Zinc and cadmium analysis in human prostate neoplasms

Exposure of environmental trace elements in prostate cancer patients: A multiple metal analysis

Prostate cancer (PCa) is the second leading cause of cancer-related deaths among men. To elucidate the connection between trace elements (arsenic: As, cadmium: Cd, lead: Pb, chromium: Cr, and nickel: Ni) and the risk of PCa, we analyzed trace element levels in the serum, urine, and tissues of PCa patients, while also examining their smoking status. We correlated these levels with their smoking habits. Notably, levels of Cd (P ≤ 0.05) and As (P ≤ 0.01) were significantly higher in the tumor tissue than in adjacent tissues. No significant differences were observed in the levels of Pb, Cr and Ni. Additionally, urinary Cd levels in 70% and arsenic levels in 2.3% of the PCa cohort were markedly higher than the CDC-reported cutoff (Cd ≤ 0.185 μg/L & As ≤100 μg/L). None displayed elevated levels of urinary Pb, Cr, and Ni. Conversely, in serum samples, the concentration of arsenic exceeded the CDC-determined limit (As ≤1.0 μg/L) in 31.69% of PCa patients. However, only 7.04% of patients had higher serum Cd levels than the CDC standard values (Cd ≤ 0.315 μg/L), while all PCa patients exceeded the Cr CDC limit (Cr ≤ 0.16 μg/L) and the Ni CDC limit (Ni ≤ 0.2 μg/L). On the contrary, no significant differences were observed in serum Pb (Pb ≤ 35.0 μg/L). Our findings establish a positive link between Cd and arsenic tissue concentrations and the risk of PCa. Subsequent studies are essential to determine whether elevated trace element levels pose a risk for the development of prostate carcinogenesis. Interestingly, among the PCa cohort comprising smokers, notably higher Cd levels were observed only in tumor tissues (P ≤ 0.01) and urine (P ≤ 0.05) compared to other elements or in other specimens.

A Systematic Review of the Zinc Content of the Normal Human Prostate Gland

The prostate gland is subject to various disorders. The etiology and pathogenesis of these diseases are not well understood. Moreover, despite technological advancements, the differential diagnosis of prostate disorders has become progressively more complex and controversial. It was suggested that the Zn level in prostatic tissue plays an important role in prostatic carcinogenesis and its measurement may be useful as a cancer biomarker. These suggestions promoted more detailed studies of the Zn content in the prostatic tissue of healthy subjects. The present study evaluated by systematic analysis presents the published data for Zn content analyzed in prostatic tissue of "normal" glands. This evaluation reviewed 1885 studies, all of which were published in the years from 1921 to 2020 and were located by searching the databases PubMed, MEDLINE, Scopus, Web of Science, Elsevier-Embase, and Cochrane Library. In addition, the personal archive of the author collected from 1966 to 2020 was also used. The articles were analyzed and "median of means" and "range of means" were used to examine heterogeneity of the measured Zn content in prostates of apparently healthy men. The objective analysis was performed on data from the 105 studies, which included 3735 subjects. It was found that the range of means of prostatic Zn content reported in the literature for "normal" gland varies widely from 17 to 547 mg/kg with median of means 109 mg/kg on a wet mass basis. The Zn content depends on many factors such as analytical method, age, level of androgens, dietary Zn intake, and the prostatic region and fraction of prostate tissue being studied. Finally, because of small sample size and high data heterogeneity, we recommend other primary studies be performed.

The role of autophagy in metal-induced urogenital carcinogenesis

Environmental and/or occupational exposure to metals such as Arsenic (As), Cadmium (Cd), and Chromium (Cr) have been shown to induce carcinogenesis in various organs, including the urogenital system. However, the mechanisms responsible for metal-induced carcinogenesis remain elusive. We and others have shown that metals are potent inducers of autophagy, which has been suggested to be an adaptive stress response to allow metal-exposed cells to survive in hostile environments. Albeit few, recent experimental studies have shown that As and Cd promote tumorigenesis via autophagy and that inhibition of autophagic signaling suppressed metal-induced carcinogenesis. In light of the newly emerging role of autophagic involvement in metal-induced carcinogenesis, the present review focuses explicitly on the mechanistic role of autophagy and potential signaling pathways involved in As-, Cd-, and Cr-induced urogenital carcinogenesis.

The use of serum zinc to prostate-specific antigen ratio as a biomarker in the prediction of prostate biopsy outcomes

AIM

To generate a combination of serum zinc (Zn) and prostate-specific antigen (PSA) in an attempt to provide better prediction of prostate biopsy outcomes with Zn/PSA ratios.

MATERIALS & METHODS

Diagnostic performances of PSA and Zn/PSA were investigated using receiver operating characteristic and the area under the curve analysis and McNemar test in 480 men. Decision curve analysis was also used to determine the net clinical benefits of the two parameters.

RESULTS

The receiver operating characteristic-area under the curve analysis established a similar diagnostic performance for both parameters. Although Zn/PSA had a higher diagnostic sensitivity, PSA was superior in terms of specificity and net clinical benefits.

CONCLUSION

Zn/PSA has no substantial superiority in the prediction of prostate biopsy outcomes.

Oxidative damage in patients with benign prostatic hyperplasia and prostate cancer co-exposed to phthalates and to trace elements

Evidence indicates that prostates exposed to environmental endocrine disruptors and trace metals will cause adverse health outcomes. We assessed the association between urinary phthalate metabolites and serum trace metal levels, and oxidative damage in benign prostatic hyperplasia (BPH) patients, prostate cancer (PCa) patients, and healthy controls. Levels of cadmium (Cd), nickel (Ni), and copper (Cu) were significantly higher in BPH patients than in controls, and mercury (Hg) was highest in PCa patients. An Hg level >1 μg/L posed a significant risk (OR: 42.86, 95% CI: 1.092-1684) for PCa, but a zinc (Zn) level >1 μg/L was marginally negative (OR: 0.979, 95% CI: 0.957-1.002). We also found strong associations between PCa and mono-isononyl phthalate (MiNP), and between BPH and mono-isodecyl phthalate (MiDP), malonyldialdehyde (MDA) were significantly higher in PCa and BPH patients than in controls; 8‑hydroxydeoxyguanosine (8‑OH‑dG) and DNA strand breakage were highest in BPH patients and lowest in controls. When the prostate was simultaneously co-exposed to phthalates and trace metals, phthalates had a less significant effect on PCa and BPH. Thus, we hypothesize that, for patients with prostate disease, exposure to trace metals is more significant than is exposure to phthalates.

Cadmium Levels in Tissue and Plasma as a Risk Factor for Prostate Carcinoma: a Meta-Analysis

Cadmium is a heavy metal that has been suggested to be a carcinogen by evidence. A number of published studies have investigated the association between cadmium levels and prostate cancer, but the results were inconsistent. Thus, we conducted a meta-analysis to get a precise estimate of this subject. After a careful searching and screening, a total of 11 publications containing 14 separated studies were included. Based on a random-effect model, the pooled data showed that cadmium levels of prostate tissues (standard mean difference (SMD) = 3.17, 95 % confidence interval (CI) = 0.60-5.74, P < 0.05) and plasma (SMD = 4.07, 95 % CI = 2.01-6.13, P < 0.05) were significantly higher in prostate cancer patients than those in the healthy controls. No difference of hair and nail cadmium levels between the prostate cancer cases and the controls was found. The data suggested that cadmium exposure might exert an influence on the tumorigenesis of prostate tissues. Future investigations with large sample sizes are needed to verify the results.

Association Between Cd Exposure and Risk of Prostate Cancer: A PRISMA-Compliant Systematic Review and Meta-Analysis

Several observational studies on the association between Cd exposure and risk of prostate cancer have yielded inconsistent results. To address this issue, we conducted a meta-analysis to evaluate the correlation between Cd exposure and risk of prostate cancer.Relevant studies in PubMed and Embase databases were retrieved until October 2015. We compared the highest and lowest meta-analyses to quantitatively evaluate the relationship between Cd exposure and risk of prostate cancer. Summary estimates were obtained using a random-effects model.In the general population, high Cd exposure was not associated with increased prostate cancer (OR 1.21; 95% CI 0.91-1.64), whereas the combined standardized mortality ratio of the association between Cd exposure and risk of prostate cancer was 1.66 (95% CI 1.10-2.50) in populations exposed to occupational Cd. In addition, high D-Cd intake (OR 1.07; 95% CI 0.96-1.20) and U-Cd concentration (OR 0.86; 95% CI 0.48-1.55) among the general population was not related to the increased risk of prostate cancer. In the dose analysis, the summary relative risk was 1.07 (95% CI 0.73-1.57) for each 0.5 μg/g creatinine increase in U-Cd and 1.02 (95% CI 0.99-1.06) for each 10 μg/day increase of dietary Cd intake. However, compared with nonoccupational exposure, high occupational Cd exposure may be associated with the increased risk of prostate cancer.This meta-analysis suggests high Cd exposure as a risk factor for prostate cancer in occupational rather than nonoccupational populations. However, these results should be carefully interpreted because of the significant heterogeneity among studies. Additional large-scale and high-quality prospective studies are needed to confirm the association between Cd exposure and risk of prostate cancer.

Current opinion on the role of testosterone in the development of prostate cancer: a dynamic model

BACKGROUND

Since the landmark study conducted by Huggins and Hodges in 1941, a failure to distinguish between the role of testosterone in prostate cancer development and progression has led to the prevailing opinion that high levels of testosterone increase the risk of prostate cancer. To date, this claim remains unproven.

PRESENTATION OF THE HYPOTHESIS

We present a novel dynamic mode of the relationship between testosterone and prostate cancer by hypothesizing that the magnitude of age-related declines in testosterone, rather than a static level of testosterone measured at a single point, may trigger and promote the development of prostate cancer.

TESTING THE HYPOTHESIS

Although not easily testable currently, prospective cohort studies with population-representative samples and repeated measurements of testosterone or retrospective cohorts with stored blood samples from different ages are warranted in future to test the hypothesis.

IMPLICATIONS OF THE HYPOTHESIS

Our dynamic model can satisfactorily explain the observed age patterns of prostate cancer incidence, the apparent conflicts in epidemiological findings on testosterone and risk of prostate cancer, racial disparities in prostate cancer incidence, risk factors associated with prostate cancer, and the role of testosterone in prostate cancer progression. Our dynamic model may also have implications for testosterone replacement therapy.

Status and Interrelationship of Zinc, Copper, Iron, Calcium and Selenium in Prostate Cancer

Deficiency or excess of certain trace elements has been considered as risk factor for prostate cancer. This study was aimed to detect differential changes and mutual correlations of selected trace elements in prostate cancer tissue versus benign prostatic hyperplasia tissue. Zinc, copper, iron, calcium and selenium were analysed in histologically proven 15 prostate cancer tissues and 15 benign prostatic hyperplasia tissues using atomic absorption spectrophotometer. Unpaired two tailed t test/Mann-Whitney U test and Pearson correlation coefficient were used to compare the level of trace elements, elemental ratios and their interrelations. As compared to benign prostatic tissue, malignant prostatic tissue had significantly lower selenium (p = 0.038) and zinc (p = 0.043) concentrations, a lower zinc/iron ratio (p = 0.04) and positive correlation of selenium with zinc (r = 0.71, p = 0.02) and iron (r = 0.76, p = 0.009). Considerably divergent interrelationship of elements and elemental ratios in prostate cancer versus benign prostatic hyperplasia was noted. Understanding of differential elemental changes and their interdependence may be useful in defining the complex metabolic alterations in prostate carcinogenesis with potential for development of element based newer diagnostic, preventive and therapeutic strategies. Further studies may be needed to elucidate this complex relationship between trace elements and prostate carcinogenesis.

Serum levels of trace elements in patients with prostate cancer

BACKGROUND

Trace elements are major components of biological structures; however, excessive levels of these elements can be toxic.

MATERIALS AND METHODS

In the present study, serum levels of trace elements were measured in 30 patients with newly diagnosed as prostate cancer and 32 healthy volunteer by using furnace atomic absorption spectrophotometry.

RESULTS

It was found that there was an increase in serum levels of Co, Cu, Mg and Pb (p<0.05), whereas a decrease in serum levels of Fe, Mn, and Zn levels in patients with prostate cancer (p<0.05).

CONCLUSIONS

These changes may be important in the pathogenesis of prostate cancers; however, further prospective studies are needed to identify relationships between prostate cancer and trace elements.

Inhibition of key markers linked with spermatogenesis and cellular ATP by subchronic exposure to leachate in a rat model

Few or no studies have measured the toxic effects of subchronic exposure to leachate using key markers linked with spermatogenesis and cellular adenosine triphosphate (ATP) in an experimental rat model. This study was undertaken to evaluate the toxic effects of leachate obtained from the Elewi Odo municipal battery-recycling site (EOMABRL) on male reproductive function using testicular hormones and biomarker of cellular ATP. EOMABRL was administered at 0, 20, 40, 60, 80, and 100% concentrations to adult male rats for 60 days. After exposure, serum was collected for hormonal biochemistry assays, and testes were collected to determine the activity of xanthine oxidase (XO) and lactate dehydrogenase (LDH). Exposure of animals to EOMABRL resulted in a 519.7, 285.7, 569.1, 606.1, and 1,793.2% increase in XO activity with a sequential decrease in LDH activity (marker of cellular ATP) by 44.1, 55.9, 61.4, 69.3, and 89.7%, respectively, compared with the control. Furthermore, EOMABRL caused a significant inhibitory effect on serum luteinizing hormone, follicle-stimulating hormone, and testosterone levels. We conclude that some possible mechanisms by which EOMABRL elicits toxicity in male rat testes could be through inhibition of LDH activity and depletion of serum hormone levels.

Comparative study of trace elements in blood, scalp hair and nails of prostate cancer patients in relation to healthy donors

Prostate cancer is the most common fatal cancers in men, and exposure to toxic elements is the most important factor in the aetiology for prostate cancer. Selected elements (Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn) were analyzed in the blood, scalp hair and nails of prostate cancer patients and counterpart healthy donors by atomic absorption spectrometry. Average concentrations of Cd, Mn, Ni and Pb were found to be significantly higher (p < 0.05) in the blood, scalp hair and nails of the patients compared with those of the healthy subjects who exhibited significantly higher concentrations of Zn. The correlation study revealed significantly diverse relationships of the elements in the blood, scalp hair and nails of the two donor groups. Variations in the elemental concentrations were also noted for various types of prostate cancer (adenocarcinoma, squamous cell carcinoma, transitional cell carcinoma and small cell carcinoma), as well as for different stages of the cancer. Multivariate apportionment of trace elements in the blood, scalp hair and nails of the patients was also significantly different than that in the healthy donors. The study evidenced considerably divergent variations in the elemental concentrations in prostate cancer patients in comparison with healthy subjects.

Serum and tissue zinc in epithelial malignancies: a meta-analysis

BACKGROUND AND OBJECTIVES

Current studies give us inconsistent results regarding the association of neoplasms and zinc(II) serum and tissues concentrations. The results of to-date studies using meta-analysis are summarized in this paper.

METHODS

Web of Science (Science citation index expanded), PubMed (Medline), Embase and CENTRAL were searched. Articles were reviewed by two evaluators; quality was assessed by Newcastle-Ottawa scale; meta-analysis was performed including meta-regression and publication bias analysis.

RESULTS

Analysis was performed on 114 case control, cohort and cross-sectional studies of 22737 participants. Decreased serum zinc level was found in patients with lung (effect size = -1.04), head and neck (effect size = -1.43), breast (effect size = -0.93), liver (effect size = -2.29), stomach (effect size = -1.59), and prostate (effect size = -1.36) cancers; elevation was not proven in any tumor. More specific zinc patterns are evident at tissue level, showing increase in breast cancer tissue (effect size = 1.80) and decrease in prostatic (effect size = -3.90), liver (effect size = -8.26), lung (effect size = -3.12), and thyroid cancer (effect size = -2.84). The rest of the included tumors brought ambiguous results, both in serum and tissue zinc levels across the studies. The association between zinc level and stage or grade of tumor has not been revealed by meta-regression.

CONCLUSION

This study provides evidence on cancer-specific tissue zinc level alteration. Although serum zinc decrease was associated with most tumors mentioned herein, further--prospective--studies are needed.

Prostate tissue metal levels and prostate cancer recurrence in smokers

Although smoking is not associated with prostate cancer risk overall, smoking is associated with prostate cancer recurrence and mortality. Increased cadmium (Cd) exposure from smoking may play a role in progression of the disease. In this study, inductively coupled plasma mass spectrometry was used to determine Cd, arsenic (As), lead (Pb), and zinc (Zn) levels in formalin-fixed paraffin embedded tumor and tumor-adjacent non-neoplastic tissue of never- and ever-smokers with prostate cancer. In smokers, metal levels were also evaluated with regard to biochemical and distant recurrence of disease. Smokers (N = 25) had significantly higher Cd (median ppb, p = 0.03) and lower Zn (p = 0.002) in non-neoplastic tissue than never-smokers (N = 21). Metal levels were not significantly different in tumor tissue of smokers and non-smokers. Among smokers, Cd level did not differ by recurrence status. However, the ratio of Cd ppb to Pb ppb was significantly higher in both tumor and adjacent tissue of cases with distant recurrence when compared with cases without distant recurrence (tumor tissue Cd/Pb, 6.36 vs. 1.19, p = 0.009, adjacent non-neoplastic tissue Cd/Pb, 6.36 vs. 1.02, p = 0.038). Tissue Zn levels were also higher in smokers with distant recurrence (tumor, p = 0.039 and adjacent non-neoplastic, p = 0.028). These initial findings suggest that prostate tissue metal levels may differ in smokers with and without recurrence. If these findings are confirmed in larger studies, additional work will be needed to determine whether variations in metal levels are drivers of disease progression or are simply passengers of the disease process.

Effect of metallothionein 2A gene polymorphism on allele-specific gene expression and metal content in prostate cancer

Metallothioneins (MTs) are highly conserved, small molecular weight, cysteine rich proteins. The major physiological functions of metallothioneins include homeostasis of essential metals Zn and Cu and protection against cytotoxicity of heavy metals. The aim of this study was to determine whether there is an association between the -5 A/G single nucleotide polymorphism (SNP; rs28366003) in core promoter region and expression of metallothionein 2A (MT2A) gene and metal concentration in prostate cancer tissues. MT2A polymorphism was determined by the polymerase chain reaction-restriction fragment length polymorphism technique (PCR-RFLP) using 412 prostate cancer tissue samples. MT2A gene expression analysis was performed by real-time RT-PCR method. A significant association between rs28366003 genotype and MT2A expression level was found. The average mRNA level was found to be lower among minor allele carriers (the risk allele) than average expression among homozygotes for the major allele. Metal levels were analyzed by flamed atomic absorption spectrometer system. Highly statistically significant associations were detected between the SNP and Cd, Zn, Cu and Pb levels. The results of Spearman's rank correlation showed that the expressions of MT2A and Cu, Pb and Ni concentrations were negatively correlated. On the basis of the results obtained in this study, we suggest that SNP polymorphism may affect the MT2A gene expression in prostate and this is associated with some metal accumulation.

Acute effects of moderate and strenuous running on trace element distribution in the brain, liver, and spleen of trained rats

OBJECTIVE

Trace elements such as manganese (Mn), cobalt (Co) and chromium (Cr) play key roles in metabolic reactions and are important in many physiological enzymatic processes. In this study, we aimed to investigate the acute effects of moderate and strenuous running (treadmill) exercise on the levels of Mn, Co and Cr in the brain, liver, and spleen of trained rats.

STUDY DESIGN

Animal experiment.

MATERIAL AND METHODS

Twenty-one Wistar-Albino adult male rats were used in the study. Rats were grouped as control group (no mandated exercise; n=8), moderate exercise group (30 min exercise duration; n=7), and strenuous exercise group (60 min exercise duration; n=6). The levels of Mn, Co, and Cr in the frontal lobe, temporal lobe, brain stem, liver, and spleen were determined by atomic absorption spectrophotometer.

RESULTS

Cr levels in liver of rats increased in parallel to the time course of running supporting the exercise training effect on the action of insulin. Compared to the control group, the level of Co significantly decreased in the brain stem of rats in the moderate exercise group (p=0.009) and in the frontal lobe of rats in the strenuous exercise group (p=0.004). In the strenuous exercise group, an examination of the brain stem revealed that the level of Mn significantly decreased (p=0.001), and levels of Co and Cr were apparently depleted to the extent that these elements were no longer detectable.

CONCLUSION

A notable finding is that during or after single bout strenuous exercise, levels of Co decreased in the spleen and particularly decreased in the brain stem of regularly trained rats. From this study, it can be inferred that sportsmen should aware trace element disturbances among the body parts or depletion of some trace elements after single bout of chronic strenuous running exercise.

Mass fractions of 52 trace elements and zinc/trace element content ratios in intact human prostates investigated by inductively coupled plasma mass spectrometry

Contents of 52 trace elements in intact prostate of 64 apparently healthy 13-60-year-old men (mean age 36.5 years) were investigated by inductively coupled plasma mass spectrometry. Mean values (M ± SΕΜ) for mass fraction (in milligrams per kilogram, on dry-weight basis) of trace elements were as follows: Ag 0.041 ± 0.005, Al 36 ± 4, Au 0.0039 ± 0.0007, B 0.97 ± 0.13, Be 0.00099 ± 0.00006, Bi 0.021 ± 0.008, Br 29 ± 3, Cd 0.78 ± 0.09, Ce 0.028 ± 0.004, Co 0.035 ± 0.003, Cs 0.034 ± 0.003, Dy 0.0031 ± 0.0005, Er 0.0018 ± 0.0004, Gd 0.0030 ± 0.0005, Hg 0.046 ± 0.006, Ho 0.00056 ± 0.00008, La 0.074 ± 0.015, Li 0.040 ± 0.004, Mn 1.53 ± 0.09, Mo 0.30 ± 0.03, Nb 0.0051 ± 0.0009, Nd 0.013 ± 0.002, Ni 4.3 ± 0.7, Pb 1.8 ± 0.4, Pr 0.0033 ± 0.0004, Rb 15.9 ± 0.6, Sb 0.040 ± 0.005, Se 0.73 ± 0.03, Sm 0.0027 ± 0.0004, Sn 0.25 ± 0.05, Tb 0.00043 ± 0.00009, Th 0.0024 ± 0.0005, Tl 0.0014 ± 0.0001, Tm 0.00030 ± 0.00006, U 0.0049 ± 0.0014, Y 0.019 ± 0.003, Yb 0.0015 ± 0.0002, Zn 782 ± 97, and Zr 0.044 ± 0.009, respectively. The upper limit of mean contents of As, Cr, Eu, Ga, Hf, Ir, Lu, Pd, Pt, Re, Ta, and Ti were the following: As ≤ 0.018, Cr ≤ 0.64, Eu ≤ 0.0006, Ga ≤ 0.08, Hf ≤ 0.02, Ir ≤ 0.0004, Lu ≤ 0.00028, Pd ≤ 0.007, Pt ≤ 0.0009, Re ≤ 0.0015, Ta ≤ 0.005, and Ti ≤ 2.6. In all prostate samples, the content of Te was under detection limit (<0.003). Additionally, ratios of the Zn content to other trace element contents as well as correlations between Zn and trace elements were calculated. Our data indicate that the human prostate accumulates such trace elements as Al, Au, B, Br, Cd, Cr, Ga, Li, Mn, Ni, Pb, U, and Zn. No special relationship between Zn and other trace elements was found.

Dietary cadmium exposure and prostate cancer incidence: a population-based prospective cohort study

BACKGROUND

Experimental data convincingly propose the toxic metal cadmium as a prostate carcinogen. Cadmium is widely dispersed into the environment and, consequently, food is contaminated.

METHODS

A population-based cohort of 41 089 Swedish men aged 45-79 years was followed prospectively from 1998 through 2009 to assess the association between food frequency questionnaire-based estimates of dietary cadmium exposure (at baseline, 1998) and incidence of prostate cancer (3085 cases, of which 894 were localised and 794 advanced) and through 2008 for prostate cancer mortality (326 fatal cases).

RESULTS

Mean dietary cadmium exposure was 19 μg per day±s.d. 3.7. Multivariable-adjusted dietary cadmium exposure was positively associated with overall prostate cancer, comparing extreme tertiles; rate ratio (RR) 1.13 (95% confidence interval (CI): 1.03-1.24). For subtypes of prostate cancer, the RR was 1.29 (95% CI: 1.08-1.53) for localised, 1.05 (95% CI: 0.87-1.25) for advanced, and 1.14 (95% CI: 0.86-1.51) for fatal cases. No statistically significant difference was observed in the multivariable-adjusted risk estimates between tumour subtypes (P(heterogeneity)=0.27). For localised prostate cancer, RR was 1.55 (1.16-2.08) among men with a small waist circumference and RR 1.45 (1.15, 1.83) among ever smokers.

CONCLUSION

Our findings provide support that dietary cadmium exposure may have a role in prostate cancer development.

Effects of chronic light/dark cycle on iron zinc and copper levels in different brain regions of rats

In this study, we aimed to investigate whether chronic shift in light/dark cycle alters brain trace element concentrations. For this purpose, 20 male Wistar albino adult rats were weighed and randomly divided into three groups. The first group (n = 6) was the control and had been subjected to 12/12-h light/dark cycle for 30 days. The second group (n = 7) was subjected to 6/18-h light/dark cycle for 15 days, and the third group (n = 7) was also subjected to 6/18-h light/dark cycle for 15 days and then returned to normal 12/12-h light/dark cycle for 15 days. When light/dark cycle protocols were completed, tissue specimens of the frontal lobe, temporal lobe, and brain stem were collected. Iron (Fe), zinc (Zn), and copper (Cu) concentrations of the frontal lobe, temporal lobe, and brain stem were determined by an atomic absorption spectrophotometer. When compared with controls, Fe levels of the temporal lobe significantly increased in 6/18-h light/dark cycle group (p < 0.05), whereas it was statistically unchanged in rats which were exposed to 6/18-h light/dark cycle then returned to the normal 12/12-h light/dark cycle period. Our results show that chronic shift in light/dark cycle affects trace element concentrations of the brain, especially Fe level in the temporal lobe, and these changes are reversible.

Prostate cancer outcome and tissue levels of metal ions

BACKGROUND

There are several studies examining prostate cancer and exposure to cadmium, iron, selenium, and zinc. Less data are available on the possible influence of these metal ions on prostate cancer outcome. This study measured levels of these ions in prostatectomy samples in order to examine possible associations between metal concentrations and disease outcome.

METHODS

We obtained formalin fixed paraffin embedded tissue blocks of prostatectomy samples of 40 patients with PSA recurrence, matched 1:1 (for year of surgery, race, age, Gleason grading, and pathology TNM classification) with tissue blocks from 40 patients without recurrence (n = 80). Case-control pairs were compared for the levels of metals in areas adjacent to tumors. Inductively coupled plasma-mass spectrometry (ICP-MS) was used for quantification of Cd, Fe, Zn, and Se.

RESULTS

Patients with biochemical (PSA) recurrence of disease had 12% lower median iron (95 µg/g vs. 111 µg/g; P = 0.04) and 21% lower zinc (279 µg/g vs. 346 µg/g; P = 0.04) concentrations in the normal-appearing tissue immediately adjacent to cancer areas. Differences in cadmium (0.489 µg/g vs. 0.439 µg/g; 4% higher) and selenium (1.68 µg/g vs. 1.58 µg/g; 5% higher) levels were not statistically significant in recurrence cases, when compared to non-recurrences (P = 0.40 and 0.21, respectively).

CONCLUSIONS

There is an association between low zinc and low iron prostate tissue levels and biochemical recurrence in prostate cancer. Whether these novel findings are a cause or effect of more aggressive tumors, or whether low zinc and iron prostatic levels raise implications for therapy, remains to be investigated.

Cadmium down-regulates expression of XIAP at the post-transcriptional level in prostate cancer cells through an NF-kappaB-independent, proteasome-mediated mechanism

Background

Cadmium has been classified as a human carcinogen, affecting health through occupational and environmental exposure. Cadmium has a long biological half-life (>25 years), due to the flat kinetics of its excretion. The prostate is one of the organs with highest levels of cadmium accumulation. Importantly, patients with prostate cancer appear to have higher levels of cadmium both in the circulation and in prostatic tissues.

Results

In the current report, we demonstrate for the first time that cadmium down-regulates expression of the X-linked inhibitor of apoptosis protein (XIAP) in prostate cancer cells. Cadmium-mediated XIAP depletion occurs at the post-transcriptional level via an NF-κB-independent, proteasome-mediated mechanism and coincides with an increased sensitivity of prostate cancer cells to TNF-α-mediated apoptosis. Prolonged treatment with cadmium results in selection of prostate cancer cells with apoptosis-resistant phenotype. Development of apoptosis-resistance coincides with restoration of XIAP expression in cadmium-selected PC-3 cells.

Conclusions

Selection of cadmium-resistant cells could represent an adaptive survival mechanism that may contribute to progression of prostatic malignancies.

Transcriptome analyses in normal prostate epithelial cells exposed to low-dose cadmium: oncogenic and immunomodulations involving the action of tumor necrosis factor

BACKGROUND

Cadmium is implicated in prostate carcinogenesis, but its oncogenic action remains unclear.

OBJECTIVES

In this study we aimed to decipher changes in cell growth and the transcriptome in an immortalized human normal prostate epithelial cell line (NPrEC) following exposure to low-dose Cd.

METHODS

Synchronized NPrEC cells were exposed to different doses of Cd and assayed for cell viability and cell-cycle progression. We investigated changes in transcriptome by global profiling and used Ingenuity Pathways Analysis software to develop propositions about functional connections among differentially expressed genes. A neutralizing antibody was used to negate the effect of Cd-induced up-regulation of tumor necrosis factor (TNF) in NPrEC cells.

RESULTS

Exposure of NPrEC to 2.5 microM Cd enhanced cell viability and accelerated cell-cycle progression. Global expression profiling identified 48 genes that exhibited >or= 1.5-fold changes in expression after 4, 8, 16, and 32 hr of Cd treatment. Pathway analyses inferred a functional connection among 35 of these genes in one major network, with TNF as the most prominent node. Fourteen of the 35 genes are related to TNF, and 11 exhibited an average of >2-fold changes in gene expression. Real-time reverse transcriptase-polymerase chain reaction confirmed the up-regulation of 7 of the 11 genes (ADAM8, EDN1, IL8, IL24, IL13RA2, COX2/PTGS2, and SERPINB2) and uncovered a 28-fold transient increase in TNF expression in Cd-treated NPrEC cells. A TNF-neutralizing antibody effectively blocked Cd-induced elevations in the expression of these genes.

CONCLUSIONS

Noncytotoxic, low-dose Cd has growth-promoting effects on NPrEC cells and induces transient overexpression of TNF, leading to up-regulation of genes with oncogenic and immunomodulation functions.

Correlations of dietary patterns with prostate health

Both genetic and environmental influences may be involved in etiology of prostate health and prostate cancer. These include ethnic origin, family history, smoking, and diet. Adiposity and excess energy intake are potentially distinct risk factors and positive associations with prostate cancer risk for both were observed among case-control and cohort studies. Some epidemiological studies support an association between dietary fat, particularly saturated or animal fats, and prostate cancer risk. Of these, several suggest reduced risk with low-fat diets high in n-3 fatty acids and increased risk with high-fat diets rich in n-6 fatty acids. Others suggested association with higher meat intake, possibly due to heterocyclic amines and polycyclic aromatic hydrocarbons, produced during grilling or frying. Positive association of prostate cancer risk with dairy intake could involve alpha-methylacyl-CoA racemase activity (required for beta-oxidation of phytanic acid present in dairy products and red meat) or the suppression of vitamin D activity by calcium. Inverse associations were observed with dietary intake of plant foods. These include cereals, soy products, and fruit and vegetable sources of carotenoids. Numerous plant constituents may act synergistically in the prevention and inhibition of prostate disorders. These diet-risk associations may lead to future individualized diet recommendations based upon genetic polymorphisms.

Prostate-specific antigen levels in relation to cadmium exposure and zinc intake: results from the 2001-2002 National Health and Nutrition Examination Survey

BACKGROUND

Cadmium exposure has been suggested as a risk factor for prostate cancer, and experimental literature suggests that the carcinogenic effect of cadmium is modified by the presence of zinc. We evaluated total prostate-specific antigen (PSA) levels in relation to urinary cadmium concentrations and dietary zinc intake.

METHODS

PSA levels were determined in 1,320 men over the age of 40 in the 2001-2002 National Health and Nutrition Examination Survey (NHANES). Urinary cadmium concentrations were measured in about one-third of the sample population, whereas dietary zinc intake was based on participants' 24-hr recall. Information on all three variables was available for 422 men in the 2001-2002 NHANES survey. We performed linear regressions to evaluate the relationships these factors after accounting for age and other covariates.

RESULTS

Little evidence for an association between cadmium and elevated PSA level was observed. However, the data provide suggestive evidence for an interaction between zinc intake and cadmium exposure (P for interaction=0.09). Among men with zinc intake less than the median level of 12.67 mg/day, an increase in 1 microg/g creatinine cadmium exposure was associated with a 35% increase in PSA level. In contrast, among men with greater than median zinc intake, little evidence for an association between cadmium and PSA was found.

CONCLUSIONS

These findings suggest a protective effect of zinc intake on cadmium-induced prostatic injury, and may provide further rationale for investigating the impact of these factors individually and jointly on the etiology of prostate cancer.

Analysis of iron, zinc, selenium and cadmium in paraffin-embedded prostate tissue specimens using inductively coupled plasma mass-spectrometry

Formalin-fixed paraffin-embedded (FFPE) tissue specimens represent a valuable and abundant resource of pathologic material for various biomedical studies. In the present study, we report the application of high-resolution inductively coupled mass-spectrometry (ICP-MS) for quantification of Fe, Zn, Se and Cd in FFPE prostate tissue. These elements have a possible role in the development of prostate diseases: while Zn and Se are needed for a healthy prostate, Cd shows multiple toxic and carcinogenic effects. Excessive accumulation of Fe induces the production of highly reactive hydroxyl radical species, which may play a role in cancer etiopathogenesis. To assess whether the levels of these metals in the FFPE prostate tissue represent their original content, we compared their levels with those in the fresh tissue (on dry weight basis) in samples obtained from 15 patients. We found that in FFPE tissue, the recoveries of Se, Fe, Cd and Zn were progressively decreased, 97+/-11% (r=0.88), 82+/-22% (r=0.86), 59+/-23% (r=0.69) and 24+/-11% (r=0.38), respectively. Thus, the use of correction factors, determined as k=0.16 for Se, k=0.20 for Fe, k=0.27 for Cd and k=0.67 for Zn, is required to estimate the retrospective levels of these elements in the parental non-processed fresh (wet) prostate tissue. The technique used in this study enables the analysis of archival FFPE prostate tissue for the concentrations of Fe, Zn, Se and Cd to study association between the levels of these metals and prostate disease.

Prediction of prostate cancer using hair trace element concentration and support vector machine method

A change in the normal concentration of essential trace elements in the human body might lead to major health disturbances. In this study, hair samples were collected from 115 human subject, including 55 healthy people and 60 patients with prostate cancer. The concentrations of 20 trace elements (TEs) in these samples were measured by inductively coupled plasma-mass spectrometry. Asupport vector machine was used to investigate the relationship between TEs and prostate cancer. It is found that, among the 20 TEs, 10 (Mg P, K, Ca, Cr, Mn, Fe. Cu, Zn, and Se) are related to the risk of prostate cancer. These 10 TEs were used to build the prediction model for prostate cancer. The model obtained can satisfactorily distinguish the healthy samples from the cancer samples. Furthermore, the cross-validation by leaving-one method proved that the prediction ability of this model reaches as high as 95.8%. It is practical to predict the risk of prostate cancer using this model in the clinics.

Case-control study of toenail cadmium and prostate cancer risk in Italy

A role of cadmium exposure in prostate cancer etiology has been suggested by epidemiologic and laboratory studies, but conclusive evidence on this topic is still lacking. We investigated the relation between cadmium exposure, estimated by determining toenails cadmium levels, and prostate cancer risk in forty patients newly diagnosed with prostate cancer and fifty-eight hospital controls recruited in two provinces from southern and northern Italy. We found an excess cancer risk in subjects in the third and fourth (highest) quartiles of toenail cadmium concentration (odds ratio 1.3 and 4.7, respectively) compared with subjects in the bottom quartile. Results were basically unchanged when limiting the analysis to each province or entering toenail cadmium concentrations as continuous values in the regression model (P=0.004). Despite the limited statistical stability of the point estimates, these findings appear to support the hypothesis that cadmium exposure increases prostate cancer risk.

Occupational risk factors for prostate cancer and benign prostatic hyperplasia: a case-control study in Western Australia

OBJECTIVE

To assess the association of selected occupational exposures with risk of prostate cancer and with risk of benign prostatic hyperplasia (BPH).

METHODS

This population-based case-control study recruited 606 men with a diagnosis of confirmed prostate cancer, 400 men who had undergone their first prostatectomy for BPH and 471 male controls randomly selected from the electoral roll between 1 August 2001 and 1 October 2002 in Western Australia. chi(2) tests and logistic regressions were used for univariate and multivariate analyses to investigate the association of the two outcomes with occupational exposure to pesticides, fertilisers, metals, wood dust, oils, diesel exhaust and polyaromatic hydrocarbons (PAHs).

RESULTS

Exposure to toxic metals at a non-substantial level increased the risk of BPH (odds ratio (OR) 1.39, 95% confidence interval (CI) 1.1 to 1.84) and led to a non-significant excess risk of prostate cancer (OR 1.25, 95% CI 0.96 to 1.61). Non-significant excess risks were observed for prostate cancer after exposure to oils other than mineral oil (OR 1.54, 95% CI 0.95 to 2.51) and for BPH after exposure to PAHs (OR 1.20, 95% CI 0.91 to 1.58). A non-statistically significant protective effect for prostate cancer was seen after exposure to organophosphate pesticides (OR 0. 69, 95% CI 0.43 to 1.12). No other associations were found for either prostate cancer or BPH and no dose-response relationships were seen for the exposures investigated.

CONCLUSIONS

These results do not provide evidence that any of the occupational factors examined are risk factors for either prostate cancer or BPH.

High levels of cadmium and lead in seminal fluid and blood of smoking men are associated with high oxidative stress and damage in infertile subjects

We measured the levels of malondialdehyde (MDA), protein carbonyls, glutathione S-transferase (GST) and reducte glutathione (GSH) in seminal plasma and spermatozoa from 95 subjects including 50 infertile patients to evaluate the association between oxidative stress and damage and the components of the anti-oxidant defenses in seminal plasma and spermatozoa of infertile subjects and concentrations of cadmium (Cd) and lead (Pb) in the blood and seminal plasma because of tobacco smoke exposure. The reactive oxygen species (ROS) in spermatozoa were also evaluated by luminol (5-amino-2,3-dihydro-1,4-phthalazinedione)-enhanced chemiluminescence assay. The sperm count, motility, and morphology in the smokers infertile group were found to be lower than those in the fertile male group and nonsmokers infertile group (p < 0.001). Concentrations of Cd, Pb, MDA, protein carbonyls, and ROS levels in the smokers infertile group were significantly higher than those in the fertile male and nonsmokers infertile male groups (p < 0.001). However, GSH levels and GST activities were decreased in the smokers infertile male group than those in the fertile male and nonsmokers infertile male groups (p < 0.001). The results indicate that smoking could affect semen quality and oxidative lipid and protein damage in human spermatozoa. From Pearson correlation analysis, positive correlations were demonstrated between the seminal plasma Cd and seminal plasma protein carbonyls and between seminal plasma Pb and spermatozoa ROS levels in smokers of the subfertile group, while there was a significant positive correlation between blood Cd and ROS levels in smokers of the fertile group. There was also a significant negative correlation of the Cd level of the blood and GSH levels of the sperm and seminal plasma. These findings suggest that cigarette smoking enhances the levels of Cd and Pb in seminal plasma and blood and the extent of oxidative damage associated with a decrease in components of the anti-oxidant defenses in the sperm of infertile males.

Comparative study of zinc levels in benign and malignant lesions of the prostate

OBJECTIVES

The normal human prostate accumulates the highest levels of zinc of any soft tissue in the body. The presence of zinc in the prostate of a number of mammalian species, including rhesus monkeys and humans, has been well documented. The aims of this study were to investigate the concentrations of zinc in various disorders of the prostate and to find a correlation between them.

MATERIAL AND METHODS

A total of 80 cases were studied (20 normal, 50 benign, 10 carcinomatous). A plasma sample was taken and zinc levels were analyzed using atomic absorption spectrophotometry.

RESULTS

The mean (+/-SD) plasma zinc level in the normal cases was 94.5+/-10.38 microg/100 ml. Amongst patients with benign diseases of the prostate gland, the plasma zinc level was 145.4+/-9.67, 162.4+/-2.22 and 172.7+/-5.27 microg/100 ml (78% rise compared to normal patients) in those with a fibromuscular prostate, chronic prostatitis and benign prostatic hyperplasia, respectively, whilst patients with malignancy had a plasma zinc level of 59.6+/-3.08 microg/100 ml (37% fall compared to normal patients). There was a highly statistically significant (p < 0.01) difference in plasma zinc levels between patients with benign and malignant prostate diseases. The effect of metastasis of carcinoma of the prostate on plasma zinc levels was not significant (p > 0.05), while there was a highly statistically significant (p < 0.01) correlation between serum prostate-specific antigen and plasma zinc levels in malignancy.

CONCLUSIONS

There appears to be a strong correlation between plasma zinc levels and various prostatic diseases. Therefore, the determination of zinc levels can be used as a diagnostic or screening tool and may lead to the formulation of methods in which zinc is used to evaluate prostatic pathology.

Introduction to neutron stimulated emission computed tomography

Neutron stimulated emission computed tomography (NSECT) is presented as a new technique for in vivo tomographic spectroscopic imaging. A full implementation of NSECT is intended to provide an elemental spectrum of the body or part of the body being interrogated at each voxel of a three-dimensional computed tomographic image. An external neutron beam illuminates the sample and some of these neutrons scatter inelastically, producing characteristic gamma emission from the scattering nuclei. These characteristic gamma rays are acquired by a gamma spectrometer and the emitting nucleus is identified by the emitted gamma energy. The neutron beam is scanned over the body in a geometry that allows for tomographic reconstruction. Tomographic images of each element in the spectrum can be reconstructed to represent the spatial distribution of elements within the sample. Here we offer proof of concept for the NSECT method, present the first single projection spectra acquired from multi-element phantoms, and discuss potential biomedical applications.

Concentrations of Toxic Metals and Trace Elements in the Meconium of Newborns from an Industrial City

OBJECTIVE

To investigate fetal exposure to toxic metals [lead (Pb), cadmium (Cd)] and fetal levels of trace elements [zinc (Zn), copper (Cu), and iron (Fe)] in newborns from an industrial city. Relationships between meconium mineral contents and parental occupation and location of residence were also tested.

METHOD

The meconium mineral contents of 117 healthy newborn infants were measured by flame atomic absorption spectrophotometer.

RESULTS

The median concentrations (interquartile range) of toxic metals and trace elements in the meconium were as follows: Pb: 46.5 (1,399) microg/g dry weight (wt), Cd: 2.3 (55.6) microg/g dry wt; Zn: 234 (3,049) microg/g dry wt; Cu: 11.8 (818.7) microg/g dry wt, and Fe 105 (2,980) microg/g dry wt. All the meconium samples contained both toxic metals and trace elements. The proportions of trace elements in the meconium samples with concentration higher than 100 microg/g dry wt of the substances tested were Zn 90%, Cu 64%, and Fe 53%. There were significantly positive correlations between the concentrations of toxic metals and trace elements. Also there were positive correlations between the levels of Zn, Fe, and parental occupations, and between the level of Fe and location of residence of the parents (proximity to the petroleum refinery or the dye industries).

CONCLUSION

All the meconium samples were positive for toxic metals, and thus may reflect environmental pollution in the city. The occupation environments and the location of the family residence are linked with levels of trace elements in meconium.

Environmental Exposure to Trace Elements and Prostate Cancer in Three New Zealand Ethnic Groups

A stratified random sample of 176 men was taken from a larger community prostate study group of 1405 eligible subjects from three ethnic groups in the Wellington region of New Zealand, in order to examine ethnic differences in exposure to cadmium (Cd), selenium (Se) and zinc (Zn) and possible associations of blood levels of Cd, Se and Zn with the prevalence of elevated serum Prostate Specific Antigen (PSA); a marker of prostate cancer. Maori and Pacific Islands men were found likely to have higher Cd exposure than New Zealand Europeans through diet, occupation and smoking. However, there was no significant difference between ethnic groups in mean blood Cd levels. Pacific Islands men had significantly higher levels of blood Se than both New Zealand European men and Maori men. Maori men had significantly higher levels of blood Zn than both New Zealand European men and Pacific Islands men. A positive association was found between blood Cd and total serum PSA. Se and Zn levels were not associated with elevated PSA. Maori and Pacific Islands men have higher prostate cancer mortality rates than New Zealand European men. Ethnic differences in mortality could be contributed to by differences in rates of disease progression, influenced by exposure and/or deficiency to trace elements. However, results did not reflect a consistent ethnic trend and highlight the complexity of the risk/protective mechanisms conferred by exposure factors. Further research is needed to ascertain whether the associations found between Cd and PSA levels are biologically important or are merely factors to be considered when interpreting PSA results clinically.

Measurement of serum zinc improves prostate cancer detection efficiency in patients with PSA levels between 4 ng/mL and 10 ng/mL

AIM

To investigate whether the measurement of serum zinc may improve the detection of prostate cancer (PCa) in men who had total prostate-specific antigen (PSA) levels higher than 4.1 ng/mL.

METHODS

A mass screening for PCa of 3940 men over 50 years old was undertaken using total serum PSA. Of the 190 men (4.8%) with elevated PSA, 143 (3.6%) underwent a transrectal ultrasonography (TRUS)-guided biopsy of the prostate, and 42 men (1% of total and 29.3% of men undergoing biopsy) were found to have cancer. The areas under the receiver operating characteristic curves (ROC-AUC) were used to compare the diagnostic power of cancer detection by means of serum zinc, and free PSA/total PSA ratio (f/t).

RESULTS

The men with levels of serum zinc that ranged from 40 ng/mL-60 ng/mL, had an age-adjusted odds ratios(OR) of 5.0. A cutoff value of 100 microg/mL for serum zinc concentration provided a sensitivity of 90.5% and a specificity of 32.7% in elevated PSA range, and a sensitivity of 93.3% and specificity of 27.1% in gray zone, respectively. In the gray zone ranges of 4.1 ng/mL-10.0 ng/mL, the ROC-AUC for zinc was 73.0% higher than 62.7% of f/t PSA ratio and 56.7% of total PSA.

CONCLUSION

PCa displays a lower serum zinc concentration. The measurement of zinc levels improves PCa detection in the gray zone compared with the f/t PSA ratio and total PSA.

Comparison of trace metal concentrations in malign and benign human prostate

Imbalance in the composition of trace metals, recognized to be essential to normal human homeostasis, besides the accumulation of potentially toxic or nonessential trace metals, may cause disease. Thus, there is a need for their analysis in cancerous and noncancerous human tissues to examine the relationship between cancer and these elements. Trace metal concentrations including Cd, Ni, Zn, Cu, Fe, Mg, and Ca in both malign and benign prostate samples were determined by atomic absorption spectrophotometry. The tissues were digested by using microwave energy. In contrast to the literature data for zinc, the concentrations of calcium and zinc in the malign human prostate were found to be significantly higher than those in the benign human prostate (p < 0.05 for both metals). Similarly, the concentrations of iron, nickel, and magnesium in the malign prostate were also found to be higher than those in the benign prostate (p </= 0.1). Therefore, it is understood that more studies are needed regarding the increase or decrease in the metal (particularly Ca and Zn) concentrations of malign prostate samples.

Chemoprevention in Chronic Prostatitis in BPH and in Low Grade Carcinoma

Prostate cancer is the most common solid malignancy in men in the United States. As a disease predominantly affecting the elderly and with the continuing aging of the population, the importance of studying and treating prostate cancer will continue to increase. Many factors have been implicated in the development of prostate cancer. It presents a variability of incidences influenced by dietary factors. The administration of substances, such as Lycopene, Polyphenols, Iso-flavonoids, Vitamin D, Vitamin E, Selenium and Zinc have a decisive role in the prevention of anti-apoptotic and pro-angiogenesis processes which are long-term developing properties of cancer cells. In this study, we will provide an overview of the current state of art between dietary habits and risk of prostate cancer.

Prevention and treatment of erectile dysfunction using lifestyle changes and dietary supplements: what works and what is worthless, part II

It seems naïve to believe that some plants or herbs do not contain specific compounds that could benefit patients with ED. Many supplements have not been investigated in a laboratory or clinical research setting before commercial sale, however,which creates a complex situation. If efficacy is or is not demonstrated through adequate research, then the benefit or lack thereof cannot be mentioned on the label. Furthermore, clinicians and the public cannot be made aware of which compounds or supplements are effective because no general standards for sale exist under the current guidelines. Dietary supplements have received a tremendous amount of publicity. The large and growing market for ED treatment seems to have contributed partly to the promotion of numerous supplements and their apparent benefits. Whether these dietary supplements have merit is questionable. Some supplements may produce results opposite to those advertised. Other supplements may be enjoying the benefits of the placebo effect. Because a placebo response of 25% to 50% has been recorded in clinical trials with effective agents, it is understandable that some supplements enjoy financial success despite the limited research espousing their use. If one to two of four individuals or one of three individuals who try a dietary supplement gain some benefit for their ED, the market for these supplements will remain extraordinary. On a larger scale, of 100,000 men who try a supplement, approximately 25,000 to 50,000 will claim some success. The challenge for clinicians is to discuss the placebo response properly and the need for good research before any intervention, especially supplements, can be advocated for general use. Table 2 summarizes some popular ED supplements and general conclusions that can be drawn from clinical investigations. Some dietary supplements may have an active ingredient that benefits patients with certain types of ED. An exciting area of future dietary supplement research is the ability of certain agents to have a synergistic effect with prescription agents for ED, thereby improving response rates in men that have failed approved ED therapy initially, especially with oral agents. Randomized clinical trials are the best method of determining which dietary supplements will become a part of conventional medicine. Therefore, more randomized trials for dietary supplements are needed so that they may have the opportunity to become a part of the mainstream milieu, which means that more funding needs to be made available for ED research. The coming years of research should bring enormous excitement and objectivity to this area of medicine.

The effects of oral zinc sulphate during radiotherapy on anti-oxidant enzyme activities in patients with head and neck cancer: a prospective, randomised, placebo-controlled study

The purpose was to determine the effects of oral zinc sulphate along with radiotherapy on anti-oxidant enzyme activities in patients with head and neck cancer. Thirty patients with head and neck cancer were randomly assigned to receive either zinc sulphate capsules (including 50 mg zinc) (n = 15) or placebo (n = 15) three times a day, starting on the day of the first radiotherapy fraction and continuing throughout the scheduled radiotherapy course including weekends and 6 weeks after radiotherapy. The patients were treated with telecobalt radiation at conventional fractionation of 2 Gy/fraction and five fractions/ week in 20-35 fractions for a period of 4-7 weeks. Blood samples for biochemical parameters were collected after an overnight fast (12 h) before radiotherapy, the first day and 6 weeks after radiotherapy. In the placebo group, three patients were excluded. No difference was detected in any final measurement activities of erythrocyte anti-oxidant enzyme such as copper-zinc superoxide dismutase (Cu-Zn SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) in the direct comparison between the zinc sulphate and the placebo group, except erythrocyte SOD activities measured the first day after radiotherapy (p < 0.03). In the respective measurement analysis of the groups in themselves, in the zinc sulphate group, while the statistical analysis for the activities of erythrocyte CAT and GSH-Px were significantly different (chi2 = 12.4, p < 0.05; chi2 = 8.9, p < 0.05, respectively) before radiotherapy, the first day and 6 weeks after radiotherapy, the activities of SOD did not differ (chi2 = 4.2, p > 0.05). In these three measurements, there was no statistical significance in the activities of enzymes in erythrocyte Cu-Zn SOD, CAT and GSH-Px in the placebo group. Before radiotherapy, plasma zinc levels were normal in 16 patients (59.2%) and were lower in 11 patients (40.8%) compared with laboratory levels. It would be worthwhile studying the effect of oral zinc sulphate supplements to improve the anti-oxidant enzyme activity in radiation-treated cancer patients, in the hope of reducing radiation-induced toxicity.

Zinc sulfate in the prevention of radiation-induced oropharyngeal mucositis: a prospective, placebo-controlled, randomized study

PURPOSE

To determine the effect of oral zinc sulphate supplementation on radiation-induced oropharyngeal mucositis in patients with head-and-neck cancer.

MATERIALS AND METHODS

Thirty patients with head-and-neck cancer were randomly assigned to receive either zinc sulfate or placebo. Primary tumors were localized in the larynx in 14 patients, in the nasopharynx in 4, in the oral cavity in 4, in a salivary gland in 1, in the maxillary sinus in 1, in neck nodes (lymphoma presenting primarily) in 3 and in neck metastases from an unknown primary in 3. In the placebo group, 3 patients were excluded; 1 patient died during treatment, 1 left the study, and 1 did not come to the 6 week control visit. The patients were treated with telecobalt radiotherapy at conventional fractionation (2 Gy/fraction, five fractions weekly, for 20-35 fractions within 4-7 weeks). The median radiation dose was 6400 cGy (4000-7000 cGy). Oral mucositis was assessed by two independent physicians, experts in radiation oncology, using the Radiation Therapy Oncology Group Acute Radiation Morbidity Scoring criteria.

RESULTS

In the zinc sulfate group, Grade 3-4 mucositis was not detected in any patient; Grade 0 mucositis was detected in 2, and Grade 1 in 8, and Grade 2 in 5 patients. In the placebo group, Grade 2 mucositis was detected in 4 and Grade 3 in 8 patients. We observed that the degree of mucositis in the patients in the zinc sulfate group was significantly lower than that in the placebo group (p < 0.05). Confluent mucositis developed earlier in the placebo group than in the zinc sulfate group after the onset of treatment (p < 0.05) and started to improve sooner in the zinc sulfate group than in the placebo group (p < 0.05).

CONCLUSIONS

Zinc sulfate is beneficial in decreasing the severity of radiation-induced mucositis and oral discomfort. These results should be confirmed by additional evaluation in randomized studies with a larger number of patients.

Regulation of metallothionein and zinc transporter expression in human prostate cancer cells and tissues

Prostate glands contain heavy metals such as zinc and cadmium, and epidemiological studies showed that both metals were associated with prostate cancer development. To understand the heavy metal metabolism in prostate glands, we investigated the regulation of metallothionein (MT), metal-responsive promoter element-binding transcription factor (MTF) and zinc transporter (ZnT) in human prostate cells and tissues. Growth of human prostate cancer cells, LNCaP and PC-3 cells, was suppressed by zinc or cadmium treatment in a dose-dependent manner. LNCaP cells expressed MT-1A, 1X and 2A mRNA, and PC-3 cells expressed MT-1X and 2A mRNA. Zinc or cadmium treatment up-regulated MTs, MTF-1 and ZnT-1 gene expression levels in both cell lines. In PC-3 cells, ZnT-1 protein was detected, and was up-regulated by the metal treatment. Human prostate cancer tissues expressed significantly lower levels of ZnT-1 gene in comparison with hyperplastic tissues. We demonstrated the ZnT-1 expression in human prostate for the first time. The present study showed that heavy metal-metabolizing proteins were involved in human prostate homeostasis, and that the metal metabolizing system might be different in malignant tissues.

Prediagnostic toenail cadmium and zinc and subsequent prostate cancer risk

BACKGROUND

Cadmium is a recognized human lung carcinogen that has also been positively associated with prostate cancer mainly in occupationally exposed men. The association between dietary and supplemental zinc intake and prostate cancer has not been consistent in epidemiologic studies. We evaluated the association between prediagnostic toenail cadmium and zinc concentrations and risk of prostate cancer in a cohort in which the primary route of exposure to cadmium and zinc is the diet.

METHODS

Included in the analysis were 115 prostate cancer cases and 227 age-matched controls nested in the prospective CLUE II study located in Washington County, MD. Participants provided toenail samples at baseline in 1989. Furnace atomic absorption and flame atomic absorption were used to determine toenail cadmium and zinc concentrations, respectively. Odds ratios (OR) and 95% confidence intervals (CI) were estimated from conditional logistic regression models.

RESULTS

Median toenail cadmium and zinc concentrations did not statistically significantly differ between prostate cancer cases (cadmium, 45.9 ppb; zinc, 155.3 ppm) and controls (cadmium, 54.5 ppb; zinc, 164.0 ppm). Prostate cancer risk did not increase with increasing concentrations of cadmium (P trend = 0.9) and did not decrease with increasing concentrations of zinc (P trend = 0.2). For both metals, the ORs for the top four fifths were each below 1.0 when compared with the bottom fifth.

CONCLUSION

Men who have high toenail cadmium concentrations in the range observed in this general population sample were not at an increased risk for prostate cancer. Although there was no evidence of a linear dose-response, these findings suggest that risk of prostate cancer may be slightly lower among men with moderate and higher zinc intake.

Interactions between cadmium and zinc in the organism

It is well known that many toxic effects of cadmium (Cd) action result from interactions with essential elements, including zinc (Zn). These interactions can take place at different stages of absorption, distribution in the organism and excretion of both metals and at the stage of Zn biological functions. Exposure to Cd leads to disturbance in Zn in the organism on the one hand, while dietary Zn intake has an important effect on Cd absorption, accumulation and toxicity on the other. The Zn status of the body is important in relation to development of Cd toxicity. Numerous data show that increased Zn supply may reduce Cd absorption and accumulation and prevent or reduce the adverse actions of Cd, whereas Zn deficiency can intensify Cd accumulation and toxicity. In this review, the interactions between these two trace elements in humans and animals are discussed on the basis of the available literature and our own results, against the background of general population exposure to Cd and common nutritional deficiency of Zn.