The turbidimetric methods in routine use at two laboratories for the microbiological assay of vitamin B12 have been compared. Attempts were made to standardize some major parts of the method, i.e., assay design, test strain (Lactobacillus leichmannii), test medium, and reference standard. The laboratories used different approaches to achieve efficient assay procedures. During a 6-year period fo...

When an innovative biologic product goes off patent, biopharmaceutical or biotechnological companies may file an application for regulatory approval of biosimilar products. Unlike small molecule drug products, biosimilars are not exact copies of their brand-name counterpart, and they are usually very sensitive to changes in environmental factors and have greater variabilities due to their compl...

AIM The purpose of the study was to compare the accuracy of M-mode echocardiography and two different two-dimensional echocardiographic approaches in the assessment of left ventricular mass and volumes in endurance-trained and strength-trained athletes, using magnetic resonance imaging as reference standard. METHODS AND RESULTS We studied 19 athletes and 10 untrained control subjects, M-mode ...

BACKGROUND General practitioners (GPs) or researchers sometimes need to identify frequent attenders (FAs) in order to screen them for unidentified problems and to test specific interventions. We wanted to assess different methods for selecting FAs to identify the most feasible and effective one for use in a general (group) practice. METHODS In the second Dutch National Survey of General Pract...

Reference Standards For reference standards used as primary standards for pharmaceutical quality control, stability testing and inprocess control of herbal medicinal products and respective starting materials a dossier together with a certificate of analysis must be available. In this dossier information on identity testing (e.g. by NMR, MS, IR, UV), purity testing (e.g. water content, residual...

have on the health of the population. Therefore, practice guidelines are necessary to influence decision making, but should not be used to enforce medical decisions. Sufficient flexibility and divergence from tailor-made diagnostic and therapeutic strategies should be allowed. Guidelines should be a reference standard against which individual decision making should be assessed, and if in the vi...

Tribometers are mechanical devices used to measure walkway coefficient of friction (COF) for the purpose of assessing slip risk. The purpose of this study was to define a tribometer reference standard and use it to assess the performance of various tribometers. Eighty subjects were randomly assigned to walk across one of four wet walkway surfaces (polished black granite, porcelain, vinyl compos...

BACKGROUND Methods used to generate items for complex measurement scales are heterogeneous and probably produce heterogeneous data, yet nothing is known about the advantages of one method over another. OBJECTIVE We aimed to compare methods of generating items for tools designed to measure quality-of-life for patients. METHODS We used five methods to develop a quality-of-life instrument for ...