Interactions of blood cells (RBCs) with a microelectrode of 50 microns diameter have been examined under flow conditions using impedance measurements at high frequencies. At such frequencies, the electrolyte resistance (Re) is assimilated to the real part of impedance, and interactions are associated with transient fluctuations of Re. Sedimentation experiments suggest that one erythrocyte contributes to a 1.1% Re increase. Effects of wall shear rate (from 25 to 140 s-1) and RBC concentration (from 8.4 x 10(5) to 2.7 x 10(6) cells/ml) have been investigated; the number of interactions rapidly decreases with wall shear rate. Event frequency is proportional to RBC concentration ranging from 3.1 x 10(6) cells/ml to 1.3 x 10(7) cells/ml. At high concentrations of RBCs, some transient events overlap. Videotaped images help to determine how many RBCs interact with the microelectrode at the same time on separate surface areas. Under flow conditions, the contribution of one RBC on the Re increase is similar to the mathematical value obtained by sedimentation and decreases slightly with wall shear rate.

Electric Impedance↗

PubMedDate not supplied

Ivermectin-based control of onchocerciasis in northern Cameroon: individual factors influencing participation in community treatment.

A study aimed at determining individual factors associated with participation in community treatment with ivermectin was conducted in a village hyperendemic for onchocerciasis in northern Cameroon. The respective influences of sex, age, place of residence, distance between the compound and the dosing point, compound size, and participation in treatment by authoritative individuals in the compound was evaluated using univariate and multivariate analysis. Participation in treatment was closely associated with the attitude of the compound heads. Participation of compound heads in treatment increased as the household size increased, and as the distance to the distribution point diminished. This may be explained by the fact that getting information on health programmes is easier in large households whose members are involved in various social activities, and in compounds located near the village centre. Staff involved in health education should take this issue into account, and try to ensure circulation of information particularly to those living in small or remote compounds.

Adolescent↗