Evaluation of Low Dose Silicon Carbide Temperature Monitors

Thermocouples are generally used to provide real-time temperature indications in instrumented tests performed at materials and test reactors. Melt wires or paint spots are often included in such tests as an independent technique of detecting peak temperatures incurred during irradiation. In addition, less expensive static capsule tests, which have no leads attached for real-time data transmission, often rely on melt wires and paint spots as a post-irradiation technique for peak temperature indication. Unfortunately, these techniques are limited in that they can only detect whether a single temperature is or is not exceeded. Silicon carbide (SiC) monitors are advantageous because a single monitor can be used to determine the peak temperature reached within a relatively broad range (200 – 800°C). Although the use of SiC monitors was proposed more than five decades ago, the ultimate performance limits of this technique are not fully understood. The Nuclear Science User Facilities (NSUF) is the United States Department of Energy Office of Nuclear Energy's only designated nuclear energy user facility. Its mission is to provide nuclear energy researchers access to world-class capabilities and to facilitate the advancement of nuclear science and technology. This mission is supported by providing access to state-of-the-art experimental irradiation testing, post irradiation examination facilities, and high performance computing capabilities as well as technical and scientific assistance for the design and execution of projects. As part of an NSUF project, low dose silicon carbide monitors were irradiated in the Belgian Reactor 2 and were then evaluated both at the SCK•CEN and at Idaho National Laboratory’s High Temperature Test Laboratory to determine their peak temperature achieved during irradiation. The technical significance of this work was that the monitors were irradiated to a dose that was significantly less than recommended in published literature. This paper will discuss the evaluation process, the irradiation test, and the performance of the low dose silicon carbide temperature monitors.

Comparative assessment of hypothalamic-pituitary-adrenal axis suppression secondary to intrabursal injection of different glucocorticoids: a pilot study

BACKGROUND

Hypothalamic-pituitary-adrenal axis (HPAA) suppression is the most common and dangerous, although often unrecognized and untreated, side effect of glucocorticoid administration. The risk and duration depend both on patient and treatment characteristics. High-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) currently represents the gold standard method to evaluate the metabolism of endogenous and exogenous steroids.

OBJECTIVE

To assess prevalence, severity, and duration of HPAA suppression subsequent to the injection of two steroids with equivalent potency but different pharmacokinetics.

SUBJECTS AND METHODS

Single-blind randomized case-control pilot study. Forty patients (22 F; age 48.7 ± 7.2 years) with shoulder calcific tendinopathy received an intrabursal injection of 40 mg of 6α-methylprednisolone acetate (MA) or triamcinolone acetonide (TA). Just before (T0) and after 1 (T1), 7 (T2), 15 (T3), 30 (T4) and 45 (T5) days, we assessed morning blood cortisol and ACTH by RIA, and 24-h urinary levels of MA, TA and free cortisol by HPLC-MS/MS.

RESULTS

HPAA function was normal at baseline. At T1, all patients presented HPAA suppression reaching the lowest cortisol, ACTH and UFC levels, that were similar between groups. At T2, mean cortisol remained lower than at baseline (p < 0.0001) in the TA group. In both groups, mean cortisol and ACTH levels progressively normalized, suggesting HPA recovery, except for three patients in the MA and two in the TA group. UFC levels remained lower than normal (p < 0.0001) up to T5, despite the disappearance of exogenous GCs. No patient developed manifestations of hypocortisolism.

CONCLUSIONS

A single 40-mg intrabursal injection of MA or TA is sufficient to suppresses HPAA up to 45 days. Although typically asymptomatic, patients should be instructed to recognize and report symptoms suggestive for hypocortisolism, to provide prompt diagnosis, and eventually, treatment, thus avoiding severe complications.

Staging, Therapy and Prognosis of Primary Non-Hodgkin's Lymphoma of Bone and a Comparison of Results with Localized Ewing's Sarcoma: Ten Years Experience at the Istituto Ortopedico Rizzoli

Thirty consecutive cases of localized primary non-Hodgkin's lymphoma of bone (PNHLB) were treated in a 10-year period at the Istituto Ortopedico Rizzoli with localized radiation (4 cases) and localized radiation and adjuvant chemotherapy (26 cases). The doses of radiation varied from 3000-4500 rad. A variety of staging procedures evolving with new diagnostic techniques over the 10 years were performed. Adjuvant chemotherapy comprised two different regimens of vincristine, adriamycin and cyclophosphamide. Twenty-four of the 26 patients (92 %) have been free of disease with a median follow-up of 75.5 months (18-144 months). Two patients developed meningeal involvement and one patient, treated with radiation therapy only, developed a local recurrence. The results are compared to the management of 68 Ewing's sarcoma patients treated during the same period. Here, higher doses of localized radiation therapy (approximately 5000 rad) and similar adjuvant chemotherapy were administered. The survival was 32 % (22/68) with a higher incidence of local recurrence (21 %). These data indicate that PNHLB should be considered a separate entity from Ewing's sarcoma and can be treated successfully with lower doses of radiation to the primary tumor and adjuvant chemotherapy. The observations are also compared to a variety of other biological characteristics of Ewing's sarcoma. Since only two patients developed meningeal relapse, our experience does not permit a firm recommendation for routine prophylactic treatment of the central nervous system in PNHLB.

Solitary Plasmacytoma of the Vertebral Column. A Report of 15 Cases

The clinical features and the treatment results of 15 patients with solitary plasmacytoma of the spine observed in a 28-year period (1950–1977) are reported. The signs at presentation were back pain in 4 cases and spinal cord compression in 11 cases. Three of these patients had paraplegia. Radiologically, the alteration encountered was an osteolytic lesion in all cases. The local treatment was radiotherapy in 11 cases and surgery plus radiotherapy in 4 cases. In 3 patients systemic chemotherapy was also employed. Seven patients are alive without signs of disease 3 to 9 years (mean 6 years) after diagnosis. Eight patients developed multiple myeloma in a period ranging from 1 to 8 years (mean 3.5 years). The relationship between multiple myeloma and solitary plasmacytoma of the spine, as well as the best treatment for the latter, are discussed.

Autologous chondrocytes implantation: indications and results in the treatment of articular cartilage lesions of the knee

Articular cartilage lesions of the knee constitute a frequent event and one that is difficult to treat. In time, different surgical methods have been used with results that are often contradictory. The authors report the indications and results of different methods used in the treatment of cartilage lesions: in particular, the experience initiated in 1997 with autologous chondrocytes implantation is discussed. Between 1997 and 2000, a total of 40 patients were submitted to autologous chondrocytes implantation injected in suspension under a periosteal flap. This method includes wide exposure of the joint lesion by arthrotomy. Between 1999 and 2001, a total of 30 patients were submitted to autologous chondrocytes implantation using a tridimensional matrix. The availability of biomaterial simplified the implant method and made arthroscopy possible. All of the patients were submitted to serial clinical follow-ups. MRI was also conducted for a second arthroscopic look. The results obtained in both series after a mean follow-up of 4 years (range 2 to 6 years) are good, and confirm the effectiveness of the method that allows for complete morphological and structural repair of lesions of the joint cartilage.

Hip prosthesis revisions with LS stem: indications and results

The authors present a study that includes 350 patients affected with loosening of hip arthroplasty and submitted to revision with a Wagner LS stem at the 4th Division of the Rizzoli Orthopaedic Institute. Several different types of cotyle (Fitek, Wagner, Standard Cup, cemented cotyle with support ring, Octopus system) were used depending on the anatomopathologic findings, combined with autoplastic grafts. Staging and grading of loosening were based on the four G.I.R. grades. A clinical evaluation of results was based on the Merle D'Aubigné parameters modified by Charnley. For radiographic evaluation the De Lee Charnley areas were studied for cotyle, the Gruen areas for the femoral stem. Overall, good results were obtained in 175 patients, fair in 137, poor in 38.

Hip arthroplasty in coxarthrosis secondary to Paget's disease

A total of 5 hip arthroplasties implanted between 1997 and 2000 in 5 patients affected with coxarthrosis secondary to Paget's disease were reviewed. The quality of the pagetic bone (sclerotic and very vascularized) resulted in a slightly longer amount of time required for surgery because of the difficulty preparing prosthetic placement and intra- and postoperative blood loss exceeding the norm. Complications were not observed. Clinical results were good in 100% of cases. Radiographically, 2 stems were assembled in varus.

Survival analysis of transfused fetuses affected by Rh-alloimmunization

The aim of the present study was to evaluate the survival rate of a group of 86 fetuses affected by Rh-alloimmunization submitted to intrauterine red blood cell transfusion. All the women had antibody titres> or = 1:32 at the time of their enrollment in the study. Crude fetal survival rate was 89.5% (77/86 cases). Data were stratified according to specific cut-off points of (1) pre-transfusion fetal haemoglobin expressed as the rate between the observed and the estimated value for each gestational age at the time of the first transfusion; (2) the difference between the haemoglobin at the beginning of the second-transfusion less that at the end of the first transfusion (delta haemoglobin); and (3) presence of ultrasound detected anomalies. Statistically significant stratification of the survival rate was observed for the level of pre-transfusion fetal haemoglobin (95% and 76.9%, respectively, p= 0.009) using a cut-off value of < 70% and > or = 70% of the expected value. Again, delta haemoglobin showed a different survival rate when a cut-off value of 6 g/dl was used to generate subgroups of fetuses: 94.6% and 80%, respectively (p= 0.0145). Among the ultrasound anomalies, the presence of hydrops showed a correlation with the survival rates. The quoted values were 97.83% (absence) and 80.0% (presence) respectively (p= 0.0058). Cox regression showed a significant association of the studied variables with the outcome (survival). The presence of hydrops was the best predictor (Odds ratio= 8.7, p= 0.0073) followed by Delta haemoglobin (Odds ratio= 2.0, p= 0.0422). The rate of pre-treatment fetal haemoglobin < 70% of the expected value did not add any significant valu and was thus removed from the final model. Weight at delivery expressed in grams showed a direct correlation with the survival rate (Odds ratio= 0.9, p= 0.1529) and was added into the model as an adjustment quantitative variable.

Loss of bone mass after total hip replacement: preliminary data

In a total of 37 females with cemented total hip replacement for monolateral coxarthrosis, of which 13 with prosthetic stem loosening, and 11 with monolateral coxarthrosis that is not prosthetized, bone mineral density (BMD) is determined by dual ray photonic absorbimetry selecting regions of interest (ROI) on the cortex of the femurs 4 cm under the lesser trochanter and on the ischium bilaterally. In females that are not prosthetized there are differences in bone mass between the two femurs and the ischium on both sides. In prosthetized patients BMD of the femur and of the ischium on the side operated on is significantly less than on the contralateral one (Student's "t" test: p < 0.001). In patients with stable prostheses, BMD of the femur operated on is greater than that in females with prosthetic stem loosening (Student's "t" test: p < 0.000). Based on a comparison between these two groups we did not observe any other significant differences in BMD among the ROI analyzed. BMD was correlated with the amount of time since surgery only in the ROIs in prosthetized femurs. The study confirms the significant bone resorption of the cortex in prosthetized femurs and documents analogously significant reduction in BMD in the ischium on the side operated on. Finally, it indicates that prosthetic stem loosening may be associated with loss of BMD in the femoral cortex which is significantly greater than that observed, during analogous periods of time in stable implants.