Yasue Kubota

Expression and localization of human oxytocin receptor mRNA and its protein in chorion and decidua during parturition.

Oxytocin (OT) is widely used to induce labor in the clinical setting. However, its physiological role in normal human parturition remains unclear. We demonstrated the enhanced expression of OT receptor (OTR) mRNA in chorio-decidual tissue, using the polymerase chain reaction after the reverse transcriptase reaction (RT-PCR) and Northern blot analysis. OTR gene expression in chorio-decidual tissue increased fivefold during the course of parturition. In situ hybridization of fetal membrane revealed the expression of OTR mRNA in maternally derived decidual cells. The OTR mRNA was also detected in fetally derived chorionic trophoblast cells. Immunohistochemistry, using a newly developed anti-OTR monoclonal antibody, demonstrated the distribution of OTR protein in fetal membrane. The distribution pattern of OTR protein and OTR mRNA was identical, indicating that the regulation of OTR expression occurs mainly at the transcriptional level. These results support the idea that the expression of decidual OTR regulates the initiation and amplification of labor. The implications of these findings with regard to the pathogenesis of preterm labor are also discussed.

Effects of imatinib mesylate (Glivec®) as a c‐kit tyrosine kinase inhibitor in the guinea‐pig urinary bladder

AIMS In the gastrointestinal tract, slow wave activity in smooth muscle is generated by the interstitial cells of Cajal (ICC). Detrusor smooth muscle strips of most species show spontaneous contractions which are triggered by action potential bursts, however, the pacemaker mechanisms for the detrusor are still unknown. Recently, ICC-like cells have been found in guinea-pig bladder, using antibodies to the c-kit receptor. We have investigated the effects of Glivec, a c-kit tyrosine kinase inhibitor, on spontaneous action potentials in guinea-pig detrusor and intravesical pressure of isolated guinea-pig bladders. METHODS Changes in the membrane potential were measured in guinea-pig detrusor smooth muscle using conventional microelectrode techniques. Pressure changes in the bladder were recorded using whole organ bath techniques. RESULTS Smooth muscle cells in detrusor muscle bundles exhibited spontaneous action potentials, and spontaneous pressure rises occurred in isolated bladders. Glivec (10 microM) converted action potential bursts into continuous firing with no effects on the shape of individual action potentials. Glivec (>50 microM) reduced the amplitude of spontaneous pressure rises in the whole bladder in a dose dependent manner and abolished spontaneous action potentials in detrusor smooth muscle cells. CONCLUSIONS The results suggest that ICC-like cells may be responsible for generating bursts of action potentials and contractions in detrusor smooth muscle. Drugs inhibiting the c-kit receptor may prove useful for treating the overactive bladder.

Elevated Nitric Oxide Concentration in the Seminal Plasma of Infertile Males: Nitric Oxide Inhibits Sperm Motility

PROBLEM: To evaluate the “effect of nitric oxide in the seminal plasma on sperm motility. METHOD: Seminal plasma concentrations of NO2—, a stable end product of nitric oxide, of 108 males of infertile couples and 15 proven fertile donors were measured and compared with spermatogram parameters. Motile sperm was incubated with a nitric oxide‐generating drug, sodium nitroprusside, for 6 hr in the absence or presence of oxyhemoglobin, an inhibitor of nitric oxide.

Genome‐Wide Analysis of Genes Related to Kidney Stone Formation and Elimination in the Calcium Oxalate Nephrolithiasis Model Mouse: Detection of Stone‐Preventive Factors and Involvement of Macrophage Activity

We previously established a mouse kidney stone formation model and showed that mice have a higher tolerance to stone formation than rats. Furthermore, we showed that the generated calcium oxalate crystal deposits could be eliminated after several days. This study investigated the transcriptome of stone formation and elimination in the mouse kidney based on gene selection using a microarray technique. Eight‐week‐old male C57BL/6N mice were administered 80 mg/kg glyoxylate for 15 days, and kidney calcium oxalate crystal depositions had increased by day 6; thereafter, depositions decreased gradually and had almost disappeared by day 15. On microarray analysis, mRNA expression in the crystal‐formed kidneys showed the significant expression of 18,064 genes. Thirty‐one, 21, and 25 genes showed at least a 2‐fold increased expression during the experimental course (days 3–15), stone formation phase‐specific (days 3–6), and stone elimination phase‐specific (days 9–15) stages, respectively. Among these genes, those related to chemotaxis and monocyte/macrophage activation were identified. Gene ontology analysis to identify overexpressed genes highlighted categories related to inflammation, immune reactions and the complement activation pathway. Quantitative PCR of 17 previously reported stone‐related genes with a significant expression on microarray analysis showed significantly increased chemokines, stone matrix proteins, and their receptors; the significant decrease of several types of transporters and superoxide dismutase; and the persistently high expression of Tamm‐Horsfall protein throughout the experiment. In conclusion, inflammation and immune reactivity through macrophage migration are involved in stone formation and elimination in mouse kidneys.

Expression of α1-Adrenoceptor Subtype mRNA as a Predictor of the Efficacy of Subtype Selective α1-Adrenoceptor Antagonists in the Management of Benign Prostatic Hyperplasia

PURPOSE We examined the correlation between the expression of alpha1-adrenoceptor subtype mRNA in the prostate and the clinical efficacy of subtype selective alpha1-adrenoceptor antagonists. We discuss the possibility of individualizing drug therapy in patients with benign prostatic hyperplasia. MATERIALS AND METHODS A total of 33 patients randomized to the tamsulosin group and 28 randomized to the naftopidil group were enrolled in this study. Each group of patients was administered 0.2 mg tamsulosin hydrochloride or 50 mg naftopidil daily for 12 weeks. Four prostate needle biopsy specimens were obtained from the transition zone to examine the expression of alpha-adrenoceptor subtypes. Specimens were stored at -80 C until used for TaqMan quantitative reverse transcriptase-polymerase chain reaction, which was performed after 12 weeks of treatment. RESULTS Based on the results of quantitative reverse transcriptase-polymerase chain reaction the tamsulosin and naftopidil groups were grouped into alpha1a-adrenoceptor dominant (22 and 12 patients) and alpha1d-adrenoceptor dominant (11 and 16, respectively) subgroups. The efficacy of tamsulosin hydrochloride and naftopidil differed depending on the dominant expression of the alpha1-adrenoceptor subtype in the prostate. Tamsulosin hydrochloride was more effective in patients with dominant expression of the alpha1a-adrenoceptor subtype, whereas naftopidil was more effective in those with dominant expression of the alpha1d-adrenoceptor subtype. CONCLUSIONS The expression level of alpha1-adrenoceptor subtype mRNA in the prostate could be a predictor of the efficacy of subtype selective alpha1-adrenoceptor antagonists in patients with benign prostatic hyperplasia. This result implies that genetic differences are responsible for the diverse responses to these drugs.

Mitochondrial permeability transition pore opening induces the initial process of renal calcium crystallization.

Renal tubular cell injury induced by oxidative stress via mitochondrial collapse is thought to be the initial process of renal calcium crystallization. Mitochondrial collapse is generally caused by mitochondrial permeability transition pore (mPTP) opening, which can be blocked by cyclosporine A (CsA). Definitive evidence for the involvement of mPTP opening in the initial process of renal calcium crystallization, however, is lacking. In this study, we examined the physiological role of mPTP opening in renal calcium crystallization in vitro and in vivo. In the in vitro study, cultured renal tubular cells were exposed to calcium oxalate monohydrate (COM) crystals and treated with CsA (2 μM). COM crystals induced depolarization of the mitochondrial membrane potential and generated oxidative stress as evaluated by Cu-Zn SOD and 4-HNE. Furthermore, the expression of cytochrome c and cleaved caspase 3 was increased and these effects were prevented by CsA. In the in vivo study, Sprague-Dawley rats were administered 1% ethylene glycol (EG) to generate a rat kidney stone model and then treated with CsA (2.5, 5.0, and 10.0 mg/kg/day) for 14 days. EG administration induced renal calcium crystallization, which was prevented by CsA. Mitochondrial collapse was demonstrated by transmission electron microscopy, and oxidative stress was evaluated by measuring Cu-Zn SOD, MDA, and 8-OHdG generated by EG administration, all of which were prevented by CsA. Collectively, our results provide compelling evidence for a role of mPTP opening and its associated mitochondrial collapse, oxidative stress, and activation of the apoptotic pathway in the initial process of renal calcium crystallization.

Kidney Stone Formation is Positively Associated with Conventional Risk Factors for Coronary Heart Disease in Japanese Men

PURPOSE We investigated the association between kidney stones and coronary heart disease risk factors in Japanese men. MATERIALS AND METHODS This cross-sectional study included 13,418 Japanese men 30 to 69 years old who voluntarily underwent medical examination between April 1995 and March 2001. Participants were divided into controls, and past and current kidney stone formers based on ultrasound results and medical history. We evaluated conventional risk factors of coronary heart disease, including overweight/obesity, hypertension, diabetes mellitus, gout/hyperuricemia, dyslipidemia and chronic kidney disease. Associations between coronary heart disease risk factors and kidney stones were investigated. RESULTS Of the 13,418 participants 404 current kidney stone formers (3.0%) had kidney stones on ultrasound and 1,231 past kidney stone formers (9.2%) had a history of kidney stones but no kidney stones on medical examination. Body mass index, systolic and diastolic blood pressure, and serum uric acid were significantly higher in past and current kidney stone formers than in controls. Logistic regression analysis indicated that the multivariate adjusted OR for overweight/obesity, hypertension, gout/hyperuricemia and chronic kidney disease significantly increased in the order corresponding to controls, and past and current kidney stone formers. CONCLUSIONS Kidney stone formers, even past stone formers, are likely to have accumulated risk factors for coronary heart disease. They could be preferentially targeted for coronary heart disease prevention.

The role of Ni2+-sensitive T-type Ca2+ channels in the regulation of spontaneous excitation in detrusor smooth muscles of the guinea-pig bladder

To explore the role of Ni2+‐sensitive T‐type Ca2+ channels in the generation of spontaneous excitation of detrusor smooth muscles.

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.

Solitary Fibrous Tumor of the Peritoneum Found in the Prevesical Space

Solitary fibrous tumors (SFT) are well recognized in the pleura, but their rare occurrence at other sites has become appreciated only in recent years. We experienced a 68-year-old male patient who presented with frequency of urination and difficulty in voiding. Computed tomographic scan revealed a solid and cystic mass which measured 12 × 10 cm in the prevesical space. This tumor showed typical histopathologic features of SFT, and was immunostained positive for vimentin, CD34 and CD99. This is an extremely rare case of SFT arising from the parietal peritoneum found in the prevesical space.