Prediction of myotonic dystrophy clinical severity based on the number of intragenic [CTG]n trinucleotide repeats.

We carried out a genotype-phenotype correlation study, based on clinical findings in 465 patients with myotonic dystrophy (DM), in order to assess [CTG] repeat number as a predictive test of disease severity. Our analysis showed that the DM subtypes defined by strict clinical criteria fall into three different classes with a log-normal distribution. This distribution is useful in predicting the probability of specific DM phenotypes based on triplet [CTG] number. This study demonstrates that measurement of triplet expansions in patients' lymphocyte DNA is highly valuable and accurate for prognostic assessment.

Self-similarity properties of alpha-crystallin supramolecular aggregates.

The supramolecular aggregation of alpha-crystallin, the major protein of the eye lens, was investigated by means of static and dynamic light scattering. The aggregation was induced by generating heat-modified alpha-crystallin forms and by stabilizing the clusters with calcium ions. The kinetic pattern of the aggregation and the structural features of the clusters can be described according to the reaction limited cluster-cluster aggregation theory previously adopted for the study of colloidal particles aggregation systems. Accordingly, the average mass and the hydrodynamic radius of alpha-crystallin supramolecular aggregates grow exponentially in time. The structure factor of the clusters is typical of fractal aggregates. A fractal dimension df approximately 2.15 was determined, indicating a low probability of sticking together of the primitive aggregating particles. As a consequence, the slow-forming clusters assemble a rather compact structure. The basic units forming the fractal aggregates were found to have a radius about twice (approximately 17 nm) that of the native protein and 5.3 times its size, which is consistent with an intermediate molecular assembly corresponding to the already known high molecular weight forms of alpha-crystallin.

Parameter resolution in two models for cell survival after radiation.

The resolvability of model parameters for the linear-quadratic and the repair-misrepair models for cell survival after radiation has been studied by Monte Carlo simulations as a function of the number of experimental data points collected in a given dose range and the experimental error. Statistical analysis of the results reveals the range of experimental conditions under which the model parameters can be resolved with sufficient accuracy, and points out some differences in the operational aspects of the two models.

[Evaluation of the dose in permanent implants of I-125]. / Valutazione della dose per impianti permanenti di 125I.

The Anderson's nomograph is currently used in 125I implants planning. For a given treatment volume, this method provides the activity and the seeds number and spacing. In order to obtain indications of the dose delivered in that 125I volume implants, we computed the average peripheral dose (APD), the average tumor dose (ATD) and the "matched peripheral dose" (MPD), for spherical, ellypsoidal and cylindrical volumes. By using the 125I source dosimetric data, we found that both the APD and the ATD are independent of sources randomizing in both position and orientation. Therefore the 125I seeds can be considered as point sources, provided that the dose values are scaled down by a factor which accounts for the spatial distribution anisotrophy. Since the computed parameters are only dependent on the implanted activity, the L. L. Anderson method can be applied even if brachytherapy treatments are associated with external beam radiotherapy ("boost"-therapy).