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Biomedical subjects

Hitoshi Masuda

Publications and source records attributed to Hitoshi Masuda.

17 recordsLinked to original sources
PubMed2003

Control of canine membranous urethra, bulbocavernosus and ischiocavernosus muscles by lumbosacral sympathetic pathways.

The membranous urethral muscles, bulbocavernosus muscle (BCM) and ischiocavernosus muscle (ICM) play a significant role on expulsion at ejaculation. Projection of the sympathetic pathways in the retroperitoneum to these muscles was investigated in the dog. Intraluminar pressure of the membranous urethra and contractions of the BCM and ICM to electrical stimulation of the lumbar splanchnic nerve (LSN) or the lumbosacral sympathetic chain (LSC) were examined. Stimulation of the LSN was performed after transection of the unilateral hypogastric nerve (HGN) to clarify its cross-innervation. Stimulation of each of the 2nd to 4th LSNs elicited elevation of the intraluminal pressure of the membranous urethra. In eight dogs whose right HGNs were transected, 15 of the 19 right LSNs, and 12 of the 16 left LSNs examined elicited elevation of the membranous urethral pressure, respectively. In five dogs whose left HGNs were transected, 6 of the 9 right LSNs and 10 of the 12 left LSNs stimulated elicited elevation of the pressure. Stimulation of the HGN caused no detectable contractions of the BCM and ICM in all six dogs examined. Stimulation of the LSC elicited responses of the BCM and ICM in all six dogs examined and the membranous urethra in three of six dogs. The maximum value of the response of the BCM was greater than that of the ICM. After consecutive transection of the ipsilateral pelvic nerve, stimulation of the LSC showed no significant changes in the responses of the BCM and ICM. The above results indicate the following: (1). each of the L2-L4 LSNs sends signals to the membranous urethra via two routes, passing through the ipsilateral or contralateral HGN; (2). the above nerve does not send effective signals to the BCM and ICM; (3). the LSC sends signals to the membranous urethra, BCM and ICM; (4). the signals from the LSC mainly pass through the pudendal nerve to the BCM and ICM; and (5). the signals were dominant to the BCM compared with the ICM.

Animals↗
PubMed2003

Successful long-term disease-free survival following multimodal treatments in a patient with a repeatedly recurrent refractory adrenal cortical carcinoma.

A 47-year-old male patient underwent surgery for a 10-cm adrenal cortical carcinoma. A large invasive adrenal mass was surgically removed en bloc with the right kidney and the lower lobe of the liver. Two months postoperatively, a 7-cm recurrent mass developed in the right psoas muscle. After a partial response was achieved by irradiation (40 Gy) and high-dose chemotherapy (carboplatin and etoposide) with peripheral blood stem cell transplantation, the patient underwent surgery with a wide excision of the psoas muscle. Twelve months after the initial surgery, an 8-cm rib metastasis developed and the patient again underwent surgery after a combination of irradiation (50 Gy) and chemotherapy (cisplatin and etoposide). The patient has been doing well without any evidence of recurrence for 5 years. Refractory or metastatic adrenal cortical carcinomas have been thought to be lethal, therefore, the present case provides support for multimodal treatments of refractory adrenocortical cancers.

Adrenocortical Carcinoma↗
PubMed2003

Adenocarcinoma arising at the ileoileal anastomotic site of Scheele's ring.

Most tumors arising after augmentation ileocystoplasty have been reported to develop adjacent to the ileovesical anastomosis. Herein, we report a case of adenocarcinoma arising at the ileoileal anastomotic site 33 years after augmentation ileocystoplasty (Scheele's ring plasty) for tuberculous contracted bladder. The present case shows the possibility of late malignancy developing at the ileoileal junction after ileal neobladder.

Adenocarcinoma↗
PubMed2003

[Fibroepithelial polyp of the anterior urethra, found during post-operative follow-up of ureteral cancer].

A 52-year-old man underwent nephroureterectomy against left distal ureteral cancer (transitional cell carcinoma, Grade 2, pTa), and was followed up by surveillance alone. Twenty-two months postoperatively, a pedunculated tumor was found in the anterior urethra by cystourethroscopy. Pathological examination of the tumor resected transurethrally revealed a fibroepithelial polyp. There have been only twelve cases of fibroepithelial polyp of the anterior urethra reported in the literature. Since 4 out of 8 adult cases among them were found during the postoperative follow up period of urothelial cancer, mechanical irritation by repeated transurethral procedures might be responsible for the development of fibroepithelial polyp of the anterior urethra in these cases. If anterior urethral tumor is found during follow-up urothelial carcinoma, benign urethral polyp should be considered in the differential diagnosis.

Carcinoma, Transitional Cell↗
PubMed2003

[A case of fibroepithelial ureteral polyp in an adult patient].

A 24-year-old man complaining of asymptomatic gross hematuria was referred to our hospital for treatment of bilateral hydronephroses (left > right) diagnosed at a previous clinic. Radiological examinations demonstrated a filling defect at the left uretero-pelvic junction. Cytological examination of the urine was negative. With the diagnosis of suspected benign ureteral polyp, the patient underwent endoscopic-assisted partial ureterectomy and pyeloplasty through a 5 cm flank incision. Histological examination revealed that the villous tumor in the ureter was a fibroepithelial polyp.

Adult↗
PubMed2002

Different distribution of nitric oxide synthase and soluble guanylyl cyclase activities in the detrusor and proximal urethra of the rabbit.

PURPOSE: We investigated the different distributions of nitric oxide synthase (NOS) and soluble guanylate cyclase activities in the detrusor and proximal urethra in the rabbit. MATERIALS AND METHODS: The detrusor and proximal urethra were excised, the mucosa and muscularis were separated and each layer was homogenized to measure the activities of NOS as well as baseline and sodium nitroprusside (SNP) activated soluble guanylate cyclase. Isometric tension experiments were performed in detrusor and urethral strips with and without mucosa. RESULTS: In the detrusor NOS and sodium nitroprusside activated soluble guanylate cyclase activities in the mucosa were much higher than in the muscularis. While in the proximal urethra NOS activity in the 2 layers was similar, SNP activated soluble guanylate cyclase activity in the muscularis was 2.8 times higher than in the mucosa. Removing the mucosa reduced nitric oxide (NO) mediated neurogenic relaxation in the proximal urethra, while no relaxation responses could be elicited by electrical field stimulation with or without mucosa in the detrusor. On the other hand, removing the mucosa did not affect SNP or 8-bromo-cyclic guanosine monophosphate induced relaxation in the detrusor and proximal urethra. CONCLUSIONS: In the detrusor NOS and soluble guanylate cyclase activities were mainly detected in the mucosa, while in the urethra these activities were distributed throughout the mucosa and muscularis. Also, the mucosa in the urethra but not in the detrusor contributed to electrical field stimulation induced, NO mediated relaxation. These findings confirm previous studies demonstrating that NO has a different role in the detrusor than in the proximal urethra.

Animals↗
PubMed2002

Intracavitary administration of OK-432 with subcutaneous priming for malignant ascites in a case of advanced renal cell carcinoma.

The intracavitary injection of OK-432 (a streptococcal preparation) with subcutaneous priming has been shown to be an effective immunotherapy for patients with malignant effusion. We applied this treatment in a case of advanced renal cell carcinoma with massive ascites. The patient received 0.2 Klinishe Einheit (KE) OK-432 in the subcutaneous injection twice (day 1 and day 7) followed by 10KE OK-432 intra-abdominal administration (day 9). The treatment was performed safely without major side-effects except for transient pyrexia. A significant reduction of ascites was noted 1 month after the treatment without subsequent re-accumulation. Intracavitary injection of OK-432 with subcutaneous priming seems to be a simple, safe and effective treatment for ascites in advanced renal cell carcinoma.

Antineoplastic Agents↗
PubMed2002

Endoscopic minilaparotomy radical nephrectomy for chronic dialysis patients.

BACKGROUND: To assess the feasibility of laparoscope-guided minilaparotomy (endoscopic minilaparotomy) for renal cell carcinoma in patients on chronic dialysis. METHODS: Endoscopic retroperitoneal minilaparotomy using a 30 degrees telescope was carried out through single skin incision (5-8 cm) in eight patients with renal cell carcinoma who were on chronic dialysis. Outcomes of the operations were compared to those in eight patients on chronic dialysis with renal cell carcinoma who underwent standard translumbar radical nephrectomy. RESULTS: Resection of the tumor was successfully completed without complication and the postoperative course was uneventful in both of the treatment groups. No significant difference in mean operative time or mean blood loss was observed between the treatment groups. Wound pain was minimal and analgesics were generally not required in the minilaparotomy group. The endoscopic laparotomy group resumed full diet and began walking earlier than the group that underwent standard radical nephrectomy. CONCLUSIONS: Endoscopic minilaparotomy seems to be a valuable alternative treatment for renal cell carcinoma in patients on chronic dialysis.

Aged↗
PubMed2002

Endoscope-assisted minilaparotomy (endoscopic minilaparotomy) for retroperitoneal Schwannoma: experience with three cases.

We have been applying endoscope-assisted minilaparotomy (endoscopic minilaparotomy) to retroperitoneal operations with favorable outcomes. Here, endoscopic minilaparotomy through a single flank incision (4-7 cm) was performed in three cases of incidentally discovered retroperitoneal Schwannoma. Resection of the tumor was successfully completed. The postoperative course was uneventful. Wound pain was mild and full oral feeding and walk were resumed the day following operation. It is concluded that endoscopic minilaparotomy is applicable to retroperitoneal Schwannoma with excellent postoperative recovery.

Aged↗
PubMed2002

Endoscopic minilaparotomy partial nephrectomy for solitary renal cell carcinoma smaller than 4 cm.

BACKGROUND: For small, incidentally discovered renal cell carcinoma, partial nephrectomy is becoming more widely accepted as an alternative to radical nephrectomy and the need for minimally invasive approach is increasing. METHODS: We carried out endoscopic minilaparotomy partial nephrectomy in seven cases of solitary renal cell carcinoma smaller than 4 cm. Five of them were without renal pedicle clamping. All procedures were done through single skin incision (5-8 cm) using a 30 degrees telescope. Hemostasis was achieved with a harmonic scalpel, a microwave tissue coagulator, an argon beam coagulator and autologous fibrin glue. RESULTS: There were no perioperative complications. All patients had negative surgical margins. The operating time was 157-275 min (average 209 min). The blood loss was 20-1200 ml (average 525 ml). Postoperatively, renal function as assessed by serum creatinine was within normal limits. Neither local recurrences nor metastases were observed during a follow-up of 6-15 months. The postoperative course was markedly improved over that expected from standard open surgery. CONCLUSIONS: With minimal morbidity and complications, endoscopic minilaparotomy partial nephrectomy is feasible for small renal cell carcinoma.

Aged↗
PubMed2002

Accumulated endogenous NOS inhibitors, decreased NOS activity, and impaired cavernosal relaxation with ischemia.

We examined whether endogenous inhibitors of nitric oxide (NO) synthesis are involved in the impaired cavernosal relaxation with ischemia in rabbits. Two weeks after cavernosal ischemia caused by partial vessel occlusion, endothelium-dependent and electrical field stimulation (EFS)-induced neurogenic NO-mediated relaxations, but not sodium nitroprusside (SNP)-induced relaxation, were significantly impaired in the isolated corpus cavernosum. The Ca(2+)-dependent NO synthase (NOS) activity and the basal and stimulated cGMP productions with carbachol or EFS were significantly decreased after ischemia. Supplementation of excess L-arginine partially recovered both of the impaired relaxations. The contents of N(G)-monomethyl-L-arginine (L-NMMA) and asymmetric N(G), N(G)-dimethyl-L-arginine (ADMA) but not L-arginine and symmetric N(G),N'(G)-dimethyl-L-arginine (SDMA) were increased in the cavernosal tissues after ischemia. Authentic L-NMMA and ADMA but not SDMA concentration dependently inhibited both relaxations without affecting the relaxation produced by SNP in the control. Excess L-arginine abolished the inhibition with L-NMMA and ADMA. These results suggest that the impaired NO-mediated cavernosal relaxations after ischemia are closely related to the decreased NOS activity and the increased accumulation of L-NMMA and ADMA.

Animals↗
PubMed2002

[Biological and pathophysiological roles of endogenous methylarginines as inhibitors of nitric oxide synthase].

Protein arginine N-methyltransferases (PRMTs) catalyse the methylation of guanidinonitrogen(s) of arginine to produce NG-monomethyl-L-arginine (L-NMMA), asymmetric NG,NG-dimethyl-L-arginine (ADMA) and symmetric NG,NG-dimethyl-L-arginine (SDMA), which are subsequently released into the cytoplasm following proteolysis. Free intracellular L-NMMA and ADMA, but not SDMA, are inhibitors of all three isoforms of nitric oxide synthases (nNOS, eNOS and iNOS). L-NMMA and ADMA, but not SDMA, are actively metabolized by dimethylarginine dimethylaminohydrolase (DDAH) to L-citrulline and methylamine (and dimethylamine). Free methylarginines are detectable in cell cytosol, plasma and tissues. Elevated ADMA has been detected in the plasma of patients or experimental animals with hypercholesterolemia, renal failure, atherosclerosis, hypertension, thrombotic microangiopathy, peripheral arterial occlusive disease and in the regenerated endothelial cells after angioplasty. Moreover, in the non-cardiovascular field, ADMA was increased in the urethral tissue following ischemia and in the plasma of patients with schizophrenia and multiple sclerosis. Altered biosynthesis of NO has been implicated in the pathogenesis of these diseases, and it is possible to consider that the accumulation of endogenous L-NMMA and ADMA underlies the impaired NO generation and increased O2- production. We described herein the biosynthesis, transmembrane transport, metabolic pathway and possible pathophysiological roles of endogenous methylarginines.

Animals↗
PubMed2002

[A comparative study assessing clinical effects of naftopidil and tamsulosin hydrochloride on benign prostatic hyperplasia].

We compared the efficacy of naftopidil with that of tamsulosin hydrochloride for benign prostatic hyperplasia patients. Eighty-five patients without improvement of quality of life (QOL) score by the administration of 50-75 mg naftopidil for more than four weeks were assigned to receive doses of 0.1-0.2 mg tamsulosin hydrochloride and 89 patients without improvement of QOL score by the administration of 0.1-0.2 mg tamsulosin hydrochloride for more than four weeks were assigned to receive doses of 50-75 mg naftopidil once a day for 8 weeks. International prostate symptom score, maximum flow rate, residual urine volume and side effect profile were determined before the administration of the first medicine, before the administration of the second medicine and after 8 weeks of treatment with the second medicine. In the group without improvement of QOL score by naftopidil, significant improvements in symptoms of urgency, weak stream and straining were observed after 8 weeks of treatment with tamsulosin hydrochloride. In the group without improvement of QOL score by tamsulosin hydrochloride, significant improvements in symptoms of incomplete emptying, intermittency and nocturia were observed after 8 weeks of treatment with naftopidil. In conclusion, improvement of symptoms by each alpha 1-blocker differs symptom by symptom. Tamsulosin hydrochloride was superior to naftopidil for the symptoms of urine flow and naftopidil was superior to tamsulosin hydrochloride for the symptom of nocturia.

Adrenergic alpha-Antagonists↗
PubMed2002

Localization and role of nitric oxide synthase and endogenous nitric oxide synthase inhibitors in the rabbit lower urinary tract.

PURPOSE: We investigated the possible role of endogenous methylarginine derivatives, such as NG-monomethyl-L-arginine (L-NMMA), asymmetrical NG, NG-dimethyl-L-arginine (ADMA) and symmetrical NG, N'G-dimethyl-L-arginine (SDMA), for regulating nitric oxide synthase in the rabbit lower urinary tract. MATERIALS AND METHODS: Strips of detrusor, trigone and proximal urethra were processed for the determination of endogenous methylarginines and L-arginine by automated high performance liquid chromatography. We also compared nitric oxide synthase activity and nitric oxide mediated functional responses to electrical field stimulation in the 3 regions. Nitric oxide synthase activity was measured by determining the conversion of [3H] L-arginine to [3H] L-citrulline. RESULTS: L-NMMA, ADMA and SDMA were detectable by high performance liquid chromatography in the detrusor, trigone and proximal urethra. Electrical field stimulation induced nitric oxide mediated prominent relaxation in the trigone and proximal urethra, while no relaxation response was observed in the detrusor. Exogenously applied 1 to 100 microM. L-NMMA and 1 to 100 microM. ADMA but not 100 microM. SDMA dependently inhibited Ca2+ dependent nitric oxide synthase activity in all regions, and electrical field stimulation induced relaxation in the trigone and proximal urethra. Inhibition with L-NMMA and ADMA was blocked in the presence of 3 mM. L-arginine but not by 3 mM. D-arginine. CONCLUSIONS: Three methylarginines and nitric oxide synthase are localized throughout the rabbit lower urinary tract. Endogenous L-NMMA and ADMA may be involved in regulating nitric oxide biosynthesis of the micturition reflex in the normal or disease state.

Animals↗
PubMed2002

Changed responsiveness of the detrusor in rabbits with alloxan induced hyperglycemia: possible role of 5-hydroxytryptamine for diabetic bladder dysfunction.

PURPOSE: We assessed whether the responsiveness of the detrusor is changed in rabbits with alloxan induced hyperglycemia. MATERIALS AND METHODS: Hyperglycemia was induced by a bolus intravenous injection of alloxan (60 mg./kg.) in Japanese White male rabbits. At 16 weeks after alloxan detrusor muscle strips prepared from age matched normoglycemic and hyperglycemic rabbits were mounted in organ chambers. Contractile responses to KCl, carbachol, adenosine triphosphate, 5-hydroxytryptamine and electrical field stimulation were compared in the 2 groups. The effect of sarpogrelate as a selective antagonist of 5-hydroxytryptamine 2A receptor on the contractile response to 5-hydroxytryptamine was also compared. RESULTS: The current experiments demonstrated that hyperglycemia caused significant decreases in neurogenic and carbachol induced contractions accompanied by unchanged adenosine triphosphate and KCl induced contractions. Neurogenic bladder contraction in the hyperglycemic rabbit was significantly potentiated by exogenously applied 5-hydroxytryptamine. Potentiation was detectable even after the desensitization of purinoceptors but undetectable in the presence of atropine. Hyperglycemia resulted in enhancement of the 5-hydroxytryptamine induced bladder contraction. Sarpogrelate tended to normalize the enhanced contraction. CONCLUSIONS: The decrease in neurogenic bladder contraction possibly accompanied by the decreased density of muscarinic receptors, the potentiation of neurogenic bladder contraction with 5-hydroxytryptamine probably due to facilitated cholinergic transmission and the enhanced contractility to 5-hydroxytryptamine would be at least in part involved in bladder dysfunction associated with hyperglycemia.

Animals↗