Biomedical subjects

T Nakada

Publications and source records attributed to T Nakada.

At least 739 records · Page 41Linked to original sources

PubMedDate not supplied

Effect of testosterone replacement therapy on serum PSA in patients with Klinefelter syndrome.

The effect of testosterone replacement therapy on serum prostate-specific antigen (PSA) was investigated in 11 patients with Klinefelter syndrome. Significant increases in serum testosterone level and prostate volume were observed after testosterone replacement therapy. However, serum PSA level did not change after testosterone replacement therapy. It would appear that serum PSA is not influenced by exogenous testosterone in patients with Klinefelter syndrome.

Adult↗

PubMedDate not supplied

Epidemiology of prostatic cancer in East Asia.

Prostate cancer has become one of the most common malignancies in the world. The incidence of prostate cancer has rapidly increasing over the last decade in East Asia. In Japan, age-adjusted death rates due to prostate cancer rose from 4.4 to 8.6 per 100,000 between 1980 and 1998. Recent research has focused on age, race-related differences, patterns of familial aggregation, genetic factors, hormones, and diet. Epidemiological approach has identified several possible risk factors that may be useful for the prevention of prostate cancer and targeting high-risk individuals for early detection.

Age of Onset↗

PubMedDate not supplied

Stress and testicular germ cell apoptosis.

Chronic immobilization stress provokes an increase in serum corticosterone, which causes the decline in testosterone concentration. The stress and glucocorticoid administration induce germ cell apoptosis in rat testes. The cell type that has been shown to undergo apoptosis is spermatogonia. Since a potent glucocorticoid receptor agonist completely suppressed glucocorticoid induced germ cell apoptosis, the regulation of transcription of gene mediated by the glucocorticoid receptor may enhance apoptosis of testicular germ cells. The apoptosis of testicular germ cells would involve certain specific gene activities and proteins, including Bcl-2 family, p53, and Fas. Molecular investigations may help to determine whether the different pathways possess mechanisms of germ cell apoptosis induced by somatic stress and glucocorticoids.

Animals↗

PubMedDate not supplied

Effect of experimentally induced renal failure on testicular testosterone synthesis in rats.

Renal insufficiency is responsible for gonadal impairment, but the pathogenesis of testicular dysfunction remains unresolved. This study examines the possible role of the endocrine disturbance and angiotensin II-induced physiological abnormality for the pathogenesis of gonadal dysfunction of two different types of chronic renal failure. Chronic renal insufficiency was induced in rats given an adenine-excessive diet or in 5/6 nephrectomized animals. Circulating levels of blood urea nitrogen, creatinine, renin-angiotensin-aldosterone (R-A-A) system androstenedione, 17 alpha-hydroxy progesterone (17 alpha-OHP), testosterone, luteinizing hormone, and follicle-stimulating hormone were assayed. Systolic blood pressure, renal blood flow, and testicular blood flow were also determined. High serum levels of 17 alpha-OHP, androstenedione, and low testosterone were noted in the normotensive group. Enhanced R-A-A system decreased testicular blood flow and low testosterone were seen in the hypertensive group. The data provide evidence that gonadal dysfunction in adenine-induced renal failure appears to be caused by the suppression of 17 beta-hydroxysteroid oxydoreductase activity, and gonadal impairment in 5/6 nephrectomized uremia can be evoked by enhanced renin-angiotensin-aldosterone system and hypertension.

17-alpha-Hydroxyprogesterone↗

PubMedDate not supplied

Deletion of Y chromosome involving the DAZ (deleted in azoospermia) gene in XX males.

The testicular histology and the presence or absence of 32 Y DNA loci was investigated, with a focus on the long arm of Y chromosome (Yq) interval 6, by means of a polymerase chain reaction strategy in 2 XX males. Seminiferous tubules lined by only Sertoli cells and a slight thickening of tubular walls were observed. The men showed an absence of 32 Y DNA loci. These facts suggest that severe spermatogenic impairment is caused by deletions of Yq interval 6 in XX males.

Adult↗

PubMedDate not supplied

Distinction of hemangiomas from hepatic tumors with delayed enhancement by incremental dynamic CT.

To analyze the patterns of contrast enhancement and to evaluate clinical utility, we performed table incremental dynamic CT in 21 patients with 30 hepatic hemangiomas and in 12 patients with 26 malignant neoplasms, which showed delayed enhancement. On incremental CT, dense, spotty peripheral enhancement was present in 23 of the 30 (77%) hemangiomas. In contrast, a circumferential bead- or band-like peripheral enhancement was seen in 19 of 26 (73%) malignant neoplasms. The findings were characteristic. We conclude that incremental CT is useful in the differential diagnosis of hepatic hemangioma in routine examination.

Adenoma, Bile Duct↗

PubMedDate not supplied

Multislice dynamic MRI of hepatic tumors.

Breath-hold multislice dynamic MRI was used to diagnose 115 hepatic tumors in 55 patients. With this technique 10 slice-section images were made during a single breath-hold, achieving nearly complete liver coverage. Early enhancement images were obtained 20 s after intravenous bolus injection of gadopentetate dimeglumine. The detection rate of untreated hepatocellular carcinomas was greater with breath-hold multislice dynamic imaging (91%) than with conventional spin echo techniques (73%), because the 10 early enhancement images obtained during a single breath-hold showed the arterial dominant phase throughout the entire liver. In cases of untreated hepatocellular carcinoma 44 (86%) of the 51 lesions showed rapid enhancement on arterial dominant phase images, and 44 (86%) were demonstrated as isointensity or low intensity areas on delayed images. In cases of hepatic hemangioma, peripheral enhancement was demonstrated in 25 (89%) of the 28 lesions on arterial dominant phase images, and partial or complete hyperintense fill-in was identified in all lesions on delayed images. In patients treated with lipiodol-transcatheter arterial embolization (TAE), the breath-hold multislice dynamic imaging technique allowed evaluation of therapeutic effectiveness by revealing the hemodynamics of each nodule without the influence of lipiodol. We conclude that breath-hold multislice dynamic MRI should be used on patients with suspected hepatic tumors and in follow-up studies after lipiodol-TAE.

Adult↗

PubMedDate not supplied

Assessing myometrial invasion by endometrial carcinoma with dynamic MRI.

OBJECTIVE: Dynamic MRI was used to analyze patterns of contrast enhancement in muscle layers in the normal uterine body and to evaluate the depth of myometrial invasion by endometrial carcinoma. MATERIALS AND METHODS: Dynamic MRI was performed in 18 normal volunteers and 22 patients with endometrial carcinoma. Eight of the 18 normal volunteers were of reproductive age, and 10 were postmenopausal. The dynamic study was performed immediately after the bolus administration of gadopentetate dimeglumine. Twelve consecutive images, including the early phase images, were obtained during the first 2 min. The delayed phase image was obtained subsequently. RESULTS: An early enhancement zone of the inner muscle layer was demonstrated in 15 normal volunteers. In all patients in whom this early enhancement zone was preserved, the tumor was confined to < 50% of the muscle layer. In the evaluation of myometrial invasion, the accuracy of dynamic MRI was 91% compared with 77% on T2-weighted images. This improvement may be attributed to greater contrast and clearer demonstration of the border between tumor and myometrium in the early phase. CONCLUSION: We consider the disruption of the early enhancement zone of the inner muscle layer to be an important indicator of myometrial invasion.

Adult↗

PubMedDate not supplied

Influence of adenine-induced chronic renal failure on testicular function in the rat.

The influence of adenine-induced chronic renal failure on the male reproductive function was investigated using male Wistar rats. Adenine-induced chronic renal failure was performed in 22 rats (adenine-treated) by providing them with an adenine-excessive diet (150 mg adenine per day) for 10 days. An additional 22 rats were fed without adenine-excessive diet and served as a control group. On days 30 and 60 after start of treatment, body weight ratio to the testis, serum levels of creatinine, urea nitrogen, luteinizing hormone (LH), follicle-stimulating hormone (FSH), 17 alpha hydroxyprogesterone (17 alpha-OHP), androstenedione and testosterone were measured. During the experiment, progressive elevation of serum creatinine and urea nitrogen was found in adenine-treated rats. Body weight ratio of the testes and serum level of LH in adenine-treated rats were similar to those in the controls. On day 60, the FSH level in adenine-treated rats was significantly higher than that in the controls (P < 0.001). While serum concentrations of 17 alpha-OHP and androstenedione in adenine-treated rats were considerably elevated compared with those in the controls on day 30 (P < 0.05). These concentrations did not differ between the two groups at day 60. Serum testosterone level was reduced in adenine-treated rats (P < 0.001). This reduction was progressive with time (P < 0.05). These results suggest that adenine itself reduces testosterone synthesis by suppressing 17 beta-hydroxysteroid oxidoreductase at the early stage of adenine-induced chronic renal failure, but that progressive renal insufficiency causes an elevation of FSH, a reduced synthesis of testosterone and its precursors at the late stage of adenine-induced chronic renal failure. Thus, hormonal conditions in the male rat with adenine-induced chronic renal failure change with time after induction.

17-alpha-Hydroxyprogesterone↗

PubMedDate not supplied

Diameters of the pulmonary arteries and veins as an indicator of bilateral and unilateral pulmonary blood flow in patients with congenital heart disease.

OBJECTIVES: This study was done to clarify which diameter, that of the pulmonary arteries (PAs) or that of the pulmonary veins (PVs), more precisely reflects pulmonary blood flow (PBF) bilaterally and unilaterally. METHODS: To evaluate bilateral PBF, we studied 15 consecutive patients with Kawasaki disease as normal patients and 30 patients with tetralogy of Fallot who received cardiac catheterization. To evaluate unilateral PBF, 20 patients with various congenital heart diseases undergoing cineangiography and lung perfusion scintigraphy were studied. The diameter of PA was measured immediately proximal to the origin of the first lobar branches bilaterally, and right PA area, left PA area, PA area (mm2), and PA index (mm2/m2) were calculated. The diameter of PV was also measured distal to the junction with the left atrium. Right PV area, left PV area, PV area (mm2), and PV index (mm2/m2) were calculated from these diameters. Pulmonary blood flow (PBF) was obtained by the Fick method during catheterization. To evaluate unilateral PBF, PBF was divided into right and left PBF according to the right/left perfusion ratio measured by lung perfusion scintigraphy. RESULTS: Evaluation of bilateral PBF was as follows: in normal patients, PA and PV areas were correlated with body surface area (r = 0.88, p = 0.0001 and r = 0.93, p = 0.0001); PA index and PV index ranged from 248 to 436 (mean = 343) mm2/m2 and from 346 to 595 (mean = 466) mm2/m2, respectively, and were constant irrespective of body surface area; PA and PV areas were correlated with PBF in normal patients, as well as in patients with tetralogy of Fallot. There was a better correlation between PV area and PBF than between PA area and PBF in normal patients, as well as a significantly better correlation in patients with tetralogy of Fallot. Evaluation of unilateral PBF was as follows: right PV area was correlated with right PBF (p = 0.0002), while right PA area was not; left PV area and left PA area were correlated with left PBF; right/left PV area ratio was correlated with the right/left perfusion ratio with better agreement than right/left PA area ratio. CONCLUSION: Our data suggest that the size of PVs in patients with congenital heart disease may be more useful than the size of PAs to indicate bilateral and unilateral PBF than the size of PAs. Differences in PV area of each lung may be a suitable indicator of discrepancy in blood flow to each lung.

Cardiac Catheterization↗

PubMedDate not supplied

Hormone profiles and contralateral testicular histology in Down's syndrome with unilateral testicular tumor.

Hormonal profiles and testicular histology were studied in two patients with Down's syndrome with unilateral testicular tumor. Plasma levels of LH and FSH were elevated above normal ranges in both cases. In case 1, plasma testosterone level was abnormally low, but prolactin level in plasma was within the normal range. Case 2 showed elevated concentration of plasma prolactin and normal level of plasma testosterone. The administration of LH-RH resulted in low response of plasma gonadotropins. The response of plasma testosterone to the administration of HCG was abnormally suppressed in both cases. Testicular histology showed reduction of Johnsen score count and tubular diameter, and an increase in wall thickness. These results indicated that male patients with Down's syndrome have an abnormality in hypothalamo-pituitary-gonadal axis.

Adolescent↗

PubMedDate not supplied

Transferrin concentration in seminal plasma with special reference to serum hormone levels in infertile men.

The concentration of transferrin in seminal plasma and serum levels of LH, FSH, testosterone, and prolactin were measured in 94 male patients attending our infertility clinic. The concentration of transferrin in patients with azoospermia was lowest among azoospermia, oligozoospermia, and normozoospermia groups. There was significant positive correlation between the concentration of transferrin in seminal plasma and sperm density. However, seminal plasma transferrin was inversely correlated with serum levels of LH, FSH, and prolactin, respectively. It is suggested that transferrin in seminal plasma contributes to the activation of seminiferous tubules and can be used as a reliable index of Sertoli cell function.

Adult↗

PubMedDate not supplied

Hormone profiles and testicular histology in azoospermic men with sex chromosome aberrations, autosomal anomalies and normal karyotype.

Hormone profiles and testicular histology were studied in azoospermic men with sex chromosome aberrations, autosomal anomalies, and normal karyotype. In patients with sex chromosome aberrations, levels of plasma gonadotropins were significantly higher than those with autosomal anomalies and normal karyotype. The testosterone level in plasma was considerably lower in those with sex chromosome aberrations than in other groups. The prolactin level in plasma was not significantly different among the three groups. The administration of LH-RH resulted in a remarkably lower response of plasma gonadotropins in sex chromosome anomalies than in other groups. The response of plasma testosterone to the administration of hCG was also significantly decreased in those with sex chromosome aberrations compared with other groups. Johnsen score count and diameter of the seminiferous tubules were considerably reduced in those with sex chromosome anomalies compared with other groups, while wall thickness and Leydig cells per seminiferous tubule were significantly increased. It would appear that hormone disturbances and testicular alterations are less marked in azoospermic men with autosomal anomalies than in those with sex chromosome aberrations.

Adult↗

PubMedDate not supplied

Gonadal function and testicular histology in Noonan's syndrome with bilateral cryptorchidism.

Testicular histology and gonadal function were studied in 2 patients with Noonan's syndrome accompanied by bilateral cryptorchidism. Plasma FSH level was elevated above the normal range, but plasma levels of LH, prolactin, and testosterone were within normal ranges in both cases. The administration of LH-RH resulted in abnormally high response of plasma gonadotropins in both cases. The response of plasma testosterone to the administration of LH-RH was poor in case 2, but case 1 showed normal response. Testicular histology showed reduction of tubular diameter, Leydig cells per seminiferous tubules, and spermatogonia per tubule in both cases. The results indicate that bilateral cryptorchid patients with Noonan's syndrome have an abnormality in the hypothalamo-pituitary-gonadal axis.

Child↗

PubMedDate not supplied

Hormone profiles and testicular histology in cryptorchid boys with marker chromosome.

Hormone profiles and testicular histology were studied in two cryptorchid boys with marker chromosome. Plasma testosterone levels were abnormally low in both cases. Plasma levels of gonadotropins and prolactin were within normal ranges in case 1, but case 2 showed decreased concentration of plasma gonadotropins and normal level of plasma prolactin. The administration of LH-RH induced low response of plasma gonadotropins in case 1 and exaggerated response in case 2. The response of plasma testosterone to the administration of hCG was poor in both cases. Testicular histology showed maturation arrest and reduction of tubular diameter and Leydig cells per seminiferous tubules in both cases. Although testicular histology in these cases were similar to those in prepubertal or pubertal boys with cryptorchidism, hormonal disturbances were more severe. It would appear that marker chromosome enhances hormonal alterations.

Adolescent↗

PubMedDate not supplied

Hormone profiles and testicular histology in azoospermic men with Y-autosome translocation and autosomal translocation.

Hormone profiles and testicular histology were studied in azoospermic men with Y-autosome translocation and autosomal translocation. Plasma levels of LH, FSH, prolactin, and testosterone were within normal ranges in these anomalies. The responses of plasma gonadotropins to LH-RH and plasma testosterone to hCG were similar in the two groups. Johnsen score count, diameter of the seminiferous tubules, wall thickness, and Leydig cells per seminiferous tubules were similar in the two groups. It would appear that hormone conditions an alterations are similar in azoospermic men with Y-autosome translocation and autosomal translocation.

Chorionic Gonadotropin↗

PubMedDate not supplied

Effect of experimental cryptorchidism on alpha 1-adrenergic receptors of rat testis.

Alpha 1-adrenergic receptors play an important role in the transport of spermatozoa through seminiferous tubules to the efferent ducts leading to the epididymis. The density of alpha 1-adrenergic receptors in adult Sprague-Dawley rat testis before and during 14 days of experimental cryptorchidism was determined by binding assays with [3H]prazosin in membrane preparations. The number of maximal binding sites (Bmax) per milligram protein began to increase at 7 days after surgery (p < .05). The testicular weight and diameter of seminiferous tubules began to decrease at 5 days after surgery (p < .01). However, Bmax per testis did not differ before and during cryptorchidism. This study demonstrates that the density of alpha 1-adrenergic receptors in rat testis is not affected by cryptorchidism.

Adrenergic alpha-Antagonists↗

PubMedDate not supplied

Alteration of collagen biosynthesis and analysis of type I and type III collagens of prostate in young rats following sex hormone treatments.

Two series of experiments were conducted to clarify the collagen biosynthesis and isolation of type I and type III collagens of young rats that received various sex hormone treatments. Evidence has been presented that (1) estradiol-17 beta treatment induces prostatic atrophy and suppresses the incorporation of [3H]proline into collagen in prostate; (2) administration of estradiol-17 beta increases the collagen content in the prostate; (3) localization of type I and III collagens in the interstitium of the prostate is detected by indirect immunofluorescence staining; (4) the ratio of type III collagen to type I collagen in the gland decreases following estradiol-17 beta treatment; and (5) neither treatment with testosterone nor administration of testosterone plus estradiol-17 beta in precastrated rats shows discernible effects on these valuables. These findings suggest that estradiol-17 beta increases the accumulation of collagen into the prostate with different extents of influence on the synthesis of type I and III collagens.

Animals↗