Search

Phenylketonuria (PKU) is a congenital metabolic autosomic recessive disease, caused by a deficit in the liver of phenyl-alanine hydroxylase, the enzyme responsible for conversion of phenyl-alanine (PHE) into tyrosine. Reduction of this enzymatic activity is responsible for increased phenyl-alanine in blood and tissues and, above all, in brain. Accumulation of PHE causes neural damage which produces a typical clinical picture with mental retardation, psychiatric symptoms and epilepsy. It is now possible to diagnose this disease early (with neonatal screening), before irreversible clinical symptoms reflecting central nervous system injury appear. Early diagnosis allows timely onset of therapy (the only possible) consisting of a special diet with reduced intake of PHE (integrated with a mix of aminoacids) whose objective is to keep levels of PHE low in the blood (3–6 mg/dl). Magnetic Resonance Imaging (MRI) is the elective diagnostic tool to evaluate in vivo the involvement of the brain in PKU. Previous MRI morphological studies in patients with PKU have reported various focal symmetrical lesions in periventricular white matter (especially parieto-occipital) of patients with PKU with PHE blood values higher than 10 mg/dl. These lesions, whose importance is not yet clear, seem to represent a reversible structural alteration of myelin, since they regress if blood PHE decreases. Proton magnetic resonance spectroscopy (1H-MRS) can measure in vivo brain metabolites which could help determine the nature of white matter lesions. In particular, changes in NAA (a marker of neuronal integrity) or mI (a potential astrocytic marker) could point to possible neurochemical dysfunction, whereas Cho levels may parallel the degree of the tissue myelination. The purpose of the present study was to evaluate morphologically and biochemically the regional specificity of white matter lesions with structural MRI and with 1H-MRSI. The study included 12 patients with PKU ten to 42 years of age. All patients underwent structural MRI scans while eight of them were also studied with 1H-MRSI. Structural MRI lesions in white matter were analyzed both qualitatively (signal intensity) and quantitatively (location and extension). 1H-MRSI metabolites were measured as the ratio of the area under each peak: NAA/Cr, NAA/Cho, Cho/Cr. Analysis of location and extension of the lesion on structural MRI data showed limited involvement of parieto-occipital white matter in three cases (with isointense or vaguely hypointense lesions in T1, and moderately hyperintense lesions in T2); medium involvement in six cases (with fairly hypointense or isointense lesions in T1, fairly or moderately hyperintense lesions in T2); serious involvement in three cases (with isointense or fairly hypointense lesions in T1, and fairly hyperintense lesions in T2). As for 1H-MRSI data, ANOVA showed a significant reduction of NAA/Cho and increase in Cho/Cr in white matter lesions, but no change in NAA/Cr. No correlation was found between clinical parameters and morphological or spectroscopic data. In conclusion, our morphological MRI data confirmed the presence of multiple signal alterations, focal and symmetrical, in deep periventricular white matter (especially posterior), with occasional involvement of subcortical white matter. However, these lesions do not seem to be strongly predictive of clinical outcome. 1H-MRSI data suggest increased Cho levels in white matter lesions. Since Cho is thought to reflect membrane turnover, these data may support the demyelinating nature of lesions, consistent with earlier post mortem studies.

The availability of an efficient, low-cost numerical simulator is essential in the design of fluid dynamic systems, both to achieve a deep understanding of the flow field and to allow a quick and economical optimization of the technical characteristics of industrial devices. With the aim of developing an adequate simulation tool for the analysis of the fluid dynamical field in general 2d domains, a positive scheme, recently proposed as a simple and yet powerful method for the approximation of conservation laws, is extended in this paper to general curvilinear coordinates. The resulting algorithm is successfully applied to several test cases of increasing complexity.

To verify statistically the hypothesis that birthdate represents a risk factor for Congenital Hypothyroidism, as proposed by some European Authors. Moreover, to verify the existence of seasonal cyclic trends in TSH levels.For the verification of birthdate as a risk factor, we considered retrospectively a data set of all consecutives newborns of Marche Region (Italy) affected by Congenital Hypothyroidism, in the period 1981-1996 (n = 92). For the evaluation of seasonal cyclic trends in TSH, we considered the level of the hormone in all newborns of Marche Region screened in the period 1989-1996. Data were collected from Neonatal Screening Register of Marche Region. All the statistical analyses are based on circular statistics techniques (Rayleigh test, Roger test, estimation of density by kernel method, Mardia test for circular-linear correlation, Maximization of Mean Vector Length).No cyclic trend was pointed out with regard to Congenital Hypothyroidism; neither seasonal rhythms nor other cyclic patterns of TSH levels were evidenced.Neither the hypothesis of birthdate as a risk factor for Congenital Hypothyroi-dism, nor the existence of seasonal variations in TSH hormone releasing were confirmed.

In this paper, discrepancies and reference inaccuracies in the paper (Grana , 2003) are pointed out. Specifically, it is demonstrated that the definitions of "lesion gradient" and "skin lesion gradient," widely used in a number of medical papers on computer analysis of pigmented skin lesions, are unambiguous, and that the "new algorithm for border description" described in the subject paper substantially relies on well-established concepts dating back over one decade ago

The authors discuss their experience regarding the three-dimensional reconstruction of the echographic image, firstly of an orbital angioma and secondly, of a malignant choroidal melanoma. Of the latter, they calculate the volume and the total external surface. Reference is also made to data regarding reproducibility, the errors of reconstruction methodology and volume calculation. However, it is more reliable than the commonly used echographic procedures.

As already described for cystic fibrosis and Friedreich ataxia, the incidence of PKU in Italy has been estimated by determining the increase of consanguineous marriages among 178 couples of PKU parents over the frequencies carefully established for the same marriages in the general Italian population for each of the 95 provinces during a 55-year period. The incidence estimated (between 1/15595 and 1/17815 according to two different formulas) is not very different from the incidence derived from screening programs (almost 1/12000). This indicates that the former method can be applied in Italy to the study of the incidence of other autosomal recessive disorders.

In the newborn and foetus in the last months of gestation it is possible to see in lateral radiography of the spine, a longitudinal radiotransparent band which may divide the bone nucleus of the vertebral body into two portions. This front vertebral separation should be considered an expression of a reversible abnormality rather than a malformation to the extent that it almost always concerns a differentiation delay in the vertebral structures. The literature and personal cases show, in fact, that the finding disappears more or less rapidly.