Sin Eng Chia

Detection of oxidative dna damage in human sperm and the association with cigarette smoking

The present study aims to evaluate oxidative DNA damage in human sperm and the association with cigarette smoking. The level of 8-hydroxydeoxyguanosine (8-OHdG) in sperm DNA, cotinine concentration in seminal plasma, and conventional seminal parameters such as semen volume, sperm density, viability, motility, and normal morphology were determined in 60 healthy subjects. It was found that the sperm DNA of smokers contained a significantly higher amount of 8-OHdG than that of nonsmokers (6.19 ± 1.71 vs. 3.93 ± 1.33 8-OHdG/105 dG, P < 0.001). The level of 8-OHdG in sperm DNA was also closely correlated to seminal cotinine concentration (r = 0.38, P < 0.05). These findings suggest that cigarette smoking enhances the extent of DNA damage in sperm. In contrast, no significant difference was observed for conventional parameters between smokers and nonsmokers, suggesting that the level of 8-OHdG in sperm may reflect the deleterious effect of cigarette smoking on sperm quality more accurately than conventional seminal parameters. Further investigation is required to understand the exact biologic and pathologic significance of oxidative damage to sperm DNA and the possibility of using 8-OHdG for the assessment of sperm quality.

The associations among semen quality, oxidative DNA damage in human spermatozoa and concentrations of cadmium, lead and selenium in seminal plasma

To explore the associations among semen quality, oxidative DNA damage in human spermatozoa and concentrations of cadmium, lead and selenium in seminal plasma, 56 non-smoking subjects were asked to collect semen by masturbation into a sterile wide-mouth metal-free plastic container after 3 days of abstinence. The conventional semen parameters were analysed. The concentrations of Cd, Pb and Se in seminal plasma were detected using atomic absorption spectrophotometer. 8-OHdG levels in sperm DNA were measured using HPLC-EC. The results showed that the geometric mean concentrations of Cd, Pb and Se were 0.78, 7.8 and 51.4 microg/l, respectively. The geometric mean of 8-OHdG/10(6) dG was 51.4 (95% CI: 21.5-123.0). A significant inverse correlation exists between Cd and sperm density (r=-0.28, P<0.05), and between Cd and sperm number per ejaculum (r=-0.27, P<0.05). In contrast, there was a significantly positive correlation between Se and sperm density (r=0.50, P<0.01), between Se and sperm number (r=0.49, P<0.01), between Se and sperm motility (r=0.40, P<0.01), and between Se and sperm viability (r=0.38, P<0.01). No statistically significant correlation was observed between Pb and semen quality. A significant inverse correlation was observed between 8-OHdG and sperm density (r=-0.34, P<0.01), between 8-OHdG and sperm number per ejaculum (r=-0.30, P<0.01), and 8-OHdG and sperm viability (r=-0.24, P<0.05). 8-OHdG was significantly correlated with Cd in seminal plasma (r=0.55, P<0.01). A significant but weak positive correlation was found between 8-OHdG and Pb concentration in seminal plasma (r=0.28, P<0.05). In contract, a significant inverse correlation was observed between 8-OHdG and Se concentration in seminal plasma (r=-0.40, P<0.01). The results indicate that Cd in seminal plasma could affect semen quality and oxidative DNA damage in human spermatozoa. Se could protect against oxidative DNA damage in human sperm cells. Pb did not appear to have any association with the semen quality when concentration of Pb in seminal plasma was below 10 microg/l.

Trace elements in blood and seminal plasma and their relationship to sperm quality

The concentrations of cadmium, lead, selenium, and zinc in blood and seminal plasma were determined in 221 Singapore men. The relationship of trace element concentration to sperm density, motility, morphology, and semen volume was also investigated. The concentrations of elements were in the following descending order: Zn > Se > Pb > Cd. Except for zinc, the concentrations were generally higher in blood than in seminal plasma. The mean concentration of zinc in seminal plasma (ZnSP) was about 30 times higher than in blood (ZnB). A significant inverse correlation was observed between blood cadmium levels (CdB) and sperm density (r = -0.24, P < 0.05) in oligozoospermic men (sperm density below 20 million/mL) but not in normospermic men. Cadmium in seminal plasma (CdSP) was also associated with low semen volume (r = -0.29, P < 0.05). These findings suggest that cadmium may have an effect on the male reproductive system. In contrast, positive correlations were observed between concentrations of selenium and zinc in seminal plasma (SeSP and ZnSP) and sperm density in normospermic men but not in oligozoospermic men. The correlation coefficients with sperm density for SeSP and ZnSP were 0.35 (P < 0.05) and 0.41 (P < 0.01), respectively. The concentrations of lead in blood (PbB) or seminal plasma (PbSP) did not appear to have any correlation with the sperm parameters studied.

Pterygium in Indonesia: prevalence, severity and risk factors.

Aim: To determine prevalence rates, severity, and risk factors for pterygium in adults in provincial Indonesia and to validate a clinical grading scheme in a population based setting. Methods: A population based prevalence survey of 1210 adults aged 21 years and above was conducted in five rural villages and one provincial town in Riau province, Sumatra, Indonesia, an area near to the equator. A one stage household cluster sampling procedure was employed: 100 households were randomly selected from each village or town. Pterygia were graded for severity (T1 to T3, by visibility of episcleral vessels) and the basal and apical extent measured by an ophthalmologist (GG) with a hand held slit lamp. Refraction was measured by hand held autorefractor (Retinomax). Face to face household interviews assessed outdoor activity, occupation, and smoking. The participation rate was 96.7%. Results: The mean age was 36.6 years (SD 13.1), 612 were male. The age adjusted prevalence rate of any pterygium was 10.0% (95% confidence intervals (CI) 8.2 to 11.7) and of bilateral pterygia was 4.1% (95% CI 2.9 to 5.3). There was a significant dose-response relation with age (2.9% (95% CI 0.4 to 5.8) for 21–29 years versus 17.3% (95% CI 10.4 to 24.2) 50 years and above; p for trend <0.001) and occupations with more time outdoors (p for trend = 0.02). This was true for both sexes, all grades of lesion (T1 to T3), and bilateral disease. A multivariate logistic regression model showed pterygium was independently related to increasing age and outdoor activity 10 years earlier. The mean basal diameter = 3.3 mm (SD 1.51, range 0.1–9.5) and extent from limbus = 1.4 mm (SD 1.18, range 0.1–8.0). Higher grade pterygia were larger for basal and apical extent (p for trend <0.001). The presence of pterygium was associated with astigmatism (defined as cylinder at least −0.5 dioptres (D); p <0.001). This association increased with increasing grade of lesion (p for trend <0.001). Median cylinder for those with pterygium (−0.50 D) was greater than for those without (−0.25D), (p <0.001), and increased with higher grade of lesion (p for trend <0.001). For eyes with pterygia, magnitude of astigmatism was associated with greatest extent from the limbus, (p = 0.03), but not basal width (p = 0.99). Conclusions: There is a high prevalence rate of pterygia in provincial Sumatra. The independent increase with age and past outdoor activity (a surrogate for sun exposure) is consistent with previous findings. Clinical grading of pterygium morphology by the opacity of the lesion was a useful additional marker of severity.

Salivary cortisol levels and work-related stress among emergency department nurses

The objective of this study was to assess and compare the self-perceived work-related stress of emergency department (ED) and general ward (GW) nurses and to assess the relationship between self-perceived stress and salivary cortisol levels in these groups of nurses. Seventy-three female ED (n = 23) and GW (n = 50) nurses from a general hospital completed a self-administered questionnaire. A modified mental health professional stress scale (PSS) was used to measure self-perceived work-related stress. Salivary samples were collected at the start and end of morning shiftwork. An enzyme-linked immunosorbent assay method was used to determine the salivary cortisol concentration (nmol/L). ED nurses perceived that nursing was more stressful (mean, 1.58; 95% confidence interval [CI], 1.35 to 1.81) than did GW nurses (mean, 1.30; 95% CI, 1.18 to 1.40). On the PSS subscales, scores of organizational structure and process, lack of resources, and conflict with other professionals were higher in ED nurses (all P < 0.01). The morning cortisol was significantly lower in ED (geometric mean, 9.10; 95% CI, 6.62 to 12.42 nmol/L) than in GW (geometric mean, 15.45; 95% CI, 11.86 to 20.14 nmol/L) nurses. Log morning salivary cortisol was negatively correlated with PSS (r = −0.255), scores of organizational structure and process, and conflict with other professionals (all P < 0.05). The difference between morning and afternoon cortisol concentration in ED nurses (geometric mean, 6.35; 95% CI 4.14 to 9.93 nmol/L) was lower than in GW nurses (geometric mean, 12.42; 95% CI, 9.38 to 16.28 nmol/L). The log value of the difference correlated marginally with PSS (r = −0.21, P = 0.07) and significantly with scores of organizational structure and process, lack of resources, and conflict with other professionals (all P < 0.05). There was no difference between the two groups in afternoon salivary cortisol level. ED nurses perceived more stress compared with GW nurses. Morning salivary cortisol concentration is better correlated with PSS compared with the morning-afternoon salivary cortisol difference. The result raises the possibility of using a single morning salivary cortisol sample to reflect self-perceived stress.

Metals in hair as biological indices for exposure

SummaryHair samples from three groups of occupationally exposed subjects were analyzed for their lead (Pb), manganese (Mn) and mercury (Hg) contents. For lead (number of subjects, n=209), the hair Pb ranged from 0.93 to 3527 μg/g (geometric mean, GM=641) and blood Pb from 33.3 to 774 μg/l (GM=341); for manganese (n=38), the hair Mn ranged from 0.20 to 52.97 μg/g (GM=2.66) and urine Mn ranged from 1.70 to 17.9 μg/l (GM=5.56); and for mercury (n=85), the hair Hg from 1.79 to 12.8 μg/g (GM=5.09) and the blood Hg from 0.63 to 57.3 μg/l (GM=10.9). The hair Pb was significantly (P<0.0001) correlated to blood Pb (r=0.85); the hair Mn to urinary Mn (r=0.45); and the hair Hg to blood Hg (r=0.53). The average metal content at the distal end was not significantly (P>0.05) different from that of proximal end. The GM levels for the distal end were 223 μg/g (95% CI 152–347) and 2.26 (95% CI 0.97–5.29); and those for the proximal end were 186 (95% CI 97–261) and 1.18 (95% CI 0.54–2.58) for Pb and Mn respectively. However, linear regression analysis of hair metal levels in the proximal end with respect to those in the distal end after logarithmic transformation showed that hair Pb in the proximal end was related to hair Pb in the distal end with a slope of 0.95 (95% Cl 0.89–1.01) whereas hair Mn in the proximal end was related to that of the distal end with a slope of only 0.52 (95% CI 0.13–0.91), reflecting the relatively constant Pb exposure as compared to the dropping Mn exposure in recent years. Metals in hair are suitable biological indicators for exposure and the distribution along the different segments of hair strands reflects the time history of exposure.

Risk perception and impact of severe acute respiratory syndrome (SARS) on work and personal lives of healthcare workers in Singapore : What can we learn?

Introduction:Healthcare workers (HCWs) were at the frontline during the battle against Severe Acute Respiratory Syndrome (SARS). Understanding their fears and anxieties may hold lessons for handling future outbreaks, including acts of bioterrorism. Method:We measured risk perception and impact on personal and work life of 15,025 HCWs from 9 major healthcare institutions during the SARS epidemic in Singapore using a self-administered questionnaire and Impact of Events Scale and analyzed the results with bivariate and multivariate statistics. Results:From 10,511 valid questionnaires (70% response), we found that although the majority (76%) perceived a great personal risk of falling ill with SARS, they (69.5%) also accepted the risk as part of their job. Clinical staff (doctors and nurses), staff in daily contact with SARS patients, and staff from SARS-affected institutions expressed significantly higher levels of anxiety. More than half reported increased work stress (56%) and work load (53%). Many experienced social stigmatization (49%) and ostracism by family members (31%), but most (77%) felt appreciated by society. Most felt that the personal protective measures implemented were effective (96%) and that the institutional policies and protocols were clear (93%) and timely (90%). Conclusion:During epidemics, healthcare institutions have a duty to protect HCWs and help them cope with their personal fears and the very stressful work situation. Singapores experience shows that simple protective measures based on sound epidemiological principles, when implemented in a timely manner, go a long way to reassure HCWs.

Male endocrine functions in workers with moderate exposure to lead

Evidence for the effect of occupational exposure to lead on the male endocrine system is conflicting. This study evaluated the primary (testicular) and secondary (hypothalamo pituitary testicular) effects of exposure to lead in 122 current lead workers and 49 non-exposed workers. The mean current blood lead concentration was 35.2 (range 9.6-77.4) micrograms/dl in the exposed workers, and 8.3 (range 2.6-14.8) micrograms/dl in the non-exposed workers. Concentrations of plasma luteinising hormone (LH) and follicle stimulating hormone (FSH) were both significantly higher in the exposed workers, but testosterone (T) was not significantly different between the two groups. In older exposed workers, however (greater than or equal to 40 years), plasma T concentrations were significantly lower, but LH and FSH concentrations were not significantly different. Compared with non-exposed workers, those exposed for less than 10 years had significantly raised LH and FSH and normal T concentrations whereas those exposed for 10 or more years had significantly lower T, and normal LH and FSH concentrations. The concentrations of LH and FSH showed a moderate increase in relation to blood lead concentrations in the range of 10 micrograms/dl to 40 micrograms/dl and thereafter reached a plateau or declined. No apparent trend for plasma T concentrations occurred. No significant difference in prolactin (PRL) concentration was noted. It is concluded that moderate exposure to lead was associated in dose related fashion with small but measurable changes in male endocrine functions that reflected both primary and secondary effects of lead on the testes and the hypothalamo pituitary testicular axis.

Self perceived work related stress and the relation with salivary IgA and lysozyme among emergency department nurses

Aims: To assess and compare the self perceived work related stress among emergency department (ED) and general ward (GW) nurses, and to investigate its relation with salivary IgA and lysozyme. Methods: One hundred and thirty two of 208 (63.5%) registered female ED and GW nurses participated in the study. A modified mental health professional stress scale (PSS) was used to measure self perceived stress. ELISA methods were used to determine the salivary IgA and lysozyme levels. Results: On PSS, ED nurses had higher scores (mean 1.51) than GW nurses (1.30). The scores of PSS subscales such as organisational structure and processes (OS), lack of resources (RES), and conflict with other professionals (COF) were higher in ED than in GW nurses. ED nurses had lower secretion rates of IgA (geometric mean (GM) 49.1 μg/min) and lysozyme (GM 20.0 μg/min) than GW nurses (68.2 μg/min, 30.5 μg/min). Significant correlations were observed between PSS and log IgA and lysozyme secretion rates. OS, RES, and COF were correlated with log IgA and lysozyme levels. Conclusion: ED nurses, who reported a higher level of professional stress, showed significantly lower secretion rates of salivary IgA and lysozyme compared to GW nurses. Salivary IgA and lysozyme were inversely correlated with self perceived work related stress. As these salivary biomarkers are reflective of the mucosal immunity, results support the inverse relation between stress and mucosal immunity.

Review of recent epidemiological studies on paternal occupations and birth defects

The main findings reported by recent epidemiological studies on paternal occupations and birth defects are reviewed, and the main limitations associated with these studies discussed. Epidemiological studies on paternal occupations and birth defects were reviewed for the period 1989 to 1999 inclusive. Systematic searches were made with search engines with related keywords. There were several common paternal occupations that were repeatedly reported to be associated with birth defects. These paternal occupations were janitors, painters, printers, and occupations exposed to solvents; fire fighters or firemen; and occupations related to agriculture. The common weaknesses in most of these studies include inaccurate assessment of exposures, different classification systems, different inclusion criteria of birth defects, and low statistical power. It is concluded that epidemiological studies, reported in the past decade, suggest that several common paternal occupations are associated with birth defects. Future studies could be focused on these specific, rather than general, occupational groups so that causative agents may be confirmed and thus enable appropriate preventive measures to be taken.