0000000000083194
AUTHOR
Donatella Mattia
Low prevalence of anti-HCV antibody among Italian children
The seroprevalence of anti-HCV antibody was studied among 2,749 children and teenagers (1,438 males and 1,311 females) living in Italy. Anti-HCV antibody testing was positive by both EIA and RIBA in ten (0.36%) subjects. The positivity rate increased with age, ranging from 0 among children less than 6 years of age to 0.8% among those aged 17-19 years chi 2 linear regression = 0.038). Anti-HCV prevalence ranged from 0.2% in northeastern regions and in Apulia to 0.6% in Sicily and Sardinia (p0.005), and no difference was seen between males (0.35%, C.I. 95%: 0.04-0.66) and females (0.38%, C.I. 95%: 0.04-0.66) (Fisher's exact test = 0.565). From these data it appears that in Italy HCV infection…
Prevalence of cytomegalovirus infection in Italy
SUMMARYBetween 1987 and 1989, the prevalence of antibody to cytomegalovirus (CMV) was determined, by the ELISA method, in serum samples from 1494 apparently healthy subjects, 3–18 years old. Subjects were selected by a systematic cluster sampling from five geographical areas in Italy. The overall prevalence of antibody was 64·2%, increasing from 54·4% in 4–6-year-olds to 73·3% in subjects 17–18 years old (P < 0·01). Prevalence of antibody was significantly higher in females (P < 0·05) and in subjects residing in the South of Italy (P < 0·01). A significant association was found with sociodemographic factors. Subjects belonging to a household with six or more persons had a 1·5-fold …
Estimating brain connectivity when few data points are available: Perspectives and limitations
Methods based on the use of multivariate autoregressive modeling (MVAR) have proved to be an accurate and flexible tool for the estimation of brain functional connectivity. The multivariate approach, however, implies the use of a model whose complexity (in terms of number of parameters) increases quadratically with the number of signals included in the problem. This can often lead to an underdetermined problem and to the condition of multicollinearity. The aim of this paper is to introduce and test an approach based on Ridge Regression combined with a modified version of the statistics usually adopted for these methods, to broaden the estimation of brain connectivity to those conditions in …
Estimation of brain connectivity through Artificial Neural Networks
Among different methods available for estimating brain connectivity from electroencephalographic signals (EEG), those based on MVAR models have proved to be flexible and accurate. They rely on the solution of linear equations that can be pursued through artificial neural networks (ANNs) used as MVAR model. However, when few data samples are available, there is a lack of accuracy in estimating MVAR parameters due to the collinearity between regressors. Moreover, the assessment procedure is also affected by the lack of data points. The mathematical solution to these problems is represented by penalized regression methods based on l 1 norm, that can reduce collinearity by means of variable sel…
Functional anatomy of motor recovery after early brain damage
Functional magnetic resonance imaging and transcranial magnetic stimulation were used to examine a 34 year-old right-handed patient, who, at the age of 6 years, had experienced sudden right hemiplegia, seizures, and stupor during a bout of measles encephalitis, followed by incomplete distal right motor recovery. Morphological MRI showed massive unilateral enlargement of the left ventricle, associated with extreme thinning of the white and gray matter, with partial preservation of the pyramidal tract. Functional MRI and transcranial magnetic stimulation revealed reorganization of the motor cortices, and integrity of the corticospinal pathway, respectively. Our findings indicate that complete…
Baseline seroepidemiology of hepatitis A virus infection among children and teenagers in Italy.
During the period from May 1987 through November 1989, the prevalence of antibodies to hepatitis A virus infection (anti-HAV) was assayed by the ELISA method in the serum samples of 5,507 (54% males, 46% females) apparently healthy subjects three to 19 years old in Italy. Subjects were selected by a systematic cluster sampling in five different geographical areas of Italy. The overall prevalence of anti-HAV was 9.5%; it increased from 2.3% among children three to five-years-old to 16.3% in teenagers 17 to 19 years old (p less than 0.001). A slight preponderance of females was observed (10% versus 9.1%), but the difference was not statistically significant. The prevalence was significantly h…
Measuring the agreement between brain connectivity networks.
Investigating the level of similarity between two brain networks, resulting from measures of effective connectivity in the brain, can be of interest from many respects. In this study, we propose and test the idea to borrow measures of association used in machine learning to provide a measure of similarity between the structure of (un-weighted) brain connectivity networks. The measures here explored are the accuracy, Cohen's Kappa (K) and Area Under Curve (AUC). We implemented two simulation studies, reproducing two contexts of application that can be particularly interesting for practical applications, namely: i) in methodological studies, performed on surrogate data, aiming at comparing th…
Single-trial Connectivity Estimation through the Least Absolute Shrinkage and Selection Operator.
Methods based on the use of multivariate autoregressive models (MVAR) have proved to be an accurate tool for the estimation of functional links between the activity originated in different brain regions. A well-established method for the parameters estimation is the Ordinary Least Square (OLS) approach, followed by an assessment procedure that can be performed by means of Asymptotic Statistic (AS). However, the performances of both procedures are strongly influenced by the number of data samples available, thus limiting the conditions in which brain connectivity can be estimated. The aim of this paper is to introduce and test a regression method based on Least Absolute Shrinkage and Selecti…
Baseline sero-epidemiology of hepatitis B virus infection in children and teenagers in Italy. A survey before mass hepatitis B vaccination
During the period May 1987 to November 1989, the prevalence of hepatitis B virus (HBV) markers was determined by ELISA in serum samples of 7405 (55% male, 45% female) apparently healthy persons 3-19 years of age in Italy. Earlier studies of adults there had shown an intermediate degree of HBV endemicity (hepatitis B surface antigen carrier rate greater than 2%). Persons were selected by systematic cluster sampling in five different geographical areas of Italy. The overall prevalence of hepatitis B surface antigen (HBsAg) was 0.6%. The overall prevalence of at least one marker of HBV was 2.8%; it increased from 1.7% among children 3-5 years of age to 4.5% in teenagers 17-19 years of age (P l…