were applied: (1) the subjects voluntarily released the load and (2) the load was unpredictably removed. The unloading resulted in a backward movement of the center of pressure, which was smaller with self-initiated than imposed disturbances in all age groups. This difference varied depending mainly on the age-related changes in the relative amplitude of the self-initiated disturbance, which decreased between 3- to 5-, and 6- to 8-year-olds (who showed no marked postural instability after self-initiated unloading), and increased again in the two older groups (9- to 10-year-olds and adults), in which it also became more consistent It was concluded that feedforward control. becomes more efficient as children grow up, but that its relative contribution to postural control does not show a monotonic pattern of development.

Adult↗
PubMed1998

Efficient antibody generation using histone H1 subfractions purified from western blots.

Linker histones from grapevine were purified by electrophoretic methods (SDS-PAGE and electrotransfer onto a nitrocellulose sheet). Individual linker histones were recovered after nitrocellulose solubilization by acetone. The proteins precipitated after this treatment were used as antigen for subsequent immunizations of mice. Such purified immunogens were injected into mice with dimethyl sulfoxide, as the presence of nitrocellulose-protein complexes in the antigen pellets after the acetone treatment was suspected. The resulting antisera were specific to the injected antigens after only the first immunization and could be used as specific probes in immunohistological studies. Our approach seems more efficient (in using less antigen and obtaining a faster response) than the classical procedure recommended for histones in general (B. D. Stollar and M. Ward, 1970, J. Biol. Chem. 245, 1261-1266) and other methods that use free linker histone as immunogen.

Animals↗
PubMed1998

Assessment of fibre orientation in reinforced concrete using Fourier image transform.

In this study, ribbon-shaped amorphous cast-iron fibres were used to reinforce a concrete matrix. X-ray photographs have been taken to detect fibres in situ. Their orientation has been investigated by automatic image analysis methods. However, this measurement should not be influenced by the digitization on the square frame of the analyser. For that purpose, the Fourier transform was used rather than the rose of direction method. This analysis revealed the transverse isotropic nature of the spatial arrangement of these fibres, whose axis of revolution corresponds to the concrete casting axis. Such a morphological characterization of the fibre-reinforced concrete reveals its mechanical behaviour.

Journal Article↗
PubMed1991

Proprioceptive control of goal-directed movements in man, studied by means of vibratory muscle tendon stimulation.

The purpose of this study was to investigate the role of propriomuscular feedback in the control of pluriarticular pointing movements, performed without visual feedback toward visual targets. The proprioceptive inputs were distorted during movements by applying vibration to the distal tendon of the biceps muscle. Various movement and vibration durations were imposed. The results show that vibration affects the spatial outcome of the movements. The effects of vibration were movement time-independent when the durations were shorter than 450 ms and became movement time-dependent with longer durations. Moreover, the effects of vibration became more marked when a short vibration was applied at the end rather than at the beginning of a slow movement. These studies suggest that at least two types of proprioceptive control loops may be involved in correcting this kind of movement, depending on the execution time. In slow movements, the final phase might be a privileged period for on-line, propriomuscular-based corrections. Lastly, it emerged that the regulation of a goal-directed movement on the basis of proprioceptive feedback processing can take place within at most 200 ms.

Journal Article↗
PubMed1990

Non-hormonal and hormonal control of glycogen metabolism in isolated sheep liver cells.

1. Control of glycogen metabolism by various substrates and hormones was studied in ruminant liver using isolated hepatocytes from fed sheep. 2. In these cells glucose appeared uneffective to stimulate glycogen synthesis whereas fructose and propionate activated glycogen synthase owing to (i) a decrease in phosphorylase a activity and (ii) changes in the intracellular concentrations of glucose 6-phosphate and adenine nucleotides. 3. The activation of hepatic glycogenolysis by glucagon and alpha 1-adrenergic agents was associated with increased phosphorylase a and decreased glycogen synthase activities. 4. The simultaneous changes in these two enzyme activities suggest that in sheep liver, activation of phosphorylase a is not a prerequisite step for synthase inactivation. 5. In sheep hepatocytes, in the presence of propionate and after a lag period, insulin activated glycogen synthase without affecting phosphorylase a. 6. This latter result suggests that the direct activation of glycogen synthase by insulin is mediated by a glycogen synthase-specific kinase or phosphatase. Insulin also antagonized glucagon effect on glycogen synthesis by counteracting the rise of cAMP.

Animals↗
PubMedDate not supplied

[Fractionated stereotactic radiotherapy: results in hypophyseal adenomas, acoustic neurinomas, and meningiomas of the cavernous sinus].

PURPOSE: In order to optimize cerebral benign tumor irradiation, fractionated stereotactic radiotherapy allows a focused-volume irradiation (2.1 cm3, 16 mm diameter) under standard fractionation conditions. Results of a retrospective and multicentric analysis are presented. PATIENTS AND METHODS: Fractionated stereotactic radiotherapy uses the ballistic principles of the radiosurgery: stereotactic localization, multi-beam irradiation, secondary collimation, three-dimensional dosimetry. Standard fractionation is possible with a re-locatable non-invasive stereotactic device. The technique has been used for treating pituitary adenomas (86 patients), acoustic neuromas (32 patients) and cavernous meningiomas (26 patients). RESULTS: 1) pituitary adenomas: cumulative tumoral objective-response rates (42 patients) were respectively 42%, 69% and 88% at 24, 48 and 60 months. The cumulative endocrinologic objective-response rates (32 patients) were respectively 53%, 75% and 85% at 24, 48 and 60 months. The cumulative risk of radio-induced hormonal deficiency varied from 18% (growth hormone [GH]) to 42% for TSH (thyroid stimulating hormone) at 48 months. No other complication was observed; 2) acoustic neuromas: 33 tumors, < 25 mm in diameter, were treated in 32 patients. Tumor control was observed in 29/33 tumors: 14 were stable, 15 decreased and three progressed. Useful hearing was maintained in 9/10 patients. Only three patients (9%) presented persistent complications; 3) cavernous meningioma: 17/19 clinical responses were noted, 20 tumoral stabilisations, one partial response and one progression (22 magnetic resonance imaging [MRI] evaluable patients). One unilateral radio-induced blindness was observed. CONCLUSION: For these benign tumors, the focused target volume obtained by the fractionated stereotactic radiotherapy seems to be better adapted to the treatment of limited benign tumors than standard radiotherapy. The use of standard fractionation reduces the risk of severe normal tissue damage, sometimes observed for radiosurgery and inherent in the use of single fraction.

Adenoma↗