Strain difference in transgene-induced tumorigenesis and suppressive effect of ionizing radiation

Transgenic expression in medaka of the Xiphophorus oncogene xmrk, under a pigment cell specific mitf promoter, induces hyperpigmentation and pigment cell tumors. In this study, we crossed the Hd-rR and HNI inbred strains because complete genome information is readily available for molecular and genetic analysis. We prepared an Hd-rR (p53^+/−, p53^−/−) and Hd-rR HNI hybrid (p53^+/−) fish-based xmrk model system to study the progression of pigment cells from hyperpigmentation to malignant tumors on different genetic backgrounds. In all strains examined, most of the initial hyperpigmentation occurred in the posterior region. On the Hd-rR background, mitf:xmrk-induced tumorigenesis was less frequent in p53^+/− fish than in p53^−/− fish. The incidence of hyperpigmentation was more frequent in Hd-rR/HNI hybrids than in Hd-rR homozygotes; however, the frequency of malignant tumors was low, which suggested the presence of a tumor suppressor in HNI genetic background fish. The effects on tumorigenesis in xmrk-transgenic immature medaka of a single 1.3 Gy irradiation was assessed by quantifying tumor progression over 4 consecutive months. The results demonstrate that irradiation has a different level of suppressive effect on the frequency of hyperpigmentation in purebred Hd-rR compared with hybrids.     

The effects of intense click sounds on velocity storage in optokinetic after-nystagmus

Vestibular evoked myogenic potentials (VEMP) occurring after click stimulation in cervical muscles are thought to be a polysynaptic response of otolith-vestibular nerve origin. In optokinetic after-nystagmus (OKAN) the direction of after-nystagmus changes and slow-phase velocity decreases with head tilt. This phenomenon may be an otolith response to the direction of gravity. We assumed that intense clicks might have some influence on OKAN via the otolith-vestibular nerve. Twelve normal subjects who showed VEMP at 75 dB normal hearing level (nHL) clicks were examined. The OKAN was recorded under four conditions: right monaural, left monaural and binaural stimulation by 75 dB nHL clicks, and absence of click stimulation. Horizontal optokinetic stimulation was applied using stepwise increasing speeds from 30 deg/s to 90 deg/s. Two seconds before the stimulus ended, clicks were sounded. The slow-phase velocity of the recorded electro-nystagmography was manually measured. There was no effect on OKAN with unilateral stimulation but binaural stimulation suppressed it. These results suggest that a velocity storage integrator is influenced by intense clicks via the otolithic area. Received: 17 November 1999 / Accepted: 30 May 2000     

Immunoelectron microscopy of AMPA receptor subunits reveals three types of putative glutamatergic synapse in the rat vestibular end organs

To characterize the synapses between hair cells and afferent nerve endings in the rat vestibular end organs, the ultrastructural localization of AMPA receptor subunits (GluR1-4) was examined by postembedding immunogold cytochemistry. Immunoreactivities for GluR2/3 and GluR4 were associated with the synapses between type I hair cells and the surrounding chaliceal nerve endings and with the bouton type nerve endings contacting type II hair cells. There was no detectable immunoreactivity for GluR1. A third type of immunoreactive synapse was found between the outer face of chalices and type II hair cells. While the linear densities of gold particles (particles per micrometer postsynaptic specialization) of bouton type endings and chaliceal nerve endings were the same, the former type of ending showed larger postsynaptic specializations and, hence, a higher number of receptor molecules. These data indicate that there are three types of putative glutamatergic synapse in the vestibular end organ.     

Purification and Partial Characterization of an Indomethacin Hydrolyzing Enzyme from Pig Liver

Purpose. Indomethacin is well known to be metabolized via O-demethylation and N-deacylation. In this paper we found an enzyme involved in the hydrolysis of amide-linkage of indomethacin and partially characterized it as well as its substrate specificity. Methods. An indomethacin hydrolyzing enzyme was purified to homogeneity from pig liver microsomes using columns of Q-Sepharose, Red-Sepharose and Blue-Sepharose. The enzyme activity was assayed by measuring of -chlorobenzoic acid liberated from indomethacin by HPLC. Results. The purified enzyme effectively hydrolyzed the amide linkage in indomethacin but not those in -naphthylacetate and -nitrophenylacetate, which are typical substrates for carboxylesterase. The subunit molecular mass of the enzyme was 65 kDa according SDS-polyacrylamide gel electrophoresis. The Michaelis constant (Km) and maximum velocity (Vmax) values for indomethacin were 67.8 µM and 9.02 nmol/min/mg protein, respectively. The amino acid sequence analysis of the enzyme after cyanogen bromide cleavage showed high homology with a mouse carboxylesterase isozyme designated as ES-male. The activity of indomethacin hydrolysis was relatively high in the pig, rabbit and human liver homogenate, but not in those from rat and mouse. On the other hand, purified human liver carboxylesterases pl 5.3 and 4.5, and pig liver carboxylesterases have no catalytic activity for indomethacin. Conclusions. These results indicate that the hydrolysis of amide-linkage of indomethacin in humans would be associated with an enzyme similar to the indomethacin hydrolyzing enzyme from pig liver microsomes described here.     

A multivariate analysis of prognostic factors related to recurrence and progression of superficial bladder cancer

Prognostic factors related to the recurrence and progression of superficial primary bladder cancers were analyzed by Cox's proportional hazards regression model. We followed 75 patients (stage Ta, 49 cases; T1, 26 cases; grade G1, 42 cases; G2, 29 cases; G3, 4 cases) after transurethral resection for 10 to 74 months (median 38 months). The antibodies reactive with the products of oncogenes [anti-c-myc oncoprotein (MYC-1); anti-c-erbB-2 oncoprotein], tumor suppressor gene [anti-p53 mutant protein (BP53-12)], growth factor receptor [anti-transferrin receptor (HBT-2)], proliferation [anti-proliferatioe nuclear antigen (Ki-67)], and malignant transformation (B1.4) were used for immunohistochemical staining. The reactivities of mAb B1.4, HBT2, and BP53-12 were significantly increased according to the grade, and those of mAb Ki-67, MYC-1, and c-erbB-2 were not. The reactivities of all antibodies were not significantly different between stages Ta and T1. As prognostic factors, stage, grade, tumor number, urinary cytology, and reactivities of the above six antibodies were used for the analysis. Urinary cytology, multifocality, and the reactivity of mAb Ki-67 showed a relative but significant high risk for recurrence, and the reactivities of mAb HBT2, mAb B1.4, and mAb Ki-67 showed a significant high risk for progression in the multivariate analysis. These results suggest that mAb B1.4 may be useful as a new prognostic factor for the progression of superficial bladder cancer.     

Refilling the lens with an inflatable endocapsular balloon: surgical procedure in animal eyes

In this report we describe the surgical details involved in refilling the lenses of 13 rabbit and 3 primate eyes using an inflatable endocapsular balloon to restore accommodation. The procedure involves endocapsular phacoemulsification through a small buttonhole or dumbbell anterior capsulotomy or minicircular capsulotomy and the simultaneous preservation of capsular integrity, including the zonules and ciliary muscles. An inflatable balloon made of thin silicone membrane is then inserted into the empty capsular bag. A liquid silicone polymer is injected into the balloon through a delivery tube, and the empty capsular bag is refilled by the inflated balloon. The procedure was found to be reproducible, and an accommodation of 6 D was confirmed in one primate eye. Capsular opacification occurred, but the proliferation and migration of residual lens epithelial cells could be hindered by abundant refilling. This lens-refilling technique may provide restoration of accommodation in future cataract surgery. Offprint requests to: O. Nishi     

Binaural advantage on usage of hearing aid together with cochlear implant--examination on speech perception (Japanese monosyllable word list 67-S and Japanese HINT)]

Six cochlear implant recipients with hearing aids in the opposite ear were studied to survey binaural advantage. They were examined in separate tests by using a hearing aid alone, cochlear implant alone, and by using both devices (bimodal condition). Test items used were the Japanese monosyllable word list 67--S and Japanese HINT. Statistically significantly results were obtained in the bimodal condition, three out of six subjects were successful in the monosyllable word test and all successful in the Japanese HINT. We conclude that all subjects enjoyed binaural advantage in speech perception in bimodal condition with no conflict at the recognition level; even when different sounds from cochlear implant and contralateral hearing aid were received. The plasticity of the brain is thought to be of importance in the bimodal condition.     

Clinical significance of nonpalpable prostate cancer with favorable biopsy features in Japanese men

OBJECTIVE: To assess the clinical significance of nonpalpable localized prostate cancers with relatively favorable six sextant biopsy features in Japanese men. PATIENTS AND METHODS: 136 nonpalpable prostate cancers of which biopsy features confined to (1) a Gleason score of 6 or less, (2) one or two positive cores per six sextant cores, and (3) 50% or less involvement of any positive core were collected. The Gleason score, tumor extension, and cancer volume were compared with preoperative serum PSA and PSA density for the patients who underwent radical prostatectomy. PSA doubling time was measured for the patients who were treated expectantly. RESULTS: Treatments chosen for 136 patients with favorable biopsy features were radical prostatectomy alone for 48 and with preoperative androgen deprivation for 30, radiation to the prostate for 12, androgen deprivation therapy for 21, and watchful waiting for 25. Of 48 patients who underwent radical prostatectomy without androgen deprivation therapy, 25% had nonorgan-confined cancers. Seven cancers (14.6%) were Gleason score of 7, but no cancers were 8 or greater. Among 42 prostatectomy specimens for which cancer volume was measured, 22 (52.4%) had cancer volume >0.5 cm(3). Pretreatment serum PSA levels were correlated neither with the Gleason score, tumor extension nor cancer volume. There was only one nonorgan-confined cancer in the 23 cancers for which PSA density was <0.2 ng/ml/g. The ability of PSA density to predict cancer volume <0. 5 cm(3) was 0.61 using a cut-off of 0.2 ng/ml/g. Of the 25 patients treated expectantly, the PSA doubling time was less than 2 years for 3 patients, while it was stable or fluctuated for 13. CONCLUSIONS: Tumor extension can be predicted based on PSA density in nonpalpable prostate cancer with favorable biopsy features, but predictability of cancer volume based on PSA or PSA density is not satisfactorily high. New parameters or biomarkers that complement needle biopsy findings are needed to predict clinical significance of T1c prostate cancer with favorable biopsy features.