The net surface charge of spermatozoa represents a characteristic of the plasmamembrane. It can be evaluated indirectly, by the measurement of the sperm electrophoretic motility (EPM). The EPM of washed human spermatozoa was determined in the microelectrophoresis to investigate three problems: (a) intra- and interindividual variation coefficients of EPM of cryopreserved spermatozoa, (b) effects of cryopreservation medium, temperature shock and cryoprotection on the EPM, (c) relationship between the EPM and the cryotolerance of the spermatozoa. The inter- and intrain-dividual variation coefficients of the sperm EPM of 24 cryopreserved semen samples of 6 fertile semen donors amounted to 7% and to 6%, respectively. The cryopreservation did not cause a significant change of sperm EPM in contrast to the temperature shock in liquid nitrogen. Temporary incubation of spermatozoa with egg yolk decreased their EPM. A significant correlation between EPM and the cryotolerance ascertained by the alteration of sperm motile efficiency could be found. After contact with egg yolk spermatozoa achieved a behaviour that corresponded to a better cryotolerance.

Cell Membrane↗

PubMedDate not supplied

Selected sperm differ from nonselected cells in their electrophoretic mobility (EPM) after demembranation.

Human semen samples were first treated by swim-up migration or by Percoll density gradient centrifugation for selection of spermatozoa. The net surface charges of spermatozoa in the resulting compartments were indirectly evaluated by the electrophoretic mobility (EPM) during spermatozoal microelectrophoresis. Significantly different electrophoretic mobilities were measured between the compartments after demembranation with 0.1% (v/v) Triton X-100. However, without intermediate treatment by the detergent no significant differences were detected between the spermatozoal EPM. In addition, spermatozoa were divided into migrated and nonmigrated spermatozoal populations by the swim-up technique, and then treated with urea to remove spermatozoal coats. No significant differences in EPM were detected between these two groups. This investigation demonstrates that selected spermatozoa from semen exhibit an additional dimension of superiority, in EPM, to nonselected spermatozoa, which may better equip them for the process of fertilization. Measurements of EPM, therefore, may provide yet another, perhaps valid, means of developing a clinical tool for evaluating the potential fertilizing capacity of a semen sample in infertility studies.

Cell Membrane↗

PubMedDate not supplied

[Muscle as a system with parametric excitation].

A mechanical model for oculorotatory muscle consisting of a neurally controlled Voigt element in parallel with a mass and in series with a passive elastic element, is proposed. The magnitude of each element without the mass and the series elasticity is shown as a function of length and the viscosity as a function of velocity. The non-linear Voigt element is shown as a time-varying element to describe the activation of muscle. The characteristics resulting from the mathematical development agree well with the experimental data published for the operating range.

Animals↗

PubMedDate not supplied

Trisomy 8 is a characteristic finding in pleuropulmonary blastoma.

The cytogenetic findings in pleuropulmonary blastoma (PPB) have not been widely studied and reported and are of interest in view of the implications that PPB has for additional tumors in the patient and the patient's relatives. Using standard tumor cytogenetic methodology, we investigated three cases of PPB encountered in our institution over a 5-year period. Trisomy 8 was the only karyotypic abnormality in a localized type 2 PPB and was present with other abnormalities in another type 2 PPB and a massive type 3 PPB. Review of the literature yielded three additional karyotyped PPBs; all had trisomy 8 as part of the abnormalities detected. Trisomy 8 appears to be a characteristic of PPB and may be related to the development of PPB and related tumors.

Chromosomes, Human, Pair 8↗