In vitro antigen ELISA for quality control of tetanus vaccines

Consistency of production is recognised as an important aspect of vaccine manufacture and suitably validated in vitro assays are required for quality control testing of these products. For the manufacture and batch release of tetanus vaccines, antigen content and integrity, and degree of adsorption of antigen to the adjuvant are critical parameters that should be monitored for consistency. Here we describe the development and use of an Enzyme Linked Immunosorbent Assay (ELISA) to quantify tetanus antigen in combined vaccine products and to measure the degree of adsorption of antigen to adjuvant. Whilst the antigen assay cannot be assumed to predict potency for different products, it can be used as part of a panel of in vitro methods to provide a more informative product profile and to monitor trends in production. The antigen assay is particularly valuable for providing quantitative information on every final lot when modifications of in vivo potency tests, such as single dilution assays, are used.     

Estimation of the mechanical lifetime of dental restorations: method and preliminary results

To assess the clinical performance of restorative materials with respect to mechanical failure, the shape of the restoration, the strength and fatigue properties and the loading history are important. This study deals with the feasibility of a method to estimate the mechanical lifetime of dental restorations. The method takes into account that the mechanical lifetime is a stochastic quantity determined by shape, strength and fatigue properties and by the cyclic nature of the mastication forces. The general outline of the method is described and the necessary experimental data are discussed. Preliminary estimates of the lifetime of a composite and an amalgam restoration are made. The method is found to be feasible and the estimated lifetimes of the restoration are of the same order of magnitude as found clinically.     

Studies of Fe3+ transport across isolated intestinal brush-border membrane of the mouse

Mouse intestinal brush-border membrane vesicles take up iron from media containing 59Fe3 +-nitrilotriacetic acid. The iron uptake by the vesicles represents accumulation of iron which relates to an osmotically active space. Uptake is linearly related to vesicle protein concentration and is inhibited by low incubation temperature and low medium free Fe3+ concentrations. Experiments with the lipid soluble iron ligand 8-hydroxyquinoline and with Triton X-100 imply that the uptake is rate limited by membrane transport.     

Classical Analysis of Variance Methods and Nonparametric Counterparts

The present investigation is concerned with the use of classical and nonparametric techniques in the analysis of experiments. Occasionally biometricians are confronted with results arising from an experiment with data which do not necessarily satisfy the assumption of Normality, the basis of the classical analysis of variance methods. Sometimes the biometrician handles such a situation by transformation of the observations and applying the classical techniques. Although this attack may lead to a satisfactory analysis, the results may be questionable in a number of cases. In analyzing continuous data without the Normality assumption nonparametric methods provide realistic alternatives. In this paper a number of problems will be discussed with and without the Normality assumption resulting in the well-known classical analysis and its nonparametric counterparts. Most of the nonparametric procedures to be discussed are based on ranks.     

Nucleocytoplasmic protein traffic in single mammalian cells studied by fluorescence microphotolysis

Fluorescence microphotolysis was employed to measure in single living cells the kinetics of nucleocytoplasmic transport and the coefficients of intracellular diffusional mobility for the nuclear non-chromosomal protein nucleoplasmin. Nucleoplasmin was isolated from Xenopus ovary and labeled fluorescently. By injection into Xenopus oocytes it was ascertained that fluorescent labeling did not interfere with normal nuclear accumulation. Upon injection into the cytoplasm of various mammalian cell types nucleoplasmin was rapidly taken up by the nucleus. In rat hepatoma cells the half-time of nuclear uptake was approx. 5 min at 37 degrees C; the nucleocytoplasmic equilibrium concentration ratio had a maximum of 6.5 +/- 1.4 and depended on the injected amount. Upon co-injection of ATPases or reduction of temperature to 10 degrees C a nucleocytoplasmic equilization but no nuclear accumulation was observed. Equilization was fast (time constant 65 s at 23 degrees C), similar to that of 10-kDa dextran permeating the nuclear envelope by simple diffusion through functional pores. Nucleoplasmin (160 kDa), however, is too large to permeate passively the nuclear envelope, which is apparent from the fact that its tryptic 'core' fragment (100 kDa) could not permeate the nuclear envelope. On the other hand, a large fluorescent protein, phycoerythrin (240 kDa), was targeted to the nucleus by conjugation with nucleoplasmin. In the nucleus-to-cytoplasm direction the nuclear envelope was completely impermeable to nucleoplasmin, independently of temperature or ATP depletion. Nucleoplasmin, its core fragment, phycoerythrin and the phycoerythrin-nucleoplasmin conjugate were mobile in both cytoplasm and nucleus.