Globular adiponectin protected ob/ob mice from diabetes and ApoE-deficient mice from atherosclerosis

The adipocyte-derived hormone adiponectin has been shown to play important roles in the regulation of energy homeostasis and insulin sensitivity. In this study, we analyzed globular domain adiponectin (gAd) transgenic (Tg) mice crossed with leptin-deficient ob/ob or apoE-deficient mice. Interestingly, despite an unexpected similar body weight, gAd Tg ob/ob mice showed amelioration of insulin resistance and beta-cell degranulation as well as diabetes, indicating that globular adiponectin and leptin appeared to have both distinct and overlapping functions. Amelioration of diabetes and insulin resistance was associated with increased expression of molecules involved in fatty acid oxidation such as acyl-CoA oxidase, and molecules involved in energy dissipation such as uncoupling proteins 2 and 3 and increased fatty acid oxidation in skeletal muscle of gAd Tg ob/ob mice. Moreover, despite similar plasma glucose and lipid levels on an apoE-deficient background, gAd Tg apoE-deficient mice showed amelioration of atherosclerosis, which was associated with decreased expression of class A scavenger receptor and tumor necrosis factor alpha. This is the first demonstration that globular adiponectin can protect against atherosclerosis in vivo. In conclusion, replenishment of globular adiponectin may provide a novel treatment modality for both type 2 diabetes and atherosclerosis.     

Lessons from the gastrin knockout mice

The gastrointestinal hormone, gastrin, was discovered a century ago as the second hormone in history. Subsequently, gastrin peptides have been identified and the genes encoding the hormone as well as its receptor have been cloned in several mammalian species including the mouse. This has facilitated the development of gastrin and gastrin receptor deficient mice as models for genetic dissection of the role of gastrins in maintaining gastric homeostasis and control of acid secretion. The gastrin knockout mice are achlorhydric due to inactivation of the ECL and parietal cells. Moreover, this achlorhydria is associated with the development of intestinal metaplasia and bacterial overgrowth, which ultimately lead to development of gastric tumors. Outside the stomach, gastrin deficiency alters pancreatic islet physiology and is associated with a moderate fasting hypoglycemia in the fasting state. But lack of gastrin does not impair islet regeneration. The association between progastrin, progastrin-derived processing intermediates and colorectal carcinogenesis has also been examined through genetic or chemical cancer induction in several mouse models, although the clinical relevance of these studies still remains to be proven. While others have focused on models of increased gastrin production, the present review will describe the lessons learned from the gastrin deficient mice. These mice help understand how dysregulation of gastrin secretion may be implicated in human disease.     

Genomic imprinting--insights from studies in mice

A subset of mammalian genes is controlled by genomic imprinting. This process causes a gene to be expressed from only one chromosome homologue depending on whether it originally came from the egg or the sperm. Parental origin-specific gene regulation is controlled by epigenetic modifications to DNA and chromatin. Genomic imprinting is therefore a useful model system to study the epigenetic control of genome function. Here we consider the value of the mouse as an experimental organism to address questions about the role of imprinted genes, about the regulation of mono-allelic gene expression and about the evolution of the imprinting function and mechanism.     

Liver damage from cocaine in mice

Four daily injections of 20 mg per kg cocaine hydrochloride into B6AF₁/J mice produced focal necrosis of liver parenchymal cells in the midzonal region. Massive liver damage and marked elevation of serum glutamic-oxaloacetic transaminase was observed after a single injection of 50 mg per kg cocaine-HC1. This damage led to increased sleep time after pentobarbital, and a decreased rate of pentobarbital metabolism $\text{in vivo}$.     

Paramutation: from maize to mice

Paramutation is the epigenetic transfer of information from one allele of a gene to another to establish a state of gene expression that is heritable for generations. RNA has recently emerged as a prominent mediator of this remarkable phenomenon in both maize and mice.     

Cell surface phenotype of lymphoid cells from normal mice and mice treated with monoclonal anti-IgD from birth

Mice treated from birth with mouse monoclonal anti-IgD antibodies develop low frequencies of B cells in the spleen, a small percentage of which express very low levels of sIgD on their cell surface and extremely low frequencies of B cells in their lymph nodes, lacking sIgD entirely. However, the splenic B cells are phenotypically mature in that a high percentage of these cells express Lyb-5, indicating that the expression of sIgD is not a prerequisite for the acquisition of a mature surface antigen repertoire of B cells. In contrast, a high density of sIgM on splenic B cells is expressed, which suggests a predominance of cells with the phenotype of immature B cells and/or activated B cells. Furthermore, the spleen cells from anti-IgD-treated mice lack cells that respond to in vitro stimulation by LPS with an increase in the density of their sIa.     

Exosomes from Plasmodium yoelii-infected reticulocytes protect mice from lethal infections

Exosomes are 30-100-nm membrane vesicles of endocytic origin that are released after the fusion of multivesicular bodies (MVBs) with the plasma membrane. While initial studies suggested that the role of exosomes was limited to the removal of proteins during the maturation of reticulocytes to erythrocytes, recent studies indicate that they are produced by different types of cells and are involved in promoting inter-cellular communication and antigen presentation. Here, we describe the isolation and characterization of exosomes from peripheral blood of BALB/c mice infected with the reticulocyte-prone non-lethal Plasmodium yoelii 17X strain. Importantly, proteomic analysis revealed the presence of parasite proteins in these vesicles. Moreover, immunization of mice with purified exosomes elicited IgG antibodies capable of recognizing P. yoelii-infected red blood cells. Furthermore, lethal challenge of immunized mice with the normocyte-prone lethal P. yoelii 17XL strain caused a significant attenuation in the course of parasitaemia, increased survival time, and altered the cell tropism to reticulocytes. These results were obtained also when the exosomes were isolated from a P. yoelii-infected reticulocyte culture indicating that reticulocyte-derived exosomes carry antigens and are involved in immune modulation. Moreover, inclusion of CpG ODN 1826 in exosome immunizations elicited IgG2a and IgG2b antibodies and promoted survival, clearance of parasites and subsequent sterile protection of 83% of the animals challenged with P. yoelli 17XL. To our knowledge, this is the first report of immune responses elicited by exosomes derived from reticulocytes opening new avenues for the modulation of anti-malaria responses.     

Enzyme levels in homogenates of liver from mice infected with Schistosoma mansoni and from uninfected mice

Enzymatic and histopathological study of the livers of 300 white mice infected with Egyptian strain of Schistosoma mansoni and of 100 noninfected control animals was carried out for a follow up period of 6 months.Significant diminution of pseudocholine esterase activity was noticed as early as the second week after infection, denoting defective synthetic function of the liver. Significant decrease of transaminases was also noticed during the fifth week, and showed correlation with the histopathological findings of cell necrosis. Glutamic oxalacetic transaminase appears to be a better index of liver cell integrity than glutamic pyruvic transaminase.Lactic dehydrogenase was only moderately diminished during the third and fourth months.Alkaline phosphatase was strikingly increased in hepatic schistosomiasis and occurred as early as the second week. Increased enzyme production and release in the circulation has been suggested.These results confirm the affection of the liver cell during infection with Schistosoma mansoni.     

Ultrastructure of diaphragm from dystrophic alpha-sarcoglycan-null mice

alpha-Sarcoglycan is a 50 kDa single-pass transmembrane glycoprotein exclusively expressed in striated muscle that, together with beta-, gamma-, and delta-sarcoglycan, forms a sub-complex at the muscle fibre cell membrane. The sarcoglycans are components of the dystrophin-associated glycoprotein (DAG) complex which forms a mechanical link between the intracellular cytoskeleton and extracellular matrix. The DAG complex function is to protect the muscle membrane from the stress of contractile activity and as a structure for the docking of signalling proteins. Genetic defects of DAG components cause muscular dystrophies. A lack or defects of alpha-sarcoglycan causes the severe type 2D limb girdle muscular dystrophy. alpha-Sarcoglycan-null (Sgca-null) mice develop progressive muscular dystrophy similar to the human disorder. This animal model was used in the present work for an ultrastructural study of diaphragm muscle. Diaphragm from Sgca-null mouse presents a clear dystrophic phenotype, with necrosis, regeneration, fibre hypertrophy and splitting, excess of collagen and fatty infiltration. Some abnormalities were also observed, such as centrally located nuclei of abnormal shape, fibres containing inclusion bodies within the contractile structure, and fibres with electron-dense material dispersed over almost the entire cell. Additionally, unusual interstitial cells of uncertain identity were detected within muscle fibres. The abnormal ultrastructure of the diaphragm from Sgca-null mice is discussed.     

利用转基因小鼠及转染色体小鼠产生人抗体的研究进展

自单克隆抗体（mAb)技术问世以来,解决了生命科学的许多重要问题,但其鼠源生导致的HAMA反应在大大限制了它在人体治疗中的应用,因此,制备人抗体成了亟待解决的难题,转入Ig基因组小鼠与转梁色体小鼠 的构建成功为解决这一难题提供了可行途径,本文就这两条小鼠的构建及其在制备人抗体中的应用进展作一综述。     

Hematopoietic stem cells from mice with erythroblastosis

The infection of newborn mice with a mouse erythroblastotic virus increases the number of hematopoietic stem cells in the spleen. Upon retransplantation of these stem cells into intermediate recipient mice certain growth parameters (doubling time, self renewal and extinction probability, etc.) which are abnormal when measured by techniques which avoid the intermediate recipient step, appear to be reverted toward normal values. The “normalization” of the stem cells is explained by the change in the environment supporting CFU growth during transplantation.     

Cloned mice derived from somatic cell nuclei

In 1997, a cloned sheep "Dolly" was produced by nuclear transfer of somatic cell. The first birth of cloned mice derived from some somatic cells were succeeded in 1998. At present, it is shown that somatic cells, cumulus cells, fibroblasts and Sertoli cells can be used to the study of cloned animal as nuclear donor. In this study investigation was designed to compare with efficiency on the production of cloned embryos by using the microinjection and the electrofusion methods for nuclear transfer. Oocyte enucleation was performed with a micromanipulator. The oocyte was held by holding pipette, and was enucleated using a beveled pipette. Microinjection method: Cell's nucleus injection was carried out by piezo-micromanipulator. Cytochalasin B treated cumulus cell was aspirated into a injection pipette, and was broken its plasma membrane using the injection pipette. Then, the cumulus cell was injected into the enucleated ooplasm directly. Electrofusion method: The cell was aspirated into a beveled pipette, and then an aspirated cell was inserted into perivitelline space. Then, the pair of enucleated oocyte and cell was fused using electrical cell fusion apparatus. The reconstituted embryos were activated after nuclear transfer using St2+. Reconstituted embryos had been produced by the microinjection showed the embryonic development to over 8-cell stages. But, the rate of fragmentation of reconstituted embryos by the microinjection showed a little high rate in comparison with the electrofusion. When some reconstituted embryos by the microinjection were transplanted to pseudopregnant females' oviduct, 9 fetuses were observed at 14 days post coitum.     

Chrysin protects mice from Staphylococcus aureus pneumonia

Aim: To elucidate the effect of chrysin on α‐haemolysin production by Staphylococcus aureus and protection against pneumonia in a murine model. Methods and Results: Haemolysis, Western blot and real‐time RT‐PCR assays were performed to evaluate the effect of chrysin on α‐haemolysin secretion by Staph. aureus. The efficacy of chrysin against human alveolar epithelial cell injury by α‐haemolysin was tested using live/dead staining or by measuring lactate dehydrogenase activity. Furthermore, we determined the protective effect of chrysin against Staph. aureus pneumonia through histopathology experiments in a mouse model. The production of α‐haemolysin by Staph. aureus was inhibited when presented with an increasing subinhibitory concentration of chrysin in vitro. Consistent with this result, chrysin prevented α‐haemolysin‐mediated cell injury and protected mice from Staph. aureus pneumonia. Conclusions: Chrysin is a potent inhibitor of α‐haemolysin expression by Staph. aureus, and it conferred a significant degree of protection against Staph. aureus pneumonia. Significance and Impact of Study: The chrysin‐mediated inhibition of α‐haemolysin production and protection against Staph. aureus pneumonia may offer a new strategy in combating pathogen infections.     

Isolation of brain mitochondria from neonatal mice

Mitochondria are key contributors to many forms of cell death including those resulting from neonatal hypoxic-ischemic brain injury. Mice have become increasingly popular in studies of brain injury, but there are few reports evaluating mitochondrial isolation procedures for the neonatal mouse brain. Using evaluation of respiratory activity, marker enzymes, western blotting and electron microscopy, we have compared a previously published procedure for isolating mitochondria from neonatal mouse brain (method A) with procedures adapted from those for adult rats (method B) and neonatal rats (method C). All three procedures use Percoll density gradient centrifugation as a key step in the isolation but differ in many aspects of the fractionation procedure and the solutions used during fractionation. Methods A and B both produced highly enriched fractions of well-coupled mitochondria with high rates of respiratory activity. The fraction from method C exhibited less preservation of respiratory properties and was more contaminated with other subcellular components. Method A offers the advantage of being more rapid and producing larger mitochondrial yields making it useful for routine applications. However, method B produced mitochondria that were less contaminated with synaptosomes and associated cytosolic components that suits studies that have a requirement for higher mitochondrial purification.     

A device for milk collection from mice

Approximately 14 days after SHN, SLN and C3H/He strains of mice gave birth, their pups were removed. After 14--16 hours away from their pups, the dam was anesthetized, injected with oxytocin and milked. The milking device consisted of a rubber-stoppered centrifuge tube containing a stainless steel catheter and polyvinyl chloride tube. It was operated by vacuum.