Biomedical subjects

D du Toit

Publications and source records attributed to D du Toit.

27 records · Page 2Linked to original sources

PubMedDate not supplied

Impaired epididymal function in patients with detached ciliary tufts in semen: a preliminary report.

Low spermatozoal ATP concentration in the presence of high alpha-glucosidase activity may indicate efficient epididymal function. It was suggested that detached ciliary tufts (DCTs) originated from the epididymis. We compared the spermatozoal ATP concentration and alpha-glucosidase activity in semen of patients with DCTs to that of a control group. Higher ATP concentration and lower alpha-glucosidase activity were found in patients with DCTs in their semen compared to the control group. These results might probably point out impaired epididymal function and further support the proposed epididymal origin of these tufts.

Adenosine Triphosphate↗

PubMedDate not supplied

The presence of alpha-glucosidase, glycerophosphocholine and carnitine in the epididymis and ejaculate of the vervet monkey (Cercopithecus aethiops) and the Chacma baboon (Papio ursinus).

The epididymis is the site of posttesticular sperm maturation in the male genital tract. Studies on human epididymides are hampered by the practical inaccessibility of epididymides of healthy men in their reproductive years. The limited use of laboratory animals therefore seems unavoidable. The objective was to establish baseline values of the epididymal markers alpha-glucosidase, glycerophosphocholine (GPC) and carnitine in the lumen of the caput, corpus and cauda epididymidis and in the ejaculate of adult male Chacma baboons and vervet monkeys. In both primates, alpha-glucosidase was found throughout the epididymis and in the ejaculate; values did not vary significantly. In monkeys, the highest concentration of GPC was found in the cauda epididymidis, but smaller amounts were found in the other regions and the ejaculate. In baboons, GPC was absent from the caput, but present in the other regions, including the ejaculate. Carnitine concentrations increased significantly from the caput to the cauda in monkeys and from the caput to the corpus in baboons. With this study, the relative concentration ranges in which these markers are present in the epididymides of these primates have been established. In future studies, changes in concentrations of these substances would probably indicate changes in epididymal function.

Animals↗

PubMedDate not supplied

Effect of rotation on the generation of reactive oxygen species in human semen.

Rotation of semen after liquefaction is a standard procedure in an Andrology laboratory. During rotation under aerobic conditions the semen is exposed to oxygen. Oxygen toxicity induces lipid peroxidation which is responsible for the loss of sperm function. The generation of reactive oxygen species was significantly increased after rotation. This may have a detrimental effect on sperm function during assisted reproduction.

Humans↗

PubMedDate not supplied

alpha-Glucosidase, sperm ATP concentrations, and epididymal function.

It has been suggested that alpha-glucosidase may be a marker of epididymal patency and function. Spermatozoal ATP concentrations decrease during passage through the epididymis, indicating efficient maturation. We correlated sperm motility with seminal plasma alpha-glucosidase activity and spermatozoal ATP. The sperm motility correlation with alpha-glucosidase activity was significantly positive, and the sperm motility correlation with spermatozoal ATP was significantly negative. It appears that high-alpha-glucosidase activity and low-spermatozoal ATP were present in semen with good sperm motility and could possibly indicate efficient epididymal function.

Adenosine Triphosphate↗

PubMedDate not supplied

High seminal sialic acid concentrations in patients with severe teratozoospermia.

Seminal plasma and sperm-bound sialic acid (SA) concentrations were evaluated in patients with severe teratozoospermia (less than 5% morphologically normal sperm) and correlated with values of a control group with greater than 20% morphologically normal sperm. The SA concentrations both in seminal plasma and on sperm were significantly higher in teratozoospermia, but the ratio of sperm-bound SA to seminal plasma SA remained virtually the same. The causes and consequences of high SA in these patients need further study.

Humans↗

PubMedDate not supplied

Epididymal markers in an andrology clinic.

The ability of the markers alpha-glucosidase, carnitine, and glycerylphosphorylcholine to indicate epididymal obstruction was studied. alpha-Glucosidase was found to be the best discriminant, with 93.4% correct classifications. The possible interrelationship between alpha-glucosidase activity, sperm ATP, and epididymal function was then studied. alpha-Glucosidase correlated positively with the percentage of motile sperm (p = 0.0212) and with the percentage of sperm with good forward progression (p = 0.0374), but correlated negatively with the sperm ATP (p < 0.0500). It was concluded that lower ATP and higher alpha-Glucosidase may be markers of efficient epididymal function. The possible epididymal origin of detached ciliary tufts (DCTs) was studied by determining ATP and alpha-glucosidase activity in patients with DCTs. The mean ATP in patients with DCTs was significantly higher (p = 0.009), but the alpha-glucosidase activity significantly lower (p = 0.0412) than in the control group. These results seem to support the epididymal origin of DCTs.

Adenosine Triphosphate↗

PubMedDate not supplied

Sialic acid concentration and sperm motility.

Sialic acid (SA) forms an integral part of the sperm membrane, and the masking properties of SA are well documented. Masking of estrogen and melatonin receptors on the sperm midpiece by SA has been demonstrated. In this paper we report on the correlation of sperm bound SA concentration and motility. We found a negative correlation between the spermbound SA concentration and both the quantitative and qualitative motility. The spermbound SA correlated positively although not significantly with the spermatozoal ATP concentration. SA may mask the receptors on the sperm membrane, affecting sperm metabolism. This will inhibit the breakdown of ATP to its lower nucleotides resulting in poor motility. This may be another reason to believe that SA may play a key role in sperm motility.

Humans↗

PubMedDate not supplied

Sperm adenosine triphosphate concentrations before and after freezing as a marker of cryolysis.

Frozen semen samples are generally used today for artificial insemination and in vitro fertilization (IVF) and have various advantages above freshly produced semen. A disadvantage is that substances may leak out of the sperm if the membrane is damaged during freezing. In this study sperm ATP concentration was determined before freezing and after thawing and correlated with fertilization in an IVF program. After freezing and thawing the average sperm motility decreased significantly (p < or = .0001). Sperm ATP concentration was also significantly lower after freezing and thawing (p = .0004). Sperm ATP concentration after thawing did not correlated with fertilization. ATP concentration was a good marker of cryolysis but not of fertilization.

Adenosine Triphosphate↗

PubMedDate not supplied

Sialic acid in semen of normozoospermic men.

Good sperm motility in normozoospermic men was associated with high bound and total sialic acid (SA) and pyruvate concentrations in the seminal plasma, as well as high endogenous (sperm) pyruvate concentrations. The presence of sialidase in the seminal plasma was also demonstrated for the first time. The results suggest that SA is metabolized to pyruvate by a N-acetylneuraminic acid (NANA)-aldolase in the seminal plasma and that pyruvate subsequently serves as an energy source for sperm.

Humans↗