Biomedical subjects

K Kohri

Publications and source records attributed to K Kohri.

At least 19 recordsLinked to original sources

PubMed2003

Mechanisms of excitatory transmission in circular smooth muscles of the guinea pig seminal vesicle.

PURPOSE: Cellular mechanisms of excitatory neuromuscular transmission in circular smooth muscles of the seminal vesicle were investigated. MATERIALS AND METHODS: Circular smooth muscles of the seminal vesicle of the guinea pig were isolated. Changes in membrane potential produced by transmural nerve stimulation were recorded using intracellular microelectrode techniques. Changes in the intracellular Ca ion concentration induced by transmural nerve stimulation were measured in preparations loaded with Ca indicator fura-PE3. Responses produced by bath applied norepinephrine and alpha,beta-methylene adenosine triphosphate (ATP) were also examined. RESULTS: Transmural nerve stimulation evoked excitatory junction potentials that triggered action potentials and also caused transient increases in [Ca2+] (Ca transients). Nifedipine abolished action potentials, leaving underlying excitatory junction potentials unchanged, and reduced the amplitude of Ca transients. Excitatory junction potentials were blocked by alpha,beta-methylene ATP or guanethidine but not by phentolamine. A train of transmural nerve stimulation evoked oscillatory changes in membrane potential and [Ca2+], which were abolished by phentolamine or inhibited by nifedipine. Nifedipine insensitive components were abolished by cyclopiazonic acid. Norepinephrine depolarized the membrane and elicited oscillatory potentials with an associated elevation in [Ca2+]. These responses were inhibited by nifedipine and abolished by additional application of cyclopiazonic acid. Transient depolarization with an associated increase in [Ca2+] was elicited by alpha,beta-methylene ATP and [Ca2+] responses but no potential changes were inhibited by nifedipine. CONCLUSIONS: Circular smooth muscles of the guinea pig seminal vesicle receive a projection of sympathetic nerves that release norepinephrine to initiate slow depolarization through the activation of alpha-adrenoceptors. These nerves also release ATP to elicit excitatory junction potentials. Neurally released norepinephrine and ATP are increased [Ca2+] by the influx of Ca2+ through L-type Ca2+ channels and also by the release of Ca2+ from internal stores.

Action Potentials↗

PubMed2002

Pseudomonas aeruginosa induces MUC5AC production via epidermal growth factor receptor.

Hypersecretory disease associated with Pseudomonas aeruginosa (PA) infections is characterised by increased goblet cells and increased mucin production. Recently, an epidermal growth factor receptor (EGFR) signalling cascade was shown to be a common pathway through which many stimuli induce mucin MUC5AC expression in airways by differentiation to a goblet cell phenotype. This study looked at whether PA products induce EGFR expression and activation and thus result in mucin MUC5AC production. Human airway epithelial (NCI-H292) cells were stimulated with PA culture supernatant (Sup). MUC5AC protein production, MUC5AC and EGFR messenger ribonucleic acid (mRNA) expression, and phosphorylated EGFR and phosphorylated p44/42 mitogen-activated protein kinase (MAPK) were all examined using enzyme-linked immunosorbent assay, by in situ hybridisation and by immunoblotting. PA Sup induced MUC5AC mRNA and subsequent protein expression, EGFR and p44/42 MAPK phosphorylation and EGFR mRNA expression. Induction of MUC5AC mRNA and protein expression and EGFR and p44/42 MAPK phosphorylation were inhibited completely by pretreatment with a selective EGFR tyrosine kinase inhibitor. Pretreatment with a selective inhibitor of MAPK kinase prevented MUC5AC production and p44/42 MAPK phosphorylation but not EGFR phosphorylation. The authors conclude that PA products induce mucin MUC5AC production in human airway epithelial cells via the expression and activation of epidermal growth factor receptor.

Cell Line↗

PubMed2001

Human prostate cancer cells adhere specifically to hemoglobin: a possible role in bone-specific metastasis.

From the supernatant of rabbit bone marrow, we isolated an organ-specific factor, which was related with the metastasis of prostate cancer to the bone and examined its adhesion to prostate cancer cells (PC-3). Molecular weight and amino acid sequence analyses of the active component obtained by high performance liquid chromatography revealed that a component identical to the alpha chain of hemoglobin accounted for 80% of the biological activity. Hemoglobin showed over 50% adhesion to PC-3 cells but only 10% adhesion to human colon cancer cell lines, representative of organ non-specific metastasis, and leukemia cells line, representative of a non-solid tumor. Some substance in the bone marrow may promote the first step of adhesion of cancer cells to bone marrow in the metastasis of prostate cancer to the bone, possibly an amino acid sequence or some tertiary structure similar to hemoglobin.

Animals↗

PubMed2001

Developing germ cells in mouse testis express pheromone receptors.

Pheromone receptors are expressed in the accessory olfactory system, which is vital for non-specific chemical communication and for sexual behavior. Under the hypothesis that some of the pheromone molecules released from female reproductive organs might regulate sperm chemotaxis or chemokinesis, we examined whether the V1R type pheromone receptor mRNAs are expressed in developing germ cells. By a reverse transcription-PCR method, we obtained nine kinds of cDNA fragments belonging to the receptor family. In situ hybridization analysis in testicular sections using probes of testicular pheromone receptors (TVRs) revealed that TVR mRNAs were expressed by spermatids. TVRs were also expressed in the accessory olfactory organ. In the testis, hybridization signals were localized in subsets of the seminiferous tubules, suggesting that TVRs were expressed by selective subsets of the spermatids. In situ hybridization study suggests also that each sperm expresses multiple pheromone receptors. The testicular pheromone receptors might have an important role in the maturation and/or migration of sperm.

Amino Acid Sequence↗

PubMed2001

Effects of citrate on renal stone formation and osteopontin expression in a rat urolithiasis model.

Previous studies have described the inhibitory effects of citrate on calcium oxalate crystallization in place of crystal growth, but the effects of citrate on matrix proteins of stones has not been studied in vivo. To examine the effect of citrate on the matrix, we investigated the effect of citrate on osteopontin (OPN) expression, which we had previously identified as an important stone matrix protein. Control rats were treated with saline while rats of the stone group were treated with ethylene glycol (EG) and vitamin D3, and the citrate groups (low-dose and high-dose groups) were treated with a citrate reagent compound of sodium citrate and potassium citrate, in addition to EG and vitamin D3. The rate of renal stone formation was lower in the citrate groups than in the stone group. This was associated with a low expression of OPN mRNA in citrate-treated rats relative to that in the stone group. Citrate was effective in preventing calcium oxalate stone formation and reduced OPN expression in rats. Our results suggest that citrate prevents renal stone formation by acting against not only the crystal aggregation and growth of calcium oxalate but also OPN expression.

Animals↗

PubMed2001

Comparison between ultrasonography and retrograde urethrography for detection of prostatic utricle associated with hypospadias.

OBJECTIVES: To evaluate the practical application and limitation of ultrasonography and retrograde urethrography in detecting prostatic utricle associated with hypospadias. METHODS: Between 1995 and 1999, 80 patients with hypospadias, 1 month to 16 years of age (mean age 3 years, 6 months), underwent ultrasonography and retrograde urethrography to detect the prostatic utricle. RESULTS: Of the 80 patients examined, the prostatic utricle was found in a total of 36 patients (45.0%) by ultrasonography and/or retrograde urethrography. Ultrasonography revealed the prostatic utricle in 27 (75%) of the 36 patients; in 6 of the 27, it was not detected by retrograde urethrography. Retrograde urethrography revealed the prostatic utricle in 30 (83%) of the 36 patients; in 9 of the 30, it was not visualized by ultrasonography. Retrograde urethrography was slightly more sensitive in detecting the prostatic utricle than was ultrasonography. In the remaining 44 patients, the prostatic utricle was not detected by either examination method. CONCLUSIONS: Although retrograde urethrography is considered the most useful method for detecting any degree of the prostatic utricle, we recommend routine ultrasonography because it is noninvasive, painless, and simple.

Adolescent↗

PubMed2001

Osteopontin in gingival crevicular fluid.

Osteopontin (OPN) is a major glycosylated phosphoprotein in bone matrix and is produced by several cells including osteoblasts, osteoclasts and macrophages. OPN levels increase in active sites of bone metabolism. Recently, several bone-related proteins were identified in gingival crevicular fluid (GCF) to seek markers of alveolar bone resorption in periodontal disease. In this study, we investigated the existence of OPN in GCF and the correlation between OPN level in GCF and probing depth (PD) of sampling sites in 98 periodontitis patients and 35 healthy subjects. An immunoblotting analysis using 10% polyacrylamide gel showed that two forms of OPN with molecular masses of 54 and 66 kDa and several degraded fragments were detected in most GCF samples from diseased sites (PD > 4 mm). In GCF samples from healthy sites (PD < or = 3 mm), only one form (54 kDa) was observed, but any degraded fragments were not detected. When OPN amounts in GCF samples were determined by ELISA, a weak. but significant correlation was observed between OPN amount in GCF and PD (r=0.32, p=0.0013). These results demonstrate that OPN exists in GCF and that OPN level in GCF increases with the progression of periodontal disease.

Adult↗

PubMed2001

KAI1 expression can be a predictor of stage A prostate cancer progression.

The disease progression and rate of cancer death were analyzed in 52 patients with stage A prostate cancer who underwent transurethral resection of the prostate (TURP) or retropubic subcapsular prostatectomy (SCP) between 1987 and 1998. We performed immunohistochemistry on 16 patients to determine the correlation between the expression of the tumor metastasis suppressor gene KAI1 and the subsequent progression of stage A prostate cancer. Nineteen and 33 of the patients had cancer at stage A1 and stage A2, respectively, and their subsequent courses were followed for an average of 53.7 months (24-134 months). Progression to clinical cancer was found in six patients (one with stage A1, and five with stage A2). This progression was evident 40.8 months (5-80 months) after TURP or SCP. Four (66.7%) of the patients died of cancer progression (average 31 months) after prostatectomy. All four patients had stage A2, poorly differentiated adenocarcinoma, and had been followed with administration of diethylstilbestrol diphosphate (DES-P). The disease-free patients (n=10) showed overexpression of KAI1 protein, compared to those with disease progression (n=6). These results indicate that progression arose mainly in the patients with stage A2 cancer, and that poorly differentiated, focal and weak expression of KAI1 protein is highly associated with disease progression. It is suggested that patients in this group should be treated with immediate total androgen blockade, radiation, or radical prostatectomy after diagnosis.Prostate Cancer and Prostatic Diseases (2001) 4, 150-153.

Journal Article↗

PubMed2001

Primary and salvage urethroplasty using Mathieu meatal-based flip-flap technique for distal hypospadias.

BACKGROUND: Numerous surgical procedures have been attempted for correction of distal hypospadias. The Mathieu procedure was employed in this study for secondary cases as well as primary cases. METHODS: The length of the skin flap is determined by measuring the distance from the meatus to the glans tip and then the ventral meatal-based skin flap is incised. The proximal skin flap is flipped and anastomosed to the distal urethral plate. Additionally, subcutaneous tissue of the flipped flap is sutured to cover the original suture lines completely. RESULTS: The Mathieu urethroplasty was successful in one stage in 13 of the 16 primary repair cases (81%). Twelve of the 13 (92%) who underwent a secondary Mathieu procedure were successfully repaired with no problems. An overall success rate of 86% was achieved at the first operation for both primary and secondary cases. In the remaining 14% of the cases, success was achieved with only one additional procedure. CONCLUSIONS: The Mathieu flip-flap procedure is feasible for relatively short urethral defects if the ventral penile skin demonstrates adequate mobility and there is no chordee. Even in patients who require revisional hypospadias surgery, the Mathieu procedure can give excellent functional and cosmetic results.

Adolescent↗

PubMed2001

One-stage repair of moderately severe hypospadias using a transverse preputial tubularized island flap.

BACKGROUND: Transverse preputial tubularized island flap (TPTIF) urethroplasty has been used for the repair of moderately severe hypospadias since Duckett described the procedure in 1980. In spite of the excellent results reported by Duckett, subsequent studies showed high complication rates. A TPTIF procedure modified to reduce the complication rate is presented. METHODS: Between 1996 and 1997, 13 boys with moderately severe hypospadias were repaired with the TPTIF procedure. Patient age ranged from 10 months to 3 years with an average age of 23 months. To prevent urethrocutaneous fistula, the neourethra was constructed with a two-layer closure and the portion of anastomosis was wrapped between the native urethra and the neourethra with the tissue of the corpus spongiosum. RESULTS: The moderately severe hypospadias was repaired without complication in 12 of 13 patients. A urethrocutaneous fistula developed at the midshaft of the penis in one patient. No meatal stenosis, urethral stricture or diverticulum developed. CONCLUSION: Transverse preputial tubularized island flap urethroplasty provided excellent cosmetic and functional results for moderately severe hypospadias, and postoperative complications could be decreased by the two-layer closure of the neourethra and application of the wrapping technique of the proximal anastomosed portion with corpus spongiosum tissue.

Child, Preschool↗

PubMed2001

Tubularized incised-plate urethroplasty for secondary hypospadias surgery.

PURPOSE: Reoperation for failed hypospadias has been considered to be seriously bothersome because abundant penile skin does not tend to remain for urethroplasty or for penile shaft skin coverage. In this study, the tubularization of incised urethral plate was employed for those who had no excessive penile skin after failure of hypospadias repair. METHODS: Five patients with hypospadias underwent tubularized incised-plate urethroplasty as salvage surgery. The surgical techniques necessary for the performance of the reoperation were not different from those for the primary repair. The urethral plate was incised sufficiently deeply in its midline from the tip of the glans to the regressed meatus. The incised urethral plate was tubularized without tension over a catheter of an appropriate size. RESULTS: Four of those who underwent secondary tubularized incised-plate urethroplasty were successfully repaired without complications. A urethrocutaneous fistula occurred at the corona in the remaining patient. CONCLUSIONS: The absence of preputial skin in reoperative cases makes tubularized incised-plate urethroplasty the ideal option, although the series was small and postoperative duration is still short. In addition, this procedure can give excellent functional and cosmetic results even in patients who require revisional hypospadias surgery.

Adolescent↗

PubMed2001

The modified Koyanagi repair for severe proximal hypospadias.

OBJECTIVE: To report the method and results of a modified one-stage Koyanagi repair (urethroplasty with a parameatal-based and fully extended circumferential foreskin flap) to preserve the vascularity to the peripheral portion of the neourethra, in the repair of severe hypospadias. PATIENTS AND METHODS: Using a skin-incision line as in the original Koyanagi repair, a circumferential incision is made approximately 5 mm proximal to the corona and the urethral plate incised as for repair of chordee. A U-shaped skin incision is then made surrounding the meatus, extended to the dorsal prepuce for approximately 8 mm and parallel to the first incision. The tissue between the prepuce and dartos is dissected on the dorsal side to fix the prepuce as a neourethra to the dartos and to maintain blood supply. After mobilizing the loop-shaped skin flap through the button-hole of the pedicle, the internal and external sides of the loop are sutured to construct a neourethra. Twenty patients (aged 10 months to 9 years) with severe proximal hypospadias underwent the one-stage modified Koyanagi repair. RESULTS: The repair was successful after the initial procedure in 14 patients, but urethrocutaneous fistulae developed in three and meatal stenosis in three. The overall success rate was thus 70%. CONCLUSIONS: There were fewer complications than reported with the original Koyanagi repair, suggesting that the attempted vascular preservation of the neourethra was effective.

Child↗

PubMed2001

Involvement of calpain for apoptosis in dysfunction of the unaffected testis in rats with experimental testicular torsion.

PROBLEM: The dynamics of calpain and involvement of apoptosis in sperm formation disorder of the unaffected testis in rats with experimental testicular torsion were investigated. METHODS OF STUDY: Using 6-week-old Wistar rats, an experimental unilateral testicular torsion model was prepared. The bilateral testes were excised 1, 3, 5, 7, 14, 35, and 70 days after the left testis was twisted, and the unaffected testes were subjected to immunohistological staining, sodium dodecyl sulfate polyacrilamide gel electrophoresis and Western blotting using anti-calpain antibodies. Apoptosis was detected by the TdT-mediated dUTP biotin nick end-labeling (TUNEL) method. RESULTS: By immunohistological staining, positive immunostaining by anti-pro mu-calpain antibody was observed in the spermatocyte nucleus, but not with anti-pro m-calpain antibody. The staining was increased until 7 days after testicular torsion, then decreased with progression of sperm formation disorder. By Western blotting, the intensity of staining with anti-pro mu-calpain antibody was increased until 7 days after torsion of the testis. Apoptosis expression in the unaffected testis was significantly inhibited by addition of a calpain inhibitor. CONCLUSIONS: It was suggested that mu-calpain may be involved in apoptosis expression in sperm formation disorder of the unaffected testis in unilateral testicular torsion.

Animals↗

PubMed2001

Effects of allopurinol on renal stone formation and osteopontin expression in a rat urolithiasis model.

BACKGROUND: The inhibitory effect of allopurinol on calcium oxalate urolithiasis has been reported, but its effect on stone matrix proteins has not been studied in vivo. To clarify the effect of allopurinol on the matrix, we investigated its effect on the expression of osteopontin (OPN), which we previously identified as an important stone matrix protein. METHODS: Control rats were not treated. Rats of the stone group were given ethylene glycol (EG) and vitamin D(3), while the allopurinol groups (low-dose group and high-dose group) were treated with allopurinol in addition to receiving EG and vitamin D(3). RESULTS: The rate of renal stone formation was lower in the allopurinol groups than in the stone group. This was associated with a low expression of OPN mRNA in allopurinol-treated rats relative to that in the stone group. CONCLUSION: Allopurinol was effective in preventing calcium oxalate stone formation and reduced OPN expression in rats. Our results suggest that allopurinol prevents renal stone formation by acting against not only the control of oxalate but also OPN expression.

Allopurinol↗

PubMed2001

Calcium oxalate crystal attachment to cultured rat kidney epithelial cell, NRK-52E.

Madin-Darby canine kidney (MDCK) cells have been used in research on crystal adhesion to epithelial cells. Recently, matrix proteins were identified, and studies of the genes and proteins expressed in renal epithelial cells have become active. The present study confirms the usefulness of the NRK-52E cell line, derived from the rat, in the study of attachment with calcium oxalate crystals. The calcium oxalate crystal suspension was distributed on top of the cells. After incubation, the monolayers were rinsed to remove non-associated crystals. After fixation, the association of crystals and NRK-52E cells was visualized using scanning electron microscopy. Calcium oxalate crystals were attached to the surface of NRK-52E cells. Under high magnification, many of the microvilli of the cells had elongated towards the crystals, and microvilli projections appeared to catch the crystals. The NRK-52E cell line is useful in the study of attachment between crystals and urinary epithelial cells in the kidney, especially for the regulation and analysis of genes and proteins.

Animals↗

PubMed2001

Intravesical combined chemoimmunotherapy with epirubicin and bacillus Calmette-Guérin is not indicated for superficial bladder cancer.

PURPOSE: The short-term effects of intravesical chemoimmunotherapy with epirubicin and bacillus Calmette-Guérin (BCG) administered repeatedly for prophylaxis of recurrence of superficial bladder cancer (pTa, pT1) were investigated in 24 patients aged a median of 70 years between March 1996 and February 1999, and were compared with those of BCG monotherapy in 50 patients from March 1990 to February 1999. PATIENTS AND METHODS: The patients underwent intravesical instillation of the Tokyo strain BCG with or without epirubicin after transurethral resection (TUR) of bladder cancer. For the combined treatment, at 1-2 weeks after TUR, epirubicin (40 mg) and BCG (80 mg) were istilled into the bladder by turns once a week for 12 weeks. For the group receiving only BCG, 80-mg instillations were done with the same schedule. Thereafter, the patients were followed by cystoscopy and urinary cytology every 3 months for up to 3 years after intravesical therapy. RESULTS AND CONCLUSIONS: At 2 years after treatment, the simple recurrence rate was 26.1% (6/23) in patients with chemoimmunotherapy and 32.0% (16/50) in BCG-treated patients. Adverse reactions, including increased frequency of urination, urgency and miction pain, were observed in 18 patients (85.7%) undergoing chemoimmunotherapy and 58.0% undergoing BCG monotherapy. One patient receiving chemoimmunotherapy was withdrawn from treatment because of symptoms of severe bladder irritation due to the instillation. Intravesical chemoimmunotherapy using epirubicin and BCG was finally found to be inferior in comparison with BCG monotherapy for the prophylaxis of recurrence of superficial bladder cancer.

Adjuvants, Immunologic↗

PubMed2001

Effects of eicosapentaenoic acid on urinary calcium excretion in calcium stone formers.

OBJECTIVES: The low incidence of atherosclerosis and other degenerative disease, including urolithiasis, in the Greenland Eskimo has been attributed to their high consumption of oily fish with its high concentration of eicosapentaenoic acid (EPA). With a westernized diet, the oxygenated products of renal prostaglandin synthesis are metabolites of the n-6 series and these are known to play important roles in several pathophysiological processes involved in calcium stone formation. Buck's group presented a hypothesis that the initiating factor for lithiasis triggers prostaglandin synthesis, and showed that this influenced by EPA treatment. METHOD: In order to ascertain the effects of EPA on plasma lipids and urinary parameters, we undertook a clinical study whereby a highly purified preparation was administrated (1,800 mg/day) to 88 patients with urinary stones for 3 months (short term) and 18 months (long term). RESULTS: Hyperlipemia improved the affected individuals and urinary calcium was significantly reduced in the hypercalciuric but not in the normocalciuric group. CONCLUSION: The results suggest that EPA by reducing urinary calcium might favorably affect urine composition in a way that possibly reduces the risk of calcium stone formation.

Adult↗

PubMed2001

[A study on the mechanism of the spermatogenic damage after vasectomy in rats].

PURPOSE: Vasectomy may result in damage to spermatogenesis. There are several explanations for this damage, including an increase of pressure in the seminiferous tubules and an autoimmune reaction. Recently, vasectomy has been reported to induce germ cell death by apoptosis. However, the exact mechanism of this vasectomy-induced germ cell apoptosis is unclear. To elucidate this mechanism, we designed a vasectomized rat model and examined the testiscular alterations and apoptotic degeneration biochemically and microhistopathologically. Particularly, we analyzed the expression of nitric oxide synthase (NOS) and nuclear factor kappa B (NF kappa B), which plays a critical role in the induction of the iNOS gene, in the testis after vasectomy to gain insight into the association between germ cell apoptosis and these factors. MATERIALS AND METHODS: The testes of 40 Wistar rats (10-weeks old) were studied at 1, 2, 5 and 10 weeks after unilateral (left) vasectomy. Wistar rats weighting 290 to 310 g were divided into 2 groups and subjected to underwent either unilateral vasectomy or sham surgery under ether anesthesia. Bilateral testes were carefully observed biochemically and histopathologically. Apoptosis was detected by an in situ end-labeling technique (detection of cellular DNA fragmentation) and electron microscopy. Neuronal NOS (nNOS), endothelial NOS (eNOS) and inducible NOS (iNOS) protein was detected by Western blotting and immunohistochemical studies using each NOS monoclonal antibody. To confirm the co-localization of cellular DNA fragmentation in germ cells and each NOS, each set of consecutive testis sections (one stained for cellular DNA fragmentation and the others for each NOS) were examined. Expression of NF kappa B proteins was examined immunohistochemically using a NF kappa B p65 polyclonal antibody. RESULTS: At 5 and 10 weeks after vasectomy, the vasectomized left testis was significantly lighter than the unvasectomized right testis and sham-operated testis. At that time, the seminiferous tubules of vasectomized testes were highly damaged, presenting narrow tubular diameter, disorder of cellular arrangement, depletion of the germ cells, and local interstitial fibrosis. Vasectomized testes demonstrated a significantly increased number of apoptotic germ cells per cross-sectional area compared with sham-operated testes at 5 and 10 weeks after operation (p < 0.01). Electron microscopy revealed apoptotic germ cells each with a darkly stained nucleus. Western blotting and immunohistochemical studies demonstrated that iNOS proteins were more strongly expressed on vasectomized testes as time passed after vasectomy. Examination of consecutive sections from the vasectomized testis revealed that visibly apoptotic germ cells that exhibited positive staining for cellular DNA fragmentation were also intensely stained for eNOS and iNOS. NF kappa B p65 proteins were more strongly expressed in the nucleus of germ cells in the vasectomized testis than in the sham-operated testis. CONCLUSIONS: We found that vasectomy results in damage to spermatogenesis in adult rats, that may induce germ cell apoptosis, and that iNOS and NF kappa B may play a critical role in the germ cell apoptosis after vasectomy.

Animals↗