Tensile strength and corrosion resistance of brazed and laser-welded cobalt-chromium alloy joints

STATEMENT OF PROBLEM: The longevity of prosthodontic restorations is often limited due to the mechanical or corrosive failure occurring at the sites where segments of a metal framework are joined together. PURPOSE: The purpose of this study was to determine which joining method offers the best properties to cobalt-chromium alloy frameworks. Brazed and 2 types of laser-welded joints were compared for their mechanical and corrosion characteristics. MATERIAL AND METHODS: Sixty-eight cylindrical cobalt-chromium dental alloy specimens, 35 mm long and 2 mm in diameter, were cast. Sixteen specimens were selected for electrochemical measurements in an artificial saliva solution and divided into 4 groups (n=4). In the intact group, the specimens were left as cast. The specimens of the remaining 3 groups were sectioned at the center, perpendicular to the long-axis, and were subsequently rejoined by brazing (brazing group) or laser welding using an X- or I-shaped joint design (X laser and I laser groups, respectively). Another 16 specimens were selected for electrochemical measurements in a more acidic artificial saliva solution. These specimens were also divided into 4 groups (n=4) as described above. Electrochemical impedance spectroscopy and potentiodynamic polarization were used to assess corrosion potentials, breakdown potentials, corrosion current densities, total impedances at lowest frequency, and polarization charge-transfer resistances. The remaining 36 specimens were used for tensile testing. They were divided into 3 groups in which specimen pairs (n=6) were joined by brazing or laser welding to form 70-mm-long cylindrical rods. The tensile strength (MPa) was measured using a universal testing machine. Differences between groups were analyzed using 1-way analysis of variance (alpha=.05). The fracture surfaces and corrosion defects were examined with a scanning electron microscope. RESULTS: The average tensile strength of brazed joints was 792 MPa and was significantly greater (P<.05) than the tensile strength of both types of laser-welded joints (404 MPa and 405 MPa). When laser welding was used, successful joining was limited to the peripheral aspects of the weld. The welding technique did not significantly affect the joint tensile strength. Electrochemical measurements indicated that the corrosion resistance of the laser-welded joints was better than of the brazed ones, primarily due to differences in passivation ability. CONCLUSION: Laser welding provides excellent corrosion resistance to cobalt-chromium alloy joints, but strength is limited due to the shallow weld penetration. Brazed joints are less resistant to corrosion but have higher tensile strength than laser welds.     

Low performance of the MSKCC nomogram in preoperatively ultrasonically negative axillary lymph node in breast cancer patients

BACKGROUND AND OBJECTIVES: In order to predict the nonsentinel lymph node (NSLN) metastases in sentinel lymph node (SLN) positive patients a nomogram was created at the Memorial Sloan Kettering Cancer Centre (MSKCC). The aim of our study was to validate the MSKCC nomogram in patients grouped by the preoperative ultrasound (US) examination of the axillary lymph nodes. METHODS: The MSKCC nomogram was validated separately in three groups of patients: (US-0) only clinically preoperatively negative axillary lymph nodes (126 patients), (US-1) US negative axillary lymph nodes (109 patients), and (US-2) US suspicious but fine needle aspiration biopsy (FNAB) negative axillary lymph nodes (41 patients). RESULTS: The predicted probability underestimates the actual probability with the mean absolute error equal to 0.116 in the US-0 group (P = 0.003), and overestimates the actual probability (mean absolute error equal to 0.084) in US-1 group (P = 0.033) and US-2 group (mean absolute error is 0.110) (P = 0.275). CONCLUSION: We found that the MSKCC nomogram overestimates the probability of the NSLN metastases in breast cancer patients with (i) preoperatively US negative or (ii) US suspicious, but FNAB negative axillary lymph nodes. We also found that MSKCC nomogram has only limited value in patients with only clinically negative axillary lymph nodes.     

Videoskopisch assistierte Herzklappenchirurgie

BACKGROUND AND PURPOSE: Advances in the development of video-assisted systems for minimally invasive surgery now allow to perform cardiac surgery via a smaller anterolateral thoracotomy in order to reduce trauma, pain and improve cosmetics. In addition, due to sternal sparing, pulmonary function should improve resulting in reduced hospital stay and costs. However, only few centers worldwide abstain from spreading the ribs thus accepting considerable pain and reduced patient comfort. The minimally invasive approach described here uses a right-sided anterolateral incision (4-5 cm), a soft-tissue retractor and femorofemoral perfusion with endoclamping under continuous TEE (transesophageal echocardiography) control. It was the aim of this retrospective analysis to determine feasibility, safety and effectiveness of the method. PATIENTS AND METHODS: At the West German Heart Center Essen, 47 patients were operated using minimally invasive endoscopic techniques between January 2004 and April 2006 on the mitral valve (n = 31), mitral and tricuspid valve (n = 9), including mini-Maze procedure in two cases, as well as atrial septal defects (n = 5) and myxomas (n = 2). Mean age was 58 +/- 15.2 years (range 29-87 years), NYHA II-III, 20 patients were male. RESULTS: All but one patient survived (2.1%). Conversion to median sternotomy was necessary in three of the first twelve patients. After a mean follow-up period of 18 months all reconstructions and valves were competent, freedom from cardiac reoperation was 100%. On a visual analog scale 91% ot the patients reported no or mild postoperative pain, 96% felt they had an aesthetically pleasing scar. All but one patients would choose the same operation again. CONCLUSION: Videoscopically assisted, endoscopic cardiac surgery can be performed safely, but requires a learning curve and intense training. After evaluation of efficacy and safety it is now the authors' exclusive approach to isolated atrioventricular valve disease with an ideal pain-free and cosmetic result.     

Diagnostic Performance of p16/Ki-67 Dual Immunostaining at Different Number of Positive Cells in Cervical Smears in Women Referred for Colposcopy

BackgroundThe aim of the study was to evaluate the diagnostic accuracy of p16/Ki-67 dual immunostaining (p16/ Ki-67 DS) in cervical cytology and the number of positive p16/Ki-67 cells to diagnose high grade cervical intraepithelial neoplasia (CIN2+) in colposcopy population.Subjects and methodsWe performed an analysis on a subset cohort of 174 women enrolled within a large-scale randomised controlled human papillomavirus (HPV) self-sampling project organised as part of the population-based Cervical Cancer Screening Programme ZORA in Slovenia. This subset cohort of patients was invited to the colposcopy clinic, underwent p16/Ki-67 DS cervical cytology and had the number of p16/Ki-67 positive cells determined.ResultsAmong analysed women, 42/174 (24.1%) had histologically confirmed CIN2+. The risk for CIN2+ was increasing with the number of positive cells (p < 0.001). The sensitivity of p16/Ki-67 DS for detection of CIN2+ was 88.1%, specificity was 65.2%, positive predictive value was 44.6% and negative predictive value was 94.5%.ConclusionsDual p16/Ki-67 immunostaining for the detection of CIN2+ has shown high sensitivity and high negative predictive value in our study, which is comparable to available published data. The number of p16/Ki-67 positive cells was significantly associated with the probability of CIN2+ detection. We observed a statistically significant and clinically relevant increase in specificity if the cut-off for a positive test was shifted from one cell to three cells.Key words: cervical cytology, high-grade dysplasia, p16/Ki-67 immunostaining     

Multi-Institutional Comparison of Non-sentinel Lymph Node Predictive Tools in Breast Cancer Patients with High Predicted Risk of Further Axillary Metastasis

Although axillary lymph node dissection (ALND) has been the standard intervention in breast cancer patients with sentinel lymph node (SLN) metastasis, only a small proportion of patients benefit from this operation, because most do not harbor additional metastases in the axilla. Several predictive tools have been constructed to identify patients with low risk of non-SLN metastasis who could be candidates for the omission of ALND. In the present work, predictive nomograms were used to predict a high (>50 %) risk of non-SLN metastasis in order to identify patients who would most probably benefit from further axillary treatment. Data of 1000 breast cancer patients with SLN metastasis and completion ALND from 5 institutions were tested in 4 nomograms. A subset of 313 patients with micrometastatic SLNs were also tested in 3 different nomograms devised for the micrometastatic population (the high risk cut-off being 20 %). Patients with a high predicted risk of non-SLN metastasis had higher rates of metastasis in the non-SLNs than patients with low predicted risk. The positive predictive values of the nomograms ranged from 44 % to 64 % with relevant inter-institutional variability. The nomograms for micrometastatic SLNs performed much better in identifying patients with low risk of non-SLN involvement than in high-risk-patients; for the latter, the positive predictive values ranged from 13 % to 20 %. The nomograms show inter-institutional differences in their predictive values and behave differently in different settings. They are worse in identifying high risk patients than low-risk ones, creating a need for new predictive models to identify high-risk patients.     

Urokinase plasminogen activator (uPA) and plasminogen activator inhibitor type-1 (PAI-1) in breast cancer - correlation with traditional prognostic factors

Background

Urokinase plasminogen activator (uPA) and plasminogen activator inhibitor type-1 (PAI-1) play a key role in tumour invasion and metastasis. High levels of both proteolytic enzymes are associated with poor prognosis in breast cancer patients. The purpose of this study was to evaluate the correlation between traditional prognostic factors and uPA and PAI-1 expression in primary tumour of breast cancer patients.

Patients and methods.

606 primary breast cancer patients were enrolled in the prospective study in the Department of gynaecological oncology and breast oncology at the University Medical Centre Maribor between the years 2004 and 2010. We evaluated the traditional prognostic factors (age, menopausal status, tumour size, pathohistological type, histologic grade, lymph node status, lymphovascular invasion and hormone receptor status), together with uPA and PAI-1. We used Spearman’s rank correlation, Mann Whitney U test and χ² test for statistical analysis.

Results

Our findings indicate a positive correlation between uPA and tumour size (p < 0.001), grade (p < 0.001), histological type (p < 0.001), lymphovascular invasion (p = 0.01) and a negative correlation between uPA and hormone receptor status (p < 0.001). They also indicate a positive correlation between PAI-1 and tumour size (p = 0.004), grade (p < 0.001), pathohistological type (p < 0.001) and negative correlation between PAI-1 and hormone receptor status (p = 0.002).

Conclusions

Our study showed a relationship between uPA and PAI-1 and traditional prognostic factors. Their role as prognostic and predictive factors remains to be further evaluated.     

Factors correlated to successful surgical treatment of 181 non-palpable invasive breast carcinomas

Surgical treatment of non-palpable solitary invasive carcinoma consists of localization, tumorectomy and sentinel lymph node biopsy which can successfully be performed with the use of isotopes (SNOLL). The aim of our study was to find out the success rate of SNOLL and the factors that correlated with complete excision of invasive carcinoma. Solitary non-palpable carcinoma was preoperatively diagnosed in 181 cases. After peritumoral injection of nanocolloid labeled with 99mTc under mammographic (N=79) or ultrasound (N=102) guidance, tumorectomy and sentinel node biopsy were performed. Clear surgical margins were obtained in 82% of cases. Surgical margins were likely to be clear (p<0.05) if: (1) the patients were older than 50 years, (2) the weight of surgical specimens >50 g, (3) the tumor radiologic diameter was ≤20 mm, (4) invasive carcinoma was ductal rather than other types of invasive carcinomas. Only one surgical procedure was sufficient for surgical treatment of 75% of cases with non-palpable solitary invasive carcinoma.