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.

[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.

Suprasellar seeding of a benign choroid plexus papilloma of the fourth ventricle with local recurrence.

A suprasellar location of a benign choroid plexus papilloma is reported. Local recurrence within the fourth ventricle was also present, 8 years after apparently complete removal. Imaging and histological findings were similar to those of the initial lesion. At surgery, the suprasellar lesion had no connection with the ventricular system. Seeding of choroid plexus papillomas is discussed, and the pertinent literature reviewed.

Recurrent intracranial neurenteric cysts.

Neurenteric cysts are cystic lesions lined by a columnar epithelium of endodermal derivation. They are rarely located in the central nervous system. We describe the case history of two recurrent neurenteric cysts located within the posterior fossa: one in the 4th ventricle and the second in the cerebellopontine angle. The literature is reviewed and the follow-up and recurrence of such cysts are discussed.

[A new, more invasive approach in the radiation diagnosis of breast cancer]. / A korai emlörák legújabb szemléletü, fokozottan invazív radiológiai diagnosztikája.

The authors discuss the state-of-the-art techniques and the increasingly invasive approach to the diagnosis of breast diseases and also summarise their own experiences. Special attention is called to the nonpalpable, preclinical stage of breast cancers. The newest techniques like MR-mammography, stereo-taxic and ultrasound directed cytology and core biopsy are demonstrated, as well as the present place of traditional breast imaging methods: mammography and diagnostic ultrasound. The preoperative localisation of nonpalpable cancers improves the safety of surgical procedures. The authors emphasize the importance of the detection of early breast cancer, for the sake of a more favourable prognosis compared to that of the palpable, advanced cases. The results of mass screening is detailed, based on statistical data.

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.

[Brain metastasis of a cutaneous neuroendocrine carcinoma. Apropos of a case]. / Métastase cérébrale d'un carcinome neuroendocrine cutané. A propos d'une observation.

The authors report the case of a 69-year-old woman with a brain metastasis from a cutaneous neuroendocrine carcinoma. The initial lesion was situated on the leg. No other secondary lesion was found. The cutaneous neuroendocrine carcinoma was initially considered to be a locally malignant tumor. In fact, it is frequently complicated by metastases. However, brain secondaries remain rare.

[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.

[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.

[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.

5-Fluorouracil combined with the [6S]-stereoisomer of folinic acid in high doses for treatment of patients with advanced colorectal carcinoma. A phase I-II study of two consecutive regimens.

BACKGROUND: Potentiation of the antitumor activity of 5-fluorouracil (5-FU) by folinic acid has been demonstrated in patients with colorectal adenocarcinoma. Modulation is due to the interaction of thymidylate synthase (TS), fluorodeoxyuridylate (FdUMP), and methylene tetrahydrofolate (5,10-CH2-FH4), 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 C6 carbon of the pteridine ring. Only the levorotatory [6S]-folinic acid is transformed into active folate cofactors. However, the [6R]-stereoisomer is not inert; it was shown to interfere with the [6S] form at the cellular level. The possibility of a deleterious effect of the unnatural stereoisomer on the modulation of 5-FU led us to carry out 2 consecutive phase I-II studies of 5-FU combined with the [6S]-stereoisomer of folinic acid given in high doses for treatment of patients with advanced colorectal carcinoma. PATIENTS AND METHODS: Treatment comprised 5-FU by i.v. infusion for 2 hours (the initial dose was 350 mg/m2/d; it was incremented by 25 mg/m2/d until a maximal dose of 550 mg/m2/d) and [6S]-folinic acid (100 mg/m2/d by rapid i.v. injection in Regimen 1, and 100 mg/m2 by rapid i.v. injection followed by a 2-hour infusion of 250 mg/m2 in Regimen 2) for 5 days, every 21 days. Twenty-five pts and 27 pts were assessed in Regimen 1 and in Regimen 2, respectively. They had had no prior chemotherapy. The median follow-up time was 9 months and 15.5 months for patients treated with Regimen 1 and Regimen 2, respectively. For pts treated with Regimen 1, the response rate was 52% (CR, 12%; PR, 40%). The median time to disease progression was 9.2 months. The probability of survival at 12 months was 73%. For pts treated with Regimen 2, the response rate was 37% (CR, 7%; PR, 30%). The median time to disease progression was 8.9 months. The probability of survival at 12 months was 67%. 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 (WHO grades > or = 3) were diarrhea, dermatitis, and mucositis. One single episode of grade 4 diarrhea occurred. After injection according to the schema in Regimen 1, [6S]-folinic acid was rapidly cleared from plasma (mean t 1/2 alpha and t 1/2 beta of 7.2 and 126 minutes, respectively). The mean concentration of the [6S]-stereoisomer two hours after injection was 5.8 mmol/L. After a rapid i.v. injection of 100 mg/m2 followed by a 2-hour infusion of 250 mg/m2, the mean concentration of [6S]-folinic acid two hours after the injection was 57.5 mmol/L. Pharmacokinetic data suggests saturation of the metabolic conversion of [6S]-folinic acid when large doses are administered. CONCLUSION: The [6S]-form of folinic acid potentiates the antitumor effect of 5-FU given concomitantly. However, increase of the daily dose of the folate did not result in a therapeutic improvement. The present results justify a more complete exploration of the pure active stereoisomer as a modulator of the fluoropyrimidines.

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.

[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.

New technique for posterior intra-articular arthrodesis using a single-block graft in cases of atlantoaxial instability. Case report of unstable atlantoaxial rotatory luxation in a 10-year-old girl.

A new method of posterior C1-2 arthrodesis, derived from the W.V. Cone and G. Bertrand, technique (Montreal, 1970) is described with two modifications: (1) the exact measurements of the ideal graft are determined preoperatively, using CT and a sterilized pasteboard horseshoe-shaped model; (2) in the sitting position, single occipital block graft was cut out microsurgically, using the preoperative model. After decortication of the graft, posterior arches of C1 and 2, and microsurgical excision of the cartilage of the C1-2 lateral joints, the graft was imbedded into the entire C1-2 space, fixed, and tightened using a braid of "nylacap" yarn. A case report of rotatory luxation and associated atlantoaxial instability in a 10-year-old girl illustrates the excellent functional results of this technique.

[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.

[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.

A multicenter, double-blind, placebo-controlled trial of the efficacy of prazosin in the treatment of dysuria associated with benign prostatic hypertrophy.

An 8-center, double-blind, placebo-controlled trial of 39 patients with benign prostatic hypertrophy was conducted to assess the effects of prazosin HCl treatment on functional urologic variables after a treatment period of 4 weeks. The randomized groups were comparable for demographic variables and symptoms, except for the mean residual urinary volume, which was significantly higher in the prazosin HCl group. Prazosin HCl elicited statistically significant improvements in the mean prostatic urethral pressure and prostate area (Mann-Whitney U test: p = 0.001 for both variables as compared with the placebo group). Functional bladder capacity also improved significantly in the group receiving the test drug (Mann-Whitney U test: p = 0.05, as compared with the placebo group). Clinical improvements were also observed in the mean maximum urinary flow, decreased nocturia frequency, and residual urinary volume. Patient preference significantly favored the prazosin HCl treatment (Mann-Whitney U test: p = 0.001). Seven patients on prazosin HCl and 5 receiving placebo reported one or more side effects during the trial phase; these were mild to moderate and disappeared or were tolerated. No statistically significant effects on blood pressure or heart rate were observed.