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Biomedical subjects

M Barbi

Publications and source records attributed to M Barbi.

9 recordsLinked to original sources
PubMed1992

Antibody response to inactivated polio vaccine (E-IPV) in children born to HIV positive mothers.

In order to evaluate the response to immunization of HIV-infected children we studied the humoral response to an enhanced potency inactivated poliovaccine (E-IPV) of 43 children born of HIV seropositive mothers. All these subjects have been followed for 32 (15-48) months in order to ascertain their infection status. After a course of 2 doses of E-IPV, 88% of children had neutralizing antibody (n.a.) titers greater than 1:4 to the 3 poliovirus serotypes and 100% to at least 2 polio strains. No statistically significant differences both as rates of n.a. positive subjects and as antibody levels were found between HIV infected children and those who lost HIV antibodies. The poorest response was observed in subjects with full-blown immunodeficiency (CD4 less than 1000/mm3, reduced response to PWM). Sixteen children also received a booster dose of vaccine one year after the completion of the primary cycle. Infected and non-infected subjects responded to the same extent with high levels of n.a. to this immunization. Interestingly, the recall dose was also able to induce high n.a. titers in those HIV infected children who showed significant decreases of n.a. titers in the months following the end of the primary cycle.

Antibodies, Viral↗
PubMed1992

Immunization in children with HIV seropositivity at birth: antibody response to polio vaccine and tetanus toxoid.

OBJECTIVE: To evaluate the humoral response to routine childhood immunization of HIV-infected children. DESIGN: Response rate, antibody titres and persistence after polio and tetanus vaccination were compared in 72 children with HIV seropositivity at birth and divided according to HIV infection status as determined by clinical and laboratory tests. METHODS: Polio antibodies were titred in a microneutralization test (positive titres, > or = 1:4), and antibody to tetanus toxoid with a passive haemagglutination method (protective titres, > or = 1:1024). RESULTS: The response rates to polio and tetanus vaccination (> 80 and > 75%) were similar in the HIV-infected and non-infected children, as were antibody levels. In the subgroup with sera obtained some months after the last dose of vaccine, polio antibody levels decreased in all four HIV-infected and in three of the seven non-infected children; protective tetanus antitoxin levels were detected in three of the six infected and in all three non-infected children. CONCLUSIONS: This study demonstrates the ability of children with HIV infection to respond adequately to the two vaccines considered, although tetanus antitoxin levels were inferior, compared with those in the seroreverted children. The unsatisfactory antibody levels observed in the admittedly few HIV-positive children studied some months after the last vaccination could be the result of a lower initial protective level and not necessarily an expression of severely impaired immunocompetence. The administration of booster doses in addition to the traditional immunization schedule could be useful in children with HIV infection.

Antibodies, Bacterial↗
PubMed1991

Use of conditioned distributions in the analysis of ion channel recordings.

A method to test the Markov nature of ion channel gating is proposed. It makes use of singly and doubly conditional distributions. The application of this method to recordings from single BK channels provides evidence that at least two states of the underlying kinetic scheme are left at a constant rate. Moreover, the probabilities, when leaving a state, of reaching another given state are shown to be constant for all the states of the system.

Animals↗
PubMed1979

Type 1 diabetes and Coxsackie virus infection.

The role played by viruses in the aetiopathogenesis of type 1 diabetes mellitus has been studied by several authors; in particular the importance of Coxsackie virus B4 infection has been stated by some authors and not confirmed by others. 43 diabetic children were studied at the time of the diagnosis of the disease. No viruses could be isolated from stools; the titres of anti-Coxsackie viruses B1 to 6 complement fixing antibodies and anti-Coxsackie virus B4 neutralizing antibodies, compared to controls, indicated that Coxsackie virus infection was not associated with the onset of diabetes in these children. A cross-reaction with anti-Coxsackie viruses sera and a human pancreas demonstrated that there are not antigens in common between these viruses and the human pancreas.

Adolescent↗
PubMed1978

Measurements of Euglena motion parameters by laser light scattering.

Measurements of Euglena gracilis motion parameters have been performed by the spectral analysis of the scattered laser light. Samples were oriented by a radiofrequency field to obtain easily interpretable spectra. Cell rotation frequency and flagellar beating frequency distributions were obtained from the homodyne spectra, whereas the Doppler lines obtained at small observation angles by heterodyne detection yielded the swimming speed distributions. We discuss the broadening of the heterodyne spectra at large angles of observation. An application of this method to the study of the photo-kinetic effect is also described.

Cell Movement↗
PubMed1978

Effects of electromagnetic fields on the motion of Euglena gracilis.

The orientation behavior of Euglena gracilis cultures in electromagnetic fields is shown to agree with the predictions of a model involving only a passive mechanism. The increase in Euglena motor activity with increasing field intensity is demonstrated by measuring various motion parameters by the laser scattering technique. The effect of electric field on the speed of Euglenas is compared with that of temperature. We conclude that the electric field warms up the culture, thus inducing an increase in cell motility.

Cell Movement↗
PubMed1977

Phase-locked responses in the Limulus lateral eye. Theoretical and experimental investigation.

The 1:1 phase locking of the neural discharge to sinusoidally modulated stimuli was investigated both theoretically and experimentally. On the theoretical side, a neural encoder model, the self-inhibited leaky integrator, was considered, and the phase of the locked impulse was computed for each frequency in the locking range by imposing the condition that the "leaky integral" u(t) of the driving signal should reach the threshold for the first time one stimulus period after the preceding impulse. As u(t) can be a nonmonotonic function, this approach leads to results that sometimes differ from those reported in the literature. It turns out that the phase excursion is often much smaller than the values of about 180 degrees predicted from previous analysis. Moreover, our analysis shows a peculiar effect; the phase locking frequency range narrows when the input modulation depth increases. The theoretical predictions are then compared with phase-locked discharge patterns recorded from visual cells of the Limulus lateral eye, stimulated by sinusoidally modulated light or depolarizing current. The phases of the locked spikes at each of a number of modulation frequencies have been measured. The predictions offered by the model fit the experimental data, although there are some difficulties in determining the effective driving signal.

Action Potentials↗
PubMedDate not supplied

Sporadic cases associated with non polio enteroviruses studied in Lombardy between 1965 and 1972.

The results of virological investigations on 492 sporadic cases with a clinical diagnosis compatible with an enterovirus etiology studied in Lombardy between 1965 and 1972 are reported. A recent infection with non polio enteroviruses was established in 54 patients, mostly children under 4 years of age. Coxsackie viruses group A were prevalent being associated with 38 cases; echoviruses were involved in 13 cases, Coxsackie B viruses only in 3 instances. The frequency of isolation was highest from patients with paralytic illnesses either spinal or facial palsy than from patients with other diagnosis.

Adolescent↗