Effect of steroid hormones on the metabolism of human spermatozoa

Information relating to the effect of steroids on the metabolism and motility of human spermatozoa is limited despite the increasing interest in the use of these hormones for the purpose of contraception.In the present study it was shown that progesterone, testosterone, and 11-β-OH-progesterone significantly inhibit the CO₂ production of human spermatozoa. Estrone was ineffective. Progesterone and testosterone, but not estrone, also significantly depressed O₂ uptake. In contrast to CO₂ production and O₂ uptake, lactic acid production was not significantly affected by any of the steroids studied. The inability of estrone to inhibit sperm metabolism was not due to its lower solubility relative to the other steroids tested.The data indicate that the effective steroids inhibit sperm respiration, but not the sperm glycolytic pathway.     

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.     

Effect of reserpine on fertilizing capacity of human spermatozoa

The effect of reserpine at various concentrations (2 × 10^?6, 2 × 10^?7, 2 × 10^?8, 2 × 10^?9 and 2 × 10^?10M) on the in vitro fertilizing capacity of human spermatozoa was studied. Spermatozoa collected from presumably fertile men were washed in BWW medium and incubated with different concentrations of reserpine for 5 hr before insemination of the zona-free hamster ova. The spermatozoal penetration of the zona-free hamster ova was scored 6 hr later and the results were analyzed statistically. Reserpine, at all the concentrations tested, caused a significant dose-dependent decrease in the penetration of the denuded hamster ova in comparison to the control (p <0.05). The percent motility of spermatozoa decreased as a function of time during the preincubation period to initiate spermatozoal capacitation but there were no significant differences in the values between the control and the reserpine — treated spermatozoa (p >0.05). These findings indicate that reserpine can affect the fertilizing capacity of human spermatozoa in vitro and provide an additional evidence to suggest the prospective use of reserpine as a vaginal contraceptive.     

The effects of hexavalent and trivalent chromium on fertilization and development in sea urchins

The action of Cr⁶⁺ (as chromate) and Cr³⁺ (as sulfate and nitrate) on fertilization and development has been investigated in sea urchins. By rearing the embryos in the presence of chromate (5 × 10^?5 to 5 × 10^?4m), the differentiation of the gut and skeleton was severely affected. The treatment of sperm before fertilization with CrO^2?₄ (10 to 30 min, 10^?4 to 10^?2m) resulted in a number of abnormal larvae, depending on the length of exposure and the CrO^2?₄ concentration. Morphological and quantitative changes of mitotic activity during cleavage were observed as a result of CrO^2?₄ exposure of zygotes, as well as of sperm and egg pretreatment. The exposure of embryos to Cr³⁺ after fertilization permitted larval differentiation, but affected the motility and hatchability of the embryos. The pretreatment of gametes with Cr³⁺ never induced larval malformations. Cr³⁺ exerted a strong depressive action on fertilization by decreasing the fertilizing capacity of sperm and leaving the fertilizability of the eggs almost unaffected.     

Copper: a biphasic regulator of caprine sperm forward progression

Abstract

Copper is essential for spermatogenesis and its presence has been demonstrated in male and female reproductive fluids in several mammalian species. However, little is known about the physiological significance of this trace element in the regulation of forward progression of mammalian sperm cells which is essential for sperm fertility potential in vivo. The purpose of this investigation was to determine the physiological role of the bivalent copper ion (Cu²⁺) on mammalian sperm forward motility using a chemically-defined medium and caprine cauda epididymal sperm model. Sperm forward motility was significantly enhanced by Cu²⁺ in a dose-dependent manner; maximal activation (approx 20%) was noted at the 5?µM level of the metal. Above 10?µM Cu²⁺ sperm motility decreased, showing that Cu²⁺ exerts a biphasic regulation on sperm motility. These findings have been confirmed using a spectrophotometric motility assay, an objective method of motility analysis. At lower concentrations (up to 5?µM), copper enhanced sperm membrane lipid peroxidation as well as the level of intra-sperm cyclic adenosine mono phosphate (c-AMP), but at a higher level it caused marked inhibition of both of the biochemical parameters. The observed correlation of Cu²⁺-dependent biphasic modulation of sperm membrane lipid peroxidation and intrasperm c-AMP with sperm forward motility is consistent with the view that Cu²⁺ regulation of sperm motility is mediated by membrane lipid peroxidation, which in turn modulates the level of intra-sperm c-AMP, a well-known activator of sperm motility.     

A dual,concentration-dependent transport system for riboflavin in rat intestine in vitro

The intestinal mucosal-to-serosal transport of riboflavin was examined using rat everted sacs. Maximum transport of 0.5 μM riboflavin occurred in the proximal small intestine. Transport of low (0.5 μM) and high (3.6 μM) concentrations of riboflavin, was linear with time for 30 min incubation and occurred at a rate of 1.55 and 3.59 pmole/g tissue wet wt/min, respectively. Transport of 0.5 μM riboflavin was pH-dependent, being maximal at pH 6.5–7.5 but decreased at lower pH. The transport process of riboflavin involves two systems: 1) an active, carrier-mediated system and 2) difussion. The active system is characterized by: a) saturation with an apparent K_t of 0.38 μM; b) Na⁺-dependence; c) energy-dependence; d) temperature-dependence; e) inhibition by structural analogue and f) accumulation against a concentration gradient. The difussion system is characterized by: a) linear increase in the rate of transport as a functio of increasing mucosal concentration of riboflavin above 1 μM; b) Na⁺-independence; c) energy-independence and d) inability to accumulate the substrte against a concentration gradient. Conclusion: the intestinal transport of low concentrations of riboflavin occurs by an active, carrie-mediated system while transport of high concentratins occurs by simple diffusion.     

Heavy Rare Earth Elements Affect <Emphasis Type="Italic">Sphaerechinus granularis</Emphasis> Sea Urchin Early Life Stages by Multiple Toxicity Endpoints

Heavy rare earth elements (HREEs) were tested for adverse effects to early life stages of the sea urchin Sphaerechinus granularis. Embryos were exposed to analytically measured HREE concentrations ranging from 10^?7 to 10^?5 M. No significant developmental defect (DD) increases were observed in embryos exposed to 10^?7 M HREEs, whereas 10^?5 M HREEs resulted in significant DD increase up to 96% for HoCl₃ versus 14% in controls. Embryos exposed to 10^?6 M HREEs showed the highest DD frequency in embryos exposed to 10^?6 M DyCl₃ and HoCl₃. Cytogenetic analysis of HREE-exposed embryos revealed a significant decrease in mitotic activity, with increased mitotic aberrations. When S. granularis sperm were exposed to HREEs, the offspring of sperm exposed to 10^?5 M GdCl₃ and LuCl₃ showed significant DD increases. The results warrant investigations on HREEs in other test systems, and on REE-containing complex mixtures.     

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.     

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.     

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.     

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.     

Immunological aspects of exposure to emissions from burning coal of high beryllium content

An epidemiological study was conducted on groups of people exposed occupationally (45 persons) and nonoccupationally (36 persons) to the combustion products of coal containing a comparatively high concentration of beryllium. The concentration of beryllium in the working atmosphere ranged between 30 and 800 × 10^?5 mg × m^?3; in the town S, dwelling place of a nonoccupationally exposed cohort between 0.39 and 1.68 × 10^?5 mg × m^?3. A group of 100 subjects who had no occupational contact with beryllium and other industrial toxic agents, and lived outside of the polluted region served as control cohort. In all examined persons the main classes of immunoglobulins and autoantibodies (lung, heart, liver, spleen, thyroid gland, suprarenals, and native DNA) and antibodies against nuclear (ANA) and mitochondrial (AMA) antigens (obtained from the lungs of intact and of experimental berylliosis rats) were determined. In both exposed groups elevated levels of IgG and IgA and increased concentrations of autoantibodies were found in comparison with the control cohort of people. Specific AMA and ANA were also found in both the exposed groups, with higher values in women. The demonstrated immunological changes in humoral immunoreactivity might be considered as signs of beryllium exposure. In the discussion the authors emphasize the increasing importance of immunological aspects in the study of environmental pollution.     

Role of low exposure to metals as male reproductive toxicants

The objective of the study was to examine the associations between environmentally relevant low metal concentrations and semen quality parameters in men. The concentrations of zinc (Zn), copper (Cu), cadmium (Cd), arsenic (As), selenium (Se), and lead (Pb) in the seminal plasma and urine were measured from 196 male human subjects in Taiwan. Urinary Cd concentrations were negatively associated with sperm viability (p = 0.006). Seminal plasma Cu concentrations of the normal group (≥?15?×?10⁶/ml) were significantly lower than those of the abnormal group (p = 0.023). However, the linear regression analysis showed a weak association between Cu concentration and sperm concentration, along with other semen parameters. No significant relationship between other metals (As, Pb, Zn, and Se) and semen quality was observed.     

In vitro demonstration of pyrimethamine resistance of “wild” Plasmodium falciparum in the Gambia

The in vitro response of wild¹ Gambian Plasmodium falciparum to pyrimethamine is described. Parasites were grown in 100 μl cultures through schizogony. The number of rings present after 48 hours in drug-treated cultures was expressed as a percentage of the controls. Neither a medium and drug change after 24 hours nor different starting parasitaemias were found to affect the outcome of the assay, although a medium and drug change did increase the multiplication rate. 60 randomly taken pure P. falciparum infections were studied. 57 were sensitive. The ID50 and ID90 of drug-sensitive infections were 1·7 × 10^?9M and 4·5 × 10^?9M pyrimethamine respectively. Three infections were resistant (5%) with individual ID50 values of > 10^?6M, 3 and 4 × 10^?9M and ID90 values of > 10^?6M, 8 and 9 × 10^?7M.     

Urinary metabolites of di(2-ethylhexyl) phthalate relation to sperm motility,reactive oxygen species generation,and apoptosis in polyvinyl chloride workers

Purpose

To measure the concentrations of urinary di(2-ethylhexyl) phthalate (DEHP) metabolites in polyvinyl chloride (PVC) workers and a control group for determining the relationship of DEHP exposure to semen quality, sperm reactive oxygen species (ROS) generation, and sperm apoptosis.

Methods

We assessed the metabolites of DEHP, namely urinary mono-(2-ethylhexyl) phthalate (MEHP), mono-(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), and mono-(2-ethyl-5-oxohexyl) phthalate (MEOHP), and semen quality, such as sperm concentration, motility, morphology, ROS generation, and DNA damage by using terminal deoxynucleotidyl transferase-mediated nick end labeling assay obtained from 47 workers employed within two PVC pellet plants and 15 graduate students in Taiwan.

Results

Sperm concentration and motility were significantly affected in the high-exposure group. The percentage and intensity of sperm ROS generation were higher in the high-exposure group than those in the control group. After adjustment for age, smoking status, and coffee consumption, the decrease in sperm motility was inversely associated with the concentration of MEHP (β = ?0.549, p = 0.0085), MEHHP (β = ?0.155, p = 0.0074), and MEOHP (β = ?0.201, p = 0.0041). Moreover, sperm apoptosis and ROS generation were positively associated with MEHHP and MEOHP concentration, respectively.

Conclusions

This was the first study to explore the associations between levels of DEHP exposure, sperm motility, ROS generation, and apoptosis. The results suggested that urinary MEHHP and MEOHP were sensitive biomarkers for reflecting the relationship between DEHP exposure and semen quality.     

Recovery of ingested asbestos fibers from the gastrointestinal lymph in rats

Using the transmission electron microscope, asbestos fibers have been assessed in lymph fluid collected from the thoracic lymph duct in five groups of rats previously exposed to asbestos fibers (by ingestion). Ten rats were gavaged a single dose weighing approximately 20 mg. Five were given pure UICC chrysotile A while another group of five had pure UICC crocidolite. All the rats of the chrysotile group were positive animals with recovery rate values ranging from 6.9 × 10^?7 to 3 × 10^?5 (90% of the fibers being recovered during the first 16 hr following the gavage). The crocidolite group had only three positive animals and lower recovery rate values of 5.7 × 10^?8 to 5.6 × 10^?7. A third group was fed a synthetic diet containing 1%, by weight, chrysotile with a majority of short fibers (90% below 4 μm). Of the 15 rats comprising this group, 13 were positive with maximum daily recovery rates ranging from 2.1 × 10^?7 to 2.1 × 10^?6. A group of eight rats fed the same kind of diet but containing a higher proportion of long fibers, showed only four positive animals, however, they had higher daily recovery rates ranging from 1.9 × 10^?5 to 2.1 × 10^?4. No fibers were encountered in the samples of the two control rats. This study demonstrates the passage of chrysotile and crocidolite fibers across the gastrointestinal wall, with the passage rate being higher for long fibers than short ones.     

Influence of sampling factors on canine sperm motility parameters measured by the Sperm Class Analyzer

The aim of the present study was to investigate the effect of different technical settings and semen processing on sperm motility parameters measured by the Sperm Class Analyzer (SCA). Semen was collected from 3 dogs, pooled, and diluted in phosphate buffered saline and subsequently assessed by the SCA for the different sperm motility characteristics. The data were statistically analyzed by ANOVA and the repeatability was assessed by coefficient of variation (CV). After a principal component analysis, the reliability was determined with intra-class correlation coefficient (ICC). In experiment 1, the CV's were below 10% for all evaluated parameters. Significant differences (P?<?0.05) were found between the different sperm concentrations (25, 50, and 75 x 10⁶ spermatozoa/ml) in all of the motion parameters assessed, yielding the highest ICC (0.81) at 25 x 10⁶ spermatozoa/ml. No significant differences (P?>?0.05) in SCA read-outs were found between the number of microscopic fields captured (1, 2, 3, 4, or 5 fields), yielding the highest ICC (0.83) when 3 fields were captured. No significant differences (P?>?0.05) in motility parameters were found between the number of cells analyzed in each field (20, 50, and 100 spermatozoa) with the exception of beat cross frequency. Reliability of the SCA was good (ICC?=?0.71 to 0.90) for all motility measurements when 20 (ICC?=?0.89) or 50 (ICC?=?0.77) cells were captured in each field, but only just acceptable (ICC?=?0.51 to 0.70) when 100 cells were counted (ICC?=?0.67). The frame settings significantly (P?<?0.05) influenced most of the measured motility characteristics. Scanning 60 frames at a frame rate of 30?Hz improved the reliability of the results (ICC?=?0.92). In conclusion, we suggest that the measurements with the SCA are ideally performed at a sperm concentration of 25 x 10⁶ spermatozoa/ml, counting at least 100 cells in three microscopic fields. We also propose that the SCA should analyze 60 frames at 30?Hz to yield consistent results of a set of measurements or a measuring instrument thus obtaining reliable motility results.     

The hydrolysis and photolysis rates of nitrapyrin in dilute aqueous solution

The hydrolysis rate of nitrapyrin (2-chloro-6-(trichloromethyl)pyridine), the active ingredient of N-SERVE® nitrogen stabilizer (a registered trademark of The Dow Chemical Company, Midland, Michigan), in buffered, distilled water followed simple first-order kinetics over the concentration range, 6.2×10^?7 to 8.7×10^?5 M. The only product of the reaction was 6-chloropicolinic acid. The rate of the reaction decreased with increasing buffer concentration at 35°C (M buffer concentration-half-life): 0.005M ? 1.7 days, 0.02M?2.0 days, 0.067M?4.0 days. The ramifications of this negative salt effect are discussed. The hydrolysis rate was independent of pH over the range, 3.2 to 8.4. Additional data were obtained for rates at 25° and 45°C. The activation energy for the reaction under these conditions was 25.0 kcal/mole. Photolysis of nitrapyrin at 25°C in 0.005M phosphate buffers at pH 5.1, 7.1, 8.0, and in a natural water also followed simple first-order kinetics over the nitrapyrin concentration range, 7.1×10?6 to 7.5×10?6M. Again, there was no observable pH effect on the rate over the pH range investigated, nor was there a rate enhancement in the natural water. The half-life of the reaction under these conditions was 0.5 day. The products of this reaction were 6-chloropicolinic acid (6-C1PA), 6-hydroxypicolinic acid (6-OHPA), and unidentified polar material formed in that order in a series of sequential reactions. Simulation of the set of sequential reactions using determined first-order rate constants at 25°C and a starting concentration of 1.7 ppm predicts that nitrapyrin will be half gone in 0.5 day, that the concentration of 6-ClPA will peak at 1.3 ppm in 1.8 days, and that the concentration of 6-OHPA will peak at 0.2 ppm in 3.7 days.     

An exploration of the disease burden due to Cryptosporidium in consumed surface water for sub-Saharan Africa

The protozoan pathogen Cryptosporidium is an important cause of diarrhoeal disease, but in many contexts its burden remains uncertain. The Global Waterborne Pathogen model for Cryptosporidium (GloWPa-Crypto) predicts oocyst concentrations in surface water at 0.5 by 0.5° (longitude by latitude) resolution, allowing us to assess the burden specifically associated with the consumption of contaminated surface water at a large scale. In this study, data produced by the GloWPa-Crypto model were used in a quantitative microbial risk assessment (QMRA) for sub-Saharan Africa, one of the regions most severely affected by diarrhoeal disease. We first estimated the number of people consuming surface water in this region and assessed both direct consumption and consumption from a piped (treated) supply. The disease burden was expressed in disability adjusted life years (DALYs). We estimate an annual number of 4.3 × 10⁷ (95% uncertainty interval [UI] 7.4 × 10⁶–5.4 × 10⁷) cases which represent 1.6 × 10⁶ (95% UI 3.2 × 10⁵–2.3 × 10⁶) DALYs. Relative disease burden (DALYs per 100,000 persons) varies widely, ranging between 1.3 (95% UI 0.1–5.7) for Senegal and 1.0 × 10³ (95% UI 4.2 × 10²–1.4 × 10³) for Eswatini. Countries that carry the highest relative disease burden are primarily located in south and south-east sub-Saharan Africa and are characterised by a relatively high HIV/AIDS prevalence. Direct surface water consumption accounts for the vast majority of cases, but the results also point towards the importance of stable drinking water treatment performance. This is, to our knowledge, the first study to utilise modelled data on pathogen concentrations in a large scale QMRA. It demonstrates the potential value of such data in epidemiological research, particularly regarding disease aetiology.     

Significance of Adenosinetriphosphate in Human Sperm as Clinical Parameter

Washed human spermatozoa from 21 individuals with an average motility of 60% (quality index 277 ± 16) had an endogenous ATP generation of 7.5 ± 3.4 nmole/10⁸spermatozoa. The ATP concentrations in spermatozoa from 16 patients with severely impaired motility of 26% (quality index 98 ± 13) was 16.9 ± 9.9 nmole/10⁸spermatozoa. There was no correlation between ATP content and motility in either group. Sperm penetration into blood serum type AB, Rh-positive, was evaluated using a capillary tube penetration test. The penetration was graded with a maximum score of 14. Spermatozoa with an initial motility of 60% reached a score of 10 ± 0.7. After addition of 20 mmole of ATP the score was significantly improved to 13 ± 0.3. Compared with these results spermatozoa with an average motility of 26% reached a score of 4 ± 1. Exogenous ATP (20 mmole) increased the score to 8 ± 1.0. In both groups reduced glutathione had a negative effect.

Human spermatozoa with high and low motility are capable to synthesize ATP. A dysfunction of the phosphorylating particles in the mitochondria appears not to be associated with low sperm motility.