Relationship between resazurin reduction test, reactive oxygen species generation, and gamma-glutamyltransferase

Clinical Update on Home Testing for Male Fertility

Male factor infertility accounts for about 50% of the incidence of infertility in couples. In current practice, the men must attend a clinic or hospital facility to provide a semen analysis, which is key to the diagnosis of the male reproductive potential. However, many men are often embarrassed with the process and conventional semen analysis requires complex, labor intensive inspection with a microscope. To mitigate these problems, one of the solutions can be at-home semen analysis. In this review we examine the literature of currently available at home semen analysis test kits, describe their limitations, and compare them to the conventional lab-based methods.

Simplified sperm testing devices: a possible tool to overcome lack of accessibility and inconsistency in male factor infertility diagnosis. An opportunity for low- and middle- income countries

Background

Manual semen assessment (MSA) is a key component in a male’s fertility assessment. Clinicians rely on it to make diagnostic and treatment decisions. When performed manually, this routine laboratory test is prone to variability due to human intervention which can lead to misdiagnosis and consequently over- or under- treatment. For standardisation, continuous training, quality control (QC) programs and pricy Computer-Assisted Sperm Analysis (CASA) systems have been proposed, yet, without resolving intra- and inter-laboratory variability. In response, promising simplified sperm testing devices, able to provide cost-effective point-of-care male infertility diagnosis are prospected as a plausible solution to resolve variability and increase access to sperm testing.

Materials and methods

A throughout literature research for semen testing, sperm analysis, smart-phone assisted semen analysis, ‘at-home’ semen testing, male infertility, infertility in developing countries, infertility in low- and middle-income countries (LMIC) and quantitative sperm analysis was performed. A total of 14 articles, specific to ‘at-home’ simplified sperm assessment, were included to treat the core subject.

Results

Continuous training and consistent QC, are sine qua none conditions to achieve accurate and comparable MSA. Compliance does not rule-out variability, nevertheless. Emerging simplified sperm assessment devices are an actual alternative to resolve the lack of standardisation and accessibility to sperm analysis. YO ® , SEEM ® , and ExSeed ® are commercially available, user-friendly smartphone-based devices which can accurately measure volume, sperm concentration (millions/ml) and total motile sperm count. More broadly, by cost-effectiveness, availability, accuracy and convenient application, these devices could effectively select patients for first-line artificial reproduction treatments such as intrauterine insemination.

Conclusions

Accuracy and cost-effectiveness make smart-phone based sperm testing devices a practical and realistic solution to overcome variability in MSA. Importantly, these tools represent an actual opportunity to standardise and improve male subfertility diagnosis and treatment, especially in LMIC. However, before clinical application is possible, guidelines, further testing with special attention on accuracy in washed sperm, availability, cost-benefit and reliability are required.

Spermatozoal large RNA content is associated with semen characteristics, sociodemographic and lifestyle factors

Semen analysis is one of the standard diagnostic tools currently used to assess male infertility and reproductive toxicity. However, semen analysis has a limited ability to separate fertile from infertile populations. Additional methods to detect impaired fertility are needed. The purpose of the present study was to evaluate how spermatozoal RNA content varies with sociodemographic and behavior/lifestyle factors, and to determine if spermatozoal large and small RNAs discriminate normal from abnormal spermatozoa. Semen specimens were collected from 133 men aged between 18 to 55 years undergoing semen analysis as part of couple infertility evaluation while 10 proven fertile donors were recruited as control group. Semen samples were classified as normal or abnormal according to World Health Organization (WHO) 2010 criteria. Sperm RNAs were extracted after somatic cells were lysed, and the association of large or small RNA content with semen quality and sociodemographic and behavioral/lifestyle factors was evaluated using a generalized additive model and one-way ANOVA. Inverse relationship was observed between large RNA content and sperm parameters such as sperm count, density and motility. Large RNA content per sperm was significantly increased in semen samples showing abnormal number of round cells. Furthermore, sperm motility was inversely associated with spermatozoal small RNA contents. Grouping donors by the number of semen abnormalities, we observed significant increased spermatozoal large and small RNA content in men with more than two semen abnormalities. Alcohol consumption was strongly associated with increased large RNA per sperm concentration after adjustment for age and BMI. Our study demonstrates a strong relationship between spermatozoal large RNA content and poor semen characteristics that may lead to a role in the assessment of male fertility, and may be used as an endpoint for reproductive toxicology risk assessment.

GGsTOP increases migration of human periodontal ligament cells in vitro via reactive oxygen species pathway

GGsTOP is a novel and selective inhibitor of gamma-glutamyl transferase (GGT), a cell-surface enzyme that has a key role in glutathione homeostasis and the maintenance of cellular reactive oxygen species (ROS). ROS are essential for wound healing. However, little is known about the molecular mechanisms underlying the inhibition of GGT by GGsTOP in human periodontal ligament cells (hPLCs). The present study assessed GGT expression in mouse periodontal ligament tissues, GGT activity in hPLCs, and the potential physiological effect of GGsTOP on hPLC migration. Immunohistochemical analysis confirmed that GGT was widely expressed in mouse periodontal ligament tissue. Treatment with GGsTOP was associated with greater proliferation and migration of hPLCs, and higher levels of cellular ROS compared with untreated hPLCs. However, the increase in intracellular ROS was attenuated in hPLCs co-cultured with the anti-oxidant N-acetylcysteine (NAC), a precursor of glutathione. The higher ROS levels associated with GGsTOP treatment were in parallel with increases in the levels of type I collagen and alpha smooth muscle actin, which was inhibited in hPLCs co-cultured with NAC. Thus, GGsTOP may promote hPLC migration and participate in the maintenance of the periodontal ligament apparatus via the ROS pathway.

Metabolic activity of sperm cells: correlation with sperm cell concentration, viability and motility in the rabbit

The resazurin reduction test (RRT) is a useful technique to assess the metabolic rate of sperm cells. RRT depends on the ability of metabolically active cells to reduce the non-fluorescent dye resazurin to the fluorescent resorufin. The aim of this study was to develop a vital fluorometric method to evaluate metabolic activity of rabbit sperm cells. Twenty-five rabbit males were included in the study. Viability and morphology, motility and metabolic activity were evaluated using an eosin-nigrosin staining, a computer-assisted semen analysis (CASA) and the RRT, respectively. Spearman rank correlation analysis was used to determine the correlation between RRT and semen parameters. After evaluation, a concentration of 10 × 106 sperm cells/ml was selected for further experiments with RRT. No significant correlation was found between the RRT results and the motility parameters. However, after RRT a significant positive correlation between relative fluorescence units and the percentage of alive spermatozoa (r = 0.62; P = 0.001) and a negative one with the percentage of sperm cells with acrosomic abnormalities (r = -0.45; P < 0.05) were detected. The vital assessment of metabolic rate of sperm cells by RRT could provide more information about semen quality than other routine semen analysis, correlating with sperm viability and acrosome status information.

Involvement of sperm plasma membrane and cytoskeletal proteins in human male infertility

OBJECTIVE

To assess the physicochemical characteristics of sperm plasma membrane and to evaluate the immunohistochemical expression of transmembrane and cytoskeletal proteins in spermatozoa isolated from normospermic fertile donors and asthenozoospermic infertile patients.

DESIGN

Case-control study.

SETTING

Academic male infertility center.

PATIENT(S)

Twenty-five infertile patients affected by idiopathic asthenozoospermia and 21 age-matched normospermic fertile donors.

INTERVENTION(S)

Sperm parameters were evaluated; membrane fluidity and hydration studies, and immunohistochemical analysis were performed in isolated spermatozoa.

MAIN OUTCOME MEASURE(S)

Semen analyses to ascertain volume, sperm count, motility, and morphology; then membrane fluidity and hydration studies and immunohistochemical analysis were performed on isolated spermatozoa.

RESULT(S)

Spermatozoa from the asthenozoospermic group exhibited a reduced fluidity at the lipid-water interface level, an increased fluidity of the deeper portion of the bilayer, and a lower plasma membrane hydration than normospermic cells. Moreover, the immunohistochemical expression of ezrin, Cdc42, CD9, F-actin, and β-tubulin was higher in normospermic samples.

CONCLUSION(S)

Our results together assume that a cytoskeletal reorganization induced by a disturbance in the physicochemical features of sperm plasma membrane, and potentially mediated by ezrin, Cdc42, and tetraspanin CD9, could have a role in idiopathic asthenozoospermia.

Effect of n-3 and n-6 polyunsaturated fatty acids on hare reproductive performances

The study was carried out on 42 breeder couples (42 males and 42 females) of European brown hare (Lepus europaeus), divided into three groups fed three different experimental diets (14 couples/treatment). Two diets were supplemented with n-3 and n-6 polyunsaturated fatty acids (PUFAs; 2% of linseed oil and soybean oil, respectively) and were compared with a control diet supplemented with a monounsaturated fatty acids (2% of olive oil). During the experimental period (from 15 April to 30 September), the following parameters were recorded: days from the beginning of trial to the first parturition, parturition interval, number of parturitions, number of leverets born (alive and dead), dead during suckling, the total number of leverets weaned and feed intake per cage (of males, females and leverets until weaning). Feed intake was not influenced by treatments. In hares fed n-3 and n-6 diets, the days from the beginning of the trial to the first parturition and the parturition interval were similar and were lower compared with control group (63.1 v. 70.6 days, and 37.8 v. 40.9 days, respectively; P < 0.05). Hares from n-6 group had a higher (P < 0.05) number of parturitions per cage during the experimental period than the n-3 and control group that showed a similar value (3.00 v. 2.36, respectively). The total number of leverets born per cage and parturition in n-6 and n-3 groups increased with respect to those fed control diet (P < 0.05). The leverets' mortality rate at birth was higher in n-6 than in n-3 and control group (3.50 v. 2.17, respectively; P < 0.05). In control group, leverets' mortality rate during suckling was lower with respect to n-3 (P < 0.05) and n-6 (P < 0.05), showing the highest value for the latter (P < 0.05). In spite of this higher mortality, the number of leverets weaned per cage and parturition was higher (P < 0.05) in n-6 compared with n-3 group, being the latter higher than the control group (3.12, 2.79 and 2.43, respectively). Our results show that the dietary PUFAs, particularly n-6 supplementation, have a positive influence on the reproductive performances of the European brown hare.

Malondialdehyde levels in sperm and seminal plasma of asthenozoospermic and its relationship with semen parameters

BACKGROUND

Toxic lipid peroxides are known to cause various impairments of sperm cells and may play a major role in the etiology of male infertility. We determined the level of lipid peroxidation as indicated by malondialdehyde (MDA) in the spermatozoa and seminal plasma of asthenozoospermic and normozoospermic males.

METHODS

MDA of spermatozoa and seminal plasma was determined in 35 asthenozoospermic and 15 normozoospermic men by spectrofluorometry. Semen analysis was done according to the WHO standard.

RESULTS

MDA concentration in the spermatozoa of asthenozoospermic was significantly higher than in normozoospermic males (0.14+/-0.059 and 0.09+/-0.04 nmol/10 x 10(6) spermatozoa respectively). The mean+/-S.D. MDA value in the seminal plasma of asthenozoospermic and normozoospermic were 1.35+/-0.42 and 1.2+/-0.3 nmol/ml seminal plasma respectively.

CONCLUSIONS

Lipid peroxidation has a deleterious effect on the semen quality and MDA is an index of lipid peroxidation which may be a diagnostic tool for the analysis of infertility in the asthenozoospermic patients.

Seminal secretory capacity of the male accessory sex glands in chronic pelvic pain syndrome (CPPS)/chronic prostatitis with special focus on the new prostatitis classification

OBJECTIVE

The aim of the study was to evaluate the secretory dysfunction of the male accessory glands in men with inflammatory versus non-inflammatory chronic pelvic pain syndrome (CPPS).

METHODS

One hundred and twelve consecutive patients symptomatic for chronic pelvic pain were included into the study. All underwent a combined granulocyte analysis in expressed prostatic secretions (EPS) and a four-glass-test followed by ejaculate analysis. Patients were subgrouped according to elevated granulocyte counts in prostatic secretions, leukocytes in semen, or any of both. The content/total enzyme activity of the secretory seminal plasma parameters gamma-glutamyl-transferase (gamma-GT), fructose, and alpha-glucosidase representing the secretory capacity of the prostate gland, the seminal vesicles, and the epididymes, respectively, were investigated.

RESULTS

The only significant findings were a reduced total enzyme activity of gamma-GT in men stratified according to elevated granulocyte counts in prostatic secretions (p=0.022; cutpoint 9.85U per ejaculate; sensitivity 61.1%, specificity 58.8%, AUC 0.6347) and in men with any inflammatory sign (p=0.033; cutpoint 9.9U per ejaculate, sensitivity 63%, specificity 58.33%, AUC 0.6404).

CONCLUSIONS

Secretory damage of the prostate gland in men with inflammatory CPPS is demonstrable provided that increased granulocytes in prostatic secretions are part of the diagnostic criteria. However, because of the low sensitivity and specificity of gamma-GT it cannot be recommended as diagnostic tool to detect inflammatory disease on the basis of reduced secretory capacity.

gamma-Glutamyltransferase dependent generation of reactive oxygen species from a glutathione/transferrin system

In the presence of molecular oxygen and iron or copper ions, a number of antioxidants paradoxically generate reactive oxygen species (ROS) leading to free radical damage of nucleic acids and oxidative modification of lipids and proteins. The present work demonstrates that the combination of three components, which are often considered as part of an antioxidant protection system, can generate ROS. Purified human gamma-glutamyltransferase (GGT) in the presence of 2 mM glutathione (GSH) and 80 microM transferrin, as an iron source, at pH 7.4 generates ROS, as measured by chemiluminescence of luminol. Initiated by the addition of purified GGT, generation of ROS reached a maximal rate in the first 6 min. Intensity of the chemiluminescence was only slightly enhanced by addition of 200 microM hydrogen peroxide. Generation of ROS was also investigated in transfected V79 cells expressing human GGT. In comparison with GGT negative V79 cells, only recombinant cells expressing a high level of GGT on the cell membrane were able to generate ROS. Generation of ROS in these cells reached a maximum within 2 min and was enhanced by 200 microM hydrogen peroxide. We further confirmed the hypothesis that cysteinylglycine (CysGly), a product of GGT/GSH reaction, identified by high-performance liquid chromatography, but not GSH, was responsible for ROS formation initiated by the reductive release of iron from transferrin. These data clearly indicate that under physiological conditions, GGT is directly involved in ROS generation.

The correlates and alleged biochemical background of the resazurin reduction test in semen

Reduction of the blue dye resazurin to pink resorufin is used to estimate the concentration of metabolically active spermatozoa in semen samples. In order to quantify the reduction of resazurin, a spectrophotometric method was developed measuring the change from blue to pink in the butanol extracted colour. The biochemical mechanisms involved in the reduction of resazurin by motile spermatozoa and seminal plasma were investigated. Addition of NADH + H+ to sperm suspension or seminal plasma increased the reduction of resazurin. The reduction reaction was inhibited by high concentrations of dicoumarol, a specific inhibitor of the diaphorase enzyme, in a dose-dependent manner. It is suggested that the sperm diaphorase enzyme transfers electrons from NADH + H+ to resazurin, reducing it to resorufin. The degree of resazurin reduction was strongly correlated with the concentration of motile spermatozoa recovered from the 90% Percoll fraction (r = 0.98, p < 0.001). A positive correlation was also found between the reducing capacity of seminal plasma (n = 62) on the one hand, and sperm concentration (r = 0.72, p < 0.0001), progressive motility (r = 0.45, p < 0.01), normal morphology (r = 0.50, p < 0.01), and gamma-glutamyltransferase (r = 0.36, p < 0.05) on the other hand. These findings, together with our previous observations that the reduction reaction is inhibited by reactive oxygen species and polymorphonuclear white blood cells, increase our understanding of the biochemical basis of the resazurin test and may provide better insight into the interpretation of this test.

Effects of resazurin on bovine oocyte fertilization and embryo development in vitro

Resazurin is a redox dye (7-hydroxy-3H-phenoxazin-3-one-10-oxide) used for assessing potential fertility of spermatozoa and functional status of eukaryotic cells. In this study, the fertilizing capacity of spermatozoa treated with resazurin and effects of resazurin on bovine embryo development in vitro was examined. Abattoir-derived bovine oocytes were collected and subjected to in vitro maturation (IVM), fertilization (IVF) and culture (IVC). In Experiment 1, bovine oocytes (n = 2767) were fertilized with spermatozoa exposed to resazurin (17.6 micrograms/ml) for 0, 15, 30, 60 min, respectively. There was no significant (P > 0.05) difference in cleavage rates. However, the proportion of embryos that developed into blastocysts, expanded and hatched blastocysts in those groups in which oocytes/embryos were treated with resazurin during IVC or IVM/IVF/IVC was significantly (P < 0.05) less than those exposed to resazurin during IVM only, or during IVF only. We conclude that resazurin did not have significant adverse effects on fertilizing capability of bovine spermatozoa; however, extended treatment of embryos with resazurin may be detrimental to embryonic development.