A laser-based system to heat nuclear fuel pellets at high temperature.

Annealing tests are of utmost importance in nuclear fuel research, particularly to study the thermophysical properties of the material, microstructure evolution, or the released gas as a function of temperature. As an alternative to conventional furnace or induction annealing, we report on a laser-heating experiment allowing one to heat a nuclear fuel pellet made of uranium dioxide, UO2, or potentially other nuclear fuel pellets in an isothermal and controlled manner. For that purpose, we propose to use an indirect heating method based on a two compartment tungsten crucible, one containing the sample and the other acting as a laser susceptor for efficient and homogeneous heating of the assembly. With this concept, we demonstrate the heating of UO2 samples up to 1500 °C at a maximum heating rate of 30 °C/s with the use of two 500 W lasers. The system is, however, scalable to higher heating rates or higher temperatures by increasing the laser power up to few kW. The experiment has been designed to heat a pressurized water reactor fuel pellet, but the concept could be easily applied to other sample geometries or materials.

An experimental platform for real-time measurement of the deformation of nuclear fuel rod claddings submitted to thermal transients.

We report on experimental development and qualification of a system developed to detect and quantify the deformations of the cladding surface of nuclear fuel pellet assemblies submitted to heat transient conditions. The system consists of an optical instrument, based on 2 wavelengths speckle interferometry, associated with an induction furnace and a model pellet assembly used to simulate the radial thermal gradient experienced by fuel pellets in pressurized water reactors. We describe the concept, implementation, and first results obtained with this system. We particularly demonstrate that the optical system is able to provide real time measurements of the cladding surface shape during the heat transients from ambient to high temperatures (up to a cladding surface temperature of 600 °C) with micrometric resolution.

Fluorouracil combined with the pure (6S)-stereoisomer of folinic acid in high doses for treatment of patients with advanced colorectal carcinoma: a phase I-II study.

BACKGROUND: Potentiation of the antitumor activity of fluorouracil (5-FU) by folinic acid has been demonstrated in patients with colorectal adenocarcinoma. Modulation is due to the interaction of thymidylate synthase, fluorodeoxyuridine monophosphate, and methylene tetrahydrofolate, which leads to the formation of a stable ternary complex with concomitant enzyme inactivation. Folinic acid consists of a mixture of equal parts of two stereoisomers differing in chirality at the C-6 carbon of the pteridine ring. Only the levorotatory (6S)-stereoisomer of folinic acid is transformed into active folate cofactors. However, the (6R)-stereoisomer of folinic acid is not inert; it was shown to interfere with the (6S) form at the cellular level. PURPOSE: The possibility of a deleterious effect of the unnatural stereoisomer on the modulation of 5-FU led us to carry out a phase I-II study of 5-FU combined with the (6S)-stereoisomer of folinic acid given in high doses for treatment of patients with advanced colorectal carcinoma. We also determined the plasma pharmacokinetics of folates after intravenous (IV) injection of (6S)-folinic acid at the dose used in this study. METHODS: Treatment consisted of 5-FU (350-550 mg/m2 per day by IV infusion for 2 hours) and (6S)-folinic acid (100 mg/m2 per day by IV bolus injection) given for 5 consecutive days; the treatment was repeated every 21 days. Twenty-five patients with advanced colorectal carcinoma, who had had no prior chemotherapy, were evaluated for antitumor activity. The quantity of folates in plasma was measured using a microbiological assay. RESULTS: The median follow-up time was 9 months (range, 3.5-15.2 months). The response rate was 52% (complete response, 12%; partial response, 40%). The median time to disease progression for responding patients was 9.2 months (range, 5.9-15+ months). The estimated probability of survival at 12 months was 73%. Palliative improvement in quality of life was achieved in most patients who had symptoms due to the tumor before the start of treatment. The dose-limiting toxic effects were grade 3 diarrhea, dermatitis, and oral mucositis. Grade 4 toxicity did not occur. Myeloid toxicity was minor. After IV injection, (6S)-folinic acid was rapidly cleared from plasma (mean half-lives: alpha = 7.2 minutes and beta = 126 minutes). The mean concentration of the unchanged compound 2 hours after injection was 5.8 mumol/L. CONCLUSION: The (6S)-form of folinic acid potentiates the antitumor effect of 5-FU given concomitantly. IMPLICATION: Our results justify a more complete exploration of the pure active stereoisomer as a modulator of the fluoropyrimidines.

Pepstatin analogues as novel renin inhibitors.

Pepstatin analogues corresponding to the general formula A-X-Y-Sta-Ala-Sta-R were synthesized in solution phase. Various changes in the nature of the A, X, and Y groups were made to improve the inhibitory potency against human plasma renin activity. The results were interpreted by use of the active-site model based on the sequence of human angiotensinogen. The tert-butyloxycarbonyl group and the isovaleryl group were found to be the most effective acyl groups (A). The analogues having a Phe residue in place of Val1 (X) and His or amino acid with an aliphatic side chain such as norleucine or norvaline in the Y position showed the highest inhibition of human plasma renin activity with IC50 values of about 10(-8)M. Esterification or amidification of the carboxyl group of the C-terminal statine did not change the inhibitory potency. The selectivity for rat, dog, pig, and monkey plasma renin of the most interesting compounds was studied.

Kidney mobility during respiration.

Radiotherapy treatment planning needs optimum definition of the target volume in its relative position to normal tissue. The motion of the kidneys during respiration has not been well quantified. They move in a tilted coronal and sagittal plane. Using fast MRI while patients held their breath we quantified the movements of the kidneys. Fourteen patients volunteered for the study. Nine MRI images of the kidneys for one volunteer were done: three in the axial plane (all in deep inspiration) and six in the coronal plane (three in deep inspiration, three in deep expiration). The maximal vertical motion of the superior pole from its end-expiratory to its end-inspiratory position is 39 mm (43 mm for the inferior pole). In deep inspiration or deep expiration the positions of the right and left kidneys appear reproducible. The mean deviation of kidney movement is less than 4 mm in all three dimensions (range, 0-6.9). For tumors close to the kidney, we advocate respiration gated radiation therapy so as to minimize the movement of this very radiosensitive structure.

Posterolateral approach and anterior spinal canal recalibration in severe spinal injury affecting T-12, L-1: a study of seven cases.

The authors present seven cases of spinal trauma at the T-12--L-1 level with severe spinal canal stenosis secondary to compressive, anterior discocorporeal lesions. Associated neurological disorders were of varying severity. Six cases were investigated by computed tomography, which enabled the degree of thoracolumbar spinal canal stenosis to be determined. In all cases, the surgical procedure involved rectification of spinal deformity, with an initial unilateral posterolateral approach permitting anterior spinal canal recalibration, either by impaction of protrusive fragments or ablation of ejected disc fragments. The stabilization was in all cases achieved by complimentary bilateral plates using Roy-Camille material, associated with posterolateral arthrodesis by grafting with reconstruction of the articulopedicular structure. The functional spinal result was excellent in all cases, and recalibration was verified by tomography. In those cases showing neurological deficiency, good and early recovery was attributable to the suppression of spinal canal stenosis. The application of this posterolateral approach for severe lesions of the thoracolumbar junction seems to represent, in all cases of recent lesions, an alternative to the anterior or combined methods, which present widely recognized difficulties at the thoracoabdominal junction.

[A new method for determination of renin inhibitors]. / Une nouvelle méthode de dosage des inhibiteurs de rénine.

To determine the concentration of renin inhibitors in plasma or other biological fluids, we developed an original approach to the already existing methods, such as HPLC or radio-inhibitor binding and enzyme inhibitor assays. We made an antigen-antibody complex by linking human renin (0.8 nM) to a specific monoclonal antibody fixed to magnetic spheres (3E8-magnogel). A binding technique with 3H-43845 (4 nM) was applied to this preparation to assess the association and dissociation kinetics of SR 43845, a highly potent and specific renin inhibitor. Standard curves were built and CI50 was 0.53 +/- 0.07 nM (n = 5). One of the application of this method is the biochemical characterization of renin inhibitors. We close several various chemical structure renin inhibitors having the inhibiting activity of 0.01 to 10,000 nM (CI50 human PRA). Preliminary results show a good correlation (r = 0.97; n = 12) with those obtained in plasma. In other respects, this new assay was applied to determine SR 43845 plasma concentrations in human pharmacokinetic studies and in primate pharmacological studies. The limit of detection was 0.09 ng/ml. Finally, it is now possible to perform a relationship between plasma concentrations of renin inhibitor and blood pressure changes or other biochemical parameters changes to allow a better understanding to the renin-angiotension system.

[Hypotensive effect of a human anti-renin monoclonal antibody (4G1D8) in the sodium-depleted alert marmoset]. / Effet hypotenseur d'un anticorps monoclonal anti-rénine humaine (4G1D8) chez le marmouset vigile désodé.

A dose-response relationship was involved after an intravenous bolus of a human antirenin monoclonal antibody (4G1D8), in sodium depleted marmosets. The sodium depletion (furosemide: 30 mg/kg/d for 2 days) was used to potentiate the contribution of the renin-angiotensin system in the blood pressure (BP) control. To record BP and inject the antibody, 2 catheters were implanted the day before the experiment. The plasma renin activity (PRA) was measured by the RIA of angiotensin I after an incubation of plasmas for 1 hour at pH 7.4. The sodium depletion induced a dramatic increase of PRA (63.68 +/- 20.03 ng/ml/h of angiotensin I compared to 2.96 +/- 1.03; p less than or equal to 0.01; n = 13). The basal BP was 102.6 +/- 2.4 mmHg (n = 17). The maximal fall in BP was noted at about 30 min for the three groups of animals treated by 4G1D8; it was -7.5 +/- 4.3 mmHg at the dose of 0.01 mg/kg (n = 4), -21.3 +/- 3.8 mmHg (p less than or equal to 0.01) at 0.10 mg/kg (n = 4), and -27.5 +/- 1.4 mmHg (p = 0.10) at 0.24 mg/kg (n = 4). At the 0.10 and 0.24 mg/kg doses, the hypotension was lasting (greater than 3 h). PRA was strongly inhibited and HR was little modified. A dose-response relationship with a human antirenin monoclonal antibody, 4G1D8, provides a very interesting pharmacological model for a comparative study of renin inhibitors.

[Primary dural lymphoma: a report of two cases with review of the literature]. / Lymphome dural primitif: à propos de deux cas et revue de la littérature.

Primary lymphoma arising in dura is exceedingly rare. We report the clinicopathologic findings of two patients with primary B-cell lymphoma of dura. Both were female, 38 and 45 years old. Prior to biopsy they were felt to have meningioma on preoperative magnetic resonance imagery. Histologically, tumors were classified as MALT-type lymphoma. Literature describe only 14 reports of similar entity. Primary lymphomas arising in dura appear to have a more favourable clinical course compared to PCNSL and may require a less aggressive treatment.

[Desmoid tumors of the mesentery in Gardner's syndrome. Value of x-ray computed tomography]. / Les tumeurs desmoïdes du mésentère dans le cadre du syndrome de Gardner. Intérêt du scanner.

3 cases of desmoid tumours of the mesentery occurring as part of Gardner's syndrome are reported. In 2 cases, CAT scanning was carried out. We underline the value of this examination compared to other imaging methods. It allows the establishment of a diagnosis, investigation for complications, the operability to be assessed and is useful for monitoring patients. Its major value is in avoiding an unnecessary laparotomy, a factor certain to produce recurrence, in certain patients. Other alternative therapy may then be proposed.

[Digestive carcinoid tumors]. / Tumeurs carcinoïdes digestives.

Three examples of intestinal carcinoid tumours are reported. As the signs in conventional radiology are non-specific and inconstant, the computed radiographic signs are stressed. Small bowel examination showed both direct signs, with intraluminal filling defects, and indirect signs with separated bowel loops, sometimes angulated and fixed. In one unusual case, all the jejunal loops were affected. On CT the specific finding was a retractile mesenteric infiltration.

[Diffuse peritoneal lymphoma in AIDS]. / Lymphome péritonéal diffus au cours d'un SIDA.

We report an unusual observation of peritoneal localisation in a non-Hodgkin lymphoma, the only sign of digestive injury. This peritoneal injury may be more frequent with AIDS patients, as in our observation. Tomodensitometry was the best exam to visual this injury.

[Contribution of computer tomography in recent traumatology of the spine. Apropos of 31 cases]. / Apport de la tomodensitométrie en traumatologie récente du rachis. A propos de 31 observations.

The authors report 31 cases of recent spinal injury (14 cervical, 17 thoraco-lumbar) which have been investigated using computerized tomography. After a critical appreciation of the conventional approach to such lesions, the authors consider the advantages and limitations of computerized tomography. Analysis of the data from 31 cases studies confirms that this technique has considerable applications in the assessment of corporeo-discal and pediculo-lamar lesions and, in particular in the determination of the degree of spinal canal stenosis and in the detection of actual potential neuroaggressive factors which are important for the choice of therapy. Computerized tomography provides information which is essential in choosing the surgical strategy to be adopted in each case, and in particular allows determination of the best approach and of the time scale for successive operations in the case of a double approach. On the other hand, computerized tomography alone does not permit precise determination, either of the degree of instability of spinal lesions or of the magnitude of static deformations.

[Traumatic injury affecting the extracranial portion of internal carotid artery (17 case reports) (author's transl)]. / Les lésions traumatiques fermées de la carotide interne au cou. A propos de 17 cas.

The authors analyse the detailed clinical course in an homogenous review of 17 cases reports of traumatic injury affecting the extracranial portion of internal carotid artery. Only cases in which there were neither cervical perforating wound nor atheromatous predisposing lesion were considered. As in cases reported in the literature, the young age of these patients, with prevalence in the second decade and in men, was attributable to the etiology. Circumstances in which diagnosis was established induce to discern two unequal groups, according as there was either a coma or immediate focal signs, or a delayed symptomatology : it occured most frequently after a free interval shorter than 48 hours, and reaching in the extrema (one instance) 40 days. Brachiofacial hemiparesis was the most frequent clinical picture. Doppler investigation was able to detect, with a rather satisfying reliability, anomalies in the carotid flow before angiography ; angiogram showed lesions nearly always facing first or second cervical vertebra and bilateral lesions in four instances. Injuries consisted in dissecting aneurysm with stenosis aspect much more often than in thrombosis. In a third of cases distal ischemic lesions below dissecting aneurysm were noted. Prognosis in these cases is very poor since eight patients in our series died without any possibility of expectation according to clinical or angiographical data. Medical therapeutics were disappointing, and this induced to consider an extension in preventive realization of extra-intracranial by pass, each time diagnosis is established and patient is lucid. Etiopathogenical aspect is the originaler part of this study, since we could precisely approach incriminated mechanisms in a methodic analysis of impacts and their results. In our review cranial or facial shock was constantly noted, always frontal and often mild. In II cases association to a frontal and upper thoracic traumatism was found ; safety belt may have been responsible in part, in the mechanism of fixation of upper thoracic orifice, in most cases where this thoracic impact seemed to be missing. Thwarted stretching of carotid artery seems to be the necessary condition for occurring of an intimal tear. Other mechanisms like direct cervical shock may certainly be found, but we did not observe any instance in this review.

[The double approach in recent cervical injury. Indications apropos of 15 cases and a review of the literature]. / Le double abord en traumatologie cervicale récente. Indications à propos de 15 cas et revue de la littérature.

The authors presented 15 cases of recent spinal cervical injuries treated with double approach procedure. Neurological disorders were variable but instability was severe in all cases. In 11 cases with severe neurological disorders the anterior procedure was made immediately, in 4 cases secondary with one or two sequences. In all cases was made discectomy and arthrodesis or removal vertebral body and arthrodesis associated with a posterior stabilization using generally bilateral plates of Roy-Camille. The functional spinal results were excellent with immediate or early mobilisation. In 4 cases with incomplete quadriplegia was observed favorable recovery. In 9 cases with complete quadriplegia two excellent recovery are obtained.

[Effects of cranioplasty on neurological function and cerebral blood flow]. / Incidence des crânioplasties sur la fonction neurologique et le débit sanguin cérébral.

The authors present a review of their experience of cranioplasty in cases showing of skull defects. Forty recent case reports were retained out of a total of 125 cases and of these, 15 showed neurological deficiency prior to cranioplasty. In 7 out of these 15 cases cranioplasty appeared to have no effect, but in the 8 remaining cases, an improvement in the neurological condition was observed. In connection with these clinical observations, a recent study of a small group of patients with skull defects used the Xenon 133 inhalation method to investigate cerebral blood flow. In all cases these was a significant postoperative improvement in cerebral blood flow. The rate varying from 15 to 30% and this improvement was even observable in the case of small skull defects of the order of 10 cm2. The mechanism giving rise to such improvements is discussed; it may be related to cerebral hemodynamic normalization after skull restoration. The improvement in cerebral blood flow brought about by cranioplasty in all the cases studied suggests that this technique may be important not only for simple skull repair but also to improve neurological function.

[Analysis of the results of surgery and nucleolysis using papain in 1085 cases of lumbar disk hernias]. / Analyse des résultats de la chirurgie et de la nucléolyse à la papaïne dans 1,085 cas de hernies discales lombaires.

1,085 patients have been treated for intervertebral disc herniation with lombo-sciatica: in 751 cases surgical discectomy without laminectomy has been performed with or without microscope; 334 underwent papain nucleolysis. The two clinical groups were separated on clinical and radiographic backgrounds: nucleolysis was performed in patients with no motor disturbance, no stenosis of the lumbar canal, no displaced fragment; the other patients received surgical treatment. The results were evaluated according to MacNab's criteria with a follow-up of 12 to 84 months (mean 17.2 months). The results after surgical treatment were excellent in 53.8% and good in 36.8% of the cases. For papain treatment they were excellent in 32.7% and good in 38.8% of the cases. Papain nucleolysis therefore appears to be an efficient method for the treatment of intervertebral disc herniations associated with lombo-sciatica but, overall, gives poorer results than surgery in spite of a strict selection procedure. In this study, complications due to papain nucleolysis were restricted to chemical spondylodiscitis (5 cases) and to 2 benign allergic syndromes. Statistical analysis of all the cases and multifactorial correlation research pointed out the importance of "workmen's compensation" as prognostic factor. Since this study, 90% of the patients presenting with disc herniation associated with lombo-sciatica recalcitrant to medical treatment undergo surgical discectomy; papain nucleolysis is reserved for sub-ligamentary and non-displaced forms without stenosis of the lumbar canal and represent 10% of our current population.

[Recalibration via a postero-lateral approach in recent traumatic stenosis of the dorsal and lumbar spine. Modalities and results apropos of 31 cases]. / Recalibrage par voie postéro-latérale des sténoses traumatiques récentes du rachis dorsal et lombaire. Modalités et résultats à propos de 31 observations.

The authors present 31 cases of spinal trauma affecting thoraco lumbar level with severe spinal canal stenosis secondary to compressive trauma of the anterior disco-corpereal region. Associated neurological disorders were of varying severity. 23 cases were investigated by computed tomography. In all cases, the surgical procedure involved rectification of spinal deformities, with initially a unilateral postero-lateral approach permitting anterior spinal canal recalibration, either by impaction of protrusive fragments or ablation of free disc fragments. The stabilization was usually achieved by complementary bilateral plates using Roy-Camille or Privat material in 22 cases, associated with postero-lateral arthrodesis by grafting with reconstruction of the articulo-pedicular structure in 19 cases. Emergency operation was done in 14 cases; in 5 cases operation was done on the 2nd or 3rd day and in 11 cases after the 3rd day. The functional spinal result was excellent, and recalibration was verified by tomography in all cases. In those cases showing neurological deficiency, good and early recovery was attributable to the suppression of spinal canal stenosis, and a consequently neurological improvement was always obtained, even for the most serious of lesions except those at the thoracis level superior to T10. The application of this postero-lateral approach for severe spinal trauma seems to represent, in all cases of recent lesions, an alternative to the anterior or combined methods. We do not share the opinion that delay in decompression does not influence the neurological prognosis and emergency operation is advisable.

[Chemonucleolysis in the treatment of surgical sciatica]. / La chémonucléolyse dans le traitement des sciatiques chirurgicales.

Enzymatic dissolution of nucleus pulposus by percutaneous injection of a papain preparation is now used frequently to treat lumbosacral disc hernias responsible for resistant sciatica. Mechanisms of action and techniques are reviewed, and the importance of applying strict criteria for indications for use emphasized. The method should be reserved for nerve root sciatica resistant to medical treatment or physiotherapy, and it constitutes the last stage of conservative treatment. Exclusion criteria are mainly "excluded" disc lesions, major dysfunction or associated spinal vertebral canal stenosis. The optimal indication is represented by the subacute disc hernia in the young. This alternative to open surgery in no way compromises the results in case of failure. Results obtained in a personal series of 150 cases are analyzed comparatively with those reported in the literature.

[Digestive carcinoid tumors]. / Tumeurs carcinoïdes digestives.

Three examples of intestinal carcinoid tumours are reported. As the sign in conventional radiology are non-specific and inconstant, the computed radiographic signs are stressed. Small bowel examination showed both direct signs, intraluminal filling defects, and indirect signs with separated bowel loops, sometimes angulated and fixed. In one unusual case, all the jejunal loops were affected. On CT the specific finding was a retractile mesenteric infiltration.