相关论文
1995 - Journal of Spacecraft and Rockets
Determination of the recombination efficiency of thermal control coatings for hypersonic vehicles

A method is presented for determining the recombination efficiency of coatings for hypersonic vehicle applications. The approach uses experimental results from arc-jet tests with an analysis to determine the efficiency for the recombination of atomic species present in the boundary layer. The analysis employs analytical solutions to the laminar boundary-layer heat-transfer equations with experimental heating-rate, temperature, and pressure measurements. The authors discuss experimental difficulties in achieving reliable materials-performance data. The utility of the method is that it provides a rapid and efficient tool for use in qualitative screening and development of materials. The effects of second-order heat-transfer terms may be as high as 50% for low-catalysis surfaces. With the second-order terms included, the maximum uncertainty in recombination-efficiency data for low-catalysis surfaces is 45%. The discussions are based on experimental data and calculations for arc-jet tests of the titanium alloy Ti-14Al-21Nb with a borosilicate-like glass coating that has a recombination efficiency of about 0.006 to 0.01. 20 refs.

2019 - Health and Technology
Characterization of the retinal changes of the 3×Tg-AD mouse model of Alzheimer’s disease

In this work, we imaged the retina of wild-type and triple-transgenic mice model of Alzheimer’s disease (AD) (3xTg-AD), at the ages of one and two months, by optical coherence tomography. Texture analysis of calculated fundus images, for the six most anterior layers of the retina, present widespread differences between groups, demonstrating that retinal changes in the animal model of AD are notorious across the neuroretina. These results and the consistency of data pave the way for the identification of texture biomarkers of disease onset and progression with potential application to the human retina.

2000 - Industrial health and Occupational Diseases
Neuronal Apoptosis and Expression of Fas and FasL Protein Induced by Acute Carbon Monoxide Poisoning in Mice

The biopsy tissue from brain was assayed by HE,TUNEL and immunohistochemistry to investigate the correlation between acute CO poisoning and apoptosis.Acute CO poisoning could induce neuronal apoptosis.The number of apoptotic cells could increase within 24 hrs.and reach the peak value at 5～7 days.After 14 days,they could restore to normal.Apoptotic cells primarily located in cerebral cortex,hippcampus and striatum.Meanwhile,Fas and FasL protein were detected in the brain after acute CO poisoning,and reached the peak value at 3～5 days.It suggested that Fas\|FasL system might be involved in the apoptotic mechanism.Apoptosis does contribute to neuronal death after acute carbon monoxide poisoning,and it might be one of the pathological mechanism.

2010 - Nucleic Acids Research
RSSsite: a reference database and prediction tool for the identification of cryptic Recombination Signal Sequences in human and murine genomes

Recombination signal sequences (RSSs) flanking V, D and J gene segments are recognized and cut by the VDJ recombinase during development of B and T lymphocytes. All RSSs are composed of seven conserved nucleotides, followed by a spacer (containing either 12 ± 1 or 23 ± 1 poorly conserved nucleotides) and a conserved nonamer. Errors in V(D)J recombination, including cleavage of cryptic RSS outside the immunoglobulin and T cell receptor loci, are associated with oncogenic translocations observed in some lymphoid malignancies. We present in this paper the RSSsite web server, which is available from the address http://www.itb.cnr.it/rss. RSSsite consists of a web-accessible database, RSSdb, for the identification of pre-computed potential RSSs, and of the related search tool, DnaGrab, which allows the scoring of potential RSSs in user-supplied sequences. This latter algorithm makes use of probability models, which can be recasted to Bayesian network, taking into account correlations between groups of positions of a sequence, developed starting from specific reference sets of RSSs. In validation laboratory experiments, we selected 33 predicted cryptic RSSs (cRSSs) from 11 chromosomal regions outside the immunoglobulin and TCR loci for functional testing.

2010 - Journal of Applied Physics
Fast and slow carrier recombination transients in highly excited 4H- and 3C-SiC crystals at room temperature

Nonequilibrium carrier recombination in highly excited epitaxial layers of 4H–SiC and free standing 3C–SiC was analyzed numerically and studied experimentally by the time-resolved free carrier absorption (FCA) technique. The measurement setup combined interband carrier excitation by a picosecond laser pulse and probing of carrier dynamics at excess carrier densities in the ΔN=1017–1020 cm−3 range by optically or electronically delayed probe pulses, thus providing temporal resolution of 10 ps and 10 ns, respectively. FCA decay kinetics at different excitation levels and subsequent numerical modeling were used to determine the bulk lifetime, surface recombination velocity, and bimolecular (B) and Auger recombination (C) coefficients at 300 K. Bulk lifetimes of ∼800 ns and ∼65 ns were determined in 4H and 3C epitaxial layers, respectively. The numerical fitting of FCA kinetics in the 4H layer provided values of B=(1.2±0.4)×10−12 cm3/s and C=(7±4)×10−31 cm6/s at lower excitations while the Auger coefficient d...

2003 - Behavioural Brain Research
Effects of magnetic field exposure on open field behaviour and nociceptive responses in mice

Results of previous studies have shown that nociceptive sensitivity in male C57 mice is enhanced by exposure to a regular 37 Hz or an irregularly varying (<1 Hz) electromagnetic field. In order to test whether these fields affect more generally mouse behaviour, we placed Swiss CD-1 mice in a novel environment (open field test) and exposed them for 2 h to these two different magnetic field conditions. Hence, we analysed how duration and time course of various behavioural patterns (i.e. exploration, rear, edge chew, self-groom, sit, walk and sleep) and nociceptive sensitivity had been affected by such exposure. Nociceptive sensitivity was significantly greater in magnetically treated mice than in controls. The overall time spent in exploratory activities was significantly shorter in both magnetically treated groups (< 1 Hz, 33% and 37 Hz, 29% of total time), than in controls (42%). Conversely, the time spent in sleeping was markedly longer in the treated groups (both 27% of total time) than in controls (11%). These results suggest that exposure to altered magnetic fields induce a more rapid habituation to a novel environment.

2005 - International journal of oncology
Serum amyloid A as a tumor marker in sera of nude mice with orthotopic human pancreatic cancer and in plasma of patients with pancreatic cancer.

We screened an orthotopic nude mouse model of human pancreatic cancer for candidate serum biomarkers and examined their presence in the plasma of pancreatic cancer patients. Nude mice were injected in the pancreas with L3.9pl human pancreatic cancer cells. One week later, the mice were randomized into 4 treatment groups: i) control, saline; ii) oral STI 571; iii) intraperitoneal gemcitabine; and iv) STI 571 and gemcitabine. After 1, 2, and 3 weeks of treatment, sera and tumors were collected from mice in each group as well as uninjected mice. All sera were analyzed by surface enhanced laser desorption ionization mass spectrometry using ProteinChip technology. Protein profiles were analyzed with the Biomarker Wizard software package. The concentration of candidate proteins was evaluated in mouse sera and plasma from 135 pancreatic cancer patients, 7 pancreatitis patients, and 113 healthy volunteers. The combination therapy inhibited tumor growth. A 11.7-kDa protein peak correlating with tumor weight was purified by gel filtration, separated by SDS-PAGE, and identified as mouse serum amyloid A (SAA) by amino acid sequencing and public database searches. The expression of SAA in mouse sera was confirmed by Western blotting and correlated with tumor weight. The level of SAA in plasma of pancreatic cancer patients correlated with clinical stage and was significantly higher than in normal volunteers (mean value: 180.1 microg/ml vs 27.9 microg/ml: P<0.01) or pancreatitis patients. For SAA used as a single tumor marker with a cut-off of 75 microg/ml, the sensitivity for pancreatic cancer was 96.5% and specificity was 31.9%. Our search for specific marker proteins to identify pancreatic cancer was unsuccessful. Although SAA is not specific for pancreatic cancer and not sensitive enough to detect stage I patients, it may be a candidate biomarker for detecting and monitoring the progressive growth of pancreatic cancer.

2017 - Journal of Hospitality Marketing & Management
Negative Word of Mouse in the Hotel Industry: A Content Analysis of Online Reviews on Luxury Hotels in Jordan

ABSTRACT The main objective of this study is to identify the nature of e-complaints directed at luxury hotels in Jordan. For this purpose, a content analysis was conducted based on 424 negative reviews posted for these hotels on the User-Generated Content (UGC) travel website TripAdvisor. The study found that the most frequent e-complaints were about service quality, the efficiency of hotel facilities, and cleanliness and hygiene. The study showed that e-complaints were mostly posted by British, American, and Emirati guests. The hotels’ responses to e-complaints were also examined. The findings suggested that less than one-half of the e-complaints (approximately 43%) received an online response from the hotel management and that more than one-half of these responses (56%) were posted within a week of the e-complaint’s posting date. Recommendations to effective e-complaint management in the hotel industry were given in light of the article’s findings.

1999 - International Journal of Industrial Ergonomics
Computer mouse and track-ball operation:: Similarities and differences in posture, muscular load and perceived exertion

Abstract Posture (optoelectronic 3D motion analysis system), muscular load (EMG), perceived exertion (rating scales), preference and productivity were investigated in 20 healthy VDU-operators (10 male and 10 female) during text editing with two different data input devices, a mouse and a track-ball. Work with the track-ball entailed lower shoulder elevation and less neck/shoulder muscle activity than work with the mouse. Arm support reduced muscle activity in the neck/shoulder region irrespective of input device used. A table height lower than 3 cm above elbow height allowed arm and shoulder support without undue shoulder elevation. Work with the track-ball entailed more wrist extension than work with the mouse. Perceived exertion ratings were lower for the shoulder and higher for the hand with track-ball than with mouse operation. Thus, biomechanical demands differ between different input devices. The women elevated and rotated their right shoulder outwards more than the men during work with both input devices. The overall EMG results showed a higher activity among the women than among the men in two of the examined muscles. This may relate to anthropometric differences which also influence biomechanical load moments. Another reason could be the observed differences in working techniques between the men and the women. Relevance to industry The design of input devices affects levels of muscular load in neck/shoulder and hand/forearm muscles. Joint positions differ depending on the size and design of the input device and the operators' anthropometry. The design of input devices should be adapted to the differences in work tasks and variations of human dimensions in order to avoid injuries and to enhance the effectiveness of VDU work.

2005 - Infection and Immunity
Responses of Mycobacterium tuberculosis to Growth in the Mouse Lung

ABSTRACT Using a promoter trap, we have identified 56 Mycobacterium tuberculosis genes preferentially expressed in the mouse lung. Quantitative real-time PCR showed that RNA levels of several genes were higher from bacteria growing in mouse lungs than from broth cultures. These results support the current hypothesis that Mycobacterium tuberculosis utilizes fatty acids as a carbon source in the mouse lung.

1989 - Photochemistry and Photobiology
SYSTEMIC IMMUNOSUPPRESSION INDUCED BY PHOTODYNAMIC THERAPY (PDT) IS ADOPTIVELY TRANSFERRED BY MACROPHAGES

Abstract— Some derivatives of hematoporphyrins are strongly retained by tumor tissue as compared to normal tissue, and exposure of these photosensitizers to radiation in the visible spectrum can cause serious biological damage. These properties have been exploited in the development of a new treatment for cancer termed photodynamic therapy (PDT). However, recent studies have also demonstrated that PDT can also induce a state of systemic immunosuppression. The purpose of this study was to determine whether PDT‐induced suppression of contact hypersensitivity (CHS) responses was an active phenomenon that could be adoptively transferred by viable splenocytes from PDT‐treated mice. Although induction of adoptively transferable suppressor cells in PDT‐treated mice required exposure to antigen, the suppressor cells were found to be antigen nonspecific in their function. Furthermore, splenocytes from PDT‐treated mice were capable of generating levels of allospecific cytotoxic T lymphocyte (CTL) activity which were comparable to those generated by normal control mice, but the ability of irradiated spleen cells from PDT‐treated mice to stimulate a mixed lymphocyte response (MLR) was dramatically impaired. Finally, chromatographic separation of T cells, B cells and macrophages showed that the cell type which mediates adoptively transferable suppression of CHS responsiveness is in the macrophage lineage.

2006 - Journal of biomechanical engineering
Compressive properties of mouse articular cartilage determined in a novel micro-indentation test method and biphasic finite element model.

The mechanical properties of articular cartilage serve as important measures of tissue function or degeneration, and are known to change significantly with osteoarthritis. Interest in small animal and mouse models of osteoarthritis has increased as studies reveal the importance of genetic background in determining predisposition to osteoarthritis. While indentation testing provides a method of determining cartilage mechanical properties in situ, it has been of limited value in studying mouse joints due to the relatively small size of the joint and thickness of the cartilage layer. In this study, we developed a micro-indentation testing system to determine the compressive and biphasic mechanical properties of cartilage in the small joints of the mouse. A nonlinear optimization program employing a genetic algorithm for parameter estimation, combined with a biphasic finite element model of the micro-indentation test, was developed to obtain the biphasic, compressive material properties of articular cartilage. The creep response and material properties of lateral tibial plateau cartilage were obtained for wild-type mouse knee joints, by the micro-indentation testing and optimization algorithm. The newly developed genetic algorithm was found to be efficient and accurate when used with the finite element simulations for nonlinear optimization to the experimental creep data. The biphasic mechanical properties of mouse cartilage in compression (average values: Young's modulus, 2.0 MPa; Poisson's ratio, 0.20; and hydraulic permeability, 1.1 x 10(-16) m4/N-s) were found to be of similar orders of magnitude as previous findings for other animal cartilages, including human, bovine, rat, and rabbit and demonstrate the utility of the new test methods. This study provides the first available data for biphasic compressive properties in mouse cartilage and suggests a promising method for detecting altered cartilage mechanics in small animal models of osteoarthritis.

2019 - Advanced materials
Nonradiative Recombination in Perovskite Solar Cells: The Role of Interfaces

Perovskite solar cells combine high carrier mobilities with long carrier lifetimes and high radiative efficiencies. Despite this, full devices suffer from significant nonradiative recombination losses, limiting their VOC to values well below the Shockley-Queisser limit. Here, recent advances in understanding nonradiative recombination in perovskite solar cells from picoseconds to steady state are presented, with an emphasis on the interfaces between the perovskite absorber and the charge transport layers. Quantification of the quasi-Fermi level splitting in perovskite films with and without attached transport layers allows to identify the origin of nonradiative recombination, and to explain the VOC of operational devices. These measurements prove that in state-of-the-art solar cells, nonradiative recombination at the interfaces between the perovskite and the transport layers is more important than processes in the bulk or at grain boundaries. Optical pump-probe techniques give complementary access to the interfacial recombination pathways and provide quantitative information on transfer rates and recombination velocities. Promising optimization strategies are also highlighted, in particular in view of the role of energy level alignment and the importance of surface passivation. Recent record perovskite solar cells with low nonradiative losses are presented where interfacial recombination is effectively overcome-paving the way to the thermodynamic efficiency limit.

2002 - Journal of Neuroscience Methods
Non-invasive induction of focal cerebral ischemia in mice by photothrombosis of cortical microvessels: characterization of inflammatory responses

In this study, we adapted the original rat photothrombosis model of Watson et al. (Ann Neurol 17 (1985) 497) for use in mice by refining the application route of the dye, illumination and stereotactic parameters. After intraperitoneal injection of the photosensitive dye Rose bengal, subsequent focal illumination of the brain with a cold light source through the intact skull led to focal cortical infarcts of reproducible size, location and geometry. Cresyl violet histology displayed well-demarcated infarcts that matured with time in a predictable manner. Microglial responses, as assessed by immunocytochemistry, against F4/80 and CD11b antigens were rapid and complete at the infarct site, but delayed and incomplete in degenerating fiber tracts and ipsilateral thalamic nuclei. In contrast to the rat, where the expression of CD4 and CD8 antigens discriminate distinct subpopulations of lesion-associated phagocytes, the expression of both markers was low to absent in the mouse model. In both rats and mice, cerebral photothrombosis shares essential inflammatory responses with focal ischemia induced by middle cerebral artery occlusion. It may provide a useful model to study functional aspects of lesion-associated and remote molecular responses in transgenic mice.

2006 - Molecular Pharmacology
Liver X Receptor (LXR)-β Regulation in LXRα-Deficient Mice: Implications for Therapeutic Targeting

The nuclear receptors liver X receptor (LXR) LXRα and LXRβ are differentially expressed ligand-activated transcription factors that induce genes controlling cholesterol homeostasis and lipogenesis. Synthetic ligands for both receptor subtypes activate ATP binding cassette transporter A1 (ABCA1)-mediated cholesterol metabolism, increase reverse cholesterol transport, and provide atheroprotection in mice. However, these ligands may also increase hepatic triglyceride (TG) synthesis via a sterol response element binding protein 1c (SREBP-1c)-dependent mechanism through a process reportedly regulated by LXRα. We studied pan-LXRα/β agonists in LXRα knockout mice to assess the contribution of LXRβ to the regulation of selected target genes. In vitro dose-response studies with macrophages from LXRα-/- and β-/- mice confirm an equivalent role for LXRα and LXRβ in the regulation of ABCA1 and SREBP-1c gene expression. Cholesterol-efflux studies verify that LXRβ can drive apoA1-dependent cholesterol mobilization from macrophages. The in vivo role of LXRβ in liver was further evaluated by treating LXRα-/- mice with a pan-LXRα/β agonist. High-density lipoprotein (HDL) cholesterol increased without significant changes in plasma TG or very low density lipoprotein. Analysis of hepatic gene expression consistently revealed less activation of ABCA1 and SREBP-1c genes in the liver of LXRα null animals than in treated wild-type controls. In addition, hepatic CYP7A1 and several genes involved in fatty acid/TG biosynthesis were not induced. In peripheral tissues from these LXRα-null mice, LXRβ activation increases ABCA1 and SREBP-1c gene expression in a parallel manner. However, putative elevation of SREBP-1c activity in these tissues did not cause hypertriglyceridemia. In summary, selective LXRβ activation is expected to stimulate ABCA1 gene expression in macrophages, contribute to favorable HDL increases, but circumvent hepatic LXRα-dominated lipogenesis.

1992 - Carcinogenesis
Inhibitory effects of diallyl sulfide on the metabolism and tumorigenicity of the tobacco-specific carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) in A/J mouse lung.

Diallyl sulfide (DAS), a component of garlic oil, has been shown to inhibit tumorigenesis by several chemical carcinogens. Our previous work demonstrated that DAS inhibited the metabolic activation of carcinogenic nitrosamines, including the tobacco-specific 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), in rat lung and nasal mucosa microsomes. In the present study, the effects of DAS on the tumorigenicity and the metabolism of NNK in A/J mouse lung were examined. Female A/J mice at 7 weeks of age were pretreated with DAS (200 mg/kg body wt in corn oil, p.o) daily for 3 days. Two hours after the final DAS treatment, the mice were either given a single dose of NNK (2 mg/mouse, i.p.) and kept for an additional 16 weeks for determining the production of pulmonary tumors, or were killed immediately so as to measure the microsomal activity in metabolizing NNK. In comparison to the vehicle control group, DAS pretreatment significantly decreased the incidence of NNK-induced lung tumors (37.9 versus 100%) and the tumor multiplicity (0.6 versus 7.2 tumors/mouse). In pulmonary metabolism of NNK, DAS pretreatment reduced the rates of formation of keto aldehyde, keto alcohol, NNAL-N-oxide, and NNK-N-oxide by 70-90%. In addition, the formation of NNK oxidative metabolites from NNK in the liver microsomes from DAS-pretreated mice was remarkably reduced. DAS also inhibited the metabolism of NNK in mouse lung microsomes in vitro. These results demonstrate that DAS is an effective chemopreventive agent against NNK-induced lung tumorigenesis, probably by inhibiting the metabolic activation of NNK.

2010 - Neuropsychologia
Everyday use of the computer mouse extends peripersonal space representation

Auditory and tactile stimuli are integrated within a limited space around the body to form an auditory peripersonal space (APPS). Here we investigate whether the APPS representation around the hand can be extended through the use of a common technological tool such as the computer mouse. When using a mouse, an action occurring in the space around the hand has a distal effect in the space defined by the computer screen; thus, the mouse virtually links near and far space. Does prolonged experience with the mouse durably extend APPS representation to the far space? We examined 16 habitual mouse users to determine whether a sound presented near the right hand or near the computer screen affected reaction times to a tactile target at the hand. When subjects sat in front of the computer, without holding the mouse, they responded faster to tactile stimuli when sounds were presented near the hand rather than near the screen, consistent with a normal segregation of APPS around the hand. In contrast, when subjects either actively used or even passively held the mouse, the difference between the effects of near and far sounds disappeared, thus showing an extension of the APPS toward the far space. This effect was selective for the effector used to operate the mouse: if tactile stimuli were presented on the left hand, rarely used to act upon the mouse, a sound presented near the hand speeded up reactions times when subjects both held and did not hold the mouse in their left hand.

2001 - The Journal of Bone & Joint Surgery
Effect of Bone Morphogenetic Protein-2-Expressing Muscle-Derived Cells on Healing of Critical-Sized Bone Defects in Mice

Background: Cells that express bone morphogenetic protein-2 (BMP-2) can now be prepared by transduction with adenovirus containing BMP-2 cDNA. Skeletal muscle tissue contains cells that differentiate into osteoblasts on stimulation with BMP-2. The objectives of this study were to prepare BMP-2-expressing muscle-derived cells by transduction of these cells with an adenovirus containing BMP-2 cDNA and to determine whether the BMP-2-expressing muscle-derived cells would elicit the healing of critical-sized bone defects in mice. Methods: Primary cultures of muscle-derived cells from a normal male mouse were transduced with adenovirus encoding the recombinant human BMP-2 gene (adBMP-2). These cells (5 ¥ 105) were implanted into a 5-mm-diameter critical-sized skull defect in female SCID (severe combined immunodeficiency strain) mice with use of a collagen sponge as a scaffold. Healing in the treatment and control groups was examined grossly and histologically at two and four weeks. Implanted cells were identified in vivo with use of the Y-chromosome-specific fluorescent in situ hybridization (FISH) technique, and their differentiation into osteogenic cells was demonstrated by osteocalcin immunohistochemistry. Results: Skull defects treated with muscle cells that had been genetically engineered to express BMP-2 had >85% closure within two weeks and 95% to 100% closure within four weeks. Control groups in which the defect was not treated (group 1), treated with collagen only (group 2), or treated with collagen and muscle cells without adBMP-2 (group 3) showed at most 30% to 40% closure of the defect by four weeks, and the majority of the skull defects in those groups showed no healing. Analysis of injected cells in group 4, with the Y-chromosome-specific FISH technique showed that the majority of the transplanted cells were located on the surfaces of the newly formed bone, but a small fraction (approximately 5%) was identified within the osteocyte lacunae of the new bone. Implanted cells found in the new bone stained immunohistochemically for osteocalcin, indicating that they had differentiated in vivo into osteogenic cells. Conclusions: This study demonstrates that cells derived from muscle tissue that have been genetically engineered to express BMP-2 elicit the healing of critical-sized skull defects in mice. The cells derived from muscle tissue appear to enhance bone-healing by differentiating into osteoblasts in vivo. Clinical Relevance: Ex vivo gene therapy with muscle-derived cells that have been genetically engineered to express BMP-2 may be used to treat nonhealing bone defects. In addition, muscle-derived cells appear to include stem cells, which are easily obtained with muscle biopsy and could be used in gene therapy to deliver BMP-2.

2015 - Proceedings of the National Academy of Sciences
Insulin resistance in brain alters dopamine turnover and causes behavioral disorders

Significance Both types 1 and 2 diabetes are associated with increased risks of age-related decay in cognitive function and mood disorders, especially depression. Insulin action has been shown to regulate neuronal signaling and plasticity. Here we investigate whether brain-specific knockout of insulin receptor (NIRKO) in mice causes behavioral changes and how these are mechanistically linked. We find that NIRKO mice exhibit age-related anxiety and depressive-like behavior. This is due to altered mitochondrial function, aberrant monoamine oxidase (MAO) expression, and increased dopamine turnover in the mesolimbic system, and can be reversed by treatment with Mao inhibitors. Thus, brain insulin resistance alters dopamine turnover and induces anxiety and depressive-like behaviors. These findings demonstrate a potential molecular link between central insulin resistance and behavioral disorders. Diabetes and insulin resistance are associated with altered brain imaging, depression, and increased rates of age-related cognitive impairment. Here we demonstrate that mice with a brain-specific knockout of the insulin receptor (NIRKO mice) exhibit brain mitochondrial dysfunction with reduced mitochondrial oxidative activity, increased levels of reactive oxygen species, and increased levels of lipid and protein oxidation in the striatum and nucleus accumbens. NIRKO mice also exhibit increased levels of monoamine oxidase A and B (MAO A and B) leading to increased dopamine turnover in these areas. Studies in cultured neurons and glia cells indicate that these changes in MAO A and B are a direct consequence of loss of insulin signaling. As a result, NIRKO mice develop age-related anxiety and depressive-like behaviors that can be reversed by treatment with MAO inhibitors, as well as the tricyclic antidepressant imipramine, which inhibits MAO activity and reduces oxidative stress. Thus, insulin resistance in brain induces mitochondrial and dopaminergic dysfunction leading to anxiety and depressive-like behaviors, demonstrating a potential molecular link between central insulin resistance and behavioral disorders.

2001 - Methods
Site- and time-specific gene targeting in the mouse.

The efficient introduction of somatic mutations in a given gene, at a given time, in a specific cell type, will facilitate studies of gene function and the generation of animal models for human diseases. We have established a conditional site-specific recombination system in mice using a new version of the Cre/lox system. The Cre recombinase has been fused to a mutated ligand binding domain of the human estrogen receptor (ER), resulting in a tamoxifen-dependent Cre recombinase, Cre-ER(T), that is activated by tamoxifen, but not by estradiol. Transgenic mice were generated expressing Cre-ER(T) under the control of a cytomegalovirus promoter. Administration of tamoxifen to these transgenic mice induced excision of a chromosomally integrated gene flanked by loxP sites in a number of tissues, whereas no excision could be detected in untreated animals. However, the efficiency of excision varied between tissues, and the highest level (approximately 40%) was obtained in the skin. To determine the efficiency of excision mediated by Cre-ER(T) in a given cell type, Cre-ER(T)-expressing mice were crossed with reporter mice in which expression of Escherichia coli beta-galactosidase can be induced through Cre-mediated recombination. The efficiency and kinetics of this recombination were analyzed at the cellular level in the epidermis of 6- to 8-week-old double transgenic mice. Site-specific excision occurred within a few days of tamoxifen treatment in essentially all epidermis cells expressing Cre-ER(T). These results indicate that cell-specific expression of Cre-ER(T) in transgenic mice can be used for efficient tamoxifen-dependent Cre-mediated recombination at loci containing loxP sites, to generate site-specific somatic mutations in a spatiotemporally controlled manner. This conditional site-specific recombination system should allow the analysis of knockout phenotypes that cannot be addressed by conventional gene targeting.

RAG-1-deficient mice have no mature B and T lymphocytes

Susumu Tonegawa
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Karl Herrup
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Peter Mombaerts
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Virginia E. Papaioannou
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S. Tonegawa
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K. Herrup
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P. Mombaerts
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R. Johnson
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V. Papaioannou
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J. Iacomini
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John Iacomini
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Randall S. Johnson

Abstract:The V(D)J recombination activation gene RAG-1 was isolated on the basis of its ability to activate V(D)J recombination on an artificial substrate in fibroblasts. This property and the expression pattern in tissues and cell lines indicate that RAG-1 either activates or catalyzes the V(D)J recombination reaction of immunoglobulin and T cell receptor genes. We here describe the introduction of a mutation in RAG-1 into the germline of mice via gene targeting in embryonic stem cells. RAG-1-deficient mice have small lymphoid organs that do not contain mature B and T lymphocytes. The arrest of B and T cell differentiation occurs at an early stage and correlates with the inability to perform V(D)J recombination. The immune system of the RAG-1 mutant mice can be described as that of nonleaky scid mice. Although RAG-1 expression has been reported in the central nervous system of the mouse, no obvious neuroanatomical or behavioral abnormalities have been found in the RAG-1-deficient mice.

摘要：V(D)J重组激活基因RAG-1是基于其在成纤维细胞人工底物上激活V(D)J重组的能力而被克隆的。这一特性和在组织和细胞系中的表达模式表明，RAG-1激活或催化免疫球蛋白和T细胞受体基因的V(D)J重组反应。我们在这里描述了通过胚胎干细胞中的基因打靶将RAG-1突变引入小鼠生殖系。RAG-1基因缺陷小鼠的淋巴器官较小，不含成熟的B和T淋巴细胞。B和T细胞分化受阻发生在早期阶段，并与无法进行V(D)J重组有关。RAG-1突变小鼠的免疫系统可描述为无泄漏的SCID小鼠。虽然RAG-1在小鼠的中枢神经系统中有表达，但在RAG-1缺陷小鼠中没有发现明显的神经解剖学或行为异常。

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