An application of multivariate ranks to assess effects from combining factors: metal exposures and semen analysis outcomes

Seminal trace elements and their relationship with sperm parameters

Male reproductive problems may derive from many reasons including the environmental toxicants which may either intaken by occupational exposure, nutrition or bad air quality. The increased exposure to these substances due to rapid industrial development and technology has raised the questions: Is there a relationship between sperm parameters and these substances, and if so, in what extent? Results of studies on the subject reported conflicting results, many of which were not investigated in the seminal plasma. The aim of the current study was to evaluate the relationship between 23 metals and trace elements in human seminal plasma and semen parameters many of which were not investigated before. Levels of 23 metals in human seminal plasma were assessed by inductively coupled plasma mass spectrometry (ICP-MS). We examined the differences between subjects with normal ejaculate (normozoospermia) and pathologic ejaculate (with at least one abnormal semen parameter) according to the WHO criteria. The only significant difference was detected for Se while the other element's difference was not statistically significant. Se was statistically significantly increased in normal semen group suggesting the positive effect of this element on semen parameters.

Long-Term Exposure to the Water of Wadi El-Rayan Lakes Induced Testicular Damage and Endocrine Disruption in Mugil cephalus

This study aimed to investigate the testicular function of Mugil cephalus that inhabit Wadi El-Rayan lakes. Testes of fish inhabiting the upper lake (site 2) and the lower lake (site 3) of Wadi El-Rayan showed significant decreases in gonadosomatic index, high accumulation levels of six metals, and eight organochlorine pesticide residues. Compared to reference fish, high percentages of histological alterations as testicular degeneration, germ cell reduction, testicular inflammation, vacuolization, and loss of tubular arrangement were observed in sites 2 and 3. Moreover, endocrine disruption signs were recorded based on the percentage of ovotestis appearance and the ovotestis severity index values. The maximum defective testicular antioxidant mechanisms were recorded in site 3 as indicated by sharp decreases in catalase, superoxide dismutase, glutathione reduced levels, and high thiobarbituric acid reactive substances. Finally, long-term exposure to Wadi El-Rayan water may impair the reproductive health of fish via testicular oxidative damage and endocrine disruption.

Chronic Exposure to Water of Lake Qaroun Induced Metal-Related Testicular Damage and Endocrine Disruption in Male Fish

The uncontrolled releasing of hazardous wastes into Lake Qaroun was adversely impacting the aquatic environment and its biota. Therefore, this approach was designed to investigate the impact of these discharges on the reproductive and testicular function of Oreochromis niloticus. Several biomarkers were applied on the testicular tissues as metal bioaccumulation levels, histological examination with recording the ovotestis appearance and antioxidant status after 45 days of exposure to 0, 10, 20, & 30% of Lake Qaroun water (LQW). The bioaccumulated Cu, Mn, Fe, Pb, and Cd were unequally distributed in the testes but all these metals showed a significant concentration-dependent elevation among the studied groups. The exposure to LQW significantly increased the histological alterations in the testicular tissues as vacuolar degeneration, loss of tubular organization, and degeneration of Leydig cell. Based on the frequent appearance of histopathological abnormalities and ovotestis recording, the most deformed testicular tissues were observed in the 30% LQW-exposed groups. The ovotestis severity index (OSI) was significantly raised in LQW-exposed groups compared to the control group. The activities of superoxide dismutase, catalase as well as glutathione-reduced levels were significantly (p < 0.05) decreased in testes after chronic exposure to LQW. On the other pole, the activities of glutathione peroxidase enzyme and malondialdehyde formation were sharply increased. In view of the above, the exposure to LQW induced metal-related oxidative damage to the testicular tissues and impaired the male reproductive health. This study showed strong correlations between the anthropogenic activities around Lake Qaroun and the reproductive dysfunction in fish.

The employment of IVF techniques for establishment of sodium, copper and selenium impact upon human sperm quality

We analysed sodium (Na), copper (Cu) and selenium (Se) levels in human semen and glutathione peroxidase activity (GPx) in seminal plasma and examined their relationships with sperm quality. Semen samples were obtained from men (n=168) undergoing routine infertility evaluation. The study design included two groups based on standard ejaculate parameters: Group I (n=39) with normal ejaculates (normozoospermia) and Group II (n=129) with a pathological spermiogram. Se concentration (but not Na or Cu) and GPx activity were significantly higher in normozoospermic males than in those with a pathological spermiogram and also in males with correct sperm motility and normal sperm morphology than in asthenozoospermic and teratozoospermic males. There were significant correlations between sperm motility, Se and GPx, between rapid progressive motility and Cu, between sperm motility and Na, between normal sperm morphology and Se and Cu and between sperm concentration and Cu and GPx. Significant correlations were found between Na and Cu, between Na and Se and between Cu and Se in human semen in relation to alcohol consumption and tobacco use. Na, Cu, Se and GPx are related to sperm characteristics and male fertility and their survey could improve male infertility diagnosis.

Presence of cobalt and chromium ions in the seminal fluid of young patients with metal-on-metal total hip arthroplasty

We aimed to investigate the effect of metal ions on the semen of males of child fathering age with metal-on-metal (MM) total hip arthroplasty (THA). Semen was collected form 11 patients with MM THA and 5 control of comparable age. Cobalt and chromium concentrations were measured in both the seminal plasma and in the blood of patients. Results showed that cobalt level was higher in the seminal plasma of MM THA patients (2.89 μg/L) compared to control patients (1.12 μg/L) (P = .011). The ejaculate volume, the sperm density, the total sperm count, the pH, and the percentage of cells with normal morphology were in the range of the World Health Organization criteria for fertile population.

Reproductive toxicity of metals in men

A combination of genetic, environmental and lifestyle factors contributes to adverse effects on the reproductive health in men. Metals are pervasive in food, water, air, tobacco smoke, and alcoholic beverages. Experimental studies suggest that many metals have adverse effects on the male reproductive function. However, information about reproductive effects of human exposure to metals is scarce and/or inconsistent. This review summarises the information from epidemiological studies of the effects of metal exposure on reproductive function in men. Factors capable of affecting these relationships were identified and discussed. A particular attention is given to the studies considering influence of concomitant exposure to various metals. These studies have generally confirmed that even moderate- to low-level exposure to lead affects certain reproductive parameters, and that exposure to cadmium affects the prostate function and serum testosterone levels. Adverse effects of mercury, manganese, chromium and arsenic on semen quality and altered serum hormone are less well documented. There is no clear evidence that boron exposure may impair reproductive health in men. Only a few studies have investigated reproductive effects of concomitant exposure to several metals and controlled for potential confounders. Future studies should consider the contribution of combined exposure to various metals and/or other factors that may influence individual susceptibility to reproductive health impairment in men.

Nonparametric methods for molecular biology

In 2003, the completion of the Human Genome Project (1) together with advances in computational resources (2) were expected to launch an era where the genetic and genomic contributions to many common diseases would be found. In the years following, however, researchers became increasingly frustrated as most reported 'findings' could not be replicated in independent studies (3). To improve the signal/noise ratio, it was suggested to increase the number of cases to be included to tens of thousands (4), a requirement that would dramatically restrict the scope of personalized medicine. Similarly, there was little success in elucidating the gene-gene interactions involved in complex diseases or even in developing criteria for assessing their phenotypes. As a partial solution to these enigmata, we here introduce a class of statistical methods as the 'missing link' between advances in genetics and informatics. As a first step, we provide a unifying view of a plethora of nonparametric tests developed mainly in the 1940s, all of which can be expressed as u-statistics. Then, we will extend this approach to reflect categorical and ordinal relationships between variables, resulting in a flexible and powerful approach to deal with the impact of (1) multiallelic genetic loci, (2) poly-locus genetic regions, and (3) oligo-genetic and oligo-genomic collaborative interactions on complex phenotypes.

Environmental exposure to metals and male reproductive hormones: circulating testosterone is inversely associated with blood molybdenum

OBJECTIVE

To explore associations between exposure to metals and male reproductive hormone levels.

DESIGN

Cross-sectional epidemiology study with adjustment for potential confounders.

SETTING

University Medical Center.

PATIENT(S)

Men recruited through two infertility clinics in Michigan.

INTERVENTION(S)

Metal concentrations and reproductive hormone levels were measured in blood samples collected from 219 men.

MAIN OUTCOME MEASURE(S)

Serum FSH, LH, inhibin B, T, and sex hormone-binding globulin levels.

RESULT(S)

Cadmium, copper, and lead were all significantly or suggestively positively associated with T when modeled individually, findings that are consistent with limited previous human and animal studies. Conversely, molybdenum was associated with reduced T. A significant inverse trend between molybdenum and T remained when additionally considering other metals in the model, and a positive association between T and zinc was also found. Finally, in exploratory analysis there was evidence for an interaction between molybdenum and zinc, whereby high molybdenum was associated with a 37% reduction in T (relative to the population median level) among men with low zinc.

CONCLUSION(S)

Although reductions in T and reproductive toxicity after molybdenum exposure have been previously demonstrated in animal studies, more research is needed to determine whether molybdenum poses a risk to human reproductive health.

Cadmium, lead, and other metals in relation to semen quality: human evidence for molybdenum as a male reproductive toxicant

BACKGROUND

Evidence on human semen quality as it relates to exposure to various metals, both essential (e.g., zinc, copper) and nonessential (e.g., cadmium, lead), is inconsistent. Most studies to date used small sample sizes and were unable to account for important covariates.

OBJECTIVES

Our goal in this study was to assess relationships between exposure to multiple metals at environmental levels and human semen-quality parameters.

METHODS

We measured semen quality and metals in blood (arsenic, Cd, chromium, Cu, Pb, manganese, mercury, molybdenum, selenium, and Zn) among 219 men recruited through two infertility clinics. We used multiple statistical approaches to assess relationships between metals and semen quality while accounting for important covariates and various metals.

RESULTS

Among a number of notable findings, the associations involving Mo were the most consistent over the various statistical approaches. We found dose-dependent trends between Mo and declined sperm concentration and normal morphology, even when considering potential confounders and other metals. For example, adjusted odds ratios (ORs) for below-reference semen-quality parameters in the low, medium, and high Mo groups were 1.0 (reference), 1.4 [95% confidence interval (CI), 0.5-3.7], and 3.5 (95% CI, 1.1-11) for sperm concentration and 1.0 (reference), 0.8 (95% CI, 0.3-1.9), and 2.6 (95% CI, 1.0-7.0) for morphology. We also found preliminary evidence for interactions between Mo and low Cu or Zn. In stratified analyses, the adjusted ORs in the high Mo/low Cu group were 14.4 (1.6, 132) and 13.7 (1.6, 114) for below-reference sperm concentration and morphology, respectively.

CONCLUSIONS

Our findings represent the first human evidence for an inverse association between Mo and semen quality. These relationships are consistent with animal data, but additional human and mechanistic studies are needed.