Monitoring of human Cytomegalovirus infection by antigenemia and viremia in the first 100 days following renal transplantation and relation to antiviral strategies.

AIM: Human Cytomegalovirus (HCMV) is a relevant pathogen in transplant recipients, particularly in the first three months post-transplantation. The use of antiviral prophylaxis and pre-emptive therapy is able to reduce incidence of HCMV infection and disease. The incidence of HCMV infection and disease in renal transplant recipients in the first 100 days post-transplantation was investigated, in relation with HCMV serological matching and therapeutic management. METHODS: Incidence of HCMV infection in the first 100 days post-transplantation was evaluated by pp65-antigenemia in 165 patients on a total number of 1241 clinical samples. Patients were divided in four groups according to donor/recipient serological matching: D(-)/R(-) (low risk of HCMV disease), D(-)/R+ and D+/R+ (intermediate risk) and D+/R(-) (high risk). Antiviral strategy (prophylaxis in high risk group; pre-emptive therapy in intermediate risk group, no therapy in low risk group) and immunosuppressive protocol were recorded. RESULTS: Incidence of antigenemia-positivity was as follows: 0/3 D(-)/R(-) patients; 59/130 (45.4%) D+/R+; 5/16 (31.3%) D(-)/R+; 4/16 D+/R(-). No significative difference was found between the four groups in terms of incidence of antigenemia-positivity in the first 100 days following transplantation. Antigenemia values >50 pp65-positive/2x10(5) peripheral blood leukocytes (used to start pre-emptive therapy) were present in 18/130 (13.8%) D+/R+; 1/16 (6.2%) D+/R(-); 0/16 D(-)/R+. Viral kinetics in patients with HCMV infection was described. CONCLUSION: No significative difference was found in terms of incidence of HCMV infection in the first 100 days post-transplantation in relation to immunosuppressive protocol and serological matching, suggesting the appropriateness of antiviral strategies and viral monitoring adopted in this setting.

Identifying relevant molecular descriptors related to carcinogenic activity of polycyclic aromatic hydrocarbons (PAHs) using pattern recognition methods.

Polycyclic Aromatic Hydrocarbons (PAHs) constitute an important family of molecules capable of inducing chemical carcinogenesis. In this work we report structure-activity relationship (SAR) studies for 81 PAHs using the pattern-recognition methods Principal Component Analysis (PCA), Hierarchical Clustering Analysis (HCA) and Neural Networks (NN). The used molecular descriptors were obtained from the semiempirical Parametric Method 3 (PM3) calculations. We have developed a new procedure that is capable of identifying the PAHs' carcinogenic activity with an accuracy higher than 80%. PCA selected molecular descriptors that can be directly correlated with some models proposed to PAHs' metabolic activation mechanism leading to the formation of PAHs-DNA adducts. PCA, HCA and NN validate the energy separation between the highest occupied molecular orbital and its next lower level as a major descriptor defining the carcinogenic activity. This descriptor has been only recently discussed in the literature as one new possible universal parameter for defining the biological activity of several classes of compounds.

Structure--activity relationship studies of substituted 17alpha-acetoxyprogesterone hormones.

Recently a new methodology, called electronic indices methodology (EIM), based on local density of state calculations (LDOS) using topological and semiempirical methods, was proposed to identify the biological activity of polycyclic aromatic hydrocarbons (PAHs). In this work we apply the concepts of the EIM approach to classify the progestational activity of 21 17alpha-acetoxyprogesterones (steroid hormones) (APs). The EIM approach pointed to a few descriptors, which correctly classify the active/inactive compounds of this class (approximately 90%). We show that these descriptors arise naturally from principal component analysis (PCA) and neural network (NN) calculations. Moreover, using only the parameters from EIM, instead of a large set of descriptors that have been used before to describe the biological activity of these hormones, we slightly improve and simplify PCA and NN results. Finally, the molecular region related to the chemical activity of these hormones naturally appears in our theoretical analysis, from the local density of states of the frontier orbitals. This shows the generality of the principles of EIM approach, and confirms that the combination of these distinct methodologies can be an efficient and powerful tool in the structure-activity studies of many different classes of compounds.

Structure-activity relationship studies of carcinogenic activity of polycyclic aromatic hydrocarbons using calculated molecular descriptors with principal component analysis and neural network methods.

Recently a new methodology based on local density of state (LDOS) calculations using topological and semiempirical methods was proposed to identify the carcinogenic activity of polycyclic aromatic hydrocarbons (PAHs). In this work we perform a comparative study of this methodology with principal component analysis (PCA) and neural networks (NN). The PCA and NN results show that LDOS quantum chemical descriptors are relevant descriptors to identify the carcinogenic activity of methylated and non-methylated PAHs. Also, we show that the combination of these distinct methodologies can be an efficient and powerful tool in the structure-activity studies of PAHs compounds. We have studied 81 methylated and non-methylated PAHs, and our study shows that with the use of these methods it is possible to correctly predict the carcinogenic activity of PAHs with accuracy higher than 80%.

Ionization potentials and electron affinities of nicotinic acid and nicotinamide calculated with HAM/3.

Ionization potentials and electron affinities of nicotinic acid and nicotinamide were calculated by HAM/3. Observed photoelectron spectra of the molecules were analyzed with the aid of the calculated ionization potentials. Chemical reactivity of the molecules was discussed.