Increased sensitivity of Apolipoprotein E knockout mice to swainsonine dependent immunomodulation

The mechanisms that mediate accelerated atherosclerosis in autoimmune diseases remain unclear. One common mechanism that has been documented in autoimmune diseases and atherosclerosis is formation of hypoglycosyalted N-glycans on the cell surface. In this study we tested the effects of swainsonine, a class II α-mannosidase inhibitor which results in formation of hypoglycosylated N-glycans, on atherogenesis and immune cell dynamics in the atheroprone and hypercholesterolemic ApoE −/− mouse. Wild type or ApoE−/− mice (8 weeks of age) were fed a normal chow diet and administered swainsonine via the drinking water for 8 weeks at which time, atherosclerosis, and systemic markers of markers of inflammation were evaluated. Interestingly, no change in the rate of atherosclerosis development was observed in ApoE −/− mice treated with swainsonine. However, swainsonine significantly increased the number of peripheral blood leukocytes in ApoE −/− mice, with trends toward similar increases in swainsonine treated wild type mice noted. Assessment of leukocyte subsets using specific markers of all major blood lineages indicated that the increase in circulating leukocytes was due to the elevated number of progenitor cells. Consistent with swainsonine having a greater effect in ApoE −/− vs. wild type mice, increases in circulating inflammatory markers (IgA, IgG and chemokines) were observed in the former. Collectively, these data demonstrate that predisposition of ApoE −/− mice to vascular disease is associated with sensitization to the immunomodulatory effects of swainsonine and indicate that changes in N-glycans may provide a mechanism linking autoimmunity to atherogenesis.     

Jejunal afferent nerve sensitivity in wild-type and TRPV1 knockout mice

The aim of this study was to investigate the contribution of the TRPV1 receptor to jejunal afferent sensitivity in the murine intestine. Multiunit activity was recorded in vitro from mesenteric afferents supplying segments of mouse jejunum taken from wild-type (WT) and TRPV1 knockout (TRPV1^−/−) animals. In WT preparations, ramp distension of the gut (up to 60 mmHg) produced biphasic changes in afferent activity so the pressure–response curve had an initial rapid increase in afferent discharge followed by a second phase of slower increase in activity. Afferent response to distension was significantly lower in TRPV1^−/− than in WT mice. Single-unit analysis revealed three functional types of afferent fibres: (1) low-threshold fibres (2) wide dynamic range fibres and (3) high-threshold fibres. There was a marked downward shift of the pressure–response curve for wide dynamic range fibres in the TRPV1^−/− mice as compared to the WT controls. The afferent response to intraluminal hydrochloric acid (20 m m ) was also attenuated in the TRPV1^−/− mice. In contrast, the response to bath application of bradykinin (1 μ m , 3 ml) was not significantly different between the two groups. The TRPV1 antagonist capsazepine (10 μ m ) significantly attenuated the nerve responses to distension, intraluminal acid and bradykinin, as well as the spontaneous discharge in WT mice. The WT jejunal afferents responded to capsaicin with rapid increases in afferent activity, whereas TRPV1^−/− afferents were not at all sensitive to capsaicin. Previous evidence indicates that TRPV1 is not mechanosensitive, so the results of the present study suggest that activation of TRPV1 may sensitize small intestinal afferent neurones.     

Increased longevity and refractoriness to Ca(2+)-dependent neurodegeneration in Surf1 knockout mice

Leigh syndrome associated with cytochrome c oxidase (COX) deficiency is a mitochondrial disorder usually caused by mutations of SURF1, a gene encoding a putative COX assembly factor. We present here a Surf1-/- recombinant mouse obtained by inserting a loxP sequence in the open reading frame of the gene. The frequency of -/-, +/+ and +/- genotypes in newborn mice followed a mendelian distribution, indicating that the ablation of Surf1 is compatible with postnatal survival. The biochemical and assembly COX defect was present in Surf1(loxP)-/- mice, but milder than in humans. Surprisingly, not only these animals failed to show spontaneous neurodegeneration at any age, but they also displayed markedly prolonged lifespan, and complete protection from Ca(2+)-dependent neurotoxicity induced by kainic acid. Experiments on primary neuronal cultures showed markedly reduced rise of cytosolic and mitochondrial Ca(2+) in Surf1(loxP)-/- neurons, and reduced mortality, compared to controls. The mitochondrial membrane potential was unchanged in KO versus wild-type neurons, suggesting that the effects of the ablation of Surf1 on Ca(2+) homeostasis, and possibly on longevity, may be independent, at least in part, from those on COX assembly and mitochondrial bioenergetics.     

Increased ventilation and CO2 chemosensitivity in acetylcholinesterase knockout mice

To investigate the effects of a permanent excess of acetylcholine (AChE) on respiration, breathing and chemosensitivity were analyzed from birth to adulthood in mice lacking the AChE gene (AChE-/-), in heterozygotes, and in control wild-type (AChE+/+) littermates. Breathing at rest and ventilatory responses to brief exposures to hypoxia (10% O2) and hypercapnia (3-5% CO2) were measured by whole-body plethysmography. At rest AChE-/- mice show larger tidal volumes (VT, + 96% in adults), overall ventilation (VE, + 70%), and mean inspiratory flow (+270%) than wild-type mice, with no change in breathing frequency (fR). AChE-/- mice have a slightly blunted response to hypoxia, but increased VE and fR responses to hypercapnia. Heterozygous animals present no consistent alterations of breathing at rest and chemosensitivity is normal. Adult AChE-/- mice have an increased VE/VO2 and a marginally higher normalized VO2. The results suggest that the hyperventilation and altered chemosensitivity in AChE-/- mice largely reflect alterations of central respiratory control.     

A neuron-specific Isca1 knockout rat developments multiple mitochondrial dysfunction syndromes

Background:Multiple mitochondrial dysfunction syndromes (MMDS) are rare mitochondrial diseases caused by mutation of mitochondrial iron–sulfur cluster synthesis proteins. This study established a rat model simulating MMDS5 disease in the nervous system to investigate its pathological features and neuronal death.Methods:We generated neuron-specificIsca1 knockout rat (Isca1f lox/flox-NeuN-Cre)using CRISPR-Cas9 technology. The brain structure changes of CKO rats were studiedwithMRI,andthebehaviorab...     

Susceptibility of mice to acute and persistent measles infection.

Intracerebral inoculation of neonatal mice with the Edmonston strain of measles virus produced an acute, lethal encephalitis and thymic dysplasia in susceptible mice. There was an age-related development of resistance to infection. This resistance was strain-dependent and appeared to be associated with the extent of virus growth in the brain. Studies on the genetic basis for susceptibility, using hybrid and backcross mice, revealed that the principal determinant of host resistance to acute infection was a dominant gene or genes which segregated independently of the H-2 complex. A small number of survivors of the acute infection showed persistence of measles virus antigens in the cerebellum and spleen for up to 2 months after inoculation. However, the low frequency of this persistence indicated that, at this time, intracerebral inoculation of neonatal mice with the Edmonston strain of measles virus constitutes a difficult model for the study of persistant measles infection.     

Baroreflex sensitivity and oxidative stress in the LDL receptor knockout mice

This study aims at observing the effect of low-density lipoprotein (LDL) receptor deficiency in cholesterol blood levels, baroreflex sensitivity (BRS), nitric oxide (NO) bioavailability, and oxidative stress. The lack of LDL receptors in mice significantly increased the cholesterol blood levels (179+/-35 vs. 109+/-13mg/dL) in the knockout (KO) mice compared to control. There was no difference in basal mean arterial pressure and heart rate between the groups. However, in KO mice the BRS was significantly attenuated and the antioxidant enzyme activities, measured in erythrocytes and heart, were significantly decreased. On the other hand, the oxidative damage measured by chemiluminescence and carbonyls was increased, while total plasma nitrate levels were lower in KO mice, indicating a decrease in NO availability. In conclusion, these results indicate that the lack of LDL receptor increased cholesterol blood levels, induced oxidative stress and decreased BRS.     

Increased susceptibility of complement factor B/C2 double knockout mice and mannan-binding lectin knockout mice to systemic infection with Candida albicans

Candida albicans is the major cause of systemic fungal infections in immunocompromised patients. We investigated the susceptibility of mice deficient in complement factor B and C2 (Bf/C2(-/-)), C1q (C1qa(-/-)), and mannan-binding lectin (MBL)-A (MBL-A) and MBL-C (MBL-A/C(-/-)) to systemic infection with C. albicans. Animals were infected i.p. with 10(8)C. albicans blastoconidia and monitored for mortality. Bf/C2(-/-) mice showed high mortality (over 90%) within the study period of 3 weeks. In contrast, mortality in C1qa(-/-) mice was below 15% whereas that of MBL-A/C(-/-) mice was 40% (P<0.001). Intravenous infection of mice with 8x10(5) blastoconidia resulted in the same trend with Bf/C2(-/-) mice being highly susceptible compared to the other strains. Histology of kidney sections of infected Bf/C2(-/-) mice showed widespread mycelia confirming the high CFU counts from cultured tissue homogenates. In C1qa(-/-), MBL-A/C(-/-) and wild type C57BL/6 mice hyphal growth was limited. However, massive inflammatory infiltration was apparent, which was not seen in Bf/C2(-/-) mice. The ability of the mouse sera to opsonize C. albicans was determined by quantification of phagocytosis of C. albicans by peritoneal phagocytes. Whilst phagocytosis mediated by Bf/C2(-/-) mouse serum was low (10.6%), more phagocytosis could be seen in MBL-A/C(-/-) (19.9%), C1qa(-/-) mice (23.9%) and wild type mice (29%). Deficiency of classical pathway activation has only a low impact whereas the lectin pathway contributes to the host defence against candidosis. The more pronounced lack of complement activation in Bf/C2(-/-) mice leads to uncontrolled infection due to an opsonophagocytic defect.     

Increased renal glomerular endothelin-1 release in gentamicin-induced nephrotoxicity

Gentamicin-induced acute renal failure is characterized by a decrease in renal plasma flow and creatinine clearance. Endothelins (ET) are potent renal vasoconstrictors. The aim of this work is to assess the role of ET-1 in gentamicin-induced renal failure. Renal glomerular release of ET-1 was measured in rats with gentamicin-induced nephrotoxicity (100 mg/kg/day, s.c. for 2, 4 or 6 days). Glomeruli were isolated and incubated for 24 h in RPMI-1640. Glomerular supernatant and plasma concentration of ET-1 were measured by RIA. Renal failure was assessed by insulin, para-aminohippuric and creatinine clearance and histological studies. Gentamicin induced a dose number-dependent increase in plasma creatinine and a decrease in creatinine clearance. This was accompanied by a marked decrease in inulin and para-aminohippuric acid clearance, as well as by a marked tubular necrosis, without alterations in glomerular structures. Plasma ET-1 concentration and glomerular ET-1 release were also increased in gentamicin-treated rats. When 10-5 M gentamicin was added to control glomeruli, ET-1 production was not modified (36.4 +/- 2.2 vs. 35.2 +/- 1.7 pg/ml/24 h). All these results suggest that elevated ET-1 plasma levels and increased glomerular release of ET-1 could mediate, at least in part, the decrease in glomerular filtration rate observed in gentamicin-induced ARF.     

Egr-1基因剔除减少炎性相关因子在实验性胰腺炎中的表达

目的：探讨Egr-1基因剔除对实验性胰腺炎小鼠胰腺组织中炎性相关因子表达的影响。 〖HTH〗方法：利用Egr-1基因剔除小鼠，采用大剂量雨蛙素诱导的实验性胰腺炎模型，观察Egr-1基因剔除后，胰腺组织水肿、MPO水平、血清淀粉酶水平、肺组织MPO水平的改变。并利用定量PCR的方法，检测胰腺组织中炎症相关因子组织因子（TF）、纤维蛋白溶酶原激活因子抑制因子（PAI-1）、单核细胞趋化吸引蛋白1（MCP-1）、Gro-1、IL-6和细胞间黏附分子-1（ICAM-1） mRNA的表达。 〖HTH〗结果：Egr-1基因剔除小鼠胰腺组织水肿明显轻于野生型，但组织MPO水平与血清淀粉酶与野生型组间相比无明显差异；肺组织MPO水平明显低于野生型。定量PCR检测结果表明， Egr-1基因剔除组，胰腺组织中TF、PAI-1，以及MCP-1、ICAM-1和IL-6　mRNA的表达，明显少于野生型组。 〖HTH〗结论：Egr-1基因剔除可明显减轻急性胰腺炎的严重程度，其作用可能通过减少胰腺组织中TF、PAI-1，以及MCP-1、ICAM-1和IL-6的表达而实现。     

Increased sensitivity to MPTP in human alpha-synuclein A30P transgenic mice

In addition to genetic factors, environmental factors have long been suspected to contribute to the pathogenesis of Parkinson's disease (PD). We investigated the possible interaction between genetic factors and neurotoxins by testing whether alpha-synuclein A30P Tg5093 transgenic mice show increased sensitivity to secondary toxic insults like 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) or rotenone. While sensitivity to chronic treatment with rotenone was not enhanced in the Tg5093 line, chronic treatment with 80 or 150 mg/kg MPTP resulted in increased deterioration of the nigrostriatal dopaminergic system as assessed by quantitation of nigral tyrosine hydroxylase (TH) positive neurons and striatal dopamine (DA) levels in Tg5093 mice when compared to non-transgenic littermate controls. Thus, the results of this study demonstrate a role for the overexpression of mutant human alpha-synuclein A30P in increased vulnerability of DA neurons to MPTP.     

Increased bone mineral density in the femora of GDF8 knockout mice

GDF8 (myostatin), a member of the transforming growth factor (TGF)-beta superfamily of secreted growth and differentiation factors, is a negative regulator of skeletal muscle growth. GDF8 knockout mice have approximately twice the skeletal muscle mass of normal mice. The effects of increased muscle mass on bone modeling were investigated by examining bone mineral content (BMC) and bone mineral density (BMD) in the femora of female GDF8 knockout mice. Dual-energy X-ray absorptiometry (DEXA) densitometry was used to measure whole-femur BMC and BMD, and pQCT densitometry was used to calculate BMC and BMD from cross-sections taken at two different locations: the midshaft and the distal metaphysis. The DEXA results show that the knockout mice have significantly greater femoral BMD than normal mice. The peripheral quantitative computed tomography (pQCT) data indicate that the GDF8 knockout mice have approximately 10% greater cortical BMC (P =.01) at the midshaft and over 20% greater cortical BMC at the metaphysis (P <.001). Likewise, knockouts show approximately 10% greater cortical thickness (P <.001) and significantly greater cortical BMD (P <.001) at both locations. These results suggest that inhibitors of GDF8 function may be useful pharmacological agents for increasing both muscle mass and BMD.     

Laforin and malin knockout mice have normal glucose disposal and insulin sensitivity

Lafora disease is a fatal, progressive myoclonus epilepsy caused in ~90% of cases by mutations in the EPM2A or EPM2B genes. Characteristic of the disease is the formation of Lafora bodies, insoluble deposits containing abnormal glycogen-like material in many tissues, including neurons, muscle, heart and liver. Because glycogen is important for glucose homeostasis, the aberrant glycogen metabolism in Lafora disease might disturb whole-body glucose handling. Indeed, Vernia et al. [Vernia, S., Heredia, M., Criado, O., Rodriguez de Cordoba, S., Garcia-Roves, P.M., Cansell, C., Denis, R., Luquet, S., Foufelle, F., Ferre, P. et al. (2011) Laforin, a dual-specificity phosphatase involved in Lafora disease, regulates insulin response and whole-body energy balance in mice. Hum. Mol. Genet., 20, 2571-2584] reported that Epm2a-/- mice had enhanced glucose disposal and insulin sensitivity, leading them to suggest that laforin, the Epm2a gene product, is involved in insulin signaling. We analyzed 3-month- and 6-7-month-old Epm2a-/- mice and observed no differences in glucose tolerance tests (GTTs) or insulin tolerance tests (ITTs) compared with wild-type mice of matched genetic background. At 3 months, Epm2b-/- mice also showed no differences in GTTs and ITTs. In the 6-7-month-old Epm2a-/- mice, there was no evidence for increased insulin stimulation of the phosphorylation of Akt, GSK-3 or S6 in skeletal muscle, liver and heart. From metabolic analyses, these animals were normal with regard to food intake, oxygen consumption, energy expenditure and respiratory exchange ratio. By dual-energy X-ray absorptiometry scan, body composition was unaltered at 3 or 6-7 months of age. Echocardiography showed no defects of cardiac function in Epm2a-/- or Epm2b-/- mice. We conclude that laforin and malin have no effect on whole-body glucose metabolism and insulin sensitivity, and that laforin is not involved in insulin signaling.     

Increased thalamocortical synaptic response and decreased layer IV innervation in GAP-43 knockout mice

The growth-associated protein, GAP-43, is an axonally localized neuronal protein with high expression in the developing brain and in regenerating neurites. Mice that lack GAP-43 (GAP-43 -/-) fail to form a whisker-related barrel map. In this study, we use GAP-43 -/- mice to examine GAP-43 synaptic function in the context of thalamocortical synapse development and cortical barrel map formation. Examination of thalamocortical synaptic currents in an acute brain slice preparation and in autaptic thalamic neurons reveals that GAP-43 -/- synapses have larger alpha-amino-3-hydroxyl-5-methyl-4-isoxazolepropionate receptor (AMPAR)-mediated currents than controls despite similar AMPAR function and normal probability of vesicular release. Interestingly, GAP-43 -/- synapses are less sensitive to blockade by a competitive glutamate receptor antagonist, suggesting higher levels of neurotransmitter in the cleft during synaptic transmission. Field excitatory postsynaptic potentials (EPSPs) from GAP-43 -/- thalamocortical synapses reveal a reduced fiber response, and anatomical analysis shows reduced thalamic innervation of barrel cortex in GAP-43 -/- mice. Despite this fact synaptic responses in the field EPSPs are similar in GAP-43 -/- mice and wild-type littermate controls, and the ratio of AMPAR-mediated to N-methyl-d-aspartate receptor (NMDAR)-mediated currents (AMPAR:NMDAR ratio) is larger than normal. This suggests that GAP-43 -/- mice form fewer thalamocortical synapses in layer IV because of decreased anatomical innervation of the cortex, but the remaining contacts are individually stronger possibly due to increased neurotransmitter concentration in the synaptic cleft. Together, these results indicate that in addition to its well known role in axonal pathfinding GAP-43 plays a functional role in regulating neurotransmitter release.     

Pathogenesis of acute and persistent murine herpesvirus infection in mice

Outbred laboratory mice were inoculated at the age of 5, 10 and 21 days by oral and/or intranasal routes with 2 different (a lethal and a nonlethal) doses of the murine herpesvirus isolate 68 (MHV-68). Severe exudative pneumonia with haematogenous dissemination of the virus to liver, heart muscle, and kidneys developed in the 5-day-old as well as in a part of the 10-day-old mice. Virus antigen was found by immunofluorescence (IF) in the alveolar lining of lungs, in heart muscle fibres, in spleen and thymic lymphocytes, in the tubular epithelium cells of kidneys, in the neurons of Gasserian ganglia and in the intima of large pulmonary vessels. Electron microscopy confirmed the transfer of virus particles through the capillary endothelium of the damaged alveolar septa. The surviving progeny and the mothers of animals, which had not succumbed to the lethal virus dose, were kept for 141-169 days when lungs and Gasserian ganglia were examined for virus presence. MHV-68 was recovered both by direct examination of the tissue homogenates as well as by the explantation technique. The results are suggestive for a dynamic persistence of MHV-68 rather than for static latency.     

Fmr1基因敲除小鼠的ABR阈值观察

目的对不同周龄的KO与WT小鼠听阈进行检测并对比,了解KO小鼠的听阈变化。方法采用PCR法鉴定FMR1基因敲除型(KO)纯合子(-/-)及其野生型(WT)纯合子(+/+)FVB近交系小鼠,实验动物150只分两组:(1)KO组(3、4、6、8、10周龄,每周龄15只,共75只;②WT组(3、4、6、8、10周龄,每周龄15,共75只,用于听性脑干反应(ABR)测试。数据及图像的采集:以ABR图形中Ⅱ波的阈值为小鼠的ABR阈值。结果 ABR阈值:3周及4周年龄组小鼠各基因型间KO小鼠的ABR阈值显著高于WT小鼠,差异有统计学意义(P<0.01);6、8、10周各组中各基因型小鼠的KO小鼠和WT小鼠的ABR阈值的差异无统计学意义(P>0.05)。结论幼年期FMR-1 KO小鼠听阈提高,成熟期FMR-1 KO小鼠听阈无异常,KO小鼠ABR的结果与AGS发生的年龄依赖性相一致。     

Increased sensitivity to error during decision-making in bipolar disorder patients with acute mania

BACKGROUND: Decision-making is a complex and important function for daily life that can be assessed quantitatively using a simple two-choice prediction task. Bipolar disorder (BD) patients are thought to show altered responsivity to positive and negative feedback. In this study we examined whether BD patients with psychotic mania show altered patterns of decision-making as a function of the frequency of incorrect predictions or error rate. METHODS: Fourteen adult DSM-IV-diagnosed BD patients with psychotic mania and 14 normal comparison subjects (NC) were tested with a two-choice prediction task using three error rate conditions (20%, 50%, or 80%). RESULTS: BD patients showed an increased sensitivity to error rate changes and switched more frequently at high error rates than NC subjects. In comparison, there were no differences between BD and NC subjects on the degree to which the response or stimulus during a previous trial predicts the current response. CONCLUSIONS: Decision-making in BD patients with psychotic mania appears to be highly sensitive to high error rates. Moreover, the patterns of responses appear distinct from what has been previously observed in acutely and chronically ill schizophrenia patients. The results of this study are informative as to the effects of errors on decision-making strategies in psychotic BD manic patients.     

Increased histamine sensitivity in mice after administration of endotoxins.

CFW mice given submicrogram doses of endotoxins intravenously became highly susceptible to the lethal effects of 0.5 mg of histamine given intraperitoneally 1 to 2 h later. The histamine-sensitizing effects of the endotoxins were transitory and disappeared within 6 to 8 h. L-Epinephrine administered intravenously immediately after histamine challenge protected mice from death, but aterenol and isoproterenol were ineffective. The histamine-sensitizing effect in endotoxins was precipitated by anti-endotoxin sera with a concomitant eightfold loss in activity. However, dissociation of the immune complex in 0.25 M acetic acid fully restored histamine-sensitizing activity. The transitory nature of the hypersensitivity produced by endotoxin and the high heat resistance of the active material prove that it is different from the histamine-sensitizing effects of pertussigen.