The proliferation rate of intracranial tumors as defined by the monoclonal antibody KI 67. Application of the method to paraffin embedded specimens

60 intracranial tumors have been studied immunohistochemically to determine the proliferation rate by staining for the monoclonal antibody KI-67, which recognizes a nuclear antigen expressed by cells in proliferation. In gliomas a clear correlation of stained nuclei to the histologically determined degree of malignancy was found: slow growing astrocytomas and oligodendrogliomas had an average proliferation rate of 1%, more malignant forms of 7–10%. Glioblastomas were found to have a growth fraction of 15%. Metastases had an even higher rate of 20% proliferating cells. In meningiomas the proliferation rate was mainly about 1%, but in three cases it was between 5% and 7%. Whether this is indicative for a higher risk of tumor recurrence, remains to be correlated to the clinical course. Hemangiopericytomas had a proliferation rate of 9% and 16%, respectively, the latter recurring within four months. It may be concluded from the results of this study, that investigation of intracranial tumors with KI 67 may be of prognostic value and can possibly contribute to an individualized tumor therapy.     

Die Proktokolektomie bei Colitis ulcerosa

Background

The coloproctomucosectomy (CPM) is the procedure of the choice for the surgical treatment of ulcerative colitis (UC). In cases with pronounced immunosuppression (IS), a 3-step (3S) procedure [i.e., subtotal colectomy and ileal pouch-anal anastomosis (IPAA) and finally ileostomy reconstruction] is often selected. Fewer perioperative complications can be expected compared to the 2-step (2S) procedure; however, an additional in-hospital stay and surgical intervention are necessary. The aim of the present study was to compare both approaches using the clinical outcome of our patients undergoing IPAA to determine efficacy of these two concepts.

Patients and methods

From 1997–2010, a total of 225 patients were operated using a 2S or 3S IPAA procedure. Clinical outcomes were evaluated based on the number of surgical steps for the ileoanal pouch procedure and IPAA. The survey was performed within the scope of prospective study.

Results

Of the 225 patients with CPM, 66 were excluded due to a diagnosis other than UC (familial adenomatous polyposis, indeterminate colitis, Crohn’s disease) and patients with permanent ILS procedures without the possibility or wish for an IPAA (n?=??54). Included were 71 patients with 2S (w?=?30, m?=?41) and 34 patients with 3S procedures (w?=?21, m?=?13). Compared to the 2S procedure, the 3S procedure was shown to have shorter operation times (246 versus 296 min; p??=?0.05), shorter hospital stays (15.5 versus 24.6 days; p?=?0.05), shorter intensive care unit stays (3.3 versus 7.2 days; p?=?0.05), and fewer major complications (5.9?% versus 22.5?%; p?=?0.035). Patients with 3S procedures had a higher BMI (26.2 versus 23.1 kg/m²; p?=?0.05) and fewer required IS (10?% vs. 62?%; p?<?0.05).

Conclusion

The decision for a 3S procedure in UC and pronounced IS is advisable and justified. Using a 3S procedure, immunosuppression and its influence on perioperative morbidity are thus reduced. The IPAA can be performed with shorter operation times, shorter hospital stays and fewer major complications.     

Therapierefraktäre chronisch entzündliche Darmerkrankungen

Surgery for inflammatory bowel disease under immunosuppressant drugs is a widely discussed topic. Because therapeutic concepts have significantly changed, almost no patient is currently without an immunosuppressant or biologic agent prior to surgery. However, the data whether biological agents and immunosuppressant are a risk factor are very inconsistent. Concerning Crohn’s disease, monotherapy with immunosuppressants or biological agents seems to have no negative influence on the postoperative results. In contrast, however, for ulcerative colitis more publications recognise biologic agents and immunosuppressants as a single therapy as a risk factor for infections. To reduce the general risk, all risk factors have to be reduced. In Crohn’s disease, nutritional status must be optimised, corticoids should be reduced, biological agents and immunosuppressant drugs should be stopped, protection of an eventual anastomosis by a stoma. For ulcerative colitis in high-risk patients, a three-stage restaurative proctocolectomy is favoured to a one- or two-staged proctocolectomy.     

Error propagation in calculated ratios

BACKGROUND: Calculated quantities that combine results of multiple laboratory tests have become popular for screening, risk evaluation, and ongoing care in medicine. Many of these are ratios. In this paper, we address the specific issue of propagated random analytical error in calculated ratios. METHODS: Standard error propagation theory is applied to develop an approximate formula for the mean, standard deviation (SD), and coefficient of variation (CV) of the ratio of two independent, normally distributed random variables. A method of mathematically modeling the problem by random simulations to validate these formulas is proposed and applied. Comparisons are made with the commonly quoted formula for the CV of a ratio. RESULTS: The approximation formula for the CV of a ratio R=X/Y of independent Gaussian random variables developed herein has an absolute percentage error less than 4% for CVs of less than 20% in Y. In contrast the commonly quoted formula has a percentage error of up to 16% for CVs of less than 20% in Y. CONCLUSION: The usual formula for the CV of a ratio functions well when the CV of the denominator is less than 10% but for larger CVs, the formula proposed here is more accurate. Random analytical error in calculated ratios may be larger than clinicians and laboratorians are aware. The magnitude of the propagated error needs to be considered when interpreting calculated ratios in the clinical laboratory, especially near medical decision limits where its effect may lead to erroneous conclusions.     

Comparison of edge analysis techniques for the determination of the MTF of digital radiographic systems

The modulation transfer function (MTF) is well established as a metric to characterize the resolution performance of a digital radiographic system. Implemented by various laboratories, the edge technique is currently the most widespread approach to measure the MTF. However, there can be differences in the results attributed to differences in the analysis technique employed. The objective of this study was to determine whether comparable results can be obtained from different algorithms processing identical images representative of those of current digital radiographic systems. Five laboratories participated in a round-robin evaluation of six different algorithms including one prescribed in the International Electrotechnical Commission (IEC) 62220-1 standard. The algorithms were applied to two synthetic and 12 real edge images from different digital radiographic systems including CR, and direct- and indirect-conversion detector systems. The results were analysed in terms of variability as well as accuracy of the resulting presampled MTFs. The results indicated that differences between the individual MTFs and the mean MTF were largely below 0.02. In the case of the two simulated edge images, all algorithms yielded similar results within 0.01 of the expected true MTF. The findings indicated that all algorithms tested in this round-robin evaluation, including the IEC-prescribed algorithm, were suitable for accurate MTF determination from edge images, provided the images are not excessively noisy. The agreement of the MTF results was judged sufficient for the measurement of the MTF necessary for the determination of the DQE.