High levels of cathepsins B, L and S in human seminal plasma and their association with prostasomes.

Semen is a heterogenous and complex fluid with different functions, some of them well known, others still obscure. The aim of this study was to investigate the presence of cathepsins B, S and L in human seminal plasma and their possible associations with other semen variables. Cathepsin B, L and S concentrations were measured in seminal plasma from 99 men utilising commercial ELISA kits. Seminal plasma cathepsin B was approximately 70 times higher, while the cathepsin L values were approximately 500 times higher and the cathepsin S values approximately 40 times higher in seminal plasma than in a group of serum samples. The study shows that seminal plasma contains high levels of cathepsins B, L and S. All three cathepsins were also bound to the surface of prostasomes.

Association of cystatin C with prostasomes in human seminal plasma.

It was recently elucidated that cystatin C, a protein targeted to the classical secretory pathway by its signal peptide sequence, can also be secreted in association with exosomes. Accordingly, we wanted to investigate whether there is a secretory link between cystatin C and prostasomes in human seminal plasma. Cystatin C concentrations in seminal plasma from 50 men including 6 vasectomized men were measured by turbidimetry on an Architect Ci8200. Some of the seminal plasma samples were also analysed utilizing an Epics Profile XL-MCL cytometer. We found high concentrations of cystatin C in seminal plasma. The 2.5-97.5 percentiles, performed by bootstrap estimation, were 25.8 [95% confidence interval (CI): 22.3-29.4] to 77.0 mg/L (95% CI: 71.9-82.1). Cystatin C is present in approximately 50 times higher concentration in seminal plasma compared with blood plasma. There was no clear difference as regards seminal plasma content of cystatin C between vasectomized men and the rest of the group. Immunoblot analysis with chicken anti-cystatin C antibody revealed a firm association of cystatin C with prostasomes. Flow cytometric analysis demonstrated that cystatin C was linked to prostasomes also meaning an at least partial prostasomal membrane surface localization.

Lack of dynein arms in immotile human spermatozoa.

Sermatozoa from two brothers who are not twins were found to be straight and immotile. Examinations of the sperm showed that oxygen consumption and lactic acid production were normal; viability tests showed that the percentage of dead sperm was not increased. The ultrastructural appearance of the sperm tail was normal except for a complete lack of dynein arms and some irregularities in the arrangement of the accessory fibers and the longitudinal columns of the fibrous sheath. The mitochondrial apparatus and the sperm head conform to the conventional model. According to the sliding-filament hypothesis first proposed by Afzelius (1959. J. Biophys. Biochem. Cytol. 5:269.), the arms are responsible for the bending movements of the tail. The simplest explanation for the simultaneous lack of arms and sperm motility appears to be that the two brothers have a genetic disorder involving production, assembly, or attachment of the dynein arms.

Semen analysis.

In view of the well known sensitivity of the seminiferous epithelium to various stress factors and to chemicals one would expect that semen analyses would be part of many screening programs to detect dangerous chemicals and environmental hazards. This is not the case, and our knowledge about the production and functional properties of human spermatozoa is mainly based on analyses of specimens from men with barren marriages. A more common use of semen analyses should enable us to better define the normal limits for many of the potentially relevant variables. Due consideration must, however, also be given the time for spermatogenesis and for transit through the epididymis as well as the influence of seminal plasma factors on many functional properties of the spermatozoa. From the scanty information available one can already now presume that careful analyses of motility and morphology of the spermatozoa under standardized conditions will be of help in the early detection of environmental hazards. A more common use of methods for the assessment of such functional properties of the spermatozoa as structural stability, membrane permeability, metabolism, and resistance to physical stress will give additional information about the effects of chemicals and other factors. To exploit these potential methods for the early detection of environmental hazards there is, however, also a need of a changed attitude towards semen analysis from the medical profession as well as from the public.

The effects of albumin, magnesium, and zinc on human sperm survival in different fractions of split ejaculates.

PIP: The effects of albumin, magnesium, and zinc on human sperm survival in different fractions of split ejaculates were studied. Of particular interest was the effect of these prostatic factors on the survival of spermatozoa in the last 1/2 of the ejaculate. The survival and motility of human spermatozoa were studied in the first and last halves of more than 50 split ejaculates from 7 men. The 4-hour survival was better in the first 1/2. The addition of human albumin (4%) to the last 1/2 maintained the survival and motility of the spermatozoa at the same level as in the first 1/2. Addition of albumin to the last 1/2 also reduced the uptake of zinc by the spermatozoa in the part of the ejaculate. Addition of magnesium (100 mcg/ml) to the second 1/2 of the ejaculate had a slight beneficial effect on sperm survival; however, the effect was much less than that achieved with albumin. Addition of zinc or colloids (dextran, Ficoll) to the last 1/2 had no effect on the survival of the spermatozoa. Dextran and Ficoll did not reduce the high uptake of zinc characteristic for spermatozoa in the second 1/2. Addition of zinc ions to the second 1/2 increased the uptake of zinc by the spermatozoa.^ieng