Adenovirus type 37 keratitis in the C57BL/6J mouse

PURPOSE: To develop a mouse model of adenoviral keratitis that will allow further study of viral and host pathogenic mechanisms. METHODS: Corneas of C57BL/6J mice were injected with adenovirus type 37 (Ad37) or virus-free dialysis buffer by a gas-powered microinjection system coupled to a glass micropipette needle. Mouse corneas were examined for signs of inflammation, by clinical examination, immunohistochemistry, and confocal microscopy; assayed for viral and chemokine mRNA expression by real-time PCR; titered to assess viral replication; and subjected to ELISA for chemokine and myeloperoxidase (MPO) protein expression. RESULTS: C57BL/6J mice corneas injected with 10(5) TCID (tissue culture infective dose) Ad37 showed stromal opacification and inflammation beginning from 1 day after injection and continuing for several months, while buffer-injected corneas showed no signs of inflammation. Ad37-injected corneas expressed adenoviral E1A 10S and E1B 19k mRNA but not IIIa, and viral titers had fallen two logs by day 4 after injection. When compared to untouched and buffer-injected corneas, Ad37-injected corneas expressed significantly higher levels of IL-6, KC, and MCP-1 mRNA at 4 hours after injection (P < 0.05). By ELISA, KC protein was significantly elevated in Ad37-injected corneas at 8 and 16 hours, and MCP-1 protein at 16 hours after injection (P < 0.05). Ad37-injected corneas showed elevated levels of MPO (P = 0.0024) at 4 days after injection consistent with immunohistochemical evidence for a predominance of neutrophils in the corneal stroma. CONCLUSIONS: Ad37 induces an acute immunopathologic response in the C57BL/6J mouse cornea, despite an absence of viral replication. This new animal model of Ad37 keratitis will facilitate studies of the molecular pathogenesis of the disorder.     

C57BL／6小鼠葡萄球菌性角膜感染模型的建立及相关研究

目的以乙基亚硝基脲（ENU）诱变技术建立小鼠葡萄球菌性角膜感染模型,探讨其主要条件致病菌的生物学特性。方法以ENU（150mg／kg）腹腔注射10周龄雄性C57BL／6小鼠,60d后与其同品系雌性小鼠配种,F1代小鼠中发现角膜混浊小鼠,以具有角膜混浊表型小鼠与C57BL／6小鼠回交的方式繁育。对角膜混浊小鼠角膜感染菌进行分离、培养、纯化、鉴定,并使用不同抗生素进行药物敏感试验。结果建立了稳定的小鼠葡萄球菌性角膜感染模型。从自发性角膜混浊（B6一Co）小鼠眼部成功分离纯化了松鼠葡萄球菌,筛选出了对该菌敏感及耐药的抗生素。对该菌敏感的抗生素有阿奇霉素、克林霉素、氯霉素、庆大霉素、利福平、四环素、阿米卡星、复方新诺明、米诺环素、左氟沙星、头孢噻吩、头孢噻肟、呋喃唑酮;对该菌耐药的抗生素有头孢西丁、青霉素、氨苄西林、新生霉素;属于中间态的抗生素为呋喃妥因。结论C57BL／6小鼠葡萄球菌性角膜感染模型为自发性动物模型,系凝固酶阴性葡萄球菌感染所致,以松鼠葡萄球菌为主。     

A paraxial schematic eye model for the growing C57BL/6 mouse

PURPOSE: The mouse eye has potential to become an important model for studies on the genetic control of eye growth and myopia. However, no data are published on the development of its optical properties. We developed a paraxial schematic model of the growing eye for the most common laboratory mouse strain, the C57BL/6 mouse, for the age range between 22 and 100 days. METHODS: Refractive development was followed with eccentric infrared photorefraction and corneal curvature with infrared photokeratometry. To measure ocular dimensions, freshly excised eyes were immediately frozen after enucleation to minimize distortions. Eyes were cut with a cryostat down to the bisecting horizontal plane, until the optic nerve head became visible. The standard deviations were +/-10 microm for repeated measurements in highly magnified videographs, taken in several section planes close to the equator in the same eyes. To evaluate inter-eye and inter-individual variability, a total of 20 mice (34 eyes) were studied, with 3-4 eyes for each of the 9 sampling ages. Schematic eye models were developed using paraxial ray tracing software (OSLO, LT Lambda Research Corporation, and a self-written program). RESULTS: The measured refractive errors were initially +4.0+/-0.6 D at approximately 30 days, and levelled off with +7.0+/-2.5 D at about 70 days. Corneal radius of curvature did not change with age (1.414+/-0.019 mm). Both axial lens diameter and axial eye length grew linearly (regression equations: lens, 1619 microm +5.5 microm/day, R=0.916; axial length, 2899 microm +4.4 microm/day, R=0.936). The lens grew so fast that vitreous chamber depth declined with age (regression equation: 896 microm -3.2 microm/day, R=0.685). The radii of curvature of the anterior lens surface increased during development (from 0.982 mm at day 22 to 1.208 mm at day 100), whereas the radii of the posterior lens surface remained constant (-1.081+/-0.054 mm). The calculated homogeneous lens index increased linearly with age (from 1.568 to 1.605). The small eye artifact, calculated from the dioptric difference of the positions of the vitreo-retinal interface and the photoreceptor plane, increased from +35.2 to +39.1 D, which was much higher than the hyperopia measured with photorefraction. Retinal image magnification increased from 31 to 34 microm/deg, and the f/number remained < or =1 at all ages, suggesting a bright retinal image. A calculated axial eye elongation of 5.4-6.5 microm was sufficient to make the schematic eye 1 D more myopic. CONCLUSIONS: The most striking features of the mouse eye were that linear growth was slow but extended far beyond sexual maturity, that the corneal curvature did not increase, and that the prominent lens growth caused a developmental decline of the vitreous chamber depth.     

Myelin/oligodendrocyte glycoprotein-specific T-cells induce severe optic neuritis in the C57BL/6 mouse

PURPOSE: The optic nerve is a common site of tissue damage in multiple sclerosis (MS) and experimental autoimmune encephalomyelitis (EAE). To determine the relationship between optic neuritis (ON) and EAE, we examined the incidence of ON in C57BL/6 (B6) mice immunized with a myelin oligodendrocyte/glycoprotein (MOG)-derived peptide or injected with MOG-specific T cells, which are known to induce EAE. METHODS: Mice were immunized with MOG35-55 or MOG40-54 peptides emulsified in complete Freund's adjuvant (CFA). Pertussis toxin (PTX) was injected intraperitoneally 1 day before and after immunization. For disease induction by adoptive transfer of primed cells, donor C57BL/6 mice were received with T-cell blasts (1-6 x 10(6)/mouse). Both EAE and ON were observed by either clinical signs or histology. RESULTS: ON developed in a high proportion of B6 mice treated with either protocol. The most severe inflammation was observed in the adoptively transferred mice. The induced ON was most frequently bilateral. In either actively or adoptively transferred diseases, both association and dissociation of EAE and ON was observed. CONCLUSIONS: Different MOG-specific T-cell subsets might be involved in the pathogenesis of EAE and ON. A better understanding of the pathogenesis of ON after induction by MOG may have important diagnostic and therapeutic implications.     

C57BL/6小鼠形觉剥夺性近视动物模型的建立

目的 探讨C57BL/6小鼠形觉剥夺性近视与眼球生物学参数的变化,揭示小鼠实验性近视形成的敏感期,以及形觉剥夺对小鼠屈光发育的影响.方法 实验研究.23日龄C57BL/6小鼠74只,随机分为3组,单眼形觉剥夺组:剥夺2周(n=12)、3周(n=20)和4周(n=18),对侧眼作为自身对照;形觉剥夺恢复组(n=10):单眼形觉剥夺4周,分别恢复4 d和7 d;正常对照组(n=14).实验前后分别用红外偏心摄影验光仪测量小鼠眼球的屈光状态,修正过的人眼角膜曲率计测量角膜曲率半径,相干光断层扫描仪测量眼球生物学参数,包括眼前节、晶状体厚度、玻璃体腔深度和眼轴长度等.对组内实验眼和对侧眼的屈光力、角膜曲率半径、眼球参数的比较采用配对t检验,不同组间比较采用独立样本t检验进行统计学分析.结果 形觉剥夺2周,实验眼相比对侧眼向近视方向漂移(-0.85±1.65)D,眼球各生物学参数未见明显改变;形觉剥夺3周,实验眼相比对照眼向近视方向漂移(-4.27±1.60)D(t=-1.72,P=0.095);形觉剥夺4周组,实验眼相比对侧眼向近视方向漂移(-5.27±1.28)D(t=-2.64,P<0.05)并伴玻璃体腔深度延长(27±13)μm和眼轴长度增加(28±12)μm;上除眼罩7 d,实验性近视完全恢复.结论 小鼠单眼形觉剥夺4周可诱导出相对近视,但诱导时间较其他近视动物模型长;去除眼罩7 d,实验性近视完全恢复;利用相干光断层扫描仪测最小鼠眼球生物学参数可以较好反映屈光度的改变.     

闪烁光对C57BL／6小鼠屈光和眼轴的影响初步观察

目的 探讨闪烁光诱导小鼠实验性近视模型的有效性和可行性.方法 实验研究.将28日龄的健康C57BL/6（B6）小鼠45只随机分为对照组、闪烁光照组、形觉剥夺组,每组15只.对照组饲养在模拟的正常光照环境中,光照时间为早8：00至晚8：00,光照度为250 lx;晚8：00至早8：00为暗室环境,光照度为0 lx.闪烁光照组使用白色LED灯闪烁光照明,时间为早8：00至晚8：00,闪烁光照频率为2 Hz,明暗周期为50%,峰值光照度为250 lx,谷值光照度约为1 lx;晚8：00至早8：00为暗室环境,光照度为0 lx;闪烁光照6周后撤去闪烁光,在与对照组同样环境中再饲养2周.形觉剥夺组使用半透明塑料眼罩遮盖右眼,饲养在与对照组相同的光照环境中.分别在实验前以及实验后2周、4周、6周、8周使用红外偏心验光仪和动物专用的A超测定仪来测量所有小鼠右眼的屈光度及眼轴,同时观察小鼠眼部和行为学变化.组间屈光度和眼轴比较采用单因素方差分析,闪烁光照组屈光度比较采用配对t检验,闪烁光照组与对照组比较采用独立样本t检验,眼轴与时间及屈光度的相关性采用回归分析.结果 闪烁光照6周后,小鼠的屈光度较对照组发生了显著的近视性改变[（-2.49±1.32）D vs（6.26±1.18）D,P＜0.01],眼轴也显著增长[（3.12±0.04）mm vs（3.08±0.02）mm,P＜0.01].闪烁光照组小鼠不同时间点眼轴与屈光度之间呈正相关（r2=0.677,P＜0.01）.实验6周末,形觉剥夺组小鼠发生的近视程度高于闪烁光照组[（-6.42±2.21）D vs（-2.49±1.32）D,P＜0.05],眼轴增长也更为显著[（3.27±0.04）mm vs（3.12±0.04）mm,P＜0.05],但是眼罩较易脱落,经常需补戴,并有晶状体混浊发生.结论 闪烁光刺激可以成功诱导出小鼠实验性轴性近视,但近视程度低于形觉剥夺诱导,是一种更为安全、方便的近视模型诱导方法.     

Photoreceptor degeneration and loss of retinal function in the C57BL/6-C2J mouse

PURPOSE: The C57BL/6-c(2J) (c2J) mouse strain has been shown in earlier studies to be highly resistant to light damage. Subsequent studies related this resistance to an amino acid substitution (leu450met) in a pigment epithelial enzyme (RPE65), which slowed the rate of rhodopsin regeneration. The present study was conducted to examine patterns of photoreceptor death, electrophysiological function (the ERG) and trophic factor expression over the life of the C57BL/6-c(2J) retina. METHODS: Observations were made on two C57BL/6J-c(2J) substrains, one albino (Tyr/Tyr) and one pigmented (Tyr/(+)), and two nondegenerative strains, one albino (BALB/cJ) and one pigmented (C57BL/6J). Mice were raised in dim cyclic light (12 hours at 5 lux, 12 hours in the dark), and a developmental series of retinas of each strain was taken between postnatal day (P)4 and (P365(+)). Retinas were examined for cell death by using the TUNEL technique, stress-induced protein expression (FGF-2 and GFAP), and measures of retinal thickness. The dark-adapted ERG was recorded in dark-adapted conditions in early adulthood (13-15 weeks) and late adulthood (>1 year). RESULTS: In both C57BL/6-c(2J) substrains, the retina showed marked degenerative features when compared with two control strains, BALB/cJ (leucine at codon 450 in RPE65) and C57BL/6J (methionine). During development and into young adulthood, photoreceptor death rates were abnormally high, levels of two stress-inducible proteins (FGF-2 and GFAP) were abnormally high, and the ERG (electroretinogram) was significantly reduced in amplitude (<50% of values in BALB/cJ or C57BL/6J). The rate of photoreceptor death remained abnormally high into young adulthood (2-3 months) but decreased to control levels by 1 year. Accordingly, the thickness of the outer nuclear layer and the ERG were stable over the same period. CONCLUSIONS: Results suggest that a still-unidentified stress increases photoreceptor death in the C57BL/6-c(2J) retina during the critical period of photoreceptor development and into young adulthood, upregulates stress-inducible factors, and markedly limits the amplitude of the ERG. These degenerative changes do not continue after early adulthood, the retina remaining stable in structure and function into late adulthood. The degenerative changes were apparent in both albino and pigmented C57BL/6-c(2J) substrains. Their genetic cause remains unknown.     

Regulation by oxygen of photoreceptor death in the developing and adult C57BL/6J mouse

We have examined the role of tissue oxygen in the regulation of photoreceptor death in the C57BL/6J mouse. Litters of C57BL/6J mice were raised in dim cyclic (12 hr dark, 12 hr 50 lx) light. Adults or litters aged P7 or P8 were placed with their mothers in plexiglass chambers in which oxygen levels were set at 21% (normoxic), 10 or 11% (hypoxic) or 70% (hyperoxic) for up to 22 days. At intervals after introduction to these chambers, retinas were examined for cell death, using the TUNEL technique. Hypoxia accelerated cell death up to five-fold during a critical developmental period from approximately P12 to 18. Thereafter hypoxia-induced cell death declined rapidly. Hyperoxia slowed photoreceptor death over the same period, to approximately half control levels. At the anterior edge of the developing retina the effects of hypoxia and hyperoxia differed markedly from the rest of the retina. In the adult, hypoxia accelerated photoreceptor death, but the acceleration was an order of magnitude weaker than during the critical period of developing retina. Hypoxia-induced photoreceptor death remained above control levels after 20 days exposure. Results suggest that the naturally occurring wave of photoreceptor death seen in developing mouse retina during their development (P12-P20) is regulated by a physiological episode of hypoxia. After P20, photoreceptor vulnerability to hypoxia falls to a low but significant level. The edge of the retina appears subject to chronic hyperoxic stress from P14 into adulthood. Tissue oxygen levels are important determinants of photoreceptor death and survival in both developing and adult retina.     

Resistance of photoreceptors in the C57BL/6-c2J, C57BL/6J, and BALB/cJ mouse strains to oxygen stress: evidence of an oxygen phenotype

PURPOSE: To assess the vulnerability of retinal photoreceptors in the BALB/cJ, C57BL/6J, and C57BL/6-c2J (c2J) mouse strains to hypoxic and hyperoxic stress. METHODS: Mice were raised in dim cyclic light. Pups aged postnatal day 7 (P7) were exposed to hypoxia (11-12% oxygen) for periods up to 23 days. Adult mice were exposed to either hypoxia (12% oxygen) or to hyperoxia (75% oxygen) for up to 2 weeks. Using the TUNEL (terminal dUTP-mediated nick end labeling) technique retinas were examined for cell death. RESULTS: In juvenile mice, hypoxia induced a robust increase in photoreceptor death in the C57BL/6J strain and a weaker increase in the C57BL/6-c2J strains. In the adult, hypoxia was associated with a small reduction in photoreceptor death in the C57BL/6-c2J strains. Hyperoxia caused substantial photoreceptor death in both the C57BL/6-c2J and C57BL/6J strains. The BALB/cJ strain was more resistant to oxygen stress than the C57BL strains. CONCLUSIONS: The difference in oxygen vulnerability between C57BL/6J and BALB/c strains may provide a useful starting point for the analysis of genetic regulation of this vulnerability. The resistance of the C57BL/6-c2J substrains to hypoxia may reflect their degenerative status.     

Developmental death of photoreceptors in the C57BL/6J mouse: association with retinal function and self-protection

We have investigated the relationship between cell death among photoreceptors and the expression of function- and stress-related proteins during the development of the retina of the C57BL/6J mouse. Retinas from mice aged P(postnatal day)4 to P63 (adult) were examined for cell death using the TUNEL technique, and for the expression of basic fibroblast growth factor (bFGF), cytochrome oxidase (CO), rod opsin and glial fibrillary acidic protein (GFAP), using immunocytochemistry. At P4, cell death is most prominent in the inner layers of retina, declining to near-zero levels by P16. Cell death among photoreceptors occurs in a discrete wave commencing at approximately P12 and remaining elevated into the 4th postnatal week, beginning, peaking and declining later than in inner retina. The onset of photoreceptor death correlates with the expression of function-related molecules, such as CO and opsin. The decline in photoreceptor death correlates with the expression of the protective factor bFGF in photoreceptors. At the anterior edge of the retina photoreceptor death and the expression of bFGF are accelerated, and the expression of bFGF and GFAP is upregulated, by an edge-specific stress. We conclude that in the mouse photoreceptors undergo a wave of death which culls the neonatal population to adult levels. The onset of photoreceptor death is related to the acceleration of photoreceptor metabolism and function between P12 and P20. The decline of photoreceptor death to the very low levels found in the adult may be mediated by the upregulation of protective factors such as bFGF. Photoreceptor death and the expression of bFGF and GFAP at the edge of the retina are regulated by a still-unidentified, edge-specific stress, from as early as P16.     

Anesthesia can cause sustained hyperglycemia in C57/BL6J mice

Effects of anesthesia on the blood glucose of C57/BL6J mice were evaluated under conditions commonly used for testing retinal sensitivity with electroretinographic (ERG) recordings. We evaluated the effects of four anesthetics: nembutal (50 mg/kg), pentothal (100 mg/kg), avertin (240 mg/kg), and ketamine/xylazine (100 mg/kg) using saline as control. We measured blood glucose (BG) levels from tail vein blood before and 15 and 60 min following intraperitoneal injections. Fifteen minutes postinjection, all four anesthetics and saline elevated BG with ketamine/xylazine and avertin having substantially greater effects than nembutal, pentothal, and saline. Only the effects of ketamine/xylazine and avertin persisted throughout the test period. Sixty minutes after injecting ketamine/xylazine BG remained elevated at 400 +/- 42 mg/dl, a 167% increase over preinjection levels. Sixty minutes after injecting avertin BG was 288 +/- 10 mg/dl, a 59% increase over preinjection levels. No sustained elevation in BG was detected 60 min following injection of nembutal, pentothal, or saline. Because BG can affect the amplitude of the ERG, caution should be exercised in the use of ketamine/xylazine or avertin. The choice of anesthesia may also be important in diabetes and metabolism research where changes in blood glucose could impact physiological processes.     

频域光学相干断层扫描对C57BL／6小鼠及色素兔眼前后节结构特点的活体观察

背景频域光学相干断层扫描（SD—OCT）可进行活体组织的测量。目前SD—OCT对人眼活体组织测量的研究已有较多报道,但对实验动物眼的活体测量结果少有研究。目的应用SD—OCT活体观察正常C57BL／6小鼠的眼前节结构及色素兔的角膜、视盘及视网膜形态结构。方法利用轴向分辨率为5μm、扫描速度为26000次／s的SD—OCT对4只健康SPF级C57BL／6小鼠8只眼扩瞳前后进行眼前节形态学检查;利用SD—OCT对6只健康SPF级色素兔12只眼进行角膜及视盘、视网膜形态学检查。结果SD—OCT进行眼前节扫描,清晰可见C57BL／6小鼠角膜、虹膜及瞳孔区对应的晶状体结构,而且扩瞳前后晶状体结构形态发生明显改变,角膜SD—OCT扫描断层图与相应的切片图结构相对应,扩瞳前平均中央角膜厚度（CCT）为（96±9）μm,平均前房深度（ACD）为（460-e8）汕m,平均角膜水平直径（wTw）为（2．86±0．41）mm;扩瞳后CCT为（96±8）μm,ACD为（356±20）μm,wTW为（2．87±0．62）mm,C57BL／6小鼠扩瞳前后CCT、wTw测量值的比较差异均无统计学意义（t=0．478,P=0．647;t=0．737,P=0．485）;扩瞳后ACD较扩瞳前明显变浅,差异有统计学意义（t=-13．022,P〈0．001）。色素兔的SD—OCT眼前节检查均可见明显的角膜及视网膜分层,结构分别与相应的组织学切片相对应,扩瞳后角膜最薄点均值为（370±10）μm,视网膜厚度均值为（175：e4）Ixm,水平扫描后手动测量数据视盘深度均值为（1．35±0．51）mm,宽度均值为（4．52±0．82）mm。结论SD—OCT作为一种非接触、非侵人性检查,可清晰呈现C57BL／6小鼠眼前节结构及色素兔相应的角膜和视网膜结构,测量指标可用于实验研究过程中相应组织结构的活体观察。     

The retinal pigment epithelium of wild type (C57BL/6J +/+) and pearl mutant (C57BL/6J pe/pe) mice

The retinal pigment epithelium (RPE) lying along the vertical meridian of the eyes of wild-type (+/+) and pearl mutant (pe/pe) mice was examined with electron microscopy and microspectrophotometry in order to compare differences in melanosome location, size, numerical density, volume density, and melanin concentration. In +/+ mice the fraction of melanosomes that lie in the apical processes was greater in the superior than in the inferior retina. Also, the numerical density and volume density of soma melanosomes were lower in the superior retina. The soma melanosomes were also located closer to the basal membrane and had a larger average diameter in the inferior retina. No significant differences in melanosome location were observed between light-adapted and dark-adapted retinas. In pe/pe mice the fraction of melanosomes in the apical processes was very low in both inferior and superior retinas. The numerical density and the volume density of soma melanosomes of pe/pe were significantly less than those of +/+. The soma melanosomes of pe/pe mice lie closer to the basal membrane than those of +/+, and they had a larger mean diameter than those of +/+. Electron micrographs depicted some melanosomes of pe/pe with irregular profiles and abnormal melanin deposition at their periphery. Microspectrophotometric measurements of individual melanosomes in semithin sections showed that maximal specific absorption and lambda max were nearly equal for both genotypes and both superior/inferior locations. These findings show that intramelanosomal melanin concentrations is normal for pe/pe. The basal membrane of the RPE of pe/pe was infolded over only 80% of the area covered by the basal surface, whereas the basal membrane in +/+ was infolded over more than 98% of the area covered. The boundary density of RPE basal infoldings was also lower in pe/pe than in +/+. Furthermore, some areas of the basal lamina of pe/pe RPE had a periodic, rather than an amorphous, structure. These findings suggest that the reduced retinal sensitivity found in intact pe/pe animals, but not in superfused, isolated pe/pe retinas, may result from impaired transport of a diffusible substance by the basal membrane of the RPE.     

正常C57BL/6J小鼠明视紫外光视网膜电图特征

目的观察小鼠紫外光敏感视锥系统（UV-cone）视网膜电图（ERG）的特点。方法实验研究。成年野生型C57BL/6J小鼠10只（10眼）,随机分成实验组和对照组,每组5只。2组均明适应（背景白光的色温为7000 K,亮度为30 cd·m^-2） 10 min后行ERG检测。实验组记录UV-cone ERG,刺激所用的紫外光波长为363 nm,刺激强度分别为0.03、0.30、1.00、3.00 mW·s·m^-2。对照组记录明视系列白光ERG。2组间最大反应a波、b波振幅的比较采用独立样本t检验。结果实验组紫外光（UV）刺激强度达到0.30 mW·s·m^-2时,ERG开始出现稳定的正向b波,其振幅为（14.8±3.0）μV;随着刺激强度增大,b波上可以记录到明显的振荡电位（前3个子波振幅较大）。而对照组b波上未见明显的振荡电位。实验组ERG最大反应b波振幅明显高于对照组（t=2.615,P＜0.05）,而a波振幅2组间差异无统计学意义（t=-1.633,P＞0.05）。结论正常成年C57BL/6J小鼠明视UV-cone ERG与传统的白光ERG在波形和最大反应幅值上存在一定的差异。     

血脂异常对C57BL小鼠晶状体的影响

目的探讨实验性血脂异常对C57BL小鼠晶状体组织结构的影响。方法将48只3月龄雄性C57BL小鼠随机分为3月龄普食组、8月龄普食组和8月龄高脂组，前两组普通饲料喂养，第3组高脂饲料喂养。各组动物按时处死后做血液生化指标检测，同时摘取眼球做光镜和电镜病理切片观察。结果8月龄高脂组小鼠的体重明显高于3月龄普食组和8月龄普食组（P〈0．01），8月龄高脂组小鼠的血脂、血液流变学指标和血清丙二醛显著高于3月龄普食组和8月龄普食组（P〈0．01），8月龄高脂组小鼠晶状体中央前囊膜厚度高于3月龄普食组和8月龄普食组（P〈0．01）。结论血脂异常能够加速C57BL小鼠的晶状体改变，其改变与白内障的发生密切相关。     

Smad1在C57BL/6小鼠形觉剥夺性近视中的作用机制

目的：：通过建立C57 BL/6小鼠形觉剥夺性近视模型,探究Smad1在近视形成中的作用机制。方法：将60只3周龄C57 BL/6小鼠随机分为实验组和正常对照组(NC),包括形觉剥夺3wk组(FDM 3W,n=20),形觉剥夺4wk组(FDM 4W,n=20),FDM3W正常对照组(FDM 3W-NC,n=10)和FDM4W正常对照组(FDM 4W-NC,n=10),实验组右眼遮盖,左眼自然暴露作为自身对照,正常对照组不予任何处理。在实验3 wk及4 wk时检测所有小鼠屈光状态,HE染色观察巩膜及视网膜组织结构变化,免疫组织化学方法及实时荧光定量PCR观察Smad1在视网膜中的表达情况。结果：(1)自身对照眼和正常对照组呈生理性远视化发展,FDM3W、FDM4W实验眼均呈相对近视化发展,差异具有统计学意义(P<0.05);(2)与自身对照组及正常对照组比较,FDM3W、FDM4W实验眼巩膜及视网膜明显变薄;实验眼视网膜中Smad1表达明显下降,差异具有显著统计学意义(P<0.01)。结论：小鼠形觉剥夺性近视眼视网膜(尤其是内核层及内丛状层)中Smad1的表达呈下调趋势, Smad1极有可能通过转导视网膜信号参与了近视发生发展过程。     

BALB/c and C57BL6 mouse strains vary in their ability to heal corneal epithelial debridement wounds

Genetically engineered mice are usually produced on a mixed genetic background and can be derived from several mouse strains including 129SvJ, C57BL6, and BALB/c. To determine whether differences in recurrent corneal epithelial erosions (RCEEs), corneal epithelial stem cell deficiency (CESCD), and cell migration rate vary between two different mouse strains (BALB/c and C57BL6), 8-week mice were subjected to 1.5 (small) or 2.8 mm (large) manual debridement wounds and allowed to heal for 4 weeks. Syndecan-1 (sdc-1) null mice backcrossed seven generations onto a BALB/c genetic background were also included in the RCEE and CESCD studies to permit comparisons between genotypes within a single strain. After sacrifice, corneas were assessed for the presence of recurrent erosions; no fewer than 15 corneas were used for each strain or genotype studied. Data show that the frequency of recurrent erosions after small wounds was 81 +/− 9% in the C57BL6 mice, 73 +/− 2% in the BALB/c mice, and 32 +/− 6% in sdc-1 null mice. Neither strain developed CESCD after small wounds. The frequency of erosions after large wounds was greater (88 +/− 8%) in the C57BL6 mice compared to BALB/c (60 +/− 2%), and sdc-1 null mice (32 +/− 5%). Four weeks after the large wounds, fixed, flat mounted corneas were assessed for evidence of CESCD with antibodies against the conjunctival keratin K8 and the goblet cell marker, the mucin Muc5AC. The frequency of CESCD 4 weeks after the large wounds was significantly greater in the C57BL6 mice than in the BALB/c or sdc-1 null mice. To assess cell migration rates, corneas were subjected to 1.5 mm wounds and allowed to heal for 12, 15, 18, 21, and 24 h. After sacrifice, corneas were stained with Richardson stain (BALB/c) or propidium iodide (C57BL6) to assess reepithelialization rates. While reepithelialization rates were similar for the early times after wounding, by 24 h the C57BL6 corneas had healed faster: 16 of 30 corneas from the C57BL6 mice were closed compared to 9 of 30 of the BALB/c wounds. BALB/c corneas appeared larger overall compared to C57BL6 corneas; measurements of the overall mass of the enucleated eyes and diameters of the flat-mounted corneas confirmed that C57BL6 eyes and corneas were 6.8% and 4.4% smaller respectively than those of BALB/c mice even though the masses of the two mouse strains at 8 weeks of age were identical. Using BrdU to label dividing cells, we found that 18 h after wounding, C57BL6 and BALB/c corneal epithelia showed similar numbers of proliferating cells. To determine if the enhanced corneal epithelial cell migration rate seen in the C57BL6 mice was specific to the cornea, we conducted time-lapse studies to assess random cell migration rates in vitro using primary cultures of mouse epidermal keratinocytes. Consistent with the in vivo data, epidermal keratinocytes derived from BALB/c mice migrated 60% slower than C57BL6 cells. These data prove that strain-specific differences in cell migration rate in vivo are present in the cornea and are accompanied by differences in the frequencies of recurrent erosions and corneal epithelial stem cell deficiency.     

Assessment of postnatal corneal development in the C57BL/6 mouse using spectral domain optical coherence tomography and microwave-assisted histology

The eyes of newborn mice are relatively underdeveloped and the lids remain closed for the first 2 weeks after birth. There after the eyes undergo a period of rapid growth for several weeks. Eventually the eyes reach an age at which many ocular structures stabilize for the remainder of the animal’s life, or for others, growth is significantly slowed. The central corneal thickness (CCT) is a parameter commonly reported in corneal studies. However there is a large discrepancy in values reported for adult mice as well as a lack of comprehensive values covering the time from birth through adulthood. In this study we report, for the first time, the use of spectral domain optical coherence tomography (SD-OCT) for in situ and in vivo determination of CCT from P0 to P250 for C57BL/6 mice. SD-OCT provided a reliable measure of CCT and we fit the data to an exponential rise to maximum growth curve resulting in a value of 49 μm for P0 and a maximum adult value of 106 μm. By comparison, corneas processed for conventional histology produced CCT values approximately 30–35% thicker and with greater variability. Ex vivo real-time imaging during fixation revealed swelling and gross distortion of the cornea beginning after only 10–15 min in fixative. The fixation artifacts were not observed when the cornea was processed using an optimized microwave fixation protocol. CCT values measured in corneas fixed with the microwave process compared favorably with values obtained with SD-OCT. We conclude that for corneal research, mice younger than 8 weeks of age should not be considered as adults since they are still in a rapid phase of growth up until that time. In addition we report the first use of microwave processed histological specimens for visualizing the murine cornea. Tissue processed in this manner has minimal artifacts, a CCT equivalent to that measured in vivo by SD-OCT and ultrastructural detail comparable to conventional fixation methods.