Biomedical subjects

A C Lapeña

Publications and source records attributed to A C Lapeña.

3 recordsLinked to original sources

PubMed2000

Human mtDNA haplogroups associated with high or reduced spermatozoa motility.

A variety of mtDNA mutations responsible for human diseases have been associated with molecular defects in the OXPHOS system. It has been proposed that mtDNA genetic alterations can also be responsible for sperm dysfunction. In addition, it was suggested that if sperm dysfunction is the main phenotypic consequence, these mutations could be fixed as stable mtDNA variants, because mtDNA is maternally inherited. To test this possibility, we have performed an extensive analysis of the distribution of mtDNA haplogroups in white men having fertility problems. We have found that asthenozoospermia, but not oligozoospermia, is associated with mtDNA haplogroups in whites. Thus, haplogroups H and T are significantly more abundant in nonasthenozoospermic and asthenozoospermic populations, respectively, and show significant differences in their OXPHOS performance.

Base Sequence↗

PubMed2000

Seminal quality correlates with mitochondrial functionality.

Oligozoospermia is an important manifestation of male subfertility and very little attention has been paid to study a possible relationship between the total number of ejaculated spermatozoa and mitochondrial functionality. In this work we report a direct correlation between spectrophotometrically measured mitochondrial enzyme activities (citrate synthase and respiratory complex I, II, I+III, II+III and IV) and seminogram parameters (sperm motility, vitality and cell concentration). In addition, total ejaculated spermatozoa correlate much better with the nuclear-encoded citrate synthase and complex II than with the mitochondrial-encoded complex I, III and IV activities. Furthermore, total number of spermatozoa has a significant but negative correlation with the ratios of complex I, complex III and complex IV to complex II (and citrate synthase). These ratios are significantly higher in aged subjects emphasizing the physiological relevance of this observation. These results suggest that the simultaneous increase of the number of ejaculated spermatozoa and the mitochondrial enrichment of citrate synthase and complex II are both parallel responses to the same regulatory events.

Humans↗

PubMed1998

Correlation of sperm motility with mitochondrial enzymatic activities.

Until now, little attention has been paid to the contribution of mitochondrial dysfunction to germinal tissue disorders. The target of this study was to investigate the relationship between sperm motility and mitochondrial respiratory chain enzyme activities. The results obtained showed that semen samples of control individuals (n = 33) have substantially higher activities of complexes I, II, and IV compared with those of asthenozoospermic subjects (n = 86). Moreover, a direct and positive correlation was found in the whole population studied between spermatozoa motility and all the mitochondrial respiratory complex activities assayed (I, II, I+III, II+III, and IV). The ratio of these enzymes to citrate synthase (a reliable enzymatic marker of mitochondrial volume) activities did not correlate with sperm motility. This suggests that motility depends largely on the mitochondrial volume within the sperm midpiece. These observations could be of physiopathological relevance because they suggest that factors affecting the mitochondrial energy production could be then responsible for particular cases of idiopathic asthenozoospermia.

Citrate (si)-Synthase↗