Mitotic and meiotic detection of radiation-induced translocations in mouse stem cell spermatogonia using fluorescencein situ hybridization

The efficiency of two methods of detection of translocations induced in mouse stem cell spermatogonia by X-ray doses of 2, 5 and 7 Gy was compared: classical multivalent analysis at diakinesis-metaphase I of meiosis and observation via fluorescencein situ hybridization analysis of mitotic or meiotic stages. Specific DNA libraries for chromosomes 1, 11 and 13 were used. The results obtained indicate that (a) chromosomes 1, 11 and 13 are more involved in multivalent formation than expected on the basis of DNA content and (b) if the mitotic FISH analysis data are corrected for the observed over-representation, the frequencies of induced translocations are similar to those recorded in the classical multivalent studies, suggesting equal scoring efficiencies in both systems.     

烹调油烟致大小鼠肺癌的实验研究

[目的]了解烹调油烟（cooking oil fumes，COF）的动物致癌性。[方法]采用动式染毒法给Balb／c小鼠（雌雄各半）吸入COF浓度为9．09、20．65、38．85mg／m^3，染毒1次／1～2d，30min／次，共150次，计8个月；SD大鼠（雌雄各半）吸入COF浓度为6、88、15．06、35．33mg／m^3，染毒1次／2d，30min／次，共191次，计12．5个月。分别制备COF慢性中毒动物模型；两实验均设空白对照组，吸入与实验组相同温度的清洁空气。[结果]COF诱发Balb／c小鼠实验组肺癌总发生率为18、95％（29／153），低、中、高浓度组肺癌发生率分别为15．09％、20、00％和22．00％，与对照组差异均有显著性。但低、中、高三组间差异无显著性（P〉0．05）；COF诱发SD大鼠肺癌总发生率为9、10％（9／99），低、中、高浓度组肺癌发生率分别为6．45％、8．57％、12．12％，高浓度组肺癌发生率高于对照组（P〈0．05）。各性别组间肺癌发生率的差别无显著性（P〉0．05）。[结论]COF可以诱导Balb／c小鼠和SD大鼠肺癌，诱发的肺癌主要为肺腺癌（小鼠28／29，大鼠7／9），余为小细胞肺癌。     

Flerobuterol: a potential antidepressant drug related to β-adrenergic agonists. Experimental profile in mice

The potential antidepressant effect of flerobuterol (dl-(fluoro-2 phenyl)-1 t-butylamino-2 ethanol), a new drug related to beta-adrenoceptor agonists, was evaluated and compared with imipramine and salbutamol using classical psychopharmacological tests in mice. Like imipramine and salbutamol, flerobuterol (0.5-32 mg kg-1, ip) fully prevented apomorphine (16 mg kg-1, sc)- and partly reversed reserpine- and oxotremorine-induced hypothermia. At higher doses (16-32 mg kg-1), flerobuterol enhanced the toxic effects of yohimbine. Unlike imipramine, flerobuterol and salbutamol did not reduce immobility duration in the behavioural despair test. Salbutamol and flerobuterol decreased locomotor activity. Flerobuterol did not induce mydriasis, did not prevent oxotremorine-induced tremors or salivary and lacrimal gland secretion and did not reduce reserpine-induced palpebral ptosis. Propranolol (8 mg kg-1, ip) but not alpha-methyl-paratyrosine (75 mg kg-1, ip) prevented the flerobuterol-induced antagonism of apomorphine-induced hypothermia. Our results suggest that flerobuterol demonstrates potential antidepressant activity, which could be related to beta-adrenoceptor activation in mice.     

Golgi study on brain of macular mutant mouse as a model of Menkes kinky hair disease

Summary This study was undertaken to elucidate, using the Golgi method, the neuropathological change in the brain of the macular mutant mouse, whose hemizygote (Ml/y) is considered to be a model of Menkes kinky hair disease (MKHD). The hemizygote mice gradually lost weight after 10 days of age and died with emaciation and seizure around day 15. The normal littermate (+/y) was well developed. In the cerebrum, the arborization of pyramidal neurons in the layer V of the Ml/y was the same as that in the +/y on day 10. However, development of arborization in the Ml/y was delayed in comparison with that in the +/y on days 12 and 14. Purkinje cells with several somal sprouts were observed in the cerebellum in both the Ml/y and +/y on day 7. The somal sprouts in the +/y had regressed gradually by day 12, while they were still in the anterior and middle lobes of the Ml/y on day 14. Additionally, the trunks of Ml/y stem dendrites became thicker and a cactus formation was recognized on the branching portion of the dendrites on day 14. Arborization of these abnormal Purkinje cells was distinctly poor compared with that in the +/y. These results suggest that the growth of the neurons is delayed in the Ml/y and simultaneously their cytoskeletal developments are disturbed, especially in the Purkinje cells. There is a close similarity in many respects to the neuropathological change in MKHD.     

Quantification of Basal and Stimulated ROS Levels as Predictors of Islet Potency and Function

We have developed a luminol-based assay using intact islets, which allows for quantification of reactive oxygen species (ROS). In addition, an index capable of characterizing metabolic and mitochondrial integrity prior to transplantation was created based on the capacity of islets to respond to high glucose and rotenone (mitochondrial respiratory chain complex I inhibitor) by production of ROS. To validate this assay, lipid peroxidation and antioxidative defense capacity were evaluated by detection of malondialdehyde (MDA) levels and glutathione peroxidase activity (GPx), respectively. Also, flow cytometric analyses of ROS (dihydroethidine), apoptosis (Annexin V, active caspases), necrosis (Topro3), and mitochondrial membrane potential (JC-1) were done in parallel to correlate with changes in luminol-measured ROS. ATP/ADP ratios were quantified by HPLC and the predictive value of ROS measurement on islet functional potency was correlated with capacity to reverse diabetes in a streptozotocin-induced diabetic NOD.scid mouse model as well as in human transplant recipients. Our data demonstrate that levels of ROS in islets correlate with the percentage of apoptotic cells and their functional potency in vivo. The ROS indices following glucose and rotenone exposure are indicative of metabolic potency and mitochondrial integrity and can be used as surrogate markers to evaluate the quality of islets prior to transplantation.     

Histopathological characterisation of effects of the mouse Pax6 missense mutation on eye development

Mutations in PAX6/Pax6 lead to a variety of ocular anomalies in humans and mice. The aim of the study was to characterise the ocular abnormalities caused by the missense Pax6^Leca4 mutation and compare them to published observations on Pax6 alleles that are functionally equivalent to Pax6⁻ null alleles (such as Pax6^Sey and Pax6^Sey-Neu) and human inherited eye diseases. Ocular features of homozygous Pax6^Leca4/Leca4 and heterozygous Pax6^Leca4/+ embryos at E12.5-E18.5, heterozygous Pax6^Leca4/+ young mice at P18 and heterozygous Pax6^Leca4/+ adults at 12 weeks were analysed histologically with their wild-type Pax6^+/+ littermates. Homozygous Pax6^Leca4/Leca4 fetuses died perinatally with no eyes although an optic cup rudiment with pigmented cells developed. Pax6^Leca4/+ mice were microphthalmic and a range of other severe ocular phenotypes affected both the anterior and the posterior segments. In contrast to Pax6^+/−, the Pax6^Leca4/+ eyes had no goblet cells in the corneal epithelium, the iris was not hypoplastic and there was no lens-corneal epithelial plug. However, microphthalmia was more severe, corneal vascularisation occurred earlier (during fetal stages), pigmented cells were present in the vitreous and corneal stroma and the ciliary body was malformed or abnormal. These results show that, although Pax6^Leca4/+ lacked some eye abnormalities commonly seen in Pax6^Sey/+ and Pax6^Sey-Neu/+ eyes, in most respects their eyes were more severely affected. These differences probably reflect both differences between the Pax6^Leca4 and the Pax6^Sey-Neu mutations and differences in modifier gene expression in different genetic backgrounds. The presence of pigmented cells in the cornea is a novel observation. Some Pax6^Leca4/+ ocular abnormalities were similar to those present in human Peters' anomaly and persistent hyperplastic primary vitreous (PHPV) so Pax6^Leca4/+ mice provide a useful model for some inherited eye diseases.     

EDTA-induced urothelial cell shedding for the treatment of superficial bladder cancer in the mouse

AIM: The aim of this study was to determine the effect of intravesical EDTA instillation on the development of intravesically implanted tumor cells in normal mice. METHODS: The mouse bladder tumor (MBT-2) model was used in female C3H/eb mice to evaluate the amount of normal urothelial cell shedding, and the degree of tumor growth inhibition following intravesical EDTA instillation in comparison with phosphate-buffered saline (PBS) instillation. RESULTS: At 1 h after instillation, the number of urothelial cells aspirated was 500-1000 per PBS-treated mouse and 10,000-20,000 per EDTA-treated mouse (P < 0.00001). The bladder weight, which reflected the effect of the agent on the tumor, was similar in the untreated and PBS-treated mice (105.46 +/- 46 mg and 106.2 +/- 50 mg, respectively). It was significantly lower in the EDTA-treated mice (80.4 +/- 42 mg) (P = 0.0045). CONCLUSIONS: Intravesical administration of EDTA results in significant normal and neoplastic urothelial cell shedding. Intravesical irrigation with EDTA may prevent adherence of the malignant cells to the bladder wall following tumor resection.     

Correlation between 5-HT7 receptor affinity and protection against sound-induced seizures in DBA/2J mice

Audiogenic seizures can be induced in DBA/2J mice following intense auditory stimulation. A number of neurotransmitters, including 5-hydroxytryptamine (5-HT), are believed to be involved in mediating this effect since it has been shown previously that depletion of 5-HT or blockade of 5-HT receptors protects DBA/2J mice from these audiogenic seizures. The present study was undertaken to determine whether antagonism of the newly identified 5-HT₇ receptor may protect DBA/2J mice from audiogenic seizures by attempting to correlate in vivo potency of compounds with their affinity at the 5-HT₇ receptor. All compounds used in the correlation were shown to be antagonists at the 5-HT₇ receptor and a statistically significant correlation was observed between 5-HT₇ affinity and doses for half-maximal response (ED₅₀) for protection of DBA/2J mice from sound-induced seizures (r = 0.80; P < 0.05). No significant correlation was observed between in vivo activity and affinity at either 5-HT_1A, 5-HT_2A or 5-HT_2C receptors. It is also unlikely that interactions between the 5-ht₅ receptor will protect DBA/2J mice from audiogenic seizures since metergoline and mesulergine which are both active in this in vivo model have no affinity for the 5-ht₅ receptor. There are similarities between the pharmacology of the 5-HT₇ receptor and that of the 5-HT_1A receptor, however the correlation between the in vivo potency in DBA/2J mice and 5-HT_1A affinity was not significant. Furthermore, the 5-HT_1A receptor antagonist WAY 100135 did not protect DBA/2J mice from audiogenic seizures at doses that antagonise 5-HT_1A receptor-mediated effects in mice. These data suggest that antagonism of 5-HT₇ receptors may protect against audiogenic seizures in DBA/2J mice although a definitive conclusion must await studies with selective 5-HT₇ antagonists. Received: 20 March 1997 / Accepted: 10 August 1997