Biomedical subjects

T Nakada

Publications and source records attributed to T Nakada.

747 records · Page 42Linked to original sources

PubMedDate not supplied

Inhibitors of collagen synthesis and hypophysectomy: effects on androgen induced growth of ventral prostate in rats.

To elucidate the effect of decreased amounts of collagen on prostatic growth, beta-aminopropionitrile, one of the agents that selectively inhibit collagen formation, was administered, with or without exogenous androgen and/or hypophysectomy, to rats of varying ages. The weight of the ventral prostate and the collagen content and the ratio of type III to type I collagen in the ventral prostate were examined. Administration of beta-aminopropionitrile, with or without exogenous androgen, reduced the collagen content in the ventral prostate in any age groups, but increased the weight of the ventral prostate only in young rats. Administration of beta-aminopropionitrile to hypophysectomized rats did not change the weight and collagen content. Administration of beta-aminopropionitrile prevented androgen-induced growth of prostatic collagen, resulting in increased prostatic weight in young rat. The ratio of type III to type I collagen in the rat ventral prostate remained unchanged by administration of beta-aminopropionitrile, exogenous androgen, hypophysectomy, or advancing age. It would appear that in young rats prostatic collagen plays an important role in suppressing prostatic growth. The ratio of type III to type I collagen is stable under various experimental conditions in the ventral prostate.

Aminopropionitrile↗

PubMedDate not supplied

Serum levels of total and free testosterone in men undergoing hemodialysis.

Serum concentrations of total and free testosterone were measured in 102 hemodialysis male patients and 45 healthy men. In hemodialysis patients, serum levels of total and free testosterone were significantly reduced compared to the controls (p < .001). Neither serum total nor free testosterone correlated with age in the controls. In contrast, both total and free testosterone in serum negatively correlated with age in hemodialysis patients (p < .05-.001). It would appear that testicular dysfunction becomes more severe with increasing age in hemodialysis patients.

Adult↗

PubMedDate not supplied

Testicular histology in experimental uremic rats.

Testicular histology in chronic renal failure was studied using stepwise-nephrectomized and adenine-treated rats. Serum levels of urea nitrogen and creatinine were significantly higher than those in sham-operated and control rats (P < .001). However, the mean tubular diameter was not different among the 4 groups. Numbers of A-spermatogonia, preleptotene and pachytene spermatocytes, and spermatids per 100 Sertoli cells were not different among the 4 groups. It would appear that testicular histology is not influenced by chronic renal failure in rats.

Animals↗

PubMedDate not supplied

Round spermatid transfer and embryo development.

With the advent of assisted reproductive technology, pregnancy has become possible without sperm. The nucleus of the round spermatid, which contains a complete haploid set of chromosomes, can be used as a substitute for spermatozoa in animals and humans. In the mouse, round spermatids from surgically induced cryptorchid and prepubertal testes can fertilize normally and develop into normal offspring. The spermatid nucleus develops into a large pronucleus only when the oocyte is activated by artificial means, such as electrostimulation and oscillogen injection. Nuclei of mouse primary spermatocyte have been injected into oocytes and found to undergo meiosis, form an embryo and produce live young. Intracytoplasmic injection of male immature germ cells may become available as a treatment for patients with azoospermia due to maturation arrest.

Animals↗

PubMedDate not supplied

Circulating levels of inhibin in hemodialysis males.

Serum concentrations of LH, FSH, testosterone, and inhibin were measured in 65 hemodialysis male patients and 60 healthy men. In hemodialysis patients, serum levels of LH, FSH, and inhibin were significantly elevated compared to the controls (p < 0.001). However, serum testosterone level was significantly reduced in hemodialysis males (p < 0.01). Neither serum LH nor FSH correlated with inhibin in the control and hemodialysis males. In hemodialysis patients, serum inhibin showed a positive correlation with serum creatinine (p < 0.05). It would appear that an elevated level of serum inhibin is caused by a decreased metabolic clearance rate or testicular dysfunction due to chronic renal failure, and indicates the abnormality of hypothalamic-pituitary-testicular axis leading to hypergonadotropic hypogonadism in hemodialysis males.

Adult↗

PubMedDate not supplied

Influence of sex hormones on prostate volume in men on hemodialysis.

The relationship between sex hormones and prostate volume in 90 men on hemodialysis and 91 healthy men was investigated. In men on hemodialysis, serum levels of total and free testosterone were significantly reduced compared with the controls (P < .001), whereas the serum estradiol level was significantly elevated in men on hemodialysis (P < .001). However, prostate volumes were not different between the 2 groups. Serum estradiol level correlated with the prostate volume in controls (P < .001), whereas total and free testosterone levels did not correlate with the prostate volume. In men on hemodialysis, serum levels of total and free testosterone and estradiol did not correlate with the prostate volume. The present study suggests that sex hormones do not play important roles in the prostate growth in men on hemodialysis.

Adult↗

PubMedDate not supplied

CAG repeat length analysis and mutation screening of the androgen receptor gene in Japanese men with idiopathic azoospermia.

Because androgens are required for normal spermatogenesis, we are investigating abnormalities in the androgen receptor as a possible cause of impaired spermatogenesis in patients with idiopathic male infertility. The CAG repeat length in exon 1 and mutations of the androgen receptor gene were studied in 30 men with idiopathic azoospermia and in 51 fertile men. In men with azoospermia, plasma luteinizing hormone (LH), follicle-stimulating hormone (FSH), and testosterone levels were measured and testicular biopsies were performed. The CAG repeat length ranged from 19 to 30 (mean 23.4 +/- 2.9) and from 17 to 28 (mean 23.7 +/- 3.2) in men with azoospermia and in controls, respectively. There was no significant difference between the 2 groups. In men with azoospermia, the Johnsen testicular biopsy score negatively correlated with plasma FSH (P < .01). However, the Johnsen testicular biopsy score did not correlate with plasma LH and testosterone levels. The CAG repeat length did not correlate with the Johnsen testicular biopsy score, or with plasma concentrations of LH, FSH, and testosterone. No abnormalities in the androgen receptor gene were detected. These facts suggest that the CAG repeat length and alterations in the androgen receptor gene are not associated with the etiology of idiopathic azoospermia.

Adult↗

PubMedDate not supplied

Common pulmonary vein atresia: a successfully corrected case.

Common pulmonary vein atresia is a rare congenital cardiac anomaly in which there is no communication between the confluence of the pulmonary veins and the heart or the major systemic venous system. We successfully treated this disease in a 5-day-old boy by performing an anastomosis of the left atrium to the common pulmonary vein. Only one patient with this lesion who survived this procedure has been reported in the literature. Early recognition of this lesion and immediate surgical intervention are the only way to save the patient's life.

Echocardiography↗

PubMedDate not supplied

Round spermatids from prepubertal mouse testis can develop into normal offspring.

We investigated fertilization and embryo development after intracytoplasmic injection of round spermatids collected from mice before puberty. The rates of normal fertilization, blastocyst formation, and development into live offspring were examined. The injection of oocytes with round spermatids from mature or prepubertal males resulted in similar rates of normal fertilization and embryo development. The rates of the development to term of two-cell embryos were also similar, regardless of the origin of the round spermatids injected. This finding suggests that round spermatids from the prepubertal testis already have the ability to fertilize normally and to allow normal embryo development.

Animals↗