Effects of androgens on fertilizing capacity of human spermatozoa

The potential functions of testosterone and 5 α-dihydrotestosterone, the androgens normally present in human seminal plasma, on human spermatozoal physiology were evaluated by studying the effects of these two steroid hormones on the $\text{in vitro}$ fertilizing capacity of human spermatozoa. Spermatozoa collected from presumably fertile men were washed in BWW medium and incubated with different concentrations (0, 100, 250, 500, 1000 pg/ml) of testosterone or 5 α-dihydrotestosterone for 5 hr before insemination of the zona-free hamster ova. Penetration of the zona-free hamster ova was scored 6 hr later and the results were analyzed statistically. Both testosterone and 5 α-dihydrotestosterone, at the concentrations tested, significantly decreased the $\text{in vitro}$ penetration of the denuded hamster ova in comparison to the controls (p < 0.05). A dose-dependent response was also observed for the 5 α-dihydrotestosterone tested. These findings indicate that exogenous testosterone and 5 α-dihydrotestosterone can inhibit the fertilizing capacity of human spermatozoa $\text{in vitro}$, and suggest that the androgens normally present in human seminal plasma may serve, in part, to prevent premature spermatozoal capacitation before the spermatozoa reach the site of fertilization $\text{in vivo}$.     

Effect of Caffeine on Human Sperm Penetration into Zona-Free Hamster ova

The effect of caffeine on spermatozoal ability to penetrate zona-free hamster ova was examined on fresh and frozen-thawed semen samples. The mean motility of 10 fresh semen samples incubated with caffeine significantly increased from 29% to 35%. Sperm penetration into zona-free hamster ova did not differ between the control group and the specimens to which caffeine was added. The same effect of caffeine on sperm motility and hamster ova penetration was noted in the frozen-thawed sperm samples. Motility was enhanced by 21%, but hamster ova penetration did not significantly change. The increase in sperm motility caused by caffeine does not change the fertilizing ability of fresh and frozen-thawed human sperm.     

Functional changes in human lymphocytes and monocytes after in vitro incubation with arginine

Human lymphocytes and monocytes obtained from healthy nonsmoking volunteers, were activated by in vitro incubation with excess arginine. Natural killer cell (NK) activity was increased three-fold after in vitro incubation with 64×10²μg/ml of arginine and 4×10²μg/ml of arginine induced 1.5 fold increase of human monocytes-mediated(HM) cytotoxicity. Production of tumor cytotoxic factor (TCF) from human monocytes significantly increased after in vitro incubation with arginine (8×10² and 32×10²μg/ml) for 24 hr. At high concentrations of arginine, in vitro growth of tumor cells was evidently suppressed. These results suggest that arginine action against tumor cells is due to, in part, not only via the enhancement of host immune functions (NK activity and HM cytotoxicity) but also direct effect to tumor cells.     

Relationship between Sperm Concentration and Polyspermy in Intact and Zona-Free Mouse Eggs Inseminated in Vitro

Intact and zona-free mouse eggs were cultured with preincubated (capacitated) spermatozoa for 1 or 4 hr. High proportions of eggs (84%-100%), examined either 1 or 4 hr after insemination, were undergoing fertilization in the intact and zona-free eggs in sperm concentration from 25-800 × 10³ sperm/ml. The average number of spermatozoa attached to the zona pellucida and to the vitellus was only slightly increased as the sperm concentration increased. Polyspermy was increased from 25-200 × 10³ sperm/ml but there was no clear correlation between the incidence of polyspermy and further increase of sperm concentration in both the intact and zona-free eggs. Besides a functional zona reaction, there was a definite vitelline block to further sperm entry. It seems that due to the chance collision of sperm and egg with the subsequent formation of a block mechanism in the zona pellucida and in the vitelline membrane within a short time, polyspermy cannot be increased by further increase of sperm concentrations.     

Effects of dieldrin on the uptake and metabolism of testosterone-1,2-3H by rodent sex accessory organs

The oral administration of dieldrin (1.25, 2.50, or 5.00 mg/kg daily × 5) significantly reduced the total uptake and subsequent metabolism of labeled androgens in the mouse anterior prostate gland. The in vivo metabolism of testosterone-1,2-³H to dihydrotestosterone-³H (DHT-³H), androstanediol-³H, or androstenedione-³H by the mouse prostate gland was lowered by pretreatment with dieldrin. Similarly, the in vitro metabolism of testosterone-1,2-³H to these aforementioned radiometabolites was reduced by dieldrin at a treatment level of 5 mg/kg (daily × 5). This highest-dose regimen also reduced the formation of the metabolites of testosterone in mouse hepatic microsomes. Varying concentrations of dieldrin (4 × 10^?7, 4 × 10^?6, or 2 × 10^?5m) in vitro effectively decreased the formation of DHT-H³ in the mouse anterior prostate gland and of androstanediol-³H in the rat ventral prostate gland.     

Inhibition of the metabolism and motility of human spermatozoa by various alkaloids

The ability of several alkaloids to inhibit the metabolism and motility of human spermatozoa has been investigated.Of the agents tested, chloroquine was the most effective in inhibiting sperm metabolism (production of carbon dioxide and lactic acid) and motility. It was active at a concentration of 3.6 × 10^?5M. Quinine and Quinacrine were active at concentrations of 5 × 10^?4M and emetine required concentrations as high as 3.6 × 10^?3M to achieve an inhibitory effect. Detailed studies with emetine showed that the time needed for inhibition of sperm motility was inversely proportional to the drug concentration and directly related to the sperm density. In addition, the inhibition was shown not to be reversible.     

Variations of gossypol sensitivity in boar spermatozoal electron transport chain segments

The concentration effect of gossypol on hypotonically-treated boar spermatozoa with either succinate or pyruvate and malate as substrate was examined. It was found that the pathways involved in the metabolism of succinate was more gossypol-sensitive. The gossypol sensitivity of various electron transport chain (ETC) segments in boar spermatozoa was also investigated with proper choice of electron donors and acceptors. The succinate to cytochrome c segment was the most sensitive one. However this inhibition threshold (1.8 × 10^?5 M gossypol), being higher than either the uncoupling threshold or the concentration threshold at which spermatozoal motility is reduced, suggests that the main target of gossypol antimotility effect does not seem to be the succinate to cytochrome c segment in the ETC.     

Differential mitotic toxicity of methylmercury in various meristematic tissues (apex,bud, root) of Elodea densa

Elodea densa plants were grown in flowing water for 25 days at methylmercury (MMC) concentrations of 7.5 × 10^?10, 7.5 × 10^?9, and 7.5 × 10^?8M. Toxicity development was different within and among the three types of meristematic tissues—apex, root, and bud. Apical cells were most sensitive to MMC and developed aberrant nuclear and mitotic characteristics at lower concentrations than did roots. Root meristems had a total inhibition of mitotic activity at 7.5 × 10^?9M with no aberrant symptoms at lower MMC levels. Conversely, the mitotic activity in bud meristems was zero in the control and increased in the presence of MMC. However, the divisions were abnormal. Higher concentrations of MMC (up to 2.5 × 10^?6M) had the unusual effect of stimulating the development of additional buds. The formation and development of root and bud initials were inhibited at levels of 7.5 × 10^?8 and 0.25 × 10^?6M MMC in the water.     

Detoxication of zinc and cadmium by the freshwater protozoan Tetrahymena pyriformis: I. The effect of water hardness

Estimated 8-hr LC₅₀ values of zinc and cadmium were less than 1 ppm in the absence of soluble calcium and magnesium, but were raised, for example, to 24 ppm of zinc and 19 ppm of cadmium by the addition of calcium plus magnesium at a concentration (500 ppm) equivalent to that of very hard water. Experiments with ⁶⁵Zn showed that uptake of this element from sublethal concentrations over 8 hr was reduced from approximately 50 × 10^?2 μg liter^?1 to 10 × 10^?2 μg liter^?1 per 10⁶ cells by the addition of 500 ppm of calcium and magnesium. Diminished uptake may partly explain the antagonism observed in the toxicity tests.     

Health Risk Assessment Related to Dermal Exposure of Chlorpyrifos: A Case Study of Rice Growing Farmers in Nakhon Nayok Province,Central Thailand

To date, pesticides, especially organophosphate pesticide such as chlorpyrifos, have been frequently applied to paddy fields over time to maintain product quality, protect agricultural crops from various pests, and increase yield. This study evaluates dermal exposure to chlorpyrifos in rice farmers along with providing a health risk assessment. Thirty-five rice farmers participated and completed an in-person interview, and patch technique was used to evaluate dermal exposure to chlorpyrifos. The chlorpyrifos residue was extracted from the gauze patches and quantified by gas chromatography equipped with flame photometric detector (GC-FPD). The results showed that chlorpyrifos concentrations were greater in males (526.34 ± 478.84 mg/kg) than females (500.75 ± 595.15 mg/kg). Average daily dose sampled from seven points on male and female farmers were 31.72 × 10^?4, 193.32 × 10^?4, 5.38 × 10^?4, 190.48 × 10^?4, 170.47 × 10^?4, 465.91 × 10^?4, and 43.04 × 10^?4 mg/kg-day. The hazard quotient (HQ) at the mean and 95th percentile level was found to be greater than acceptable (HQ > 1). Rice-growing farmers in this area may be at risk for adverse health effects due to continuous dermal exposure to chlorpyrifos from their improper use of personal protective equipment (PPE).     

The effects of arsenic compounds on human and bovine lymphocyte mitogenesis in vitro

The response of human and bovine peripheral blood lymphocytes to PHA stimulation was measured in the presence of low concentrations of sodium arsenite and sodium arsenate. In bovine lymphocytes, 41% augmentation of the response occurred at 10^?6m arsenite with a return to the normal response at 2.5 × 10^?6m. Complete inhibition of mitogenesis occurred at 6 × 10^?6m. In the presence of sodium arsenate, similar results were obtained but at the higher concentrations of 2 × 10^?5 (for 57% augmentation), 5.2 × 10^?5, and 1.9 × 10^?4m, respectively. The possible significance of these findings in view of the known relationship between chronic arsenicalism and human skin cancer is discussed. It is suggested that arsenic compounds may, by potentiating mitogenesis, increase the possibility of errors in DNA replication, some of which could be potentially carcinogenic. Additionally, interference with the immune response could enable potentially cancerous cells to escape immune surveillance.     

Contraceptive potentiality of STS-557--a feasibility study in male bonnet monkey (Macaca radiata)

STS-557 (17 alpha-cyanomethyl-17 beta-hydroxy-estra-4, 9(10)-diene-3-one) was administered (i.m.) to two groups (4 in each group) of adult male bonnet monkeys at a daily dose of 10 mg/monkey for 12 weeks (first group) and 5 mg/monkey for 14 weeks (second group). Treatment with the 10 mg dose resulted in a significant decline in the count, motility, acrosin and hyaluronidase activities and the fertilizing ability (zona-free hamster egg penetration assay) of spermatozoa by the 6th week of initiation of treatment. The circulating level of STS-557 was low after one week and increased from the 2nd week of treatment when the serum level of testosterone was significantly reduced. Complete recovery was observed by the 11th week after withdrawal of treatment. The treatment with the 5 mg dose had minor and inconsistent effect on the motility, hyaluronidase and acrosin activity, and the fertilizing ability of spermatozoa in addition to the blood level of testosterone. STS-557 may have the potentiality to be used as a chemical contraceptive in the male but compensation for the reduced level of blood testosterone may be necessary.     

Study of the effect of ulipristal acetate on human sperm ability to interact with tubal tissue and cumulus-oocyte-complexes

ObjectiveUlispristal acetate (UPA) is a selective progesterone receptor modulator widely used for emergency contraception (EC). The described main mechanism of action is by inhibiting or delaying ovulation; however, the postovulatory effects of the drug are still on debate. Therefore, the aim of this study was to determine whether UPA could interfere with human sperm fertilizing ability.Study designHuman motile spermatozoa were incubated under capacitating conditions with or without UPA, and then used to inseminate human tubal explants, mouse cumulus-oocyte complexes and zona-free hamster eggs. The ability of UPA to interact with human sperm progesterone (P)-binding sites was investigated by incubating the cells with fluorescent-labeled P and analyzing them by fluorescence microscopy.ResultsUPA did not affect the ability of human sperm to bind to human tubal tissue explants surface or to penetrate the mouse cumulus mass and the zona-free hamster eggs. In addition, concentrations of UPA much higher than those present in the plasma of EC pill users were required to bind to human sperm P-binding sites.ConclusionsOur study supports a lack of an agonist or antagonist action of UPA on different functional parameters associated with the fertilizing ability of human sperm.ImplicationsThis study provides new functional evidence supporting that the contraceptive action of UPA is not related to effects on human sperm cells, contributing to a better understanding of the mechanism of action of UPA as EC.     

The selective binding of steroids by human spermatozoa

The binding of steroids to human ejaculated spermatozoa has been investigated. The studies on the $\text{in vitro}$ binding of ³H-steroids to spermatozoa, under the chosen experimental conditions, showed that: (1) the attachment of the steroid molecules is complete within sixty minutes, (2) binding occurs independently of spermatozoal metabolic energy, (3) most of the steroid molecules bind to the plasma membrane, (4) the steroid binding to the spermatozoa is of low affinity in nature, and (5) the affinity for binding to spermatozoa varies with different steroids. It is proposed that there are different kinds of steroid binding sites on the spermatozoal plasma membrane.     

Cadmium-induced sterility: Possible involvement of the cholinergic system

Acute and chronic effects of cadmium exposure on spermatozoan choline acetyl transferase (ChAT) were studied to investigate the mechanism of cadmium induced sterility. Cadmium at dosages of 1 mg/kg and 2 mg/kg given orally inhibited ChAT in all segments of spermatozoa obtained from rat epididymis. Maximum inhibition was observed about 72 hr after treatment. Decreased ChAT activity was seen in chronic experiments where animals were exposed to cadmium via drinking water; surprisingly, a greater decrease was observed at the lower dosage. Cadmium also inhibited ChAT activity of rat cauda spermatozoa, and human spermatozoa when they were incubatedin vitro at a concentration of 5 × 10^?4M. Cadmium decreased human spermatozoan motility when incubated at a concentration of 5 × 10^?4M. Acetyl-choline (ACh) and physostigmine (a cholinesterase inhibitor), however, increased spermatozoan motility. The results indicate that cadmium may produce sterility by inhibiting spermatozoan choline acetyltransferase, decreasing acetyl choline synthesis, and impairing spermatozoan motility, and could be a potential reproductive hazard to humans.     

Relationship Between Acrosome Reaction and in Vitro Fertilization of Zona-Free Hamster Eggs by Bonnet Monkey (Macaca Radiata) Spermatozoa

The relationship between acrosome reaction, as studied by FITC-RCA staining technique, and the penetration of bonnet monkey spermatozoa into zona-free hamster eggs was investigated. The acrosomes of unreacted spermatozoa fluoresced, whereas those of acro-some-reacted sperm did not fluoresce owing to decreased binding of the lectin. The percentage of acrosome-reacted sperm increased following 3 h of incubation in BWW medium. The assessment of acrosome reaction by the FITC-RCA staining technique correlates well with the in vitro fertilization of zona-free hamster eggs.     

Patterns of Metal Accumulation by Natural River Biofilms During Their Growth and Seasonal Succession

To evaluate the factors influencing patterns of metal accumulation by river biofilms, concentrations of chromium (Cr), nickel (Ni), copper (Cu), and lead (Pb) in biofilms from Erh-Jen River and San-Yeh-Kung Creek were investigated during their growth and seasonal succession. Different metal-accumulation patterns during biofilm development were observed between the two rivers. Mature biofilms (grown for 21–28 days) in both rivers showed maximum metal accumulation (≤3.24 × 10⁴, 1.55 × 10⁴, 7.40 × 10³, and 7.80 × 10² μg g^?1 of Cr, Ni, Cu, and Pb, respectively) and bioconcentration factors (≤7.15 × 10⁵, 1.60 × 10⁵, 2.60 × 10⁵, and 4.22 × 10⁵ l kg^?1 of Cr, Ni, Cu, and Pb, respectively). These types of biofilms had the characteristics of being good metal accumulators and the ability to integrate metal-exposure conditions, suggesting that they were suitable biomonitors for metal-contaminated water. Seasonal succession in metal-accumulation ability of 1-month-old biofilms from Erh-Jen River was mainly affected by changes in bacterial and algal biomass and chemical oxygen demand in water, whereas that from San-Yeh-Kung Creek was primary influenced by concentrations of total nitrogen in water. Synergistic interaction between these four metals on metal-binding sites within biofilms was also shown.     

Increased Solubility and Bioavailability of Hydroxy-Cr(III) Precipitates in the Presence of Hydroxamate Siderophores

Siderophores are a diverse group of low molecular weight biogenic metallophores with a particular affinity for Fe(III) but they also have potential to complex a number of other polyvalent metal cations, including Cr(III). Here we show that two hydroxamate siderophores, desferrioxamine B and rhodotorulic acid, at environmentally relevant concentrations, facilitate the dissolution of hydroxy-Cr(III) precipitates from a common layer silicate. Desferrioxamine B and rhodotorulic acid induced maximum initial Cr dissolution rates of 11.3?±?1.7?×?10^??4  and 9.03?±?0.68?×?10^??4 µmol m^??2 h^??1, respectively, yielding maximum solution Cr concentrations of 0.26?±?0.01 and 0.20?±?0.02 µmol m^??2, respectively. These data demonstrate that hydroxamate siderophores may play an important role increasing the dispersal of Cr in natural environments, thus facilitating greater bioavailability of this potential toxin.     

The Association Between Global DNA Methylation and Telomere Length in a Longitudinal Study of Boilermakers

The objectives of this study were to determine if global DNA methylation, as reflected in LINE‐1 and Alu elements, is associated with telomere length and whether it modifies the rate of telomeric change. A repeated‐measures longitudinal study was performed with a panel of 87 boilermaker subjects. The follow‐up period was 29 months. LINE‐1 and Alu methylation was determined using pyrosequencing. Leukocyte relative telomere length was assessed via real‐time qPCR. Linear‐mixed models were used to estimate the association between DNA methylation and telomere length. A structural equation model (SEM) was used to explore the hypothesized relationship between DNA methylation, proxies of particulate matter exposure, and telomere length at baseline. There appeared to be a positive association between both LINE‐1 and Alu methylation levels, and telomere length. For every incremental increase in LINE‐1 methylation, there was a statistically significant 1.0 × 10^?1 (95% CI: 4.6 × 10^?2, 1.5 × 10^?1, P < 0.01) unit increase in relative telomere length, controlling for age at baseline, current and past smoking status, work history, BMI (log kg/m²) and leukocyte differentials. Furthermore, for every incremental increase in Alu methylation, there was a statistically significant 6.2 × 10^?2 (95% CI: 1.0 × 10^?2, 1.1 × 10^?1, P = 0.02) unit increase in relative telomere length. The interaction between LINE‐1 methylation and follow‐up time was statistically significant with an estimate ?9.8 × 10^?3 (95% CI: ?1.8 × 10^?2, ?1.9 × 10^?3, P = 0.02); suggesting that the rate of telomeric change was modified by the degree of LINE‐1 methylation. No statistically significant association was found between the cumulative PM exposure construct, with global DNA methylation and telomere length at baseline.     

Effect of dietary protein status on glucose utilization by the pentose cycle in pig adipose tissue

We investigated the effects of three levels of dietary protein (12, 18 and 23%) on lipid metabolism in pig adipose tissue (PAT). Eight-week-old male pigs were fasted for 96 hr and then refed for the same period of time. Adipose tissue biopsy samples were obtained and incubated for 3 hr in Hanks' salts containing 5.5 mM [1-¹⁴C], [6-¹⁴C], [U-¹⁴C] and [3-³H] glucose as well as 10 mM [2-¹⁴C] acetate and pyruvate. Fatty acids, CO₂, lactate and glyceride-glycerol yields were determined. An increase in dietary protein decreased (P<.05) glucose utilization and subsequent in vitro lipogenesis in PAT. A calculation of the role of the pentose cycle (PC) revealed a capacity to provide 60 to 90% of the NADPH required to support the observed rates of de novo fatty acid synthesis when glucose was a substrate. Several algorithms used to model PC acitivity in rat adipose tissue appeared to be inadequate for PAT because of a severe lack of triose phosphate pool equilibration and because of an apparent lack of CO₂ evolvement from the Krebs' Cycle. Tritium incorporation into fatty acids from [3-³H]glucose was related to ¹⁴CO₂ production from [1-¹⁴C]glucose and may be used to estimate glucose metabolism through the PC.