Correlation between sperm creatine phosphokinase activity and sperm concentrations in normospermic and oligospermic men

The Role of Melatonin to Ameliorate Oxidative Stress in Sperm Cells

It is widely accepted that oxidative stress (OS) coming from a wide variety of causes has detrimental effects on male fertility. Antioxidants could have a significant role in the treatment of male infertility, and the current systematic review on the role of melatonin to ameliorate OS clearly shows that improvement of semen parameters follows melatonin supplementation. Although melatonin has considerable promise, further studies are needed to clarify its ability to preserve or restore semen quality under stress conditions in varied species. The present review examines the actions of melatonin via receptor subtypes and its function in the context of OS across male vertebrates.

Creatine as a Promising Component of Paternal Preconception Diet

Male fertility has been declining globally over the past several decades, advancing from a personal issue to a public health problem. Beyond any doubt, a reduction in fertility (often characterized by low sperm count or motility) can severely threaten reproductive health and lifecourse framework in a long-term fashion. Aside from uncovering the currently unknown etiology of modern-day male infertility, the scientific and medical community faces a double burden: finding an efficient biomarker of impaired fertility and exploring any intervention that can act to enhance fertility. A plethora of nutritional compounds have been recognized as possible modulators of semen quality, and specific dietary patterns and nutrients appear to be accompanied by a lower risk of male infertility. Creatine, a conditionally essential nutrient, has caught attention as a male fertility-promoting candidate due to its role in sperm energy metabolism. This mini-review describes the creatine-related bioenergetics of spermatozoa, explores a connection between creatine levels and sperm quality in men, and critically examines available evidence for interventional studies with creatine to affect sperm viability.

Sperm Oxidative Stress during In Vitro Manipulation and Its Effects on Sperm Function and Embryo Development

Reactive oxygen species (ROS) generated at low levels during mitochondrial respiration have key roles in several signaling pathways. Oxidative stress (OS) arises when the generation of ROS exceeds the cell's antioxidant scavenging ability and leads to cell damage. Physiological ROS production in spermatozoa regulates essential functional characteristics such as motility, capacitation, acrosome reaction, hyperactivation, and sperm-oocyte fusion. OS can have detrimental effects on sperm function through lipid peroxidation, protein damage, and DNA strand breakage, which can eventually affect the fertility of an individual. Substantial evidence in the literature indicates that spermatozoa experiencing OS during in vitro manipulation procedures in human- and animal-assisted reproduction are increasingly associated with iatrogenic ROS production and eventual impairment of sperm function. Although a direct association between sperm OS and human assisted reproductive techniques (ART) outcomes after in vitro fertilization (IVF) and/or intracytoplasmic sperm injection (ICSI) is still a matter of debate, studies in animal models provide enough evidence on the adverse effects of sperm OS in vitro and defective fertilization and embryo development. This review summarized the literature on sperm OS in vitro, its effects on functional ability and embryo development, and the approaches that have been proposed to reduce iatrogenic sperm damage and altered embryonic development.

Cytotoxic and genotoxic effects of titanium dioxide nanoparticles in testicular cells of male wistar rat

Serious concerns have been expressed about potential risks of engineered nanoparticles. Regulatory health risk assessment of such particles has become mandatory for the safe use in consumer products and medicines; also, the potential effects on reproduction and fertility are relevant for this risk evaluation. In the present study, we examined the effects of intravenously injected titanium dioxide nanoparticles (TiO2-NPs; 21 nm), with special emphasis on reproductive system. Antioxidant enzymes such as catalase, glutathione peroxidase, and superoxide dismutase showed a significant decrease, while significant increase in lipid peroxidase was observed. Our results confirmed the bioaccumulation of TiO2-NPs in testicular cells. In TiO2-NPs-treated animals, various functional and pathological disorders, such as reduced sperm count, increase in caspase-3 (a biomarker of apoptosis), creatine kinase activity, DNA damage, and cell apoptosis were observed. Moreover, the testosterone activity was decreased significantly in a dose-dependent manner in the animals treated with TiO2-NPs as compared with control group animals. It is concluded that TiO2-NPs induce oxidative stress, which produce cytotoxic and genotoxic changes in sperms which may affect the fertilizing potential of spermatozoa.

Semen Characteristics After Overnight Shipping: Preservation of Sperm Concentrations, HspA2 Ratios, CK Activity, Cytoplasmic Retention, Chromatin Maturity, DNA Integrity, and Sperm Shape

We tested several approaches that can be used to preserve sperm attributes and the objective biochemical markers of sperm maturity and function for assessment in a remote centralized laboratory after overnight shipping of semen samples. Addition of phenyl-methyl-sulfonyl-fluoride (PMSF) to a final concentration of 20 microg/mL semen at 4 degrees C has preserved sperm concentrations and HspA2 isoform ratios, even at room temperature, simulating a shipping delay in moderate ambient temperatures. Regarding the attributes of individual spermatozoa, the patterns of CK-immunocytochemistry (demonstrates cytoplasmic retention in diminished-maturity spermatozoa); aniline blue staining pattern (tests chromatin maturity); sperm shape assessed by both Kruger strict morphology and computer assisted morphometry; and sperm DNA integrity, as tested by DNA nick translation, all remained unchanged. Thus, the PMSF-4 degrees C conditions preserved sperm concentrations and the cytoplasmic and nuclear biomarkers of sperm cellular maturity and function for next-day analysis. This shipping method will facilitate the early detection of subtle changes in semen quality that can affect sperm function, even when there has been no decline in sperm concentrations to signal possible toxic effects. Furthermore, sample preservation will enable investigators to evaluate semen for toxicology studies and for diagnosis of male infertility from remote locations. Home collection of semen should enhance study participation, and semen assessment in centralized laboratories will address concerns regarding interlaboratory variations and quality control.

Effect of abamectin exposure on semen parameters indicative of reduced sperm maturity: a study on farmworkers in Antalya (Turkey)

Environmental exposure to pesticides may cause serious health risks including fertility and reproductive function. The aim of this study was to highlight whether there is a relationship between exposure to abamectin and male fertility parameters of farmworkers. Twenty male farmworkers who were using abamectin and 20 men not exposed to pesticides were recruited as experimental and control groups, respectively. Semen analysis, molecular markers of sperm maturity and serum reproductive hormone levels were evaluated. In experimental group, high plasma abamectin levels were detected. These men have decreased sperm motility. Moreover, diminished molecular markers of sperm maturity, such as decreased hyaluronic acid (HA) binding of sperm, increased numbers of aniline blue positive sperm and increased percentage of creatine kinase (CK) positive sperm, were observed in abamectin-exposed men. Their serum testosterone, LH and FSH levels did not change significantly. We conclude that exposure to abamectin may impair male fertility by effecting semen quality.

The therapeutic effect of a pulsed electromagnetic field on the reproductive patterns of male Wistar rats exposed to a 2.45-GHz microwave field

INTRODUCTION

Environmental exposure to man-made electromagnetic fields has been steadily increasing with the growing demand for electronic items that are operational at various frequencies. Testicular function is particularly susceptible to radiation emitted by electromagnetic fields.

OBJECTIVES

This study aimed to examine the therapeutic effects of a pulsed electromagnetic field (100 Hz) on the reproductive systems of male Wistar rats (70 days old).

METHODS

The experiments were divided into five groups: microwave sham, microwave exposure (2.45 GHz), pulsed electromagnetic field sham, pulsed electromagnetic field (100 Hz) exposure, and microwave/pulsed electromagnetic field exposure. The animals were exposed for 2 hours/day for 60 days. After exposure, the animals were sacrificed, their sperm was used for creatine and caspase assays, and their serum was used for melatonin and testosterone assays.

RESULTS

The results showed significant increases in caspase and creatine kinase and significant decreases in testosterone and melatonin in the exposed groups. This finding emphasizes that reactive oxygen species (a potential inducer of cancer) are the primary cause of DNA damage. However, pulsed electromagnetic field exposure relieves the effect of microwave exposure by inducing Faraday currents.

CONCLUSIONS

Electromagnetic fields are recognized as hazards that affect testicular function by generating reactive oxygen species and reduce the bioavailability of androgen to maturing spermatozoa. Thus, microwave exposure adversely affects male fertility, whereas pulsed electromagnetic field therapy is a non-invasive, simple technique that can be used as a scavenger agent to combat oxidative stress.

The role of sperm creatine kinase in the assessment of male fertility

The lack of reliable methods to assess sperm fertilizing potential has been a long-standing problem for infertile couples and for their physicians. The most widely used tests, the measurements of sperm concentrations, motility, velocity and morphology in the ejaculate, are of limited utility. Indeed, following intrauterine insemination, a treatment that compensates for low motile sperm concentrations, there were no significant differences found in semen parameters among those who did or did not achieve pregnancies. Other available assays probing for selected sperm functions, such as membrane integrity, acrosome enzyme activity, bovine cervical mucus penetration test, zona-free hamster oocyte penetration test and sperm binding to various carbohydrates,10–13 have all failed thus far to consistently predict male fertility. It became increasingly obvious that there was a need to identify cellular markers of sperm quality and fertilizing potential.

Fertility testing and ICSI sperm selection by hyaluronic acid binding: clinical and genetic aspects

The testis-expressed chaperone protein, HspA2 (previously creatine kinase M isoform) was established as a measure of human sperm cellular maturity, function and fertility. The presence of HspA2 in the synaptonemal complex is likely to link low HspA2 expression and increased frequency of chromosomal aneuploidies in arrested-maturity spermatozoa. A relationship also exists between HspA2 expression in elongating spermatids and the associated spermatogenetic events, including plasma membrane remodelling and the formation of zona pellucida and hyaluronic acid (HA) binding sites. The HA receptor of mature spermatozoa, when coupled with HA-coated slides and/or Petri dishes, allows visual observation of sperm-HA binding, providing a basis for sperm maturity testing, a major improvement in semen evaluation, and selection of mature spermatozoa for intracytoplasmic sperm injection (ICSI). Thus, in HA-selected spermatozoa the frequency of chromosomal disomy and diploidy is reduced 4- to 6-fold compared with semen sperm fractions. This reduction is similar to the increase in numerical chromosomal aberrations in ICSI children. Combined studies of sperm shape and chromosome probes demonstrated that sperm morphology does not aid selection of haploid spermatozoa. The HA-mediated sperm selection is a novel and efficient technique that may alleviate potential problems related to ICSI fertilization with visually selected spermatozoa.

Hyaluronic acid binding ability of human sperm reflects cellular maturity and fertilizing potential: selection of sperm for intracytoplasmic sperm injection

PURPOSE OF REVIEW

The current concepts of sperm biochemical markers and the central role of the HspA2 chaperone protein, a measure of sperm cellular maturity and fertilizing potential, are reviewed.

RECENT FINDINGS

Because HspA2 is a component of the synaptonemal complex, low HspA2 levels and increased frequency of chromosomal aneuploidies are related in diminished maturity sperm. We also suggest a relationship between HspA2 expression in elongating spermatids and events of late spermiogenesis, such as cytoplasmic extrusion and plasma membrane remodeling that aid the formation of the zona pellucida binding and hyaluronic acid binding sites. The presence of hyaluronic acid receptor on the plasma membrane of mature sperm, coupled with hyaluronic acid coated glass or plastic surfaces, facilitates testing of sperm function and selection of single mature sperm for intracytoplasmic sperm injection. The frequencies of sperm with chromosomal disomy are reduced approximately fourfold to fivefold in hyaluronic acid selected sperm compared with semen sperm, comparable to the increase in such abnormalities in intracytoplasmic sperm injection offspring. Hyaluronic acid binding also excludes immature sperm with cytoplasmic extrusion, persistent histones, and DNA chain breaks.

SUMMARY

Hyaluronic acid mediated sperm selection is a novel technique that is comparable to sperm zona pellucida binding. Hyaluronic acid selected sperm will also alleviate the risks related to intracytoplasmic sperm injection fertilization with sperm of diminished maturity that currently cause worldwide concern.

Effect of varicocelectomy on sperm creatine kinase, HspA2 chaperone protein (creatine kinase-M type), LDH, LDH-X, and lipid peroxidation product levels in infertile men with varicocele

OBJECTIVES

To determine the total sperm creatine kinase, HspA2 chaperone protein (creatine kinase-M isoform), lactate dehydrogenase (LDH), LDH-X activities, and lipid peroxidation product (malondialdehyde [MDA]) levels in infertile men with varicocele and to examine the possible effect of varicocelectomy on these parameters.

METHODS

Eighty-one men were enrolled in this study. The study population consisted of a control group (n = 25) and a varicocele group (n = 56). Of the 56 patients with varicocele, 26 underwent microsurgical subinguinal varicocelectomy at our institution between July 2002 and July 2003. The standard semen parameters (sperm concentration and motility and Kruger morphology) and total sperm creatine kinase, HspA2, LDH, and LDH-X activities, and MDA levels were assessed in the control and varicocele groups. The differences were compared between the two groups. The same parameters were repeated at 6 months postoperatively in the varicocelectomy group and the preoperative and postoperative results were compared.

RESULTS

The sperm concentration was significantly lower in the varicocele group than in the control group (P = 0.01). The mean sperm HspA2 activities were significantly lower and the LDH activities and MDA levels were significantly greater in the varicocele group than in the control group (P = 0.005 and P = 0.001, P < 0.001, respectively). No statistically significant difference was found in the semen parameters in the varicocelectomy group preoperatively and postoperatively. Sperm HspA2 activities increased significantly after varicocelectomy compared with preoperatively (P < 0.001).

CONCLUSIONS

Our data suggest that sperm HspA2 activities are lower and LDH activities and MDA levels are greater in infertile men with varicocele. These data also suggest that varicocelectomy increases HspA2 activities in these patients.

Human sperm maintain their shape following decondensation and denaturation for fluorescent in situ hybridization: shape analysis and objective morphometry

The relationship between abnormal sperm morphology and chromosomal aberrations has been of interest. Thus far, however, studies have focused on frequencies of sperm with either abnormal morphology or aneuploidies in semen samples, not on detection of individual spermatozoa exhibiting both abnormal morphology and aneuploidy. To assess the feasibility of simultaneous evaluation of both attributes in an individual sperm cell, we investigated whether sperm shape is preserved after decondensation and denaturation, procedures that are required for fluorescent in situ hybridization (FISH). On 21 slides, 395 sperm were fixed, photographed, and then digitized by the computer-assisted Metamorph morphometry program for individual evaluation before decondensation. To establish whether sperm of various shapes would behave in similar manners, the cells were also classified, according to their head shapes, into symmetrical (n = 115), asymmetrical (n = 115), irregular (n = 115), and amorphous (n = 50) categories. Following decondensation and subsequent denaturation, sperm that had been photographed initially were relocalized and digitized for morphometry. Head area, perimeter, long axis, short axis, shape factor, and tail length were evaluated in each of the 395 sperm in both the native and decondensed states. After the decondensation and denaturation protocol of the FISH procedure, the sperm exhibited a proportional increase in dimensions as compared to their original sizes. Their initial shapes were preserved with high fidelity whether the sperm were in the symmetrical, asymmetrical, irregular, or amorphous categories. Hybridization with the chromosome probes had no further effect on sperm shape or size. We provide images to demonstrate how these findings facilitate studies about the relationship between sperm shape and chromosomal content or aberrations in individual spermatozoa.

Failed fertilization: is it predictable?

PURPOSE OF REVIEW

The purpose of this review is to critically examine the ability of screening tests to predict fertilization failure.

RECENT FINDINGS

Failed fertilization occurs in 5-10% of in-vitro fertilization cycles and 2-3% of intracytoplasmic sperm injection cycles. Failed fertilization may result from impaired spermatozoa, oocyte deficiencies or defects in the in-vitro sperm/oocyte medium. In the in-vitro fertilization setting most cases are caused by male factor deficiencies, whereas failure of oocyte activation is the most common cause of failed fertilization after intracytoplasmic sperm injection. Although the standard semen analysis has limited ability to predict fertilization failure, strict sperm morphology criteria, sperm-zona binding ratios and zona pellucida induced acrosome reaction tests provide increased capacity to avoid this outcome. The quality of the semen sample on the day of oocyte retrieval and fertilization performance in previous in-vitro fertilization cycles may also guide the appropriate use of intracytoplasmic sperm injection. However, the routine use of the latter technique in cases of non-male factor infertility is contraindicated.

SUMMARY

The ever improving techniques highlighted in this analysis offer improved ability to predict failed fertilization.

Hyaluronic acid binding by human sperm indicates cellular maturity, viability, and unreacted acrosomal status

OBJECTIVE

To test, both in semen and washed-sperm fractions, whether hyaluronic acid (HA) binding is restricted to sperm that have completed cellular maturation.

DESIGN

Comparisons of sperm in semen and in HA-bound sperm fractions.

SETTINGS

University-based diagnostic and research andrology laboratory.

PATIENT(S)

Semen samples originated in men being tested for infertility.

INTERVENTION(S)

The attributes of sperm maturity were tested by immunocytochemistry with creatine kinase and HspA2 antisera (highlights cytoplasmic retention in diminished-maturity sperm), aniline blue chromatin staining (detects persistent histones), pisum sativum lectin staining (reveals acrosomal integrity), and the FertiLight viability kit (highlights viable and nonviable sperm).

RESULT(S)

All markers of sperm maturity and immaturity supported the hypothesis that HA-bound sperm are mature. Nonbinding sperm exhibited cytoplasmic and nuclear properties of diminished maturity. The acrosomal status of HA-bound sperm was either unreacted or slightly capacitated, but not acrosome reacted. Only viable sperm exhibited HA binding.

CONCLUSION(S)

Sperm that are able to bind to HA are mature and have completed the spermiogenetic processes of sperm plasma membrane remodeling, cytoplasmic extrusion, and nuclear histone-protamine replacement. Hyaluronic acid-bound sperm show unreacted acrosomes. These studies provide further insights into the relationship between spermiogenesis and sperm function.

New semen quality scores developed by principal component analysis of semen characteristics

The purpose of this study was to determine whether semen characteristics can be reduced to 2 semen quality (SQ) scores and whether these new scores can help the clinician in assessing the reproductive outcome. A cross-sectional sample of 250 patients seeking infertility treatment were analyzed for semen characteristics. In addition, 177 male-factor patients (prostatitis with infection, n = 40; varicocele, n = 77; varicocele with infections, n = 11; and vasectomy reversal, n = 43) were also assessed. Sperm motion kinetics were measured by computer-assisted semen analysis (CASA) (concentration, percent motility, curvilinear velocity [VCL], straight-line velocity [VSL], average path velocity [VAP], linearity [LIN], and amplitude of lateral head displacement [ALH]). Sperm morphology was assessed by both World Health Organization (WHO) guidelines and Tygerberg strict criteria. The principal component analysis model was used to construct an SQ score and a relative semen quality (RQ) score. A separate set of 25 normal donors was included as controls to determine normal ranges of the semen scores. Among the patient samples, SQ and RQ scores (median and 25% and 75% interquartile values) were 89.9, 25.1, and 130.4 and 106.1, 45.2, and 165.9, respectively. The SQ score for the varicocele and varicocele with infection groups was comparable (78.6 +/- 17.4 and 84.8 +/- 20.6) but significantly different from the control (100 +/- 10, P <.001 and.03). Vasectomy reversal patients had an SQ score of 78.2 plus or minus 16.8 that was significantly lower than controls (P <.001). The correlation among semen characteristics allows for the efficient combining of semen measures. The composite scores can summarize overall SQ and quantity. Both SQ and RQ scores provide meaningful information on the quality of semen specimens for the clinician.

Biochemical markers of sperm function: male fertility and sperm selection for ICSI

The expression of a 70 kDa chaperone protein, HspA2 (formerly called CK-M), has been identified in mature human spermatozoa. The central role of HspA2 has been established, as the expression level of this protein is related to sperm cellular maturity, DNA integrity, chromatin maturity, chromosomal aneuploidy frequency and sperm function, including fertilizing potential. The spermiogenetic events of cytoplasmic extrusion and remodelling of the plasma membrane, which facilitate the formation of zona pellucida binding site(s) in human spermatozoa, are related. Finally, the presence of the hyaluronic acid (HA) receptor on the plasma membrane of mature sperm coupled with the HA-coated slide sperm-binding assay, facilitates the testing of infertile men and the selection of single mature spermatozoa for ICSI. Because mature spermatozoa have no residual cytoplasm, the HA-bound sperm fraction is also enriched in spermatozoa that are normal by the Kruger strict morphology method.

Sperm maturity and treatment choice of in vitro fertilization (IVF) or intracytoplasmic sperm injection: diminished sperm HspA2 chaperone levels predict IVF failure

OBJECTIVE

To reexamine whether low sperm HspA2 ratios (formerly sperm CK-M ratio) are predictive for failure to cause pregnancies by in vitro fertilization (IVF) and to explore whether there are other male or female factors that may be predictive for IVF pregnancy outcome.

DESIGN

Retrospective, cohort study.

SETTING

University-based IVF program.

PATIENT(S)

In 119 IVF cycles, three patient groups were studied: 25 men had a <10% sperm HspA2 ratio and a lack of pregnancies (HS <10% group), 50 men had a >10% sperm HspA2 ratio and no pregnancies (HS >10%NP group), and another 44 couples had a >10% sperm HspA2 ratio but did achieve pregnancies (HS >10%P group).

INTERVENTION(S)

Sperm HspA2 ratio determinations within 1 year of the IVF cycles and analysis of male and female IVF cycle parameters.

MAIN OUTCOME MEASURE(S)

Sperm HspA2 ratio determinations within 1 year of the IVF cycles and analysis of male and female IVF cycle parameters.

RESULT(S)

In the three groups, male and female ages, number and maturation level of oocytes, and morphology of embryos were similar. In the HS < 10% group, mean sperm concentration and motility were close to normal, the fertilization and cleavage rates were lower, and cycles without any oocyte fertilization were higher. These parameters were similar in the two HS > 10% groups. The receiver operating characteristic curve in men with sperm HspA2 ratios of <17% (diminished and borderline sperm maturity) provided a cutoff value of 10.84% HspA2 ratio with a 100% positive predictive value for failure to achieve pregnancy, whether the men were oligospermic or normospermic.

CONCLUSION(S)

HspA2 ratios of <10% in the diminished sperm maturity range predict the failure to cause pregnancies by IVF. Thus, IVF should be bypassed in favor of ICSI. The occurrence of pregnancy with ICSI depends on the maturity of sperm selected, and it may not be as likely as in other indications for ICSI.

Prognosis for sperm fertilizability: analysis of different variables in men

An overview of various sperm tests is presented. The standard semen analysis obtained by most clinicians evaluating infertility usually consists of sperm concentration, percent motility, quality of motility, and sperm morphology. Unfortunately, unless the motile density is extremely low, the count and motility are not good prognosticators of fertility potential. Values above the norm for normal fertile couples unfortunately cannot reliably predict normal fertility potential. It is important to find sperm tests that are easy to perform, are relatively inexpensive, and provide an accurate prognosis. Strict morphology was hoped to be such a tool with initial optimism that it was far superior to standard morphology. Unfortunately, this test also failed to be the ideal inexpensive prognostic test after further evaluation. One test that is inexpensive and highly correlates with fertilizability is the presence of antisperm antibodies since their presence frequently does not alter count, motility, or morphology. This test should be performed as part of the routine semen analysis. Other tests highly correlate with the achievement of pregnancy and are simple and inexpensive to perform, but, interestingly, do not correlate with fertilizability. These include the hypoosmotic swelling test (HOST) and the sperm stress test. Abnormalities in these tests imply a different abnormality of sperm that leads to conception failure and that is the transfer of a toxic factor from the sperm to oocyte to embryo that prevents the embryo from implanting. Certainly, the simple, inexpensive HOST should be performed routinely. Other tests of sperm function, e.g., sperm penetration assay, sperm zona pellucida binding assay, and acrosome reaction, have their definite place in the evaluation of the infertile male. However, because they are expensive and difficulty to perform they lend themselves to certain specific circumstances but not to routine testing.

Membrane fluidity and lipid content of human spermatozoa selected by swim-up method

In this work, we examined whether spermatozoa (spz) from normospermic fertile patients and selected by a swim-up (S-U) procedure had a particular membrane fluidity related to their maturity and their lipid content as compared with the sperm cells from the whole ejaculate (total sperm). Swim-up selected sperm had a reduced cytoplasmic space as revealed by a lower creatine kinase (CK) activity compared with total sperm (2 +/- 1 vs. 12 +/- 5 mUI/10(7) spz, p < 0.05). The cholesterol (Chol) and total phospholipid (PL) contents were significantly lower in S-U selected sperm than in total sperm (0.72 +/- 0.08 vs. 1.20 +/- 0.30 nmol/10(6) spz for Chol and 1.77 +/- 0.17 vs. 2.78 +/- 0.50 nmol/10(6) spz for PL, p < 0.05) and such a decrease was observed for the three major membrane PL: phosphatidylethanolamine (PE), phosphatidylcholine (PC) and sphingomyelin (SM). However, these decreases were not associated with a change in either Chol/PL or PC/(PC + PE) molar ratios. Membrane fluidity estimated by fluorescence polarization remained comparable between the S-U sperm fraction and total sperm (fluorescence polarization anisotropy, r, which is inversely proportional to the fluidity: 0.235 +/- 0.006 vs. 0.230 +/- 0.005). The sperm membrane fluidity obtained in normospermic patients was compared with abnormospermic ones (oligoasthenoteratospermia). In abnormospermic patients, the membrane fluidity was decreased in migrated spermatozoa compared with total sperm (anisotropy: 0.210 +/- 0.010 vs. 0.250 +/- 0.013, p < 0.01). Our data suggest that the S-U method selected a subpopulation of mature spermatozoa characterised by a low content of Chol and PL, likely related to a reduced membrane area. The fact that Chol/PL and PC/(PC + PE) molar ratios were unchanged shows a maintenance of the membrane quality. This was confirmed by the fluorescence anisotropy measurement showing no difference in plasma membrane fluidity between S-U selected sperm and total sperm. In abnormal semen the migrated spermatozoa had a lower fluidity compared with total sperm suggesting a defective sperm function. These results bring new elements characterizing the S-U selected spermatozoa.

Creatine kinase as an indicator of sperm quality and maturity in men with oligospermia

OBJECTIVES

To determine the differences among the creatine kinase (CK) levels in the spermatozoa of subfertile men with mild, moderate, or severe oligospermia and to examine the differences in CK activity between infertile patients with various clinical diagnoses and a group of normal healthy donors (control). CK is a marker of sperm maturity that correlates with the sperm fertilizing capacity. Elevated levels are associated with an increased rate of functional abnormalities and increased cytoplasmic retention.

METHODS

We compared the CK levels in 51 oligospermic men who could not initiate a pregnancy. Patients were categorized according to their degree of oligospermia as defined by the total sperm count: mild (greater than 10 to 40 x 10(6); n = 30), moderate (5 to 10 x 10(6); n = 11), and severe (less than 5 x 10(6); n = 10). These patients were further classified according to their diagnosis (ie, varicocele, n = 24; unexplained infertility, n = 17; vasectomy reversal, n = 9; and unknown diagnosis, n = 1). A separate group consisting of 25 healthy donors was included as a control group. A computer-assisted semen analyzer assessed the sperm characteristics, and the CK levels were measured using a CK test kit after the enzyme was extracted with Triton-X.

RESULTS

The CK levels were significantly higher in the sperm of the severely oligospermic group (8.8 +/- 6.5 IU/10(8) sperm) than in the moderate (0.50 +/- 0.19 IU/10(8) sperm) and mild (0.49 +/- 0.15 IU/10(8) sperm) groups (P <0.0001). The mean CK level in the severely oligospermic group was 18-fold higher than that in the moderate (P = 0.03) and mild (P <0.001) groups. The CK levels were significantly higher in all three infertile groups compared with the donor group (0.06 +/- 0.01 IU/10(8) sperm). Patients with varicocele had the highest CK level (3.42 +/- 2.56 IU/10(8) sperm) compared with patients in the vasectomy reversal group (1.73 +/- 0.98 IU/10(8) sperm) and the idiopathic infertility group (0.26 +/- 0.08 IU/10(8) sperm).

CONCLUSIONS

Elevated CK levels are associated with severe oligospermia, irrespective of the clinical diagnosis. CK may be a sensitive indicator of sperm quality and maturity in the follow-up of patients treated for male factor infertility.

Putative creatine kinase M-isoform in human sperm is identifiedas the 70-kilodalton heat shock protein HspA2

We previously described a putative creatine kinase M isoform in human sperm that is developmentally regulated and expressed during late spermiogenesis, simultaneous with cytoplasmic extrusion. We have now identified this protein as the testis-expressed 70-kDa heat shock protein chaperone known as HspA2 (the human homologue of mouse Hsp70-2). We have isolated and characterized HspA2 (formerly CK-M) by amino acid sequencing and have localized it by immunocytochemistry to spermatocytes at low levels, to spermatids, and in the tail of mature sperm. The specificity of the CK-M/HspA2 antiserum to HspA2 was demonstrated on immunoblots of one- and two-dimensional SDS-PAGE. In agreement with our earlier biochemical data, immunocytochemistry of testicular tissue indicated that HspA2 is selectively expressed in mature spermatids and in sperm about to be released in the seminiferous tubuli. The identity of HspA2 has been further confirmed by cross-absorption of the mouse HSP70-2 antibody by the HspA2/CK-M fraction, and by identical immunostaining patterns of human testicular tissue using either the anti-CK-M/HspA2 or an anti-mouse Hsp70-2 antisera. During spermiogenesis, both cytoplasmic extrusion and plasma membrane remodeling, which facilitate the formation of the zona pellucida binding site, involve major intrasperm protein transport, which may be chaperoned by HspA2. Accordingly, in immature human sperm, which fail to express HspA2, there is cytoplasmic retention and lack of zona pellucida binding. The present findings provide the biological rationale for the role of the human HspA2 as an objective biochemical marker of sperm function and male fertility, which we have established in earlier clinical studies.

Morphometric assessment of mature and diminished-maturity human spermatozoa: sperm regions that reflect differences in maturity

As part of our studies on sperm maturity and function, we examined the head, midpiece and tail of human spermatozoa using computerized morphometry in order to determine which regions reflect the differences between mature spermatozoa and spermatozoa of diminished cellular maturity. We studied 20 men, who were divided into two groups based on their lower (LCKM: 14.6 +/- 7.0%, n = 8) and higher sperm creatine kinase (CK-M) isoform ratios (HCKM: 48.0 +/- 4.3%, n = 12) in the initial semen. Using a sequential centrifugation method which relies on the lower density of immature spermatozoa with retained extra cytoplasm, we prepared three sperm fractions with progressively declining maturity, as confirmed with CK-M isoform ratio measurements. Following the sequential fractionation, we affixed the spermatozoa to glass slides, stained the midpiece and the sperm contour, and photographed 25 spermatozoa in each of the 60 fractions (1509 spermatozoa in all). The spermatozoa were then individually digitized on the Image-1 system, and the dimensions of the head, midpiece, and tail were determined. While the data showed significant differences in the midpiece and tail dimensions between the mature and diminished-maturity sperm fractions, the head dimensions were similar and did not reflect sperm maturity. We postulated that the relationship between the biochemical markers of sperm maturity and sperm morphology is based on common spermiogenic events. The data support this idea. In immature spermatozoa in which cytoplasmic extrusion, CK-M isoform expression, and tail sprouting are all diminished, the retained extra cytoplasm in the midpiece and shorter tail length contribute to the morphological variations that we identified by morphometry and considered in sperm morphology. These morphometric features, in association with fluorochrome-coupled biochemical probes, can facilitate the identification of mature spermatozoa in computer-assisted semen analysis.

Sperm creatine kinase activity in normospermic and oligozospermic Hungarian men

PURPOSE

Our purpose was to measure sperm creatine phosphokinase (CK) activity, which reflects cytoplasmic retention in immature spermatozoa, in normospermic and oligozospermic Hungarian men.

METHODS

A study of 109 randomly selected men in a university-based andrology laboratory was done.

RESULTS

CK activity differed between normospermic and oligozospermic men (0.21 +/- 0.02 vs. 1.19 +/- 0.15 CK IU/10(8) sperm; n = 56 and n = 53; mean +/- standard error of the mean, respectively). There was an inverse correlation between sperm concentration and CK activity (r = -0.70; n = 109). However, 28% of men in the range with less than 10 million sperm/ml had normal sperm CK activity (below the mean + 2 standard deviations of the group with greater than 30 x 10(6) sperm/ml), whereas 36% of men in the group with 20-30 million sperm/ml and 5% in the group with greater than 30 million sperm/ml had elevated CK activities, indicating that the incidence of mature and immature spermatozoa in specimens is independent from the sperm concentrations.

CONCLUSIONS

The improved facility of sperm CK activity measurements, compared with sperm concentrations, in the assessment of sperm maturity was confirmed in a Hungarian population. The CK measurements aid the selection of the most efficient treatment for couples with male-factor or unexplained infertility, particularly when considering the options of intrauterine insemination, varicocelectomy followed by a waiting period, or ovulation workup/induction in wives of men who are oligozospermic but may have fertile sperm.

Optimal utilization of cryopreserved human semen for assisted reproduction: recovery and maintenance of sperm motility and viability

PURPOSE

Our purpose was to evaluate sperm motility and viability and the maintenance of these parameters in already cryopreserved semen samples following repeated freezing/thawing cycles.

METHODS

Human spermatozoa were subjected to five cycles of cryopreservation/thawing. Recovery of sperm motility and viability and the proportion of viable nonmotile sperm were determined up to 6 hr after thaw.

RESULTS

Sperm motilities (prefreeze motility, 70.1%; n = 9 samples) after each of five freeze/thaw cycles were 24.4, 8.0, 3.5, 1.5 and 1.8%. The recovery of sperm viability was higher than that of motility after each cycle: 39.1, 25.3, 22.6, 17.8, and 16.5%. Recoveries of motility and viability were improved if the thawed samples were left in the original cryopreservation medium prior to refreezing vs. if a washing/ resuspension step was included. The recovery of sperm motility in the first thawing cycle was indicative of the expected motile sperm recovery in the second thawing cycle.

CONCLUSIONS

Cryopreserved semen that is intended to be reused in future assisted reproduction treatments should be thawed only once and aliquoted in the original freezing medium before refreezing. The recovery of sperm motility and viability in the second thawing cycle, thus the applicability of the sample in conventional in vitro fertilization or intracytoplasmic sperm injection may be anticipated in > 90% of the samples. In view of intracytoplasmic sperm injection it is important that sperm viability is maintained better than motility; after the first, second, and third thawing cycles the ratios of motile:nonmotile viable sperm were 1:1, 1:4, and 1:7, respectively.

Creatine kinase activity in human spermatozoa and seminal plasma lacks predictive value for male fertility in in vitro fertilization

OBJECTIVE

To examine the predictive value of creatine kinase in human spermatozoa and seminal plasma from patients treated in an IVF program.

DESIGN

Prospective, blind clinical study.

SETTING

Male infertility clinic.

PATIENT(S)

Seventy-three patients and 32 fathers (age, <45 years).

INTERVENTION(S)

Determination of creatine kinase activity in seminal plasma, washed spermatozoa, and swim-up purified spermatozoa from patients treated in an IVF program.

MAIN OUTCOME MEASURE(S)

Creatine kinase activity in seminal plasma, washed spermatozoa, and swim-up purified spermatozoa.

RESULT(S)

Creatine kinase activity in washed spermatozoa correlated significantly with normal sperm morphology. No significant correlations were found between creatine kinase activity or creatine kinase isoenzyme ratio in seminal plasma, washed spermatozoa, or swim-up purified spermatozoa and success in the IVF program. The percentage of spermatozoa with normal morphology was significantly lower in patients whose sperm did not fertilize than in patients whose sperm did fertilize oocytes and in the control group of proven fathers.

CONCLUSION(S)

Total creatine kinase activity and creatine kinase isoenzyme distribution are not sperm function markers for prediction of male fertility in IVF treatment.

Review: in vitro spermicidal tests

This review analyzes in vitro spermicidal tests that have been used to evaluate the spermicidal activity of contraceptive products. Special requirements and processes in numerous technologies were also reviewed. Nonoxynol-9 (N-9) was used as an example of a vaginally delivered spermicidal agent, and its spermicidal potency was compared by various spermicidal tests, such as Sander-Cramer, computer-assisted semen analysis, hypoosmotic swelling test, cervical mucus penetration test, and flow cytometry, and advantages and disadvantages of each test were specified. This provides an insight into the different aspects of sperm functionality on which each spermicidal agent exerts its activity. A rationale of the best combination of in vitro spermicidal tests, with particular emphasis on a simple and efficient strategy that targets the complete fertility control, was explained.

Creatine kinase in trout male germ cells: purification, gene expression, and localization in the testis

High creatine kinase (CK) activity (16.5 +/- 7.6 IU/mg) is present in trout spermatozoa. In order to partly characterize the CK isozyme predominantly present in sperm and to study the expression of this protein in spermatogenesis, we purified to homogeneity a CK (s-CK) from trout sperm, by nitrogen cavitation followed by two chromatography steps (DEAE-Trisacryl and Blue Sepharose). Specific antisera to 5-CK were developed. A cDNA encoding for a CK named TCK1, and whose transcript shows enhanced testicular expression, was previously isolated from trout testis (Garber et al., 1990: Biochim Biophys Acta 1087:256-258). A CK subunit expressed in vitro by this cDNA cross-reacts with anti-s-CK. A 21-amino-acid residue sequence near the N-terminus of s-CK is identical to the cDNA-derived sequence of TCK1, which is unlike any previously reported CK sequence. Using in situ hybridization, the TCK1 mRNA was detectable in primary and secondary spermatocytes and in early spermatids. Immunohistochemical staining of testis and various organs revealed that s-CK was confined to testis and, in this organ, to late spermatids and spermatozoa. In gill, some cells exhibited a positive signal, but another study rules out the presence of s-CK in this organ (Garber et al., 1990: Biochim Biophys Acta 1087:256-258). These results demonstrate that s-CK/TCK1 is a germ cell-specific protein, the transcription of which starts in meiotic germ cells, while translation starts in late spermatids.

Biochemical markers of early and late spermatogenesis: relationship between the lactate dehydrogenase-X and creatine kinase-M isoform concentrations in human spermatozoa

As part of our research program on biochemical markers of sperm maturity, we have studied sperm creatine kinase (CK) and lactate dehydrogenase (LDH) concentrations and the isoform ratios of the CK-M [% CK-M/(CK-M + CK-B)] and LDH-X [% LDH-X/(LDH-X + LDH-a)] in 50 oligospermic and 95 normospermic men [corrected]. Because the synthesis of LDH-X is initiated in early spermatogenesis, and that of CK-M commences in late spermiogenesis simultaneously with cytoplasmic extrusion, we proposed two working hypotheses:(1) LDH and CK concentrations reflect the retained cytoplasm in sperm, thus the activities of both enzymes will be related and will be higher in oligospermic specimens, which have a higher incidence of immature spermatozoa; and (2) because in normally developed sperm both LDH-X and CK-M are present, there will be a correlation between LDH-X and CK-M ratios in the mature sperm populations. However, among men with immature sperm samples with late spermiogenetic defect and diminished CK-M ratios, there will be two groups: one which completed spermatogenesis prior to spermiogenetic failure (normal LDH-X and diminished CK-M ratios), and another group with defects in both spermatogenesis and spermiogenesis (low LDH-X and diminished CK-M ratios). Because of this heterogeneity, LDH-X ratios will be a poor predictor of sperm maturity. The data support the hypotheses: (1) LDH and CK concentrations were higher in oligospermic vs. normospermic men (P < 0.001). (2) The LDH and CK concentrations were related (r = 0.65, P < 0.001, N = 145), and there were inverse correlations between CK, LDH, LDH-X, or CK-M ratios vs. sperm concentrations (P < 0.001 in all four). (3) The CK-M and LDH-X ratios were different between the oligospermic and normospermic groups (P < 0.001), although the means of the LDH-X ratios were narrower (LDH-X:1:1.3; CK-M:1:1.9). (4) Dividing the 145 samples by the cut-off value of mean minus 1 SD of the CK-M and LDH-X ratios (11% and 32%, respectively) demonstrated that the CK-M ratios discriminated better than LDH-X ratios between the samples with mature and immature sperm. These data on the biochemical markers of early and late spermatogenesis support the studies in which CK better reflected sperm quality than LDH or LDH-X (Orlando et al., 1994: Int J Androl 17:13-18) and the > 10% sperm CK-M ratio predicted with a rate of 30.4% per cycle in the occurrence of pregnancies in a blinded study of 84 IVF couples (Huszar et al., 1992: Fertil Steril 57:882-888).

Relationships between biochemical markers for residual sperm cytoplasm, reactive oxygen species generation, and the presence of leukocytes and precursor germ cells in human sperm suspensions

In this study, we have examined the relationship between creatine phosphokinase (CPK), a biochemical measure of human sperm quality (Huszar et al., 1988a,b, 1990; Huszar and Vigue, 1994), and a marker for the presence of residual cytoplasm in human spermatozoa, glucose-6-phosphate dehydrogenase (G6PDH). We then determined whether the diagnostic potential of these enzymes was related to the capacity of the sperm suspensions to generate reactive oxygen species (ROS) and/or the presence of leukocytes and precursor germ cells. Across the data set as a whole, G6PDH and CPK were highly correlated with each other and, to a lesser extent, with the generation of ROS. Contamination of the sperm suspensions with leukocytes might have contributed to these associations, since the presence of such cells was also significantly correlated with CPK, G6PDH, and ROS. However, even after the leukocytes had been carefully removed, G6PDH was still highly correlated with CPK (r = 0.794), indicating that both criteria were providing similar information of the cytosolic component of human sperm suspensions. In the absence of leukocyte contamination, CPK and G6PDH activities were also correlated with the presence of precursor germ cells, and this association may, in part, explain the diagnostic value of these criteria. An additional component of their prognostic value may be reflected in the statistically significant association observed between G6PDH activity and ROS generation. A possible mechanism for such an association is suggested, which should be amenable to experimental verification.

Effect of sodium nitroprusside on sperm motility, viability, and lipid peroxidation

OBJECTIVE

To analyze the effect of sodium nitroprusside, a nitric oxide releaser, on sperm motion and lipid peroxidation-induced membrane damage in cryopreserved human sperm.

DESIGN

Post-thaw, cryopreserved, human sperm samples were washed and divided into three aliquots. Each aliquot was incubated with either 0, 50, or 100 nM sodium nitroprusside.

INTERVENTIONS

Samples were analyzed for lipid peroxidation (measured by malonaldehyde-thiobarbituric acid reactivity) at 3 hours post-thaw.

MAIN OUTCOME MEASURES

Percent viability and motion parameters were assessed at 0, 10, and 30 minutes and 2, 3, 5, and 6 hours post-thaw.

RESULTS

All results represent a mean +/- SEM, n = 10. Lipid peroxidation in samples incubated with 50 nM sodium nitroprusside (15.1 +/- 2.1 nM malonaldehyde/10(8) sperm) or 100 nM sodium nitroprusside (13.2 +/- 2.1 nM malonaldehyde/10(8) sperm) was significantly lower than in controls (22.7 +/- 3.1 nM malonaldehyde/10(8) sperm). Percent viability was significantly reduced from 0 minutes (60.6% +/- 3.5%) to 6 hours post-thaw in controls (38.0% +/- 5.1%) but not in 50 nM (46.8% +/- 10.4%) or 100 nM (48.8% +/- 6.5%) sodium nitroprusside-treated samples. Compared with controls (18.3% +/- 3.4%), maintenance of percent motility at 3 hours post-thaw was significantly improved in 50 nM (24.5% +/- 2.9%) and in 100 nM (26.3% +/- 3.2%) sodium nitroprusside-treated samples. Straight line velocity maintenance was significantly improved in 50 nM (37.3 +/- 1.3) and in 100 nM (37.0 +/- 1) sodium nitroprusside-treated samples as compared with controls (30.5 +/- 1.7). Significant improvements in curvilinear velocity maintenance compared with controls (56.3 +/- 2.9) also were observed in 50 nM (65.9 +/- 2.1) and 100 nM (72.1 +/- 4.1) sodium nitroprusside-treated samples. Significant differences in the motion parameters of sodium nitroprusside-treated samples were maintained at 5 and 6 hours post-thaw in comparison to controls.

CONCLUSION

These results suggest that sodium nitroprusside is beneficial to the maintenance of post-thaw sperm motion and viability for up to 6 hours and that reduction of lipid peroxidative damage to sperm membranes may be the mechanism for these benefits.

Creatine kinase in non-muscle tissues and cells

Over the past years, a concept for creatine kinase function, the 'PCr-circuit' model, has evolved. Based on this concept, multiple functions for the CK/PCr-system have been proposed, such as an energy buffering function, regulatory functions, as well as an energy transport function, mostly based on studies with muscle. While the temporal energy buffering and metabolic regulatory roles of CK are widely accepted, the spatial buffering or energy transport function, that is, the shuttling of PCr and Cr between sites of energy utilization and energy demand, is still being debated. There is, however, much circumstantial evidence, that supports the latter role of CK including the distinct, isoenzyme-specific subcellular localization of CK isoenzymes, the isolation and characterization of functionally coupled in vitro microcompartments of CK with a variety of cellular ATPases, and the observed functional coupling of mitochondrial oxidative phosphorylation with mitochondrial CK. New insight concerning the functions of the CK/PCr-system has been gained from recent M-CK null-mutant transgenic mice and by the investigation of CK localization and function in certain highly specialized non-muscle tissues and cells, such as electrocytes, retina photoreceptor cells, brain cells, kidney, salt glands, myometrium, placenta, pancreas, thymus, thyroid, intestinal brush-border epithelial cells, endothelial cells, cartilage and bone cells, macrophages, blood platelets, tumor and cancer cells. Studies with electric organ, including in vivo 31P-NMR, clearly reveal the buffer function of the CK/PCr-system in electrocytes and additionally corroborate a direct functional coupling of membrane-bound CK to the Na+/K(+)-ATPase. On the other hand, experiments with live sperm and recent in vivo 31P-NMR measurements on brain provide convincing evidence for the transport function of the CK/PCr-system. We report on new findings concerning the isoenzyme-specific cellular localization and subcellular compartmentation of CK isoenzymes in photoreceptor cells, in glial and neuronal cells of the cerebellum and in spermatozoa. Finally, the regulation of CK expression by hormones is discussed, and new developments concerning a connection of CK with malignancy and cancer are illuminated. Most interesting in this respect is the observed upregulation of CK expression by adenoviral oncogenes.

Defective calcium influx and acrosome reaction (spontaneous and progesterone-induced) in spermatozoa of infertile men with severe teratozoospermia

OBJECTIVE

To evaluate the acrosome reaction and its prerequisite, a calcium influx, in spermatozoa of infertile men with a high incidence of abnormal sperm forms.

DESIGN

Prospective, controlled study.

SETTING

Academic tertiary assisted reproduction center.

PATIENTS

Patients (n = 14) were allocated in the study after semen evaluation showed teratozoospermia (< 14% normal sperm forms) as diagnosed by strict criteria.

INTERVENTIONS

After swim-up separation of the motile fraction, acrosome reactions were evaluated using Pisum sativum agglutinin (both spontaneously and exogenously induced with P and the calcium ionophore A23187, both at 10 microM); the intracellular-free [Ca2+]i was assessed by the fluorescent fura-2 indicator (basal and after P).

RESULTS

Patients did not show the typical P-induced wave of [Ca2+]i that was observed in controls but rather a blunted response, no response at all, or abnormal basal [Ca2+]i levels. The percent of basal acrosome reaction was significantly lower for patients versus controls postswim-up, and at 1 hour and 3 hours. Furthermore, there was a significant difference in the response of acrosome reaction to P both at 1 hour and 3 hours, with patients showing almost no response at all. However, patients' acrosome reaction response to the calcium ionophore was similar to those of fertile men.

CONCLUSION

Infertile patients with a high incidence of abnormal sperm forms as diagnosed by strict criteria have a low incidence of spontaneous acrosome reaction and a diminished P-stimulated acrosome reaction, whereas the nonspecific response to a calcium ionophore is conserved. Parallel abnormalities of [Ca2+]i were observed in patients, suggesting that these sperm populations may have a defective nongenomic P sperm receptor and/or abnormalities of other membrane transduction systems.

Simultaneous measurement of sperm LDH, LDH-X, CPK activities and ATP content in normospermic and oligozoospermic men

Total lactate dehydrogenase (LDH), LDH-X, creatine phosphokinase (CPK) activities and ATP content were measured in washed spermatozoa from 188 normospermic and 94 oligozoospermic men. These four biochemical parameters were significantly higher (p < 0.001) in spermatozoa from oligozoospermic men than in those from normospermic men and were related inversely to sperm concentration. In oligozoospermic men the activity of sperm LDH and LDH-X was related significantly to sperm CPK activity (r = 0.5486 and r = 0.4442, respectively), whereas this relationship was less evident in normospermic men (r = 0.4124 and r = 0.3844, respectively). Sperm ATP content was related weakly to sperm LDH, LDH-X and CPK activities both in oligozoospermic and normospermic men. After separation on a discontinuous (40% and 80%) Percoll gradient LDH, LDH-X, CPK activities and ATP content in 80% separated sperm fractions from 48 normospermic and 30 oligozoospermic men were found to be significantly lower than in the initial semen sample in both groups of subjects. The 80% separated sperm fractions from oligozoospermic and normospermic men did not differ in their LDH or LDH-X activities or ATP content, whereas sperm CPK activity was still significantly higher in oligozoospermic men. These data suggest that, of the four parameters studied, high levels of intracellular CPK activity are the most relevant biochemical feature of spermatozoa from oligozoospermic men.

Creatine kinase immunocytochemistry of human sperm-hemizona complexes: selective binding of sperm with mature creatine kinase-staining pattern

OBJECTIVE

To examine the clinical significance of the increased sperm cytoplasmic content that is due to a fault of spermatogenesis, we have further studied the relationship between increased sperm creatine kinase (CK) concentrations and diminished fertilizing potential in men. In the present work, we used CK immunocytochemistry of human sperm-hemizona (HZ) complexes to examine whether the distribution of mature (clear heads), intermediate (sperm heads with light stippling), and immature (heads with heavy stippling or with solid CK staining) spermatozoa bound to the HZ would follow the incidence of these sperm in the samples tested, or if there is a preferential binding by the mature sperm.

DESIGN

Two pairs of HZ were exposed to washed semen and to their swim-up sperm fractions. The sperm and sperm-HZ complexes were treated with a CK antibody followed by horseradish peroxidase immunostaining, and the sperm were evaluated for maturity.

SETTING

Men presenting for fertility evaluation were studied in two university-based andrology laboratories.

RESULTS

The binding of the HZ was selective for mature sperm as indicated by the incidence of intermediate and immature sperm in washed semen versus bound to the HZ (intermediate: 20.0% versus 1.4%; immature: 7.6% versus 0.5% [mean +/- SEM]) or in swim-up sperm fractions versus the HZ (intermediate: 18.7% versus 3.4%; immature: 2.5% versus 0.2%). The binding was almost exclusive to normal sperm (96.4% to 98.1%) whether the HZ were exposed to washed semen or swim-up fractions in spite of the five to ten times higher incidence of intermediate and immature sperm.

CONCLUSIONS

Mature sperm selectively bind to the zona. We suggest that spermatozoa with immature CK-staining patterns are deficient in the site(s) of oocyte recognition and binding.

Association between human in vitro fertilization rate and pregnancy outcome: a possible involvement of spermatozoal quality in subsequent embryonic viability

A conventional view of mammalian fertilization is that the active component of the process: the spermatozoon, by virtue of its progressive motility and acrosomal enzymes, penetrates an otherwise passive oocyte. This concept has placed bias on spermatozoal normality as largely determining the outcome of fertilization; once this has been achieved then the contribution of the spermatozoon is often forgotten, and attention switches to the maternally derived "blue-print" for early embryonic development. Paternal genomic contribution is known to start at the eight-cell stage in the human, but this is usually after the time when early cleavage stage (2 to 8-cell stage) embryos are replaced in human assisted reproductive technologies (ART) procedures such as in vitro fertilization and embryo transfer (IVF-ET). Hence, fundamental abnormal contributions to embryogenesis derived from the fertilizing spermatozoon have often been ignored. Human IVF-ET has permitted far greater powers of analysis of the fertilization event, and fertilization success appears to be determined in such a system by three main factors: spermatozoal quality, oocyte quality, and quality of in vitro culture conditions (the gamete environment). If the second two factors are more carefully controlled than the first, as is the usual emphasis in routine human IVF practice, then any large variation in fertilization rates that are also significantly related to embryonic viability and ultimately pregnancy outcome, may be thought to be more directly associated with original quality of the fertilizing spermatozoon. An analysis of results of 758 IVF cases provides preliminary evidence to show that there is a close association between human in vitro fertilization rate and subsequent embryo viability following replacement. In accepting this hypothesis as a possibility, we should drastically change our attitude from one of the spermatozoon as a robust, simple initiator of embryonic development, and embrace the idea of the vulnerability of such germ cells both during and after their production, and how detrimental influences on this might profoundly affect embryogenesis after successful fertilization.

Incomplete development of human spermatozoa is associated with increased creatine phosphokinase concentration and abnormal head morphology

Our previous creatine phosphokinase (CK) activity studies in human sperm revealed differences among men and among sperm populations within the same specimen. Samples with low sperm concentrations, high incidence of abnormal sperm morphology, and diminished fertility had higher per sperm CK activity. In the present work, we demonstrated, with 14C-FDNB covalent CK active site modification and with direct CK immunocytochemistry, that the higher CK activity is related to an increased content of CK and of other proteins in sperm. Also, sperm heads with higher CK content were significantly larger and rounder and showed a higher incidence of amorph configuration. We suggest that these biochemical and morphological irregularities are related and are due to a failure of spermatogenesis, more specifically, to a higher retention of cytoplasm, which in normal sperm development is lost to the Sertoli cells as residual bodies. Thus higher CK activity and larger or irregular head size in human sperm signify cellular immaturity and a failure to complete spermatogenesis.

Evaluation of testicular function

The evaluation of testicular function is based primarily on a detailed medical history, a careful physical examination, basal measurements of FSH, LH and testosterone and a routine semen analysis. In a patient with androgen deficiency, the diagnosis can often be made with these basic tests. The clinician will then decide on other investigations to localize the organic lesion and to plan further treatment for the patient. Sperm function tests are often performed in patients presenting with infertility. These newer tests may help to delineate the abnormality of the spermatozoa at each stage during the achievement of fertilizing capacity such as adequate forward motility, penetration of cervical mucus, acrosome reaction, development of hyperactivated motility, binding to the zona pellucida, and fusion with the oocyte. Currently, many of these sperm function tests depend on cumbersome bioassays with many limiting factors contributing to their availability, accuracy and precision. The development of biochemical tests as markers of sperm function may allow more precise definition of sperm functional abnormalities. With the continued improvement of computer-aided sperm analysis, objective motion parameter measurements are possible and morphological assessment are being developed. These newer objective methods of semen analysis have to be shown to be valuable in the clinical assessment of patients with testicular dysfunction.

NADH-dependent oxidoreductase (diaphorase) activity and isozyme pattern of sperm in infertile men

Diaphorase activities were measured in spermatozoa from 104 infertile men. The relationships between enzyme activity, sperm characteristics (density, motility, viability), and distribution of electrophoretic patterns were examined. There was a highly significant difference (p less than .001) between the sperm diaphorase activities in specimens with sperm concentration above 40 million per milliliter (0.685 +/- 0.5 mIU/10(6) sperm; n = 57) when compared with the diaphorase values of the oligospermic specimens with sperm density below 40 million per milliliter (1.53 +/- 1.5 mIU/10(6) sperm; n = 47). However, there was no evidence to support any relationship between sperm diaphorase activities, sperm motility, viability, and the distribution of three diaphorase electrophoretic patterns. This indicates that these parameters do not account for the differences between the diaphorase activity of spermatozoa of infertile men with sperm concentrations below and those above 40 million per milliliter.

LDH and LDH-X activity in sperm from normospermic and oligozoospermic men

Total lactate dehydrogenase (LDH) activity was measured in washed sperm from 74 oligozoospermic patients and 148 normospermic men. In the same samples, an additional iso-enzyme specific for germ cells, LDH-X was also measured. Both enzymatic activities were significantly higher in sperm from oligozoospermic patients than in those from normospermic men (P less than 0.001). In oligozoospermic patients, sperm LDH and LDH-X activities were related inversely to sperm concentration (r = -0.61 and r = -0.53, respectively). In normospermic men, this inverse relationship was less evident (r = -0.28 and r = -0.25, respectively). After separation of sperm on a discontinuous gradient of Percoll, LDH and LDH-X activities were increased in the non-migrated-sperm fractions and reduced in the migrated-sperm fractions in both groups of subjects when compared to the initial semen specimens. In addition, migrated sperm from oligozoospermic and normospermic men did not differ in their LDH and LDH-X activities. Although the possible contribution of immature germ-cells to these findings remains to be defined, the data suggest clearly that high levels of intracellular LDH and LDH-X are a biochemical feature of sperm from oligozoospermic subjects.

Spermatogenesis-related change in the synthesis of the creatine kinase B-type and M-type isoforms in human spermatozoa

We have demonstrated earlier that the per sperm creatine-N-phosphotransferase (CK) activity was increased in oligospermic vs. normospermic men. The increased sperm CK activity is related to higher concentrations of cellular CK, which may indicate a defect of cytoplasmic extrusion during spermatogenesis. In the present work, we examined whether in spermatozoa, similar to muscle, there is a change in the synthesis of B-CK and M-CK isoforms during cellular differentiation. In 109 normospermic and 50 oligospermic specimens (sperm concentrations 60.6 +/- 3.7 vs. 8.8 +/- 1.3 million sperm/ml; all values expressed as mean +/- SEM), the relative concentrations of the M-CK isoform (M-CK/M-CK + B-CK) were 27.2% +/- 2.1% vs. 6.7% +/- 0.9% (P less than 0.001). The per sperm CK activities showed comparable differences (0.21 +/- 0.02 vs. 0.89 +/- 0.1 CK IU/100 million sperm; P less than 0.001) in the two groups, and there was a close correlation between per sperm CK activities and M-CK concentrations (R = 0.69, P less than 0.001, N = 159). This indicates that the loss of cytoplasm and the commencement of M-CK isoform synthesis are related events during the last phase of spermatogenesis, also that the incidence of spermatozoa with incomplete cellular maturation is higher in oligospermic specimens. In characterizing the M-CK, we found that sperm (unlike muscle tissue) lack the MB hybrid of CK dimers. However, in the presence of muscle M-CK, the muscle-sperm MB-CK hybrid has formed. Thus in sperm and muscle the M-CK isoforms are structurally different, whereas the B-CKs are apparently homologous.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of the relationship between defective sperm function and the generation of reactive oxygen species in cases of oligozoospermia

The ability of human spermatozoa to exhibit sperm-oocyte fusion in response to the ionophore, A23187, was examined in relation to the capacity of these cells to generate reactive oxygen species. In 70 fertile control donors, there was an overwhelming pattern of high levels of sperm-oocyte fusion associated with low levels of reactive oxygen species production. By contrast, 88% of the 74 oligozoospermic patients exhibited less than 25% oocyte penetration in response to A23187 and 58% exhibited no penetration whatsoever. Of the 40 oligozoospermic patients who failed to respond to A23187, nine had low levels of reactive oxygen species production in association with impaired liquefaction of seminal plasma. Of the remainder, 17 (55%) exhibited defective sperm function together with elevated production of reactive oxygen species. These observations, which are the first to describe a biochemical defect in the spermatozoa of oligozoospermic patients, may carry significant implications for the etiology and treatment of this condition.