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Biomedical subjects

Y Igawa

Publications and source records attributed to Y Igawa.

At least 37 records · Page 2Linked to original sources
PubMed1999

Functional and molecular biological evidence for a possible beta3-adrenoceptor in the human detrusor muscle.

The possible existence of a beta3-adrenergic receptor (beta3-AR) in the human detrusor muscle was investigated by in vitro functional studies and analysis of mRNA expression. Isoprenaline, noradrenaline and adrenaline each produced a concentration-dependent relaxation of the human detrusor. The rank order for their relaxing potencies was isoprenaline (pD2 6.37+/-0.07) > or = noradrenaline (pD2 6.07+/-0.12) > or = adrenaline (pD2 5.88< or =0.11). Neither dobutamine (beta1- and beta2-AR agonist) nor procaterol (beta2-AR agonist) produced any significant relaxation at concentrations up to 10(-5) M. BRL37344A, CL316243 and CGP-12177A (beta3-AR agonists), relaxed the preparations significantly at concentrations higher than 10(-6) M. The pD2 values for BRL37344A, CL316243 and CGP-12177A were 6.42+/-0.25, 5.53+/-0.09 and 5.74+/-0.14, respectively. CGP-20712A (10(-7) - 10(-5) M), a beta1-AR antagonist, did not affect the isoprenaline-induced relaxation. On the other hand, ICI-118,551, a beta2-AR antagonist, produced a rightward parallel shift of the concentration-relaxation curve for isoprenaline only at the highest concentration used (10(-5) > M) and its pKB value was 5.71+/-0.19. Moreover, SR58894A (10(-7) - 10(-5) M), a beta3-AR antagonist, caused a rightward shift of the concentration-relaxation curve for isoprenaline in a concentration-dependent manner. The pA2 value and slope obtained from Schild plots were 6.24+/-0.20 and 0.68+/-0.31. The beta1-, beta2- and beta3-AR mRNAs were all positively expressed in detrusor smooth muscle preparations in a reverse transcription polymerase chain reaction assay. In conclusion, the present results provide the first evidence for the existence of the beta3-AR subtype in the human detrusor. They also suggest that the relaxation induced by adrenergic stimulation of the human detrusor is mediated mainly through beta3-AR activation.

Adrenergic alpha-Agonists↗
PubMed1999

A case of ileal ureter with proximal antireflux system.

BACKGROUND: The initial experience of constructing a new antirefluxing valve at the uretero-ileal junction with ileal substitution is reported. METHODS: A new antirefluxing valve was constructed at the uretero-ileal junction with ileal substitution by fixing the distal part of the ureter between the psoas muscle and ileal segment (the ileo-psoas tunnel technique). DISCUSSION: The valve created by the technique has been working effectively for preventing the ileo-ureteral reflux. Pre-operative hydronephrosis was improved and the renal function has been well preserved. CONCLUSION: The ileo-psoas tunnel technique is worthwhile when ileal substitution of the ureter is indicated.

Carcinoma, Transitional Cell↗
PubMed1999

Bladder dysfunction after proximal urethrolysis in female dogs.

BACKGROUND: Functional changes in the bladder after proximal urethrolysis are not recognized, despite the development of neuroanatomical studies of the female urethra or functional studies of the urethra after cystectomy. The aim of the present pilot study is to investigate possible functional changes in the bladder after proximal urethrolysis in female dogs. METHODS: The bilateral nerve branches to the urethra were resected by separating the urethra from the anterior vaginal wall in 10 female dogs. Pre- and postoperative cystometrograms were recorded under anesthesia and the bladder capacity, threshold pressure for micturition and bladder stiffness (the inverse of compliance) were compared. RESULTS: Fourteen days postoperatively, the bladder capacity significantly decreased and the threshold pressure and bladder stiffness significantly increased. Eight weeks after surgery, the threshold pressure and bladder stiffness remained high, but the bladder capacity tended to return to baseline values. CONCLUSIONS: These results indicate that proximal urethrolysis with bilateral sections of the nerve branches to the urethra produces a low-compliant bladder in the early postoperative period and suggest that afferent stimuli from the urethra may participate in maintaining a compliant bladder during filling.

Animals↗
PubMed1999

Serous-lined extramural tunnel technique for uretero-ileal implantation in urinary diversion.

PURPOSE: We present our initial experience of a serous-lined extramural tunnel technique for anti-refluxing uretero-ileal anastomosis in five cases of orthotopic ileal bladder and four cases of continent ileal pouch. METHODS/RESULTS: Ureters were implanted into serous-lined tunnels formed from a detubularized W-configurated ileal segment. Neither upper tract dilatation nor reflux were observed in any patient postoperatively. CONCLUSION: The technique can provide an effective uretero-ileal anastomosis for reflux prevention with minimal use of the ileal segment and without the use of any artificial materials.

Adolescent↗
PubMed1999

Simple anti-reflux uretero-ileal anastomosis: an experimental study in dogs.

PURPOSE: To develop more simple and effective anti-reflux techniques applicable to the ileal reservoir, we examined the usefulness of a novel anti-reflux uretero-ileal anastomosis creating a flap valve mechanism. MATERIALS AND METHODS: Five dogs were used. A 4 cm. long ileal segment was isolated and its oral part (2.5 cm.) was detubularized. The detubularized ileal plate was anastomosed to the dome of the bladder. The left ureter was cut and its proximal end was spatulated and anastomosed end-to-side to the ileal plate. The end of the 1.5 cm. long afferent limb (non-detubularized part of the ileal segment) was closed and fixed down to the ileal plate to create an extramural tunnel. In this way, the reimplanted ureter was covered by the afferent limb. The dogs were evaluated between 3 and 4 months postoperatively. RESULTS: None of the 5 dogs used showed vesico-ureteral reflux or hydronephrosis. Histological examination showed an intact ureter enclosed with a normal ileal wall. CONCLUSION: Our proposed anti-reflux uretero-ileal anastomosis is simple and reliable. This technique may be suitable for applying to a urinary reservoir, especially as an alternative to the intussuscepted nipple valve.

Anastomosis, Surgical↗
PubMed1999

Effects of intravesical capsaicin and resiniferatoxin on distension-induced bladder contraction in conscious rats with and without chronic spinal cord injury.

PURPOSE: To compare conscious, normal rats and rats with chronic spinal cord injury (CSI) in terms of the rhythmic bladder contractions (RBCs) induced by intravesical infusion of saline, and to determine how these contractions are influenced by intravesical capsaicin and resiniferatoxin. MATERIALS AND METHODS: Female Sprague-Dawley rats, normal or with spinal transection at the level of Th8-Th9, were investigated cystometrically under isovolumetric conditions before and after intravesical administration of capsaicin or resiniferatoxin. RESULTS: Spinal transection induced a significant increase in bladder weight. In both control and CSI animals, intravesical saline instillation induced reproducible RBCs that could be blocked by hexamethonium. Four weeks after the transection, the CSI animals had a significantly larger threshold volume than the controls, even after correction for bladder weight. The mean amplitude and duration of the RBCs did not differ between the two groups, but the frequency was significantly lower in CSI animals. Both capsaicin (0.1 and 1 mM) and resiniferatoxin (1 and 10 microM), instilled intravesically, were found to inhibit RBCs in both normal and CSI rats. There were no qualitative differences in the response to the drugs between the two groups. However, resiniferatoxin was approximately 100 times more potent than capsaicin. CONCLUSION: Capsaicin and resiniferatoxin inhibited RBCs in both normal and CSI rats, suggesting that activity in sensory fibers (C and Adelta), which are sensitive to the action of these drugs, is initiated by bladder filling in both types of rat.

Administration, Intravesical↗
PubMed1999

[A case of transitional cell carcinoma presenting as rupture of a renal arteriovenous malformation].

A 76-year-old man was seen at this hospital for the treatment of asymptomatic gross hematuria. Retrograde pyelography revealed a filling defect in the left lower calyx. The diagnosis was left renal pelvic carcinoma by urinary cytology. The patient underwent left nephrouretectomy with partial cystectomy. Hemosiderin accumulation on histological examination demonstrated an arteriovenous malformation in the left lower calyx. Transitional cell carcinoma was confirmed apart from the arteriovenous malformation, and no relation between the two was seen. These findings suggest the coexistence of a renal arteriovenous malformation with a renal pelvic and ureteral carcinoma. Hematuria was due probably to rupture of the renal arteriovenous malformation.

Aged↗
PubMed1999

Distribution of doxorubicin in the bladder wall and regional lymph nodes after bladder submucosal injection of liposomal doxorubicin in the dog.

PURPOSE: Liposome-encapsulated doxorubicin (Lip-Dox) has increased therapeutic efficacy and reduced toxicity compared to free doxorubicin (Dox). To assess the utility of Lip-Dox for local control of bladder cancer, we examined the distribution of Dox in the bladder wall and the regional lymph nodes of dogs after bladder submucosal injection of Lip-Dox. MATERIALS AND METHODS: In 8 dogs (group SM), Lip-Dox (2 mg.:1 ml.) was injected into the submucosal layer of each lateral bladder wall by using a flexible cystoscope. The other 8 dogs (group IV) underwent intravenous injection of free Dox (4 mg.). Both groups of animals were sacrificed at 1, 3, 5 or 7 days after the injections. The concentration of Dox was measured in both the mucosal and muscle layers of 5 bladder wall sites and also in the external iliac lymph nodes bilaterally. RESULTS: The Dox-concentration in the lymph nodes of group SM was significantly higher (about 15-100 times) than that of group IV throughout the whole follow-up period. The Dox-concentration in the bladder wall for group SM was significantly higher than that in group IV (about 70-930 times at the lateral walls and 2-830 times at the other sites). CONCLUSION: The present results demonstrate that Lip-Dox injected into the bladder submucosally distributes well, both in the whole bladder wall and in regional lymph nodes and remains at a high concentration in these tissues for at least one week after injection.

Animals↗
PubMed1999

Enhanced continent mechanism of tapered ileum by extramural support from pouch-abdominal wall: an experimental study in dogs.

PURPOSE: To construct a reliable continent tube, which is easy to catheterize, we created and evaluated a new continent cutaneous diversion using a tapered ileum combined with extramural support from the pouch-abdominal wall. MATERIALS AND METHODS: Six dogs underwent a procedure in which two ileal segments were tapered and anastomosed to the ileal pouch. One of the segments (continent) was placed between the back surface of the rectus muscle and the wall of the ileal pouch creating a continent tube. The other segment (control) was brought out into the abdominal skin directly without any support from the pouch-abdominal wall. Urodynamic and radiological studies were carried out postoperatively in all dogs. RESULTS: In the continent tubes, the maximum closure pressure with a full pouch was significantly higher than those with an empty pouch (p<0.01). The maximum closure pressures of the continent tubes were significantly higher than those of the control tubes when the pouch was empty (p<0.01). The leak point pressures of the continent tubes were significantly higher than those of the control tubes (p<0.001). In all dogs, the retrograde radiogram of the continent tubes showed perfect canalization without stenosis. CONCLUSION: This study suggests that the continent mechanism of tapered ileum can be greatly enhanced by fixing it between the abdominal and pouch walls, also allowing easy catheterization in contrast to the submucosal tunnel technique.

Abdominal Muscles↗
PubMed1998

Species differences in the distribution of beta-adrenoceptor subtypes in bladder smooth muscle.

1. The beta-adrenoceptor (beta-AR) subtypes mediating relaxation of the rabbit, rat and canine detrusors were subjected to functional investigation using selective beta-AR agonists and antagonists. 2. In all three species, isoprenaline, noradrenaline and adrenaline each produced a concentration-dependent relaxation of the detrusor. The rank order for their relaxing potency was isoprenaline>adrenaline>noradrenaline in rabbits and rats, but isoprenaline>noradrenaline>adrenaline in dogs. 3. Dobutamine did not produce relaxation of the detrusors at concentrations that are selective for beta1-AR. The selective beta2-AR agonist, procaterol, had a more potent relaxing effect on rabbit and rat detrusors than on the canine detrusor. CGP-12177A, a selective beta3-AR agonist, was more effective in the rabbit than in the other two species. On the other hand, the relaxing effect of another beta3-AR agonist, CL316243, was more pronounced in dogs and rats than in rabbits. 4. CGP-20712A (10(-9) to 10(-7) M), a selective beta1-AR antagonist, caused a slight rightward shift of the concentration-relaxation response curve for isoprenaline in the canine detrusor (pA2 9.41), but not in the rabbit and rat detrusors. ICI-118,551, a selective beta2-AR antagonist, antagonized the isoprenaline-induced relaxation in rabbits (pA2 9.45) and rats (pA2 9.05), but not in dogs. Bupranolol, a non-selective beta-AR antagonist, caused a rightward shift of the concentration-relaxation curve for isoprenaline in the rabbit (pA2 9.32) and rat (pA2 8.98). However, higher concentrations (3 x 10(-8) to 10(-5) M) were needed to induce a rightward shift of the curve for isoprenaline in the dog (pA2 8.19) than in the other two species. 5. We have confirmed that the distribution of beta-AR subtypes in the detrusor muscle varies significantly from species to species and we provide here the first evidence of the presence of beta3-AR in the detrusor. It is suggested that the relaxation induced by adrenoceptor agonists in urinary bladder smooth muscle may be mediated mainly via beta2-AR in rabbits, via both beta2- and beta3-AR in rats, but mainly via beta3-AR in dogs.

Adrenergic beta-Agonists↗
PubMed1998

Transcutaneous electrical stimulation of thigh muscles in the treatment of detrusor overactivity.

OBJECTIVE: To investigate the clinical effects on detrusor overactivity of a new method of transcutaneous reciprocal electrical stimulation of the thigh muscles. PATIENTS AND METHODS: Nineteen patients with detrusor overactivity, comprising 14 with detrusor hyperreflexia (DH) and five with idiopathic detrusor instability (IDI), were studied. Electrical stimulation was applied alternately to the quadriceps and hamstring muscles of one or both legs through surface electrodes for 20 min. The treatment was given once a day for 14 days and then the patients were evaluated urodynamically. RESULTS: All 19 patients tolerated the therapy well and none reported any adverse effects. The mean maximum cystometric capacity increased significantly (P < 0.05) after treatment. In 11 of the 19 patients, the maximum cystometric capacity was increased by > 50% of the pretreatment value; this occurred in eight of 14 of those with DH and in three of five of those with IDI. In six of the 11 who responded in this way, there was a clinical improvement in their urinary incontinence and frequency for several weeks to 3 months after the period of therapy. A second 14-day treatment was also effective in all four patients who underwent a repeat trial. CONCLUSION: This method of transcutaneous electrical stimulation can inhibit DH as well as IDI with no adverse effects. The suppressive effect on detrusor overactivity may persist for several months and repeat trials appear to be effective. Thus, we believe that this new stimulation technique should be tried as an alternative to other types of electrical stimulation and augmentation cystoplasty.

Adult↗
PubMed1998

Ileal pouch with an umbilical stoma: a continent mechanism created by the extramural tunnel technique.

We present an initial experience of creating an extramural continent valve in the ileal pouch in 4 patients who required continent urinary diversion. Using the appendix or a tapered ileal segment, the continent valve was created by the extramural tunnel technique along the anterior suture line of the pouch to facilitate the umbilical anastomosis. All patients were continent postoperatively with easy catheterization. This technique can provide a simple and effective continent pouch formed entirely from the ileum.

Follow-Up Studies↗
PubMed1998

Carcinoembryonic antigen positive adenocarcinoma of a female urethral diverticulum: case report and review of the literature.

Paraurethral glands of the female urethra, which are assumed to be embryologically homologous to the male prostate gland, are possible origins for diverticular cancer of the urethra. A case of primary adenocarcinoma arising in a female urethral diverticulum is presented. Pathology revealed a columnar/mucinous type adenocarcinoma which stained positively for carcinoembryonic antigen (CEA) and negatively for PSA. Normal paraurethral ducts located near the urethra and normal urethral epithelium also stained positively for CEA. These findings suggest that the adenocarcinoma in our case originated from the paraurethral duct near the urethral lumen.

Adenocarcinoma↗
PubMed1998

[Posttraumatic priapism in a 6-year-old boy: a case report].

A 6-year-old boy showed priapism after blunt perineal trauma. We diagnosed him with venous priapism mainly based on clinical symptoms, although we could not deny an arterial type. In fear of possible erectile dysfunction as a late complication of the venous type, we performed a shunt operation. The shunt was created between glans penis and corporacavernosa, resulting in disappearance of priapism and preservation of erectile function. We also reviewed 14 cases reported previously.

Child↗
PubMed1997

Capsaicin-induced nitric-oxide-dependent relaxation in isolated dog urethra.

Capsaicin (5 x 10[-8] to 5 x 10[-5] M) produced a non-adrenergic and non-cholinergic phasic relaxation in a concentration-dependent manner in isolated dog urethral preparations precontracted by noradrenaline. The mode of action of capsaicin was investigated with special reference to the possible involvement of endogenous nitric oxide (NO). A marked tachyphylaxis was observed in the responses to capsaicin. Pretreatment with NG-nitro-L-arginine-methyl-ester (L-NAME) prevented or markedly reduced the inhibitory effect of L-NAME. Methylene blue inhibited the capsaicin-induced relaxation. In preparations stored at 4 degrees C for 72 h, the reduction in the capsaicin-induced relaxation was significantly greater than that in the relaxation induced by either electrical field stimulation or by sodium nitroprusside. We conclude that capsaicin produces an endogenous-NO-dependent relaxation in the isolated dog urethra via mechanisms that deteriorate during cold storage of the preparations.

Animals↗
PubMed1997

Incontinent ileal tube repaired by infolding with the ileal pouch wall.

In a patient who had undergone construction of a continent ileal pouch we successfully repaired an incontinent ileal tube by infolding it in an imbricated portion of the ileal pouch wall. For 2 years postoperatively the patient has been urine continent and has catheterized the pouch easily. We believe this infolding technique is useful for reconstructing the continent mechanism in patients with incompetent ileal valves.

Fecal Incontinence↗