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Dive into the research topics where Masashi Iijima is active.

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Featured researches published by Masashi Iijima.


The Aging Male | 2011

Androgen replacement therapy contributes to improving lower urinary tract symptoms in patients with hypogonadism and benign prostate hypertrophy: a randomised controlled study.

Kazuyoshi Shigehara; Kazuhiro Sugimoto; Hiroyuki Konaka; Masashi Iijima; Masato Fukushima; Yuji Maeda; Atsushi Mizokami; Eitetsu Koh; Hideki Origasa; Teruaki Iwamoto; Mikio Namiki

Purpose. We performed a randomised controlled study regarding the effects of androgen replacement therapy (ART) on lower urinary tract symptoms (LUTS) in hypogonadal men with benign prostate hypertrophy (BPH). Methods. Fifty-two patients with hypogonadism and BPH were randomly assigned to receive testosterone (ART group) as 250 mg of testosterone enanthate every 4 weeks or to the untreated control group. We compared International Prostate Symptom Score (IPSS), uroflowmetry data, post-voiding residual volume (PVR) and systemic muscle volume at baseline and 12 months after treatment. Results. Forty-six patients (ART group, n = 23; control, n = 23) were included in the analysis. At the 12-month visit, IPSS showed a significant decrease compared with baseline in the ART group (15.7 ± 8.7 vs. 12.5 ± 9.5; p < 0.05). No significant changes were observed in the control group. The ART group also showed improvement in maximum flow rate and voided volume (p < 0.05), whereas no significant improvements were observed in the controls. PVR showed no significant changes in either group. In addition, the ART group showed significant enhancement of mean muscle volume (p < 0.05), whereas no significant changes were seen in the controls. Conclusion. ART improved LUTS in hypogonadal men with mild BPH.


Asian Journal of Andrology | 2016

Effects of long-term androgen replacement therapy on the physical and mental statuses of aging males with late-onset hypogonadism: a multicenter randomized controlled trial in Japan (EARTH Study)

Hiroyuki Konaka; Kazuhiro Sugimoto; Hideki Orikasa; Teruaki Iwamoto; Toshinari Takamura; Yoshiyu Takeda; Kazuyoshi Shigehara; Masashi Iijima; Eitetsu Koh; Mikio Namiki

Androgen replacement therapy (ART) efficacy on late-onset hypogonadism (LOH) has been widely investigated in Western countries; however, it remains controversial whether ART can improve health and prolong active lifestyles. We prospectively assessed long-term ART effects on the physical and mental statuses of aging men with LOH in Japan. The primary endpoint was health-related quality of life assessed by questionnaires. Secondary endpoints included glycemic control, lipid parameters, blood pressure, waist circumference, body composition, muscular strength, International Prostate Symptom Scores (IPSS), International Index of Erectile Function-5 (IIEF-5) scores, and serum prostate-specific antigen levels. Of the 1637 eligible volunteers, 334 patients > 40 years with LOH were randomly assigned to either the ART (n = 169) or control groups (n = 165). Fifty-two weeks after the initial treatment, ART significantly affected the role physical subdomain of the short form-36 health survey (SF-36) scale (P = 0.0318). ART was also associated with significant decreases in waist circumstance (P = 0.002) and serum triglyceride (TG) (P = 0.013) and with significant increases in whole-body and leg muscle mass volumes (P = 0.071 and 0.0108, respectively), serum hemoglobin (P < 0.001), IPSS voiding subscore (P = 0.0418), and the second question on IIEF-5 (P = 0.0049). There was no significant difference between the groups in terms of severe adverse events. In conclusion, in patients with LOH, long-term ART exerted beneficial effects on Role Physical subdomain of the SF-36 scale, serum TG, waist circumstance, muscle mass volume, voiding subscore of IPSS, and the second question of IIEF-5. We hope our study will contribute to the future development of this area.


Journal of Andrology | 2016

A PLK4 mutation causing azoospermia in a man with Sertoli cell-only syndrome

Toshinobu Miyamoto; Y. Bando; Eitetsue Koh; Akira Tsujimura; Yasushi Miyagawa; Masashi Iijima; Mikio Namiki; M. Shiina; K. Ogata; Naomichi Matsumoto; Kazuo Sengoku

About 15% of couples wishing to have children are infertile; approximately half these cases involve a male factor. Polo‐like kinase 4 (PLK‐4) is a member of the polo protein family and a key regulator of centriole duplication. Male mice with a point mutation in the Plk4 gene show azoospermia associated with germ cell loss. Mutational analysis of 81 patients with azoospermia and Sertoli cell‐only syndrome (SCOS) identified one man with a heterozygous 13‐bp deletion in the Ser/Thr kinase domain of PLK4. Division of centrioles occurred in wild‐type PLK4‐transfected cells, but was hampered in PLK‐4‐mutant transfectants, which also showed abnormal nuclei. Thus, this PLK4 mutation might be a cause of human SCOS and nonobstructive azoospermia.


International Journal of Urology | 2014

Comparison of testosterone fractions between Framingham Heart Study participants and Japanese participants

Masaki Taya; Eitetsu Koh; Kouji Izumi; Masashi Iijima; Yuji Maeda; Tomohiko Matsushita; Teruaki Iwamoto; Mikio Namiki

To determine testosterone fractions in Japanese men and to compare these values with those of Framingham Heart Study participants.


The Journal of Urology | 2011

A Novel Y Chromosome Microdeletion With the Loss of an Endogenous Retrovirus Related, Testis Specific Transcript in AZFb Region

Ho-Su Sin; Eitetsu Koh; Masaki Taya; Masashi Iijima; Kazuhiro Sugimoto; Yuji Maeda; Atsumi Yoshida; Teruaki Iwamoto; Mikio Namiki

PURPOSE We identified the endogenous retroviruses associated with TTYs (testis specific transcripts linked to the Y) in the AZFb region. We evaluated the relationship between endogenous retroviruses, and TTY expression patterns and function in spermatogenesis. MATERIALS AND METHODS We identified family members of TTYs in the AZFb region using computational screening. After investigating the relationship between the endogenous retrovirus genome and TTY expression patterns we screened genomic polymerase chain reaction products from TTY13 amplified from 790 Japanese men, including 275 with azoospermia, 285 with oligozoospermia and 230 who were fertile. RESULTS Computational screening revealed that 3 members of the TTY family, TTY9, 10 and 13, were regulated by endogenous retroviruses in the AZFb region. Homologous recombination between long terminal repeat of the TTY13 associated human endogenous retrovirus-K14C resulted in TTY13 deletion events. These deletions were more common in patients with azoospermia and oligozoospermia than in fertile males. Specifically 15.63% of the azoospermia group, 10.88% of the oligozoospermia group and 0% of fertile controls had only the deletion variant, indicating an association between the homologous recombination rate and the severity of spermatogenesis failure that was statistically significant (p <0.05). CONCLUSIONS Because of the finding of what are to our knowledge novel microdeletions due to endogenous retrovirus in the AZFb region, our study raises the possibility that specific variations in genomic structure may contribute to some forms of human idiopathic male infertility.


The Aging Male | 2017

Effects of testosterone replacement therapy on hypogonadal men with osteopenia or osteoporosis: a subanalysis of a prospective randomized controlled study in Japan (EARTH study)

Kazuyoshi Shigehara; Hiroyuki Konaka; Eitetsu Koh; Kazufumi Nakashima; Masashi Iijima; Takahiro Nohara; Koji Izumi; Yasuhide Kitagawa; Yoshifumi Kadono; Kazuhiro Sugimoto; Teruaki Iwamoto; Atsushi Mizokami; Mikio Namiki

Abstract Objective: We investigated the effects of testosterone replacement therapy (TRT) on bone mineral density (BMD) among hypogonadal men with osteopenia/osteoporosis. Methods: From our previous EARTH study population, 74 patients with a clinical diagnosis of osteopenia or osteoporosis and hypogonadism were included in this study, as the TRT (n = 35) and control (n = 34) groups. The TRT group was administered 250 mg of testosterone enanthate injection every 4 weeks for 12 months. The BMD, waist circumference, body mass index, body fat percentage, and muscle volume were measured at baseline and at 12 months. Blood biochemical data, including total cholesterol, triglycerides, HDL-cholesterol, hemoglobin A1c, and adiponectin values were also evaluated. Results: At the 12-month visit, BMD significantly increased in both groups. However, comparisons on changes of parameter values from baseline to the 12-month visit between the TRT and control groups were significantly different in BMD (5.0 ± 5.0 vs. 3.0 ± 3.2; p = .0434) and in adiponectin value (−0.90 ± 3.33 vs. 0.10 ± 2.04; p = .0192). There were no significant changes in other parameters. Conclusions: TRT for 12 months could improve BMD with a decrease in adiponectin levels among hypogonadal men with osteopenia/osteoporosis.


BJUI | 2017

Changes in penile length after radical prostatectomy: Investigation of the underlying anatomical mechanism

Yoshifumi Kadono; Kazuaki Machioka; Kazufumi Nakashima; Masashi Iijima; Kazuyoshi Shigehara; Takahiro Nohara; Kazutaka Narimoto; Kouji Izumi; Yasuhide Kitagawa; Hiroyuki Konaka; Toshifumi Gabata; Atsushi Mizokami

To measure changes in penile length (PL) over time before and after radical prostatectomy (RP), and to investigate the underlying mechanisms for these changes.


International Journal of Urology | 2014

New molecular diagnostic kit to assess Y-chromosome deletions in the Japanese population

Masashi Iijima; Eitetsu Koh; Kouji Izumi; Masaki Taya; Yuji Maeda; Kouichi Kyono; Atsumi Yoshida; Mikio Namiki

Deletions in the azoospermia factor regions are the most common known molecular genetic cause of human male infertility involving spermatogenetic failure. Testing for these deletions in Japanese DNA samples using conventional sequence‐tagged site probes occasionally lead to considerable non‐specific or faint products in the Japanese population. The aim of the present study was to evaluate the sensitivity and specificity of a newly developed kit for the detection of azoospermia factor microdeletions in the Japanese population.


Asian Journal of Andrology | 2013

Aberrant methylation of the TDMR of the GTF2A1L promoter does not affect fertilisation rates via TESE in patients with hypospermatogenesis

Kazuhiro Sugimoto; Eitetsu Koh; Masashi Iijima; Masaki Taya; Yuji Maeda; Mikio Namiki

Increasing evidence shows a relationship between epigenetic regulation and male infertility. The GTF2A1L gene promoter contains the DNA methylation site of a tissue-specific differentially methylated region (TDMR). Eighty-six patients with non-obstructive azoospermia were assessed for the DNA methylation state of CpG islands in the GTF2A1L promoter using testicular genomic DNA. Based on histological criteria, 26 of the 86 patients had normal spermatogenesis (controls), 17 had hypospermatogenesis and 26 had a Sertoli cell-only phenotype or tubular sclerosis. GTF2A1L TDMR methylation was significantly lower in testes DNA from control samples than from hypospermatogenic samples (P=0.029). Patients with hypospermatogenesis were divided into two subgroups: high DNA methylation (HM, n=5) and low DNA methylation (LM, n=12). The GTF2A1L TDMR methylation rate differed significantly between the HM and LM groups (P=0.0019), and GTF2A1L expression was significantly higher among the LM than in the HM patients (P=0.023). High TDMR methylation was correlated with low GTF2A1L gene expression levels. Both groups demonstrated relatively good outcomes with respect to sperm retrieval, fertilisation, pregnancy and childbirth rates. We observed that aberrant GTF2A1L gene expression was not correlated with fertilisation rates. The testicular sperm extraction (TESE) technique may be used to overcome male infertility due to aberrant TDMR methylation.


International Journal of Urology | 2011

Myelodysplastic syndrome treated effectively with testosterone enanthate

Masashi Iijima; Kazuyoshi Shigehara; Kazuhiro Sugimoto; Izumi Kouji; Masato Fukushima; Yuji Maeda; Hiroyuki Konaka; Atsushi Mizokami; Eitetsu Koh; Mikio Namiki

We report a case of myelodysplastic syndrome (MDS) treated effectively with testosterone enanthate. A 70‐year‐old man was diagnosed with low‐risk MDS in 1998, and he was first given methenolone acetate orally because of gradual progression of anemia and thrombocytopenia. However, this treatment was not effective, so we changed the treatment to testosterone enanthate because of his symptoms with late‐onset hypogonadism. Three months after testosterone replacement therapy (TRT), anemia and thrombocytopenia had improved, and mean platelet count and hemoglobin had significant increases from 2.36 ± 0.45 × 104 to 3.83 ± 0.78 × 104/µL, and from 11.7 ± 0.81 to 15.2 ± 1.00 g/dL, respectively, which contributed to a decrease in platelet transfusion requirement. Since then, the patient has been on a good clinical course. The present case suggests that testosterone enanthate administration could be an alternative treatment for men with MDS, even in the case where treatment with anabolic‐androgenic steroids is not successful, and suggests another interesting effect of TRT on platelets.

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