Dietary Consumption of Antioxidant Vitamins in Relation to Prostate Cancer Risk in Japanese Men: The Japan Public Health Center-based Prospective Study

BACKGROUND

Many epidemiological studies have investigated dietary intake of antioxidant vitamins in relation to prostate cancer risk in Western countries, but the results are inconsistent. However, few studies have reported this relationship in Asian countries.

METHODS

We investigated the association between intake of vitamins, including lycopene, α-carotene, β-carotene, vitamin C, vitamin E, with prostate cancer risk in the Japan Public Health Center-based Prospective (JPHC) study. 40,720 men without history of cancer finished the food frequency questionnaire (FFQ) and were included in the study. Hazard ratios (HRs) and 95% confidence intervals (CIs) of prostate cancer risk were calculated according to the quintiles of energy-adjusted intake of vitamins using Cox models.

RESULTS

After an average of 15.2 years (617,599 person-years in total) of follow-up, 1,386 cases of prostate cancer were identified, including 944 localized cases and 340 advanced cases. No associations were observed in consumption of antioxidant vitamins, including α-carotene, β-carotene, vitamin C, and vitamin E, and prostate cancer risk. Although higher lycopene intake was associated with increased risk of prostate cancer (highest vs lowest quintile, HR 1.24; 95% CI, 1.04-1.47; P for trend = 0.01), there was a null association of lycopene intake with risk of prostate cancer detected by subjective symptoms (HR 1.12; 95% CI, 0.79-1.58; P for trend = 0.11).

CONCLUSION

Our study suggested no association between antioxidant intake of vitamins and prostate cancer risk.

A U-shaped association between the triglyceride to high-density lipoprotein cholesterol ratio and the risk of incident type 2 diabetes mellitus in Japanese men with normal glycemic levels: a population-based longitudinal cohort study

Background

Several studies have verified that a high baseline TG/HDL-C ratio is a risk factor for incident type 2 diabetes mellitus (T2DM). However, for low baseline TG/HDL-C levels, the findings were inconsistent with ours. In addition, the association between baseline TG/HDL-C ratio and the risk of incident T2DM in Japanese men with normal glycemic levels is unclear. As a result, our study further investigated the relationship between baseline TG/HDL-C and the risk of incident T2DM in Japanese men with normal glycemic levels.

Methods

This was a secondary longitudinal cohort study. We selected 7,684 male participants between 2004 and 2015 from the NAGALA database. A standardized Cox regression model and two piecewise Cox regression models were used to explore the relationship between the baseline high-density lipoprotein cholesterol ratio (TG/HDL-C) and incident T2DM.

Results

During a median follow-up of 2,282 days, 162 men developed incident T2DM. In the adjusted model, the baseline TG/HDL-C ratio was strongly associated with the risk of incident T2DM, and no dose-dependent positive association was observed between the baseline TG/HDL-C ratio and incidence of T2DM throughout the baseline TG/HDL-C quartiles. Two-piecewise linear regression analysis showed a U-shaped association between baseline TG/HDL-C ratio and incidence of incident T2DM. A baseline TG/HDL-C ratio below 1.188 was negatively associated with incident T2DM (H.R. = 0.105, 95% CI = 0.025, 0.451; P = 0.002). In contrast, a baseline TG/HDL-C ratio >1.188 was positively associated with incident T2DM (H.R. = 1.248, 95% CI = 1.113, 1.399; P<0.001). The best TG/HDL-C threshold for predicting incident T2DM was 1.8115 (area under the curve, 0.6837).

Conclusion

A U-shaped relationship between baseline TG/HDL-C ratio and incident T2DM in Japanese men with normal glycemic levels was found.

Care needs of Japanese men for sexual dysfunction associated with prostate cancer treatment

PURPOSE

Prostate cancer (PC) treatment causes sexual dysfunction (SD) and alters fertility, male identity, and intimate relationships with partners. In Japan, little attention has been paid to the importance of providing care for SD associated with PC treatment. This study is aimed at clarifying the care needs of Japanese men regarding SD associated with PC treatment.

METHODS

One-to-one semi-structured interviews were conducted with 44 PC patients to identify their care needs. Data were analyzed using thematic analysis.

RESULTS

Four core categories emerged from the analysis. (1) "Need for empathy from medical staff regarding fear of SD": patients had difficulty confiding in others about their sexual problems, and medical staff involvement in their SD issues was lacking. (2) "Need for information that provides an accurate understanding of SD and coping strategies before deciding on treatment": lack of information about SD in daily life and difficulty understanding information from medical institutions, caused men to regret their treatment. (3) "Need for professional care for individuals and couples affected by SD": men faced loss of intimacy because of their partners' unwillingness to understand their SD issues or tolerate non-sexual relationships. (4) "Need for an environment that facilitates interaction among men to resolve SD issues": men felt lonely and wanted to interact with other patients about their SD concerns.

CONCLUSION

These findings may help form care strategies tailored to these needs and applicable to other societies with strong traditional gender norms.

Analysis of the correlation between gene copy deletion in the AZFc region and male infertility in Japanese men

Deletion of the azoospermia factor c (AZFc), located on the long arm of the Y chromosome, is a cause of male infertility. The structure of the Y chromosome is diversified by the copy number of various genes, such as deleted in azoospermia (DAZ), basic protein Y2, chromodomain Y1, testis-specific transcript Y-linked 4, and Golgi autoantigen golgin subfamily a2 like Y, located in the AZF region. In this study, we investigated the deletion of each gene copy and analyzed its relationship with Japanese male infertility. Deletions of single nucleotide variants of each gene copy in 721 proven fertile men as controls, 139 patients with non-obstructive azoospermia (NOA), and 56 patients with oligozoospermia (OS) were analyzed via polymerase chain reaction-restriction fragment length polymorphism analysis. Their association with infertility was analyzed using logistic regression analysis adjusted for the Y-chromosome haplogroup, D1a2a. Deletions of DAZ/II in the r1 region and DAZ/V in the r1 and r2 regions showed significant associations with NOA (odds ratio [OR] = 4.15, 95 % confidence interval [CI] = 1.18-14.6, P = 0.026; OR = 4.19, 95 % CI = 1.19-14.7, P = 0.025, respectively). They did not show any association with OS. Partial deletion of the AZFc region affects spermatogenesis in Japanese male.

Sexual dysfunction associated with prostate cancer treatment in Japanese men: a qualitative research

Purpose

We investigated the experiences of Japanese men with sexual dysfunction associated with various prostate cancer treatments.

Methods

We included 38 Japanese men who underwent the following initial treatments for prostate cancer: radical prostatectomy (n = 10), external beam radiotherapy (n = 12), brachytherapy (n = 5), and androgen deprivation therapy (n = 11). Semi-structured interviews were conducted regarding sexual dysfunction associated with prostate cancer treatment. Data were analyzed using a content analysis method. To obtain a unique experience for each treatment, we confirmed and organized the treatment method from which the code that constituted each category was derived. The category reliability was calculated based on Scott’s formula for the matching rate of the classification by three qualitative researchers. The criterion for good reliability was set at 70%.

Results

Japanese men with sexual dysfunction associated with prostate cancer treatments experienced the following: a desire to maintain sexual function and conflict in decision-making concerning the initial treatment for prostate cancer; a loss of values related to sexual dysfunction; an uncertainty regarding the consequences of sexual dysfunction; a sense of calm with fewer adverse effects of sexual dysfunction at the early treatment stage; an effort to accept sexual dysfunction; and management of their changed body at the later treatment stages. The concordance rates for the categories were 70% and 78%. Additionally, there were glimpses of experiences common to all treatments and trends in treatment-specific experiences.

Conclusion

It is necessary to provide care based on the experience of Japanese men with sexual dysfunction after prostate cancer treatment.

Engagement in different sport disciplines during university years and risk of locomotive syndrome in older age: J-Fit+ Study

Background

Among former Olympic-level athletes, engagement in different sport disciplines has been associated with mortality risk in subsequent years. However, limited evidence is available on whether engagement in different sport disciplines at a young age is associated with locomotive syndrome (LS) risk later in life. This study examined the relationship between engagement in different sport disciplines during university years and LS risk in older age among former university athletes.

Methods

Participants were 274 middle-aged and 294 older men alumni who graduated from a school of physical education in Japan. LS risk was defined as answering “yes” to any of the Loco-check questions. Data on university sports club membership were collected using questionnaires. University clubs were classified into three groups of cardiovascular intensity (low, moderate, high), following the classification system of sport disciplines by the American College of Cardiology. This classification considers the static and dynamic components of an activity, which correspond to the estimated percent of maximal voluntary contraction reached and maximal oxygen uptake achieved, respectively. University clubs were grouped based on the risk of bodily collision (no, yes) and extent of physical contact (low, moderate, high). Relationships between engagement in different sport disciplines and LS risk were analyzed using Cox proportional hazards models, and adjusted for age, height, weight, joint disease, habitual exercise, and smoking and drinking status.

Results

Adjusted hazard ratios and 95% confidence intervals associated with the low, moderate, and high cardiovascular intensity sports were 1.00 (reference), 0.48 (0.22–1.06, P = 0.070), and 0.44 (0.20–0.97, P = 0.042) in older men, respectively; however, there was no significant association between these parameters among middle-aged men. Engagement in sports associated with physical contact and collision did not affect LS risk in either group.

Conclusions

Engagement in sports associated with high cardiovascular intensity during university years may reduce the risk of LS in later life. Encouraging young people to participate in such activities might help reduce LS prevalence among older populations.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12199-021-00958-w.

Association of physical fitness and motor ability at young age with locomotive syndrome risk in middle-aged and older men: J-Fit+ Study

Background

Physical fitness and motor ability are associated with the incidence of locomotive syndrome (LS) in older adults. The relationships between physical fitness and motor ability at a young age to LS risk in later life remain unclear. This study examined the association between physical fitness and motor ability among university students and their risk of LS in middle and old age.

Methods

The participants were 231 male alumni aged 48–65 years from the Department of Physical Education of a university in Japan. Physical fitness and motor ability test results during their fourth year at the university were used. Physical fitness tests included the side-step test, vertical jump test, back muscle, grip strength, trunk lift, standing trunk flexion, and step-test. Motor ability was tested using the 50-m and 1500-m run, running long jump, hand-ball throw, and pull-up test. LS risk was assessed using a seven-question standardized self-administered Loco-check questionnaire. Participants were divided into three groups (low, medium, and high) based on physical fitness and motor ability test results at young age, and LS risk was assessed at an older age across the three groups using Cox proportional hazards models.

Results

From the 2017 follow-up survey, the median follow-up period was 37 years (interquartile range, 33–41), and LS risk was suspected for 31 (13.4%) participants. Better performance on the side-step test was associated with the reduced risk of LS (hazard ratio 0.32; 95% confidence interval, 0.101–0.983, P = 0.047).

Conclusions

Good agility (side-step test) at a young age may reduce the future risk of LS among middle-aged and older men.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12877-021-02047-7.

Daily dietary isoflavone intake in relation to lowered risk of depressive symptoms among men

BACKGROUND

The relationship between isoflavone intake and depressive symptoms has been examined among premenopausal and postmenopausal women but not among men. Therefore, we investigated whether isoflavone intake is associated with depressive symptoms among men.

METHODS

This cross-sectional study was conducted between 2008 and 2011. A total of 1335 Japanese men aged 19-83 participated in the present study. Isoflavone intake was measured using the Brief-type Self-administered Diet History Questionnaire (BDHQ). Depressive symptoms were assessed using the Self-rating Depression Scale (SDS), and two cut-off values (i.e., 40 and 50) were used. Multiple logistic regression analysis was conducted to examine the association between isoflavone intake and depressive symptoms.

RESULTS

When the cut-off value for SDS was specified as 40, the odds ratios (ORs) for depressive symptoms were higher for the categories that were characterized by high rather than low levels of isoflavone intake in the crude model (p = 0.002). This association remained unchanged (p = 0.029) when potential cofounds were controlled for in Model 3. Multivariate linear regression analysis also showed a significant inverse association between isoflavone intake and SDS scores (p = 0.027; final adjusted model).

LIMITATIONS

Cross-sectional study is difficult to draw any conclusions about causality CONCLUSIONS: The findings suggest that a high level of dietary isoflavone intake is associated with a lower prevalence of depressive symptoms among men. Therefore, isoflavone intake may have a beneficial effect on men's mental health.

Distribution of Human Papillomavirus Genotype in Anal Condyloma Acuminatum Among Japanese Men: The Higher Prevalence of High Risk Human Papillomavirus in Men Who Have Sex with Men with HIV Infection

Human papillomavirus (HPV) infection is known to cause anal condyloma acuminatum (CA) and squamous cell carcinoma. Men who have sex with men (MSM) with HIV infection are frequently co-infected with HPV, especially high risk HPV (HR-HPV) that causes anal squamous cell carcinoma. However, there are few reports of HPV genotype studies in anal lesion of Japanese men. We tried to estimate the distribution of HPV genotypes in anal CA tissue specimens from the Japanese men to elucidate the risk of anal cancer. A total of 62 patients who had anal CA surgically excised were enrolled. They included 27 HIV-positive MSM, 18 HIV-negative MSM, 1 HIV-positive man who have sex with women (MSW), and 16 HIV-negative MSW. HPV genotypes in anal CA tissue were determined by the polymerase chain reaction technique with reverse line blot hybridization. HR-HPV was detected in 45.2% of the CA tissue specimens and high grade squamous intraepithelial lesion (HSIL) was observed in 15.3%. Moreover, the prevalence of HR-HPV in the HIV-positive MSM (70.4%) was higher than the HIV-negative MSM (33.3%, p = .0311) or the HIV-negative MSW (18.8%, p = .0016). The conditional logistic regression analysis suggested HIV positivity as the primary risk factor for the HR-HPV infection in CA. In addition, HSIL was detected in higher frequency in CA tissues from HIV-positive MSM (25.9%) than HIV-negative MSW (0.0%, p = .0346). HR-HPV and HSIL were frequently detected in anal CA tissues from Japanese MSM patients with HIV infection, suggesting the necessity of surveillance for this population.

An independent validation study of three single nucleotide polymorphisms at the sex hormone-binding globulin locus for testosterone levels identified by genome-wide association studies

Study question

Are the single nucleotide polymorphisms (SNPs) rs2075230, rs6259 and rs727428 at the sex hormone-binding globulin (SHBG) locus, which were identified by genome-wide association studies (GWASs) for testosterone levels, associated with testosterone levels in Japanese men?

Summary answer

The SNP rs2075230, but not rs6259 and rs727428, is significantly associated with testosterone levels in Japanese men.

What is already known

Previous GWASs have revealed that rs2075230 is associated with serum testosterone levels in 3495 Chinese men and rs6259 and rs727428 are associated with serum testosterone levels in 3225 men of European ancestry.

Study design, size, and duration

This is an independent validation study of 1687 Japanese men (901 in Cohort 1 and 786 in Cohort 2).

Participants/materials, setting and method

Cohort 1 (20.7 ± 1.7 years old, mean ± SD) and Cohort 2 (31.2 ± 4.8 years) included samples obtained from university students and partners of pregnant women, respectively. The three SNPs were genotyped using either TaqMan probes or restriction fragment length polymorphism PCR. Blood samples were drawn from the cubital vein of the study participants in the morning, and total testosterone and SHBG levels were measured using a time-resolved immunofluorometric assay. Association between each SNP and testosterone levels was evaluated by meta-analysis of the two Japanese male cohorts.

Main results and the role of chance

The age of the two cohorts was significantly different (P < 0.0001). We found that rs2075230 was significantly associated with serum testosterone levels (β_STD = 0.15, P = 7.2 × 10⁻⁶); however, rs6259 and rs727428 were not (β_STD = 0.17, P = 0.071; β_STD = 0.082, P = 0.017, respectively), after adjusting for multiple testing in a combined analysis of two Japanese male cohorts. Moreover, rs2075230, rs6259 and rs727428 were significantly associated with high SHBG levels (β_STD = 0.22, P = 3.4 × 10⁻¹²; β_STD = 0.23, P = 6.5 × 10⁻⁶ and β_STD = 0.21, P = 3.4 × 10⁻¹⁰, respectively).

Large scale data

Not applicable.

Limitations, reasons for caution

This study had differences in the age and background parameters of participants compared to those observed in previous GWASs. In addition, the average age of participants in the two cohorts in our study also differed from one another. Therefore, the average testosterone levels, which decrease with age, between studies or the two cohorts were different.

Wider implications of the findings

The three SNPs have a considerable effect on SHBG levels and hence may indirectly affect testosterone levels.

Study funding/competing interests

This study was supported partly by the Ministry of Health and Welfare of Japan (1013201) (to T.I.), Grant-in-Aids for Scientific Research (C) (26462461) (to Y.S.) and (23510242) (to A.Ta.) from the Japan Society for the Promotion of Science, the European Union (BMH4-CT96-0314) (to T.I.) and the Takeda Science Foundation (to A.Ta.). There are no conflicts of interest to declare.

Associations of central aortic pressure and brachial blood pressure with flow mediated dilatation in apparently healthy Japanese men: The Circulatory Risk in Communities Study (CIRCS)

BACKGROUND AND AIMS

Endothelial dysfunction is considered the first stage in the development of atherosclerosis and cardiovascular disease, and brachial flow-mediated dilation (FMD) is a measure of endothelial function. It is uncertain which of central systolic aortic pressure (CAP) or brachial systolic blood pressure (SBP) is more strongly associated with FMD. Therefore, we examined the correlations of CAP and SBP with FMD in Japanese men.

METHODS

The study subjects comprised 507 male volunteers aged 30-79 years that were residents in two communities under the Circulatory Risk in Communities Study (CIRCS) between 2013 and 2015. The low percent change of FMD (%FMD) ≤5.0%, after 5 min of reactive hyperemia evaluated by the brachial artery diameter, was used to assess endothelial dysfunction. Values of CAP and SBP were divided into tertiles, with the lowest tertile used as a reference.

RESULTS

After adjustment for cardiovascular risk factors, the multivariable odds ratio (95% CI) of low FMD for the highest versus lowest tertile of CAP was 1.5 (0.9-2.6) for total subjects and 1.4 (0.5-3.8) for those with, and 2.4 (1.2-4.8) for those without antihypertensive medication use. The corresponding odd ratios for the highest versus lowest tertile of SBP were 0.9 (0.5-1.5), 0.8 (0.3-2.2), and 1.3 (0.7-2.5), respectively.

CONCLUSIONS

Higher CAP levels were associated with low FMD for men without antihypertensive medication, but such an association was not found for SBP levels.

Aloe sterol supplementation improves skin elasticity in Japanese men with sunlight-exposed skin: a 12-week double-blind, randomized controlled trial

Background/objective

Recently, it was confirmed that the daily oral intake of plant sterols of Aloe vera gel (Aloe sterol) significantly increases the skin barrier function, moisture, and elasticity in photoprotected skin. This study aimed to investigate whether Aloe sterol intake affected skin conditions following sunlight exposure in Japanese men.

Methods

We performed a 12-week, randomized, double-blind, placebo-controlled study to evaluate the effects of oral Aloe sterol supplementation on skin conditions in 48 apparently healthy men (age range: 30–59 years; average: 45 years). The subjects were instructed to expose the measurement position of the arms to the sunlight outdoors every day for 12 weeks. The skin parameters were measured at 0 (baseline), 4, 8, and 12 weeks.

Results

Depending on the time for the revelation of the sunlight, the b* value and melanin index increased and the skin moisture decreased. After taking an Aloe sterol tablet daily for 12 weeks, the skin elasticity index (R2, R5, and R7) levels were significantly higher than the baseline value. There were no differences between the groups in these skin elasticity values. In the subgroup analysis of subjects aged <46 years, the change in the R5 and R7 was significantly higher in the Aloe group than in the placebo group at 8 weeks (P=0.0412 and P=0.0410, respectively). There was a difference in the quantity of sun exposure between each subject, and an additional clinical study that standardizes the amount of ultraviolet rays is warranted. No Aloe sterol intake-dependent harmful phenomenon was observed during the intake period.

Conclusion

Aloe sterol ingestion increased skin elasticity in the photodamaged skin of men aged <46 years.

Fiber intake and risk of subsequent prostate cancer in Japanese men

BACKGROUND

Dietary fiber may reduce the risk of prostate cancer, possibly by increasing circulating concentrations of sex hormone-binding globulin and improving insulin sensitivity. However, results from previous epidemiologic studies of fiber intake and prostate cancer are inconsistent, and to our knowledge, no study has comprehensively evaluated the effects of soluble and insoluble fiber on prostate cancer in Asia.

OBJECTIVE

The objective was to examine the association between fiber intake and prostate cancer in Japanese men.

DESIGN

We conducted a population-based prospective study in 43,435 Japanese men aged 45-74 y. Participants responded to a validated questionnaire, which included 138 food items. Follow-up was from 1995 through 2009. HRs and 95% CIs of incidence were calculated according to quartiles of fiber intake.

RESULTS

During the 11.6-y follow-up, of the 825 men newly diagnosed with prostate cancer, 213 had advanced-stage cancer, 582 had organ-localized disease, and 30 had an undetermined stage of disease. Among them, 217 cases were detected by subjective symptoms. Total fiber was not associated with total or advanced prostate cancer, with respective multivariable HRs for the highest and lowest quartiles of 1.00 (95% CI: 0.77, 1.29; P-trend = 0.97) and 0.67 (95% CI: 0.42, 1.07; P-trend = 0.30). Total fiber and insoluble fiber intake were associated with a decreased risk of advanced cancers detected by subjective symptoms, with multivariate HRs (95% CIs) across increasing quartiles of 1.00, 0.58, 0.62, and 0.44 (0.21, 0.92; P-trend = 0.05) for total fiber and 1.00, 0.60, 0.52, and 0.46 (0.22, 0.93; P-trend = 0.04) for insoluble fiber. Soluble fiber intake showed no association with prostate cancer.

CONCLUSIONS

Dietary fiber is inversely associated with advanced prostate cancer detected by subjective symptoms even among populations with relatively low intake, such as Japanese. These results suggest that a very low intake of dietary fiber is associated with an increased risk of prostate cancer.

Y chromosome gr/gr subdeletion is associated with lower semen quality in young men from the general Japanese population but not in fertile Japanese Men

Several case-control studies have investigated whether Y chromosome haplogroups or deletions are associated with spermatogenic failure. However, the relationships between Y chromosome haplogroups or deletions and semen quality in general population have not been elucidated. In this study, we assessed relationships between Y chromosome haplogroups or deletions and semen parameters in 791 fertile Japanese men and 1221 young men from the general Japanese population. We found that the haplogroup D2 (M55 lineage) was significantly associated with lower semen parameters, especially total motile sperm count (P = 0.00051, beta = -0.097), in men from the general population but not in fertile men. In addition, we found that the gr/gr subdeletion was associated with semen quality and in particular, strongly associated with decreased sperm motility (P = 0.00041, beta = -3.14) and total motile sperm count (P = 0.00031, beta = -0.099) in men from the general population but not in fertile men. The combined analysis of fertile Japanese men and men from the general Japanese population showed that the haplogroup D2 (M55 lineage) and the gr/gr subdeletion were strongly associated with reduced sperm motility (P = 0.00056, beta = -2.71, and P = 7.7 × 10(-5), beta = -3.05, respectively) and that haplogroup O2b1 was strongly associated with elevated sperm motility (P = 0.00089, beta = 2.94). These observations add further support for the view that the gr/gr subdeletion diminishes sperm motility that consequently may result in male infertility.

Effects of smoking on outcomes after acute atherothrombotic stroke in Japanese men

BACKGROUND

The effects of smoking on clinical outcomes following acute stroke remain controversial.

METHODS

We evaluated the influence of smoking on 90-day outcomes after acute atherothrombotic stroke in 292 Japanese men extracted from the database of the Edaravone and Argatroban Stroke Therapy for Acute Ischemic Stroke randomized parallel-group trial that tested the safety and efficacy of edaravone and argatroban therapy in 814 patients in 2004-2008. Smokers were matched with non-smokers of the same age for identical age distribution in the smoker and non-smoker groups. Poor 90-day outcomes (defined as death, Barthel index<60, or modified Rankin score>3) were evaluated using a logistic regression model. Significant variables (P<0.05) in univariate analysis were further evaluated by multivariate logistic regression analysis using a forward-selection method.

RESULTS

Body temperature, age, National Institute of Health Stroke Scale score at admission, systolic blood pressure, and smoking status were selected in the final model. Smokers had significantly increased odds of poor 90-day functional outcomes independent of other statistically significant predictor variables (adjusted odds ratio, 2.28; 95% confidence interval, 1.15-4.55; P=0.019).

CONCLUSIONS

In Japanese men, smoking leads to poor functional outcomes at 3 months after acute atherothrombotic stroke.

Serum testosterone levels using the radioimmunoassay method in healthy Japanese male volunteers

Aim:  The objective of the present study was to measure serum free and total testosterone values using the radioimmunoassay (RIA) method in healthy Japanese male volunteers with no current diseases. Methods:  Two hundred and fifty-one healthy men who had no medical illness and received no current medical treatment were selected from 405 male volunteers. Free and total testosterone were measured in blood samples using the RIA method. Results:  Free but not total testosterone significantly decreased with age. Mean free testosterone values from morning blood samples for each age decade from the 20s to the 70s were 17.0, 14.6, 12.5, 10.6, 8.9 and 8.5 pg/mL, respectively. Mean total testosterone values from morning blood samples for each age decade from the 20s to the 70s were 4.7, 4.2, 4.4, 4.2, 4.2, 4.0 and 4.0 ng/mL, respectively. The rates of healthy volunteers that fell within the standard reference ranges for free and total testosterone were 97% and 97%, respectively. However, 19% of the total testosterone values were considered to indicate hypogonadism according to the International Society for the Study of the Aging Male (ISSAM) criteria (<3.17 ng/mL). Conclusions:  Our data corresponded to the standard reference ranges of Japanese men but not the ISSAM criteria. It may be more appropriate to establish a standard reference range for serum testosterone for individual countries. (Reprod Med Biol 2006; 5: 37-41).

Lifestyle and the development of dyslipidemia: a 4-year follow-up study of middle-aged Japanese Male Office Workers

To examine the lifestyle factors related to the development of dyslipidemia [low-density lipoprotein (LDL) cholesterol ≥ 150 mg/dL, high-density lipoprotein (HDL) cholesterol < 40 mg/dL, or triglyceride ≥ 250 mg/dL], 979 dyslipidemia-free Japanese male office workers aged 35 to 54 years were followed up for four years. The numbers of new incidence cases during the follow-up period were 216 for high LDL cholesterol level, 109 for low HDL cholesterol level, and 78 for high triglyceride level. From the Cox proportional hazards model, adjusted hazard ratios (HRs) for the incidence of high LDL cholesterol level were 0.62 [95% confidence interval (CI): 0.47-0.82] for consuming alcohol every day, 1.39 (95% CI: 1.10-1.77) for 5-kg/m(2) increase in body mass index (BMI), 1.45 (95% CI: 1.10-1.91) for snacking between meals every day, and 1.64 (95% CI: 1.18-2.30) for not eating vegetables every day. As for the incidence of low HDL cholesterol level, adjusted HRs for current cigarette smoking, consuming alcohol every day, and 5-kg/m(2) increase in BMI were 1.74 (95% CI: 1.17-2.59), 0.61 (95% CI: 0.41-0.89), and 1.79 (95% CI: 1.29-2.46), respectively. Adjusted HRs for the incidence of high triglyceride level were 1.73 (95% CI: 1.07-2.77) for current cigarette smoking, 1.74 (95% CI: 1.10-2.77) for 5-kg/m(2) increase in BMI, and 0.50 (95% CI: 0.27-0.90) for working 10 h per day or more. These results suggest that an increase in BMI, current cigarette smoking, and snacking between meals every day is closely associated with an increased risk of atherogenic lipid profiles. On the other hand, alcohol consumption and eating vegetables every day may have an anti-atherogenic effect on serum lipid profiles.