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Biomedical subjects

C N Zaharia

Publications and source records attributed to C N Zaharia.

At least 19 recordsLinked to original sources
PubMed1999

A micropopulational modelling of a viral epidemic by using a special neural network.

A general forward neural network was adapted for a simulation of viral epidemics. This involves the introduction of a strongly dependence upon history, upon the cumulated values of the corresponding neuron (individual) activations (states of infection) specifying the activation (health) states of the contaminated individuals, represented by the activated neurons and the dynamic parameters of the neural network: the matrix of the synaptic connection and the vector of the activation thresholds (corresponding to the matrix of the viral transfers between the various individuals and to the vector of the minimal individual contamination doses of virus). The recurrence relations and the learning procedures were also adapted to these processes. This methodology was used for the study of the micropopulational spreading of viral epidemics in various epidemiological situations.

Computer Simulation↗
PubMedDate not supplied

[Complex studies of virology, microbiology, biochemistry and epidemiology in the adults of a semi-closed community vaccinated against influenza with the inactivated NIVGRIP vaccine intranasally].

A study was conducted on the specific and non specific immunomodulator effects of the inactivated vaccine NIVGRIP. The results revealed the seroconversion of HAI antibodies against influenza and mumps viruses and the reduction of viral and microbial flora of the pharynx. The kinetics of some proteins specific to the acute stage (siderophiline antitrypsin, microglobulin, complement C1q and C2 factors, C reactive protein and fibronectin) was also investigated and significant quantitative modifications were noticed in vaccinated subjects. The mean illness duration (acute respiratory disease) was three times as short in vaccinated subjects as in controls.

Acute-Phase Proteins↗
PubMedDate not supplied

[Epidemiological and virological research on influenza and viral respiratory infections in the southeastern region of Romania in the cold season of 1991-1992].

Investigations pointed out the high level of respiratory diseases and pneumonias in children, especially in the youngest ones (0-1 year-old) during all the surveyed period. An influenza outbreak during the second half of February was registered in the infantile population--school and low-age children--which gave most of the cases. Serology and isolations incriminated an influenza virus related to the A/Beijing 353/89 (H3N2) strain. Isolations worked out after the influenza epidemics pointed out circulation of parainfluenza and adenoviruses. The necessity is emphasized of the anti-influenza vaccination of low-age children.

Acute Disease↗
PubMedDate not supplied

Automated densitometry of polyacrylamide gel electrophoregrams.

A device is described which enables to convert a spectrophotometer in a high performance densitometer. Test samples for the evaluation of densitometric characteristics are presented. The estimations can be carried out in the UV-visible range without applying the common staining procedure, on either cylindrical or plane gel plates in absorption or fluorescence. Polyacrylamide gel migrated commercial protein mixtures as well as A(H1N1) influenza virus and Sendai virus polypeptides were used as biological samples.

Densitometry↗
PubMedDate not supplied

[Methodology for the development of expert systems of viral epidemiology].

The proposed methodology for the elaboration of the base of knowledge uses a tree of the hierarchical entities and a simplified variant of the natural language. The resolution system is based on an extension of the predicate calculation containing, in an explicit way, entities of different nature, and among these the correlations giving the rules of deduction.

Artificial Intelligence↗
PubMedDate not supplied

Influence of organic solvents and pH on some characteristics of influenza virus A(H1N1). Note 1. Influence of organic solvents on the spectral characteristics of fluoresceine isothiocyanate-conjugated influenza virus A(H1N1).

The fluorescence of fluoresceine isothiocyanate (FITC)-conjugated influenza virus A(H1N1) was enhanced following addition of ethanol, acetone or dimethylsulfoxide (DMSO) and decreased after addition of dioxane; light scattering values increased in the presence of any of these organic solvents. The effect of the organic solvents could be correlated with the excess values delta epsilon of the dielectric constant. Out of the four organic solvents it was DMSO that caused the slightest changes in the fluorescence and light scattering of the FITC/virus system.

Dose-Response Relationship, Drug↗
PubMedDate not supplied

Influence of organic solvents and pH on some characteristics of influenza virus A(H1N1). Note 2. Effect of pH on some spectral and structural characteristics of influenza virus A(H1N1).

Spectrophotometric determinations as regards absorption at 280 nm, 260 nm and 224-237 nm, emission at 280-350 nm and light scattering at 550 nm were performed with suspensions of influenza virus A/Brasil/11/78 (H1N1) over a pH range from 2 to 12. The results obtained proved that changes in spectral parameters were minimal in the pH range from 6 to 10, a fact which could be correlated both with the preservation of the intact virion structure (as visualized by electron microscopy) and with the domain of biological stability of influenza virus.

Hydrogen-Ion Concentration↗
PubMedDate not supplied

Gel filtration through Sephadex G25 of virus fluorescent compound systems. Comparison with ultracentrifugation results.

A stable interaction could be made evident between influenza A(H1N1) or Sendai virus and two fluorescent naphthalic acid derivatives solubilized in DMSO. The virus-compound interaction was studied spectrophotometrically and spectrofluorometrically, at the wavelengths characteristic of virus protein and of the two compounds, in samples subjected to gel filtration or ultracentrifugation. The percentages of virus-bound compound obtained by the two methods were similar in the case of the vinyl-sulfonic derivative (affecting virus structure to a lesser extent) and considerably different in that of the isocyano derivative (causing important structural damage).

Chromatography, Gel↗
PubMedDate not supplied

Electron microscopic observations concerning the action of some aromatic compounds on the morphology of Sendai virus.

The interaction between Sendai virus and some fluorescent aromatic compounds with reactive chemical groups ( a vinyl-sulfonic and an isocyano naphthalic acid derivative) leads to alterations of the surface and inner structure of virus corpuscles. The intensity of the changes depends on the type of reactive group. No such morphological changes were induced by 1-amino-2-anthraquinone-sulfonic acid, a compound whose interaction with the virus is exclusively of physical nature.

Anthraquinones↗
PubMedDate not supplied

Changes in light scattering, absorption, fluorescence and biological characteristics of influenza virus A(H1N1) exposed to sonication.

Influenza virus A/Brasil 11/78 (H1N1) was sonicated for different time intervals (2-328 sec) in a continuous flow Ultrasonics F600 device at 20 kHz, 600 W. Marked changes in the structure of the virions were made evident by light scattering, absorption and fluorescence measurements. Light scattering data indicated that the turbidity of the influenza virus samples is inversely proportional to the square of the wavelength. A sharp decrease in hemagglutinating activity and infectivity occurred following sonication for more than 50 sec.

Hemagglutinins, Viral↗
PubMedDate not supplied

Physical methods for the analysis of molecular interactions in dyes utilizable in viral biology studies.

The possibilities of the main physical methods for the analysis of molecular interactions in solution are discussed on the ground of recent data of the literature. Spectrophotometry, (micro)cryoscopy and the isopiestic method are presented in more detail. These methods were applied to several dyes of common use in viral biology studies and to some new chromophore structures. The results obtained demonstrate the occurrence of molecular aggregation in solution in several of the above mentioned systems, both upon concentration rises and in the presence of inorganic ions.

Coloring Agents↗
PubMedDate not supplied

Electron optic aspects of sonically disintegrated influenza virus A(H1N1).

Purified influenza virus A(H1N1) was sonicated in a continuous flow Ultrasonics F600 device at 20 kHz, 600 W. Electron optic examination of samples collected at different time intervals revealed morphologic alterations of the virus particles, gradually increasing in intensity: detachment of surface components, disruption of the viral corpuscles and of their constitutive elements, appearance of ghosts and of clustered viral components different in size and orientation.

Influenza A Virus, H1N1 Subtype↗