Genotoxicity assessment of three reference chemicals in rat hepatocytes by alkaline comet assay / 上海预防医学

Objective:To establish a comet test method for detection of genotoxicity of three reference chemicals in rat liver cells. Methods:6-10 week old Sprague Dawley rats were randomly divided into 4 groups， with normal saline （0.9% NaCl solution） as negative control group. Animals in three test groups were treated， respectively， with ethyl methanesulfonate （EMS） 200 mg/kg， N-methyl-N-nitrosourea （MNU） 50 mg/kg， and D-mannitol 2 000 mg/kg. There were 10 animals in each group， 5 males and 5 females. The animals received two times （21 h interval） of test compounds through intragastric administration， and their clinical symptoms and body weight changes were recorded during the experiment. The rats were sacrificed 3 h after the last exposure. The liver was weighed， then used to prepare single-cell suspensions for the alkaline comet test which determines the average tail DNA content percentage （DNA%） of hepatocytes and other comet indicators. Results:（1） D-mannitol， EMS and MNU did not show significant toxicity in the whole animal. （2） The mean values of tail DNA content percentage （DNA%） of rat hepatocytes in EMS ［（60.07±24.69）%］ and MNU ［（41.66±22.35）%］ groups were higher than that in the negative control group ［（2.32±1.39）%］ and the difference was statistically significant （P<0.05）. The difference between D-mannitol group ［（3.06±3.30）%］ and the negative control group was not significant （P>0.05）. Conclusion:This laboratory has established a comet test method using hepatocytes from treated rats. Among three testing chemicals， EMS and MNU have displayed genotoxicity by this assay， but no genotoxicity was observed in D-mannitol treated animals.

Some Chemical Carcinogens for Leukaemia Induction and Their Animal Models

Animal models have been providing invaluable contributions to the better understanding of mechanisms of cancer (including leukaemias) development and effectiveness of most of the treatments. Chemical carcinogens are generally used to study the biology of cancers including leukaemias in many animal models, including rats and mice. The studies in most cases are aimed at the development and evaluation of cancer treatments and preventions. Some of the most common chemical carcinogens used in animal models for leukaemias include N-ethyl-N-nitrosourea (ENU), N-methyl-N-nitrosourea (MNU), dimethyl benz(a)anthracene (DMBA) and benzo(a)pyrene (BaP). This review provides highlights on different animal models of leukaemia induced by the chemical carcinogens mentioned earlier, at the same time discussing the contributions of these models to the leukaemia diagnosis in laboratory animal models for subsequent development of treatment.

Development of a Post-vitrectomy Injection of N-methyl-N-nitrosourea as a Localized Retinal Degeneration Rabbit Model

Since genetic models for retinal degeneration (RD) in animals larger than rodents have not been firmly established to date, we sought in the present study to develop a new rabbit model of drug-induced RD. First, intravitreal injection of N-methyl-N-nitrosourea (MNU) without vitrectomy in rabbits was performed with different doses. One month after injection, morphological changes in the retinas were identified with ultra-wide-field color fundus photography (FP) and fundus autofluorescence (AF) imaging as well as spectral-domain optical coherence tomography (OCT). Notably, the degree of RD was not consistently correlated with MNU dose. Then, to check the effects of vitrectomy on MNU-induced RD, the intravitreal injection of MNU after vitrectomy in rabbits was also performed with different doses. In OCT, while there were no significant changes in the retinas for injections up to 0.1 mg (i.e., sham, 0.05 mg, and 0.1 mg), outer retinal atrophy and retinal atrophy of the whole layer were observed with MNU injections of 0.3 mg and 0.5 mg, respectively. With this outcome, 0.2 mg MNU was chosen to be injected into rabbit eyes (n=10) at two weeks after vitrectomy for further study. Six weeks after injection, morphological identification with FP, AF, OCT, and histology clearly showed localized outer RD - clearly bordered non-degenerated and degenerated outer retinal area - in all rabbits. We suggest our post-vitrectomy MNU-induced RD rabbit model could be used as an interim animal model for visual prosthetics before the transition to larger animal models.

Detection of N-ethyl-N-nitrosourea-induced Pig-a gene mutation in rats by immunomagnetic separation technique combined with flow cytometry / 中国实验动物学报

Objective To optimize the detection test of Pig-a gene mutation in peripheral blood of rats by enriching and detecting mutant erythrocytes, using immunomagnetic separation technique in combination with flow cytometry. Methods SD rats were administered with 20,40 and 80 mg/(kg·bw)doses of N-ethyl-N-nitrosourea(ENU) continually for 3 days. The peripheral blood samples of rats were collected on the 7th,14th and 28th days, respectively, after treatment. Immunomagnetic separation columns were used to enrich RETCD59- and RBCCD59- cells, and then flow cytometry was used to count the number of pre-column and post-column peripheral erythrocytes. Results Compared with the control group,the frequencies of RETCD59- and RBCCD59- were significantly increased in each ENU group(P<0.05). With immunomagnetic separation technique, the test of Pig-a gene mutation of a sample could be completed within 3 minutes,and the number of detected RETCD59- or RBCCD59-cells was up to 2×104or 9×104, respectively. Conclusions In this study,immunomagnetic separation in combination with flow cytometry is used to establish and optimize the Pig-a gene mutation test in rat peripheral blood,showing a high-throughput detection and improved accuracy and efficiency of the experiment.

Procarbazine and CCNU Chemotherapy for Recurrent Glioblastoma with MGMT Promoter Methylation

BACKGROUND: While procarbazine, CCNU (lomustine), and vincristine (PCV) has been an alternative chemotherapy option for malignant gliomas, it is worth investigating whether the combination of only procarbazine and CCNU is comparable because vincristine adds toxicity with uncertain benefit. The purpose of this study was to evaluate the feasibility of procarbazine and CCNU chemotherapy for recurrent glioblastoma multiforme (GBM) with O6-methylguanine-DNA-methyltransferase (MGMT) promoter methylation. METHODS: Eight patients with recurrent GBM following concurrent chemoradiotherapy and temozolomide (TMZ) adjuvant therapy were enrolled in this trial; they received no other chemotherapeutic agents or target therapy. They received CCNU (75 mg/m²) on day 1 and procarbazine (60 mg/m²) through days 11 and 24 every 4 weeks. The median cycle of CCNU and procarbazine was 3.5 (range: 2–6). RESULTS: One patient achieved stable disease. The median progression-free survival (PFS) with procarbazine and CCNU chemotherapy was eight weeks (range: 5–73), and the PFS rates were 25% and 12.5% at 16 and 30 weeks, respectively. The median overall survival (OS) from the initial diagnosis to death was 40 months, and the median OS from the administration of procarbazine and CCNU chemotherapy to death was 9.7 months (95% confidence interval: 6.7–12.7). Serious adverse events were found at six visits, and two cases were considered to be grade 3 toxicities. CONCLUSION: The efficacy of procarbazine and CCNU chemotherapy is not satisfactory. This study suggests the need to develop other treatment strategies for recurrent and TMZ-refractory GBM. Trial registry at ClinicalTrials.gov, NCT017337346.

Therapeutic effects of mesenchymal stem cells (MSCs) on N-methyl-N-nitrosourea (MNU)-induced retinitis pigmentosa in C57BL mice / 眼科新进展

Objective To investigate the therapeutic effects of mesenchymal stem cells (MSCs) on N-methyl-N-nitrosourea (MNU)-induced retinal degeneration in C57BL mice.Methods Different doses of MNU (30 mg · kg-1,45 mg · kg-1,60 mg · kg-1,75 mg · kg-1 and 90 mg · kg-1) were injected to C57BL mice for 7 days.Then electroretinogram (ERG) detection and HE staining were performed to examine retinal electrophysiological function and morphological changes on day 1,day 3 and day 7 after MNU treatment,respectively.Then we could explore the optimum condition to establish stable animal model of retinitis pigmentosa.MSCs were transplanted to C57BL mice by intravitreal or tail intravenous injection.Then ERG detection and HE staining were performed to evaluate the effect of MSCs on retinitis pigmentosa induced by MNU.Results When compared with control group,30 mg · kg-1 and 45 mg · kg-1 MNU could cause mild retinal damage in morphology and function in mice;while 60 mg · kg-1 and above dose of MNU induced serious retinal damage,leading to decreased ERG amplitude of the retina (all P ＜ 0.001) and outer nuclear layer (ONL) thickness (all P ＜ 0.001).On day 1 and day 3 after single dose of 60 mg · kg-1 MNU injection,ERG amplitude of the retina was decreased,and outer nuclear layer thickness became thin;while the retinal damage was serious badly in morphological structure on day 7,with the ERG amplitude extinguished (all P ＜ 0.001),ONL thickness thin (all P ＜ 0.001) and internal and external nuclear layer fusion.When compared with MNU alone treatment group,following injection of 60 mg · kg-1 MNU for 1 day MSCs were transplanted to C57BL mice by intravitreal or tail intravenous injection,and the amplitude of ERG and retinal ONL thickness were increased on day 7 after MSCs transplantation (all P ＜ 0.001).Conclusion MSCs transplantation has a certain therapeutic effect on MNU-induced retinitis pigmentosa in C57BL mice.

Helicobacter pylori combined with MNU gavage for preparing balb/c mouse gastric cancer model / 重庆医学

Objective To investigate Helicobacter pylori combined with N-methyl-N-nitrosourea (MNU) gavage for preparing balb/c mouse gastric cancer model.Methods Eighty balb/c mice were randomly divided into four groups after 1-week adaptive feed,normal group,model group Ⅰ,Ⅱ and Ⅲ,20 cases in each group.The model group Ⅰ,Ⅱ and Ⅲ were given Helicobacter pylori bacteria liquid (CFU=109/mL) gavage,once every other day for 5 times;then,the freshly configured MNU solution 0.15,0.3,0.6 mL gavages were in turn given,MNU and pure water allocation ratio was 5mg:3mL.Once gavage per week for continuous 10 weeks.Results The model group II had 66.67% adenocarcinoma,the model group I were gastritis with mild atypical hyperplasia,and all mice in the model group III died.Conclusion This method can prepare the gastric cancer model.

Nestin Expression in the Adult Mouse Retina with Pharmaceutically Induced Retinal Degeneration

The present study investigated the temporal pattern and cellular localization of nestin in the adult mouse retina with pharmaceutically induced retinal degeneration using N-methyl-N-nitrosourea (MNU). After a single intraperitoneal injection of MNU in 8-week-old C57BL/6 mice, the animals were sacrificed at 1, 3, 5, 7, and 21 days (n = 6, in each stage). The eyes were examined by means of immunohistochemical tests using nestin, ionized calcium-binding adaptor molecule (Iba-1), CD11b, F4/80, and glial fibrillary acidic protein (GFAP). Western blot analysis and manual cell counting were performed for quantification. Nestin expression was increased after MNU administration. Nestin+/Iba-1+ cells were migrated into outer nuclear layer (ONL) and peaked at day 3 post injection (PI). Nestin+/CD11b+ cells were also mainly identified in ONL at day 3 PI and peaked at day 5. Nestin+/F4/80+ cells were shown in the subretinal space and peaked at day 3 PI. Nestin+/GFAP+ cells were distinctly increased at day 1 PI and peaked at day 5 PI. The up-regulation of nestin expression after MNU administration in adult mouse retinal microglia, and monocyte/macrophage suggests that when retinal degeneration progresses, these cells may revert to a more developmentally immature state. Müller cells also showed reactive gliosis and differentiational changes.

Establishment of rat model of orthotopic bladder cancer induced by MNU and diagnosis value of MRI / 吉林大学学报(医学版)

Objective:To construct the rat models of orthotopic bladder cancer induced by N-methyl-nitrosourea (MNU),and to evaluate the value of magnetic resonance imaging (MRI)in the noninvasive diagnosis of the bladder cancer model.Methods:Sixty femail SD rats were divided into experiment group (n=45)and control group (n=15).The rats experiment group were induced with MNU (2 mg per rat)by intravesical administration every other week,for 4 times.Meantime,the rats in control group were treated with normal saline (0.2 mL per rat)by intravesical administration.At the end of the 14th week,all rats were examined by MRI and the pathological changes of bladder tissue were detected.Results:In experiment group,43 rats were alived and 2 rats were died at the end of the 14th week;the survial rate was 95.6% and the death rate was 4.4%;the abnormal signals were found in each of 43 rats by MRI which manifested as bladder tumor, and the same results were identified by pathology;the tumor formation rate was 100%.In control group,14 rats were alived and 1 rat was died at the end of the 14th week;the survival rate was 93.3%,and the death rate was 6.7%;there was no abnormal signal in the MRI examination and no bladder cancer in the pathological examination;the tumor formation rate was 0.The tumor formation rates of bladder cancer of the rats in two groups had significant difference (P 0.05).Conclusion:The method to establish the rat models of orthotopic bladder cancer induced by MNU is simple and reliable;the results of MRI are consistent with the pathological results and MRI examination is a reliable diagnostic method concerning this model.

Expression changes of Rhodopsin and recoverin in MNU-induced photoreceptor degeneration in rats / 国际眼科杂志(Guoji Yanke Zazhi)

AIM: To investigate the time - effect relationship between the expression of rhodopsin and recoverin and photoreceptor damage induced by N - nethl - N -nitrosourea ( MNU) . METHODS: Thirty-six 7-week old Sprague-Dawley ( SD ) rats were intraperitoneally injected with MNU ( 60mg/kg ) and were put to death by dislocation of cervical vertebra 6, 12, 24h; 3, 7d after injection ( 6 per group) , respectively. As a control, six rats were injected with phosphate buffer saline (PBS) 5mL/kg and sacrificed on d3 after injection. The degree of photoreceptor apoptosis was detected by HE staining, terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling ( TUNEL ) and transmission electron microscope ( TEM ) in the right eyes. The mRNA expressions of rhodopsin and recoverin were detected different time after injection by Western blot and immunohistochemical method in the left eyes. RESULTS:The dissolution of photoreceptor nucleus and apoptosis body were first perceived at 12h by TEM; most of cells at outer nuclear layer were presented positive reaction. The apoptotic index reached peak ( 29. 7% ±2.3%) at 24h which was coincided with the observation of TEM. The results of immunohistochemistry displayed that rhodopsin and recoverin were on a declining curve with time extension. Furthermore, the results of Western blot indicated that rhodopsin had dramatic decline at 6h after injection (P CONCLUSION:60mg/kg MNU intraperitoneally injection one - time may specifically induce photoreceptor apoptosis, The mechanism of down - regulation of rhodopsin and recoverin may be related to the selected apoptosis of photoreceptors.

Microarray expression analysis of the N-methyl-N-nitrosourea-induced retinal degeneration in rat / 中华实验眼科杂志

Background The rat model of N-methyl-N-nitrosourea (MNU)-induced photoreceptor cell apoptosis is often used to study retinal degeneration.But the changes in the gene expression patterm in retinal degeneration in rats have not been reported.Objective This study was undertaken to investigate regulation of gene expression in the retina of MNU-induced retinal degeneration in rats by performing microarray analysis of retinal RNA.Methods Fifty 6-week-old SD rats were numbered and randomized into the normal group and the model group.The retinal degeneration model was established by a single hypodermic injection of 40 mg/kg of MNU,and the rats in the normal group received equivalent volume of physiological saline in the same way.The rats were sacrificed 12 hours or 24 hours after injection.Retinal sections from the right eyes were prepared for the measurement of the retinal thickness by histopathological examination,and retinas from the left eyes were used to confirm the differential gene expression as detected by microarray (normal group and 12 hours model group).Genes exhibiting changes in expression by ≥2.0 folds were further confirmed using real-time PCR.Results The whole thickness of the retina declined in the rats from the 24 hours model group compared to the normal group and 12 hours model group (t =9.926,P=0.002;t=2.736,P=0.028).The thickness of the outer nuclear layer was (26.58±2.90) μm in the 24 hours model group,showing a significant decrease in comparison with (38.11 ± 1.01) μm in the normal group and (35.07t3.03) μm in the 12 hours model group (t=6.028,P=0.009;t=6.839,P=0.006).However,there was no significant difference in retinal thickness between the normal group and the 12 hours model group (whole thickness:t=1.541,P=0.324;outer nuclear layer thickness:t=2.040,P=0.134).Microarray analysis of the rat genes showed that out of 17 000 genes,142 genes involved in biological process and 94 genes involved in molecular functions were differentially expressed,where most of them participate in the mitogen activated protein kinase signaling pathway,Tolllike receptor signaling pathway and apoptosis pathway.Real-time PCR analysis demonstrated that the expression of CCL2,IL-1b,CCL3,c-fos,c-myc,p53 and MMP3 were consistently up-regulated,conforming with the results from microarray analysis.Conclusions The changes in gene expression pattern appear in the early stage of MNUinduced retinal degeneration.These microarray results provided clues to understanding the molecular pathways underlying photoreceptor degeneration and indicating the directions for future studies.

Effect of N-ethyl-N-nitrosourea on the fatality, recovery of fertile period and breeding record in C57BL/6J mice / 동물의과학연구지

N-ethyl-N-nitrosourea (ENU) is a potent mutagen in a mouse model by inducing point mutation in a random manner and, in particular, causing heritable base substitutions in spermatogonia. In this study, systematic development of phenotype-driven mutant mice with large scale was carried out by using ENU. Nine-week-old male mice of C57BL/6J received intraperitoneal injection at three times with 100 mg/kg of ENU at weekly intervals for three weeks. After injections with ENU, the changes of body weight, fatality, recovery of fertile period, and breeding record were measured in these mice. Body weight lost as a result of ENU treatments was reversed after the last ENU injection. Live fertile male mice recovered from infertility from 104 to 165 days after ENU treatments were mated with C57BL/6J female mice for generation of G1 offspring. An average birth rate was 5.9 mice from 1 pair of paternal and maternal mice. All of 231 G1 offspring mice were analyzed by modified-SHIRPA with standard procedure at nine weeks of age. Among G1 mice, 166 mice were identified as mutagenic phenotypes in 20 test items. The changes in mutagenic phenotypes after ENU treatments, for instance, pattern in the region with a different color, touch escape, changes in head morphology, pupil, and teeth, and negative geotaxis etc., were found in these mice. Taken together, these results indicate that ENU may be a trans-generational mutagen in C57BL/6J mice.

Brain tumor and Gliadel wafer treatment.

Glioblastoma is a rapidly progressive and extremely fatal form of brain tumor with poor prognosis. It is the most common type of primary brain tumor. Even with the most aggressive conventional treatment that comprises surgery followed by radiotherapy and chemotherapy, most patients die within a year of diagnosis. Developments in molecular and cell biology have led to better understanding of tumor development, leading to novel treatment strategies including biological therapy and immunotherapy to combat the deadly disease. Targeted drug delivery strategies to circumvent the blood-brain barrier have shown efficiency in clinical trials. Gliadel wafer is a new approach to the treatment of glioblastoma, which involves controlled release delivery of carmustine from biodegradable polymer wafers. It has shown promising results and provides a silver lining for glioblastoma patients.

Preventive and therapeutic effects of curcumin on bladder cancer in rats / 肿瘤

Objective: To establish N-methyl-N-nitrosourea (MNU)-induced bladder cancer model in Wistar rats, and to investigate the preventive and therapeutic effects of curcumin on bladder cancer, as well as to explore its potential mechanism. Methods: The bladder cancer in Wistar rats was induced by intravesical infusion of 1.5 mg MNU at 0, 2, 4, 6 and 8 weeks. The rats were divided into two groups, including the preventive group [receiving 0.2 mL curcumin (160 μmol/L) at 1, 3, 5, 7 and 9 weeks] and the therapeutic group [receiving 0.2 mL curcumin (160 μmol/L) at 10, 12, 14, 16 and 18 weeks]. The rats in the preventive group and the therapeutic group were sacrificed at 13 weeks and 23 weeks, respectively. The bladder cancer tissues were stained with hematoxylin and eosin (HE) for pathological examination. The apoptosis of tumor cells in the bladder cancer tissues was detected by fluorescence staining. Results: In the preventive group, three rats developed bladder cancer at 13 weeks (23.1%, 3/13), and the muscle invasion of superficial transitional cell carcinoma of bladder (TCC) was not observed. In the vehicle control group, the incidence of bladder cancer was 66.7% (8/12). Six rats had superficial TCC, and two rats had TCC with muscle invasion. There were significant differences in the incidence and histologic staging of bladder cancer between the preventive group and the vehicle control group. The pathological results of the preventive group revealed that curcumin could not decrease the histologic stage of the developed cancer, but evidently increase the apoptosis rate of bladder cancer cells. Conclusion: Curcumin can effectively inhibit the tumorigenicity and progression of rat bladder cancer induced by MNU, and this mechanism may be related to apoptosis of tumor cells, but it has no effect on the developed bladder cancer. Copyright© 2011 by TUMOR.

Damage of photoreceptor cells by N-methyl-N-nitrosourea in cats / 中华实验眼科杂志

Background To establish the ideal animal model of retinitis pigmentosa (RP) is very important for onward relevant study.Previous research determined that N-methyl-N-nitrosourea (MNU) can selectively damage photoreceptors via intravenous injection in mammal.However,whether MNU can be used to create an RP model needs to be investigated.Objective This experiment was designed to evaluate the toxic effect of MNU on photoreceptor cells of cats.Methods MNU was injected into 20 2-year-old cats via femoral vein and randomized into 20mg/kg, 25mg/kg, 30mg/kg, 35mg/kg and 40mg/kg MNU groups,and equal amount of normal saline solution was used in the same way in 4 normal cats as the control group.The activity,pupil size and light reflex were observed after injection of MNU.The cats were sacrificed and eyeballs were enucleated for histological examination to evaluate the structural and morphological changes of photoreceptors at 24 hours,72 hours,7 days and 14 days after the administration of MNU.This experimental study complied with the Statement for the Use of Animals in Ophthalmic and Vision Research.Results Dilated pupil and inertia of light reaction were found in experimental cats on the 7th days in the various groups.In 24 hours after MNU injection,the damage of photoreceptors was primarily characterized by pyknosis and disorder.In 72 hours after MNU injection,attenuation of the outer nuclear layer and disruption of cells were seen.Loss of photoreceptors and disappearance of the outer nuclear layer were observed on the 7th and 14th day.The extent of retinal photoreceptor cell damage was dependent on the dose of MNU.Conclusion MNU can selectively induce serious damage of the photoreceptor cells in cats retina in a time- and dose-dependent manner.

Morphological and functional evaluation of an animal model for the retinal degeneration induced by N-methyl-N-nitrosourea / 대한해부학회지

The retinal degeneration (RD) is a general cause of blindness. To study its pathophysiology and evaluate the effects of new therapeutic agents before clinical trials, it is essential to establish reliable and stable animal models. This study evaluated a RD animal model in which blindness was induced by N-methyl-N-nitrosourea (MNU), a potent retinotoxin leading to apoptosis of photoreceptors. MNU was applied to the Sprague-Dawley rats by a single intraperitoneal injection in different doses (40, 50, and 60 mg/kg). The retinal functions were examined at 1 week after MNU injection by electroretinogram (ERG). Afterwards, each retina was examined by hematoxylin and eosin stain and immunohistochemistry with anti-glial fibrillary acidic protein antibody. Upon MNU injection of 40, 50 and 60 mg/kg, the ERG amplitude of a-waves showed significant reductions of 7, 26, and 44%, respectively, when compared to that of normal a-waves. The b-wave amplitudes were about 89, 65, and 58% of normal b-waves in the response to scotopic light stimulus. At 1 week, 2 weeks, and 4 weeks after MNU injection (50 mg/kg), all scotopic ERG components decreased progressively. In addition, degeneration of retinal neurons was observed in a time- and dose-dependent manner after MNU injection. Taken together, functional reduction following RD induced by MNU correlates with morphological changes. Thus, this RD rat model may be a useful model to study its pathophysiology and to evaluate the effects of new therapeutic agents before clinical trials.

Establishment and CT Diagnosis of Orthotopic Rat Model of Bladder Cancer / 中国实验动物学报

Objective To establish an orthotopic rat model of bladder cancer induced by N-methyl.nitrosourea (MNU)and to evaluate the diagnostic value of CT(computed tomography)scanning in this experimental model.Methods 50 SD rats were randomly divided into the control group(group A)with 15 rats and experimental group(group B)with 35 rats.Each rat of group B was treated with 2 mg MNU per dose every other week,totally 4 doses,by per urethra administration.Meanwhile,each rat of group A was treated with normal saline.Then,at the 14th week,all the rats were evaluated by CT scanning and pathological examination.Results Abnormal changes were detected in each of the 28 rats in group B by CT scanning,and manifested as local mass,thickening bladder wall accompanied with heterogeneous density.Bladder cancer was diagnosed by pathology.However,no bladder tumor was detected by CT scanning and pathologicalexamination in group A.Conclusion A rat model of orthotopic bladder cancer can be established by per urethra administration of MNU.CT scanning is a reliable diagnostic technique concerning this model.Furthermore,this technique can render US a more suitable rat model for further experimental studies on chemotherapy and radiotherapy of bladder Cancer.

Pharmacokinetics of BCNU-PLA Delayed Release Wafer Embedded in Brain of Dogs / 中国康复理论与实践

@#Objective To observe the pharmacokinetics and concentration of 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) in brain tissue after BCNU-polylactic acid (PLA) delayed release wafer embedded in brain tissues of dogs.Methods 10% BCNU-PLA delayed release wafer were prepared and embedded in brains of 12 dogs. Peripheral blood of dogs was taken and the animals were executed for brain tissue after surgery in different times. BCNU concentrations in blood and brain tissue were quantified by high-performance liquid chromatography.Results BCNU was able to be detected at 22nd hour, and the Cmax (average 243.64 ng/ml) appears at 35th hour after surgery. The average BCNU concentration in brain tissue was 26.60 μg/g at 5th day after surgery.Conclusion BCNU-PLA delayed release wafer is a useful type for treatment of malignant gliocoma.

Point Mutation of Hoxd12 in Mice

PURPOSE: Genes of the HoxD cluster play a major role in vertebrate limb development, and changes that modify the Hoxd12 locus affect other genes also, suggesting that HoxD function is coordinated by a control mechanism involving multiple genes during limb morphogenesis. In this study, mutant phenotypes were produced by treatment of mice with a chemical mutagen, N-ethyl-N-nitrosourea (ENU). We analyzed mutant mice exhibiting the specific microdactyly phenotype and examined the genes affected. MATERIALS AND METHODS: We focused on phenotype characteristics including size, bone formation, and digit morphology of ENU-induced microdactyly mice. The expressions of several molecules were analyzed by genome-wide screening and quantitative real-time PCR to define the affected genes. RESULTS: We report on limb phenotypes of an ENU-induced A-to-C mutation in the Hoxd12 gene, resulting in alanine-to-serine conversion. Microdactyly mice exhibited growth defects in the zeugopod and autopod, shortening of digits, a missing tip of digit I, limb growth affected, and dramatic increases in the expressions of Fgf4 and Lmx1b. However, the expression level of Shh was not changed in Hoxd12 point mutated mice. CONCLUSION: These results suggest that point mutation rather than the entire deletion of Hoxd12, such as in knockout and transgenic mice, causes the abnormal limb phenotype in microdactyly mice. The precise nature of the spectrum of differences requires further investigation.

Expression of immediate early gene following N-methyl-N-nitrosourea-induced retinal degeneration in SD rats / 中国药理学通报

Aim To study the molecular mechanism of retinal toxicity induced by N-methyl-N-nitrosourea (MNU) in SD rats. Methods A single intraperitoneal injection of 60 mg?kg~(-1) MNU was given to 50-day-old female SD rats. After MNU treatment for different times, the rats were sacrificed and both eyes were enucleated immediately and processed for histological examination. The apoptotic index of photoreceptor cells was calculated by TUNEL labeling and the expression of c-jun and c-fos genes was detected by RT-PCR technique. Results After the application of MNU for 24 h,the disorientation of photoreceptor outer segments was seen. The outer nuclear layer and photoreceptor layer were almost completely lost at 7 d. Apoptosis had already started at 12 h post-MNU and peaked at 24 h. MNU time-dependently up-regulated the expression of c-jun and c-fos genes. Conclusion MNU has a toxic effect on retina by up-modulating expression of c-jun and c-fos genes to promote photorecptor cells apoptosis.