A conglomeration of preclinical models related to myocardial infarction

Cardiovascular diseases are the main source of death and morbidity in developed and developing nations. Animal models are required to propel our understanding of the pathogenesis, increase our knowledge, disease progress, and mechanism behind cardiovascular disorder, providing new approaches focused to improve the diagnostic and the treatment of these pathological conditions and additionally to test various therapeutic ways to deal with tissue regeneration and re-establish heart working following damage. A perfect model framework ought to be reasonable, effectively controlled, reproducible, and physiologically illustrative of human disease, show cardinal signs and pathology that resembles after the human ailment and ethically stable. The decision of selection of animal model should be considered precisely since it influences exploratory results and whether results of the research can be sensibly matched with the human. In this way, no specific technique splendidly reproduces the human disease, and relying upon the model, extra cost burden, resources, infrastructure and the necessity for technical hands, should also be kept under consideration. Here we have discussed and compiled various methods of inducing myocardial infarction in animals, basically by surgery, chemicals and through genetic modification, this may benefit the researchers in getting a complied data regarding various methods through which they can induce myocardial infarction in animals.

Protection Against Electroshock- and Pentylenetetrazol-induced Seizures by the Water Extract of Rehmannia glutinous can be Mediated through GABA Receptor-chloride Channel Complexes

Epilepsy is a brain disorder that affects millions of people worldwide. It is characterized by recurrent and unpredictable seizures that are usually controlled with antiepileptic/anticonvulsive drugs. However, most antiepileptic drugs produce various side effects such as tolerance and sedation. Thus, there is a growing interest for alternative anticonvulsive drugs, preferably from natural or herbal sources. In this study, we evaluated the anticonvulsive effects of Rehmannia glutinosa (RG). The anticonvulsive effect of RG extract was evaluated using electroshock- and chemical-induced seizure tests in mice. To identify its probable mechanism of action, the effects of RG extract on Cl− influx was measured in vitro. We found that RG extract has anticonvulsive effects against electroshock-induced seizures, as indicated by an increased seizure threshold in mice. The RG extract also decreased the percentage of seizure responses induced by the GABAergic antagonist, pentylenetetrazole. These results suggest that the anticonvulsive effects of RG extract are mediated through a GABAergic mechanism. In support of this mechanism, our in vitro test showed that RG extract increases intracellular Cl− influx. Furthermore, RG extract did not show sedative and/or muscle relaxant effects in the open-field and rota-rod tests. Altogether, these results confirm that RG extract could be a herbal anticonvulsant and a potential alternative for clinical use.

Feasibility of constructing keratectasia animal model using collagenase type Ⅱ / 中华实验眼科杂志

Background Keratoconus is a chronic and progressive non-inflammatory ectatic disorder characterized by corneal thinning and irregular corneal topography,and its pathgenesis is a hot topic.A suitable animal model of keratoconus is still lacking,which limits the progress of relevant research.Corneal ectasia is a main anatomical basis of keratoconus,so we assume that keratoconus model could be constructed by simulating corneal ectasia.Objective This study was to investigate the influence of collagenase type Ⅱ on biomechanical responses detected by corneal visualization Scheimpflug technology (Corvis ST) and the feasibility of construction of rabbit model of corneal ectasia using coliagenase type Ⅱ.Methods This study protocol was approved by Ethic Committee of Peking University First Hospital and followed the Statement about experimental animal use and care from Association for Research in Vision and Ophthalmology (ARVO).Keratectasia models were established in 10 right eyes of 10 New Zealand white rabbits by soaking 8 mm-diameter central cornea using collagenase type Ⅱ solution prepared by PBS solution containing 15％ dextran (200 μl of 5 mg/ml) for 30 minutes after epithelial debridement,and only 200 μl PBS solution containing 15％ dextran was used in the same way in the left eyes as controls.The average corneal curvature (Km) and central corneal thickness (CCT) were measured with hand-held electronic corneal curvature meter and corneal ultra-sonic pachymetry respectively before modeling and 14 days after modeling.Corneal biomechanical parameters and intraocular pressure were measured in vivo by using Corvis ST at day 14 after modeling.The rabbits were sacrificed at day 14 after modeling,and corneal sections were prepared for hematoxylineosin staining and transmission electron microscopic examination.Results There were no significant differences in Km and C CT between model group and control group before modeling (Km:[48.28±2.29] D vs.[48.82± 1.63] D;CCT:[356.50± 19.13] μm vs.[356.20±21.66] μm;both at P＞0.05).The Km increased to (48.87±2.27) D and CCT decreased to (340.40±19.84)μm at day 14 after modeling,which were significantly different from (46.86±1.47) D and (367.80±23.38)μm (both at P＜0.01).The maximal deformation amplitude of model group and control group was (1.25±0.07) mm and (1.15 ±0.13) mm,respectively,showing a considerable difference between them (t=2.65,P＜0.05).No significant differences were found in applanation 1/2 time,applanation 1/2 length,applanation velocity,radius of curvature and peak distance between the two groups (all at P＞0.05).The morphology and ultrastructure examinations revealed that the arrangement of collagen fibers was loose and disorder and the interfiber space was enlarged in comparison with control group.Conclusions Collagenase type Ⅱ can lower corneal biomechanical properties.Soaking of cornea with collagenase type Ⅱ may be a potential way to establish a keratectasia animal model.

The dynamic change of CD133 expression in chemical-induced liver carcinogenesis in mice / 肿瘤

Objective: To detect the dynamic change of expression of CD133, a marker of liver cancer stem cell, at different stages of liver carcinogenesis induced by chemicals in C57BL/6J mice. Methods: The tumorigenesis and the growth of chemical (diethylnirtosamine/carbon tetrachloride/ethanol)-induced primary HCC (hepatocellular carcinoma) in 50 male C57BL/6J mice were observed. Another 45 male C57BL/6J mice which had not been exposed to carcinogenic chemicals were used as the normal controls. The mice were randomly sacrificed every two weeks, and the liver tissues were removed to observe the change of pathology. The expression of CD133 mRNA was detected by RFQ-PCR (real-time fluorescent quantitative PCR), and the expression of CD133 protein was detected by immunohistochemistry and Western blotting. The percentage of CD133-positive cells was analyzed by FCM (flow cytometry). Results: The primary HCC was successfully induced in male C57BL/6J mice after chemical intervention for 20 weeks. The results of RFQ-PCR and FCM showed that the expression level of CD133 in the chemicalinduced group was obviously higher than that in the normal control group after 8 weeks (P < 0.05, P < 0.001). The expression level of CD133 kept on rising in the chemical-induced group as time progressed, and it was significantly higher at the 16th week than at earlier stages (P < 0.001). Western blotting result showed that the CD133 weak expression could be observed at the 4th week. As time progressed, the expression level of CD133 protein was gradually increased. The result of immunohistochemistry showed that the expressions of CD133 in the chemical-induced group were weakly, moderately and strongly positive at the 8th, 16th and 20th week, respectively; while the expression of CD133 was negative in the normal control group. Conclusion: The liver cancer stem cell marker CD133 is involved in the development and progression of liver cancer, and its expression level is gradually increased in the process of carcinogenesis. Copyright © 2012 by TUMOR.

Carcinogenesis of Murine Astrocytes in Culture

Astrocytes play important roles in normal brain development and the physiological processes. In particular, 30% of the brain volume consists of astrocytes, and they are the primary target cell in the brain for cellular injuries from chemical exposures. The present study attempts to establish an immortalized murine astrocyte cell line to study the mechanisms of chemical-induced carcinogenesis of astrocytes. Primary astrocytes isolated from mice were transfected with plasmid carrying the SV40 T antigen. Clonal cells obtained after G418 selection were continuously subcultured to establish an immortalized astrocyte cell line. The cell line was positive on GFAP expression and was sensitive to exposure to such chemicals as MNNG. Cells were treated with MNNG for 5 days, with doses ranging from 0.001ug/ml to 1ug/ml. Dose-dependent cellular transformations of astrocytes were observed. Treatments at 0.01ug/ml showed the most distinct characteristics of neoplastic transformation. Subsequent treatment with TPA produced higher levels of neoplastic cell transformation than MNNG treatment alone, as evidenced by increases of saturation density, soft-agar colony formation and cell aggregation. Promotional effects of TPA on cell transformation was further demonstrated by the shortening duration of foci appearance. Addition of hydrocortisone to the culture media resulted in further promotion of cell transformation in astrocytes treated with MNNG and TPA, suggesting that glucocortocoid also plays a role in the promotion of chemical-induced astrocyte transformation. The present study demonstrates that astrocytes are susceptible to chemical-induced carcinogenicity and subject to mechanisms of multistage carcinogenesis. Analysis of MNNG-transformed astrocytes showed that, while the expression of TGF-beta was decreased, expression of GFAP, IL-1betaand fibronectin were increased. The results suggest that these factors are associated with mechanisms of MNNG-induced astrocyte transformation and may be used as potential candidates for biomarkers representing astrocyte-related tumors and cell toxicities. The study showed scientific evidence that growth factors, cytokine and the extracellular matrix are involved in processes of chemical-induced transformation of astrocytes. In addition, the present work provided an excellent opportunity to develop an immortalized astrocyte cell line that can be used for studying mechanisms of astrocyte-related diseases.

p53 Suppressor Gene Ove rex p ression in the Cornea after Mechanical-and Chemical-induced Epithelial Injury

p53 suppressor gene expression and protein production increases in response to DNA damage and the subsequent cell cycle prolongation permits DNA repair or, in the severe cases, leads to apoptosis. These concepts led us to investigate the expression of p53 as a potential key regulator of DNA repair in the cornea after mechanical-and chemical-induced injury. Mechanical-induced injury was performed by denuding a4mmdiameter area of the central epithelium from the corneas of Sprague Dawley rats. Chemical-induced injury was performed by applying a 3.5 mmdiameter filter paper disc of saturated n-heptanol to the cornea. Samples were collected on the 1st 3rd and 7th day of treatment. We performed immunohistochemistry and Western blot analysis on corneal buttons. Control group did not receive any treatment. The immunohistochemical analysis demonstrated that p53 is localized in the anterior stromal keratocytes. Western blot analysis indicated p53 bandsin the lanes of the mechanically and the chemically injured corneas. Our results suggest that injury to the corneal epithelium triggers the activation of p53.

Hazardous effects of nickel and cobalt production on the eyes / 眼科

IN Jin Chuan Non-ferrous Mining Area, 414 workers in constant contact with nickel and cobalt production and 100 controls not in direct contact were studied ophthalmologically. At the production line, the air contents of Ni and Co were 2.7～18 and 3.69～11.1 times respectively higher than those in working areas of the controls, and the urine and hair contents of these elements in the workers were also significantly higher than those in the controls, in positive correlation with the air contents. In comparison with the controls, the workers manifested more serious limbal pigmentation in the cornea, conjunctivitis, and lens opactiy which, though positively correlated with the indices of Ni and Co, was of a mild nature that did not interfere with the visual function.

A Study of Epileptiform Hippocampal Unit Activity Induced by Introcerebroventrocular injection of Kainic Acid in the Awake Rat / 第三军医大学学报

After introcerebroventricular injection of kainic acid(KA) in the awake rat, three types of hippocampal unit responses, i. e- positive units, negative units and indifferent units, were recorded- Most positive units were hippocampal complex spike cells which correspond histologically to hippocampal pyramidal cells, and most hippocampal complex spike cells fired in positive bursts after KA treatment. In the early period after KA injection, the positive units were concentrated in CA3 area. It was suggested that:(1)the activities of positive units may be considered as the typical epileptiform hippocampal unit activity induced by KA, and the firing characteristics of the negative units may be the result of influence of hippocampal inhibitory interneurons or that of the excessive cellular depolarization;(2) the hippocampal pyramidal cells were more sensitive to the epileptogenic effect of KA than the hippocampal interneurons, and some pyramidal cells in CA3 area may serve as "pacemaker neurons" in KA induced epileptogenesis.