An immunohistochemical study of the role of matrix metalloproteinases and their tissue inhibitors in chronic mitral valvular disease (valvular endocardiosis) in dogs

While the pathogenesis of chronic valvular disease (CVD) in dogs remains unclear, alterations in the activity of specific metalloproteinase enzymes and their inhibitors within the valve stroma are suspected of having a role. This study describes the immunohistochemical distribution pattern of matrix metalloproteinase (MMP) types 2, 9 and 14 and their tissue inhibitors, termed tissue inhibitors of metalloproteinase (TIMP), types 2 and 3, in normal canine mitral valves (MVs) (n=10) and in dogs with mild (n=7), moderate (n=14) and severe (n=9) CVD. In normal MVs, MMP-2 and -14, and TIMP-2 were expressed in isolated stromal cells. Tissue inhibitor of metalloproteinase-3 exhibited moderate intracellular and mild extracellular expression. With increasing severity of CVD, the expression of MMP-2 decreased. The number of stromal cells expressing MMP-14 increased, predominantly in the margins of the nodular lesions. Tissue inhibitor of metalloproteinase-2 and -3 expression increased both intra- and extracellularly. Matrix metalloproteinase-9 was not detected in normal or diseased valves. In conclusion, CVD was characterised by alterations in the distribution and intensity of valvular MMP and TIMP expression, suggesting that depressed catabolism and the accumulation of extracellular matrix components within affected valves contributes to their structural alteration and consequent loss of function.     

日粮营养对动物脂肪组织基因表达的影响

脂肪组织是一个强大的分泌器官,它能分泌许多与能量、脂肪代谢相关的酶、激素等.调控能量代谢和脂肪组织生长.本文综述了日粮对动物脂肪组织中基因表达作用的研究状况.并阐述了营养成分对这些基因上下游表达的作用机制.     

Reconstruction of corneal epithelium with cryopreserved corneal limbal stem cells in a rabbit model

The integrity and transparency of the cornea plays a key role in preserving vision. This paper reports a procedure to create an artificial sheet of corneal epithelium from cryopreserved limbal stem cells (LSCs) and to use this for corneal transplantation. Corneal LSCs were isolated from biopsy specimens of rabbit limbal lamellar and cryopreserved in liquid nitrogen at 2–4 passages. The cells were grown in culture medium for 12–14 days on top of a cell-free human amniotic membrane framed on a nitrocellulose sheet. The corneal epithelium generated was transplanted into the right eyes of 14 LSC deficient (LSCD) rabbits (seven experimental animals, seven controls) with corneal damage. The seven LSCD rabbits in the experimental group were transplanted with a corneal epithelial sheet generated from the cryopreserved corneal LSCs. Four LSCD rabbits were used as the vehicle control and were transplanted with a cell-free amniotic membrane, and the remaining three LSCD rabbits were negative controls without transplantation. Over a 2-month recovery period, 2/7 animals in the experimental group recovered completely, four recovered partially and one did not respond. In the control groups, three negative controls and three vehicle controls lost their vision completely, and one of the vehicle controls partially recovered transparency of the cornea Following treatment, corneal transparency of the experimental rabbits was significantly improved compared to controls (P < 0.05). The results indicated that cryopreserved corneal LSCs can repair damaged rabbit cornea, suggesting a possible new clinical approach to reconstruction of corneal epithelium.     

Histomorphological findings and expression of matrix metalloproteinases and their tissue specific inhibitors (TIMPs) in normal tricuspid valves and in chronic tricuspid valvular disease in dogs

The histomorphological findings and immunohistochemical expression of matrix metalloproteinases (MMPs-1, 2, 9 and 14) and their tissue inhibitors (TIMPs-2, 3 and 4) are reported in the parietal (pTV) and septal leaflets (sTV) of the tricuspid valves in normal dogs and dogs with chronic valvular disease (CVD). The layers of the normal sTV were not as well defined as in the pTV and the spongiosa of the sTV contained abundant mucopolysaccharides (MPS) and adipocytes. In CVD, there was expansion of the spongiosa of the pTV due to deposition of MPS, leading to formation of nodules along the free edge. In CVD, there was fibrosis of the atrialis of the sTV and formation of nodular deposits of MPS in the spongiosa and ventricularis, mainly affecting the proximal and middle parts of the leaflet. In dogs with normal pTV and sTV, MMPs-1 and 14 and TIMPs-2, 3 and 4 were expressed, while MMPs-2 and 9 were absent. In mild CVD, expression of MMPs-2, 9 and 14 were increased in the pTV, whereas small foci within the spongiosa contained MMP-9 and TIMP-3 positive cells. In advanced CVD, MMP-14 also was increased in the pTV. In mild CVD, there was increased expression of MMPs-1 and 2 and TIMP-2, but decreased expression of TIMP-4, in the sTV. Small foci with expression of MMP-14 and TIMPs-2, 3 and 4 were also present in the sTV in mild CVD. In advanced CVD, there was increased expression of MMPs-2 and 9 and TIMP-2 in the sTV. In CVD there is upregulation of various MMPs in the pTV, whereas there is a complex alteration in expression of MMPs and TIMPs in the sTV.     

Effects of gibberellin and its inhibitors on growth and gene expression in Poa pratensis北大核心CSCD

研究了不同浓度的赤霉素及其抑制剂烯效唑和多效唑对草地早熟禾生长及赤霉素相关基因表达的影响,为外源生长调节剂在草坪养护管理中的高效利用提供理论依据。以1/2 Hogland营养液培养的草地早熟禾为材料,随机分成7组,分别施用不同浓度的赤霉素、烯效唑、多效唑,测定根及叶片的生长量、叶绿体分布、叶绿素含量以及赤霉素相关基因的表达量。结果显示：与对照比较,外源烯效唑和多效唑均显著抑制草地早熟禾的伸长生长以及干/鲜重,但提高了根冠比、叶绿素a、叶绿素b及类胡萝卜素含量（P<0.05）;增加了叶肉细胞层数,使叶绿体充满在叶片上下表皮之间的叶肉细胞中;赤霉素合成代谢途径关键酶基因PpKAO、PpKS1、PpGA₃ox、PpGA₂ox表达量显著下调,赤霉素信号转导受体蛋白基因PpGID1显著上调（P<0.05）。外源赤霉素对草地早熟禾的伸长生长具有促进作用,但降低了根、叶的干/鲜重,提高根冠比,显著提高了赤霉素分解基因PpGA₂ox表达量（P<0.05）。总之,烯效唑、多效唑对草地早熟禾生长发育及基因表达的调控作用与赤霉素相反,但无明显浓度效应;在草坪修剪后立即喷施1000倍的烯效唑或多效唑,对减少用工成本,增加草坪观赏性、提高园林绿化中的草坪草管护水平具有重要意义。     

Decreased expression of matrix metalloproteinases and tissue inhibitors of metalloproteinase in the kidneys of hereditary nephrotic (ICGN) mice

Matrix metalloporoteinases (MMPs), which are dominantly regulated by tissue inhibitors of metalloproteinase (TIMPs), play important roles in extracellular matrix (ECM) degradation and are involved in the progression of kidney diseases. In glomeruli and tubulointerstitum of hereditary nephrotic (ICR-derived glomerulonephritis: ICGN) mouse kidneys, hyper-accumulation of ECM components occurred, and MMP activity decreased. In the present study, because lower levels of MMP activity may contribute to the progression of renal fibrosis in ICGN mice, Western blotting analysis and immunohistochemical staining for MMPs and TIMPs were performed to verify the expression levels of these proteins. Levels of MMP-2, MMP-9, MT1-MMP, TIMP-1 and TIMP-2 in the kidneys were decreased in ICGN mice in comparison with normal ICR mice. These results indicate that small amounts and low levels of activity of MMPs cause the progression of renal fibrosis in ICGN mice.     

The activity of matrix metalloproteinases (MMPS) and tissue inhibitors of metalloproteinases (TIMPs) in mammary tumors of dogs and rats

We conducted zymography for detecting the activity of matrix metalloproteinases (MMPs) and reverse zymography for the activity of tissue inhibitors of metalloproteinases (TIMPs) in canine spontaneous and rat 7, 12-dimethylbenz(a)anthracene (DMBA)-induced mammary tumor tissues. The activities of MMPs of canine mammary tumors were quite higher than those of the rat chemically induced tumors. The activities of MMPs were significantly higher in malignant tissues than in benign ones of canine tumors, whereas the activity of only MMP-2 was higher in both benign and malignant rat tumors compared to normal tissues. There were no differences of MMPs activities between benign and malignant rat tumors. The results of reverse zymography indicated that the activities of TIMP-1, -2 and -3 were strikingly higher in rat tumors than in canine tumors. The activities were higher in malignant tissues than in benign ones of dogs, and higher in tumor tissues than in normal mammary tissues of rats. The results of film in situ zymography for tissue localization of gelatinolytic activity showed that the digested area was more extended in malignant tumors than in benign ones of dogs. However, the area was similarly extended in both benign and malignant rat tumors. These results may indicate that the canine spontaneous malignant mammary tumors possess more aggressive nature than the rat chemically induced counterpart, resulting from the high level of MMPs and low level of TIMPs activities of the tumor tissues.     

Effects of SNPs and alternative splicing within HGF gene on its expression patterns in Qinchuan cattle

Background: Identification of genetic variants, including SNPs(Single Nucleotide Polymorphisms), CNVs(Copy Number Variations) and alternative splicing, within functional genes has received increasing attention in animal science research. HGF(Hepatocyte Growth Factor) is a very important growth factor that works as a mitogen or a morphogen during tissue growth, development and regeneration. However, to date, the functions of genetic variants within the bovine HGF gene, particularly their effects on m RNA expression, have not been determined well.Results: The present study aimed to perform association analysis between genetic variants and m RNA expression for the bovine HGF gene in Qinchuan cattle using various strategies, including PCR-RFLP(Restriction Fragment Length Polymorphism), q PCR(Quantitative Real-time quantitative PCR), TA cloning, DNA sequencing and bioinformatics analysis. A total of five SNPs were identified and only SV1 locus significantly affected HGF m RNA expression in fetal skeletal muscle(P 0.05). Heterozygous genotype individuals showed significantly higher HGF expression(P 0.05), which was significantly greater in the CTCCAGGGTT combined genotype than that in theCCCCGGGGTT combined genotype(P 0.05). In addition, two alternative splicing variations, HGF-W and HGF-M,were identified, which resulted from alternative 3′ splice sites of exon 5, and HGF-W showed higher m RNA levels than HGF-M in all tissues.Conclusion: In summary, genetic variations within the HGF gene affected m RNA expression. These findings provide new insight into the molecular characteristics and functions of bovine HGF.     

Pharmacokinetics, intramuscular bioavailability and tissue residue profiles of ceftazidime in a rabbit model

This study investigated the disposition kinetics and plasma availability of ceftazidime in rabbits after single intravenous (i.v.) and intramuscular (i.m.) injections of 50 mg kg-1 b.wt. Tissue residue profiles were studied after repeated intramuscular injections of 50 mg kg-1 b. wt, twice daily for five consecutive days. A microbiological assay with Bacillus subtilis as the test organism was used to measure its concentrations in plasma and tissues. The plasma concentration-vs-time curves were best described by a two compartment open model. The decline in plasma drug concentration was biexponential with half-lives of 0.258 h for t1/2 alpha, 2.22 h for t1/2 beta, for distribution and elimination phases, respectively, following i.v. injection. After intramuscular injection of ceftazidime at the same dose, it was detected in plasma at 5 min and reached its minimum level 12 h post-injection. The peak plasma concentration (Cmax) 66.3 micrograms.ml-1 was attained at 0.779 h (Tmax). The elimination half-life (T1/2el,) was 2.12 h, the mean residence time (MRT) was 3.06 h and the systemic bioavailability was 96.6%. In vitro protein binding percent of ceftazidime in rabbit's plasma was ranged from 13.3 to 21.6%. The limit of quantification (LOQ) for the assay was 0.01 microgram.ml-1 in plasma and tissues. The tissue level concentrations were highest in the kidneys, and decreased in the following order: liver > heart > muscles and plasma. No ceftazidime residues were detected in tissues and plasma after 72 h. It is concluded that tissue kinetics is an important tool in predicting and controlling drug residues in edible tissues of food producing animal.     

小花棘豆中毒对家兔睾丸细胞凋亡及Bcl-2、Bax表达的影响

将24只家兔随机分为对照组和试验Ⅰ、Ⅱ、Ⅲ组,试验组饲粮分别按照Ⅰ组15%(苦马豆素含量30mg/kg)、Ⅱ组30%(苦马豆素含量60mg/kg)、Ⅲ组45%(苦马豆素含量90mg/kg)的比例添加小花棘豆,对照组仅饲喂青干草,试验期70d;分别于攻毒后第14,35,70天每次每组随机采集2只家兔的睾丸,通过TUNEL法检测细胞凋亡,real-time PCR检测Bcl-2、Bax mRNA的表达,免疫组化检测Bcl-2、Bax蛋白的表达。结果显示:从第35天开始,试验Ⅱ组和Ⅲ组家兔睾丸细胞凋亡指数、Bcl-2和Bax mRNA的表达均与对照差异极显著(P<0.01),试验Ⅰ组家兔睾丸细胞凋亡指数、Bcl-2和Bax mRNA的表达均与对照差异显著(P<0.05);试验组家兔睾丸组织Bcl-2蛋白表达均明显低于对照,Bax蛋白表达均明显高于对照,其差异性随中毒时间的延长而变化。结果表明:小花棘豆中毒可导致家兔睾丸组织生精细胞凋亡,且与小花棘豆中毒呈现一定的时间-剂量效应,这种作用可能与Bcl-2和Bax基因表达有关。     

氨基多糖纳米微粒对 RAW264.7 细胞株TNF-α基因mRNA表达量的影响

本试验探讨氨基多糖纳米微粒(Chitosan nanoparticle,CNP)对巨噬细胞RAW264.7细胞株中肿瘤坏死因子-α(TNF-α)基因mRNA表达量的影响.以巨噬细胞株RAW264.7为腹腔巨噬细胞模型,分别作用RAW264.7细胞12、18 h及24 h后,运用RT-PCR半定量法分析TNF-α mRNA表达水平的变化.结果表明:CNP有明显的提高TNF-α mRNA表达量的作用.CNP组TNF-α mRNA表达量12、18 h及24 h分别为91%、63.2%和152.5%;对照组TNF-α mRNA表达量12、18 h及24 h分别为78.9%、51.2%及109.3%.CNP组与对照组相应时间段mRNA表达量相比均有所提高,提高了15.3%、23.4%及39.5%.其中CNP组24 h TNF-αmRNA表达量与其他各组相比差异显著(P＜0.05).CNP能提高巨噬细胞株RAW264.7 TNF-α mRNA的表达,因此发挥抗肿瘤作用.     

Effects of tissue inhibitor of metalloproteinases on canine chondrocytes cultured in vitro with tumor necrosis factor-alpha

OBJECTIVE: To elucidate tissue inhibitor of metalloproteinase (TIMP)-mediated effects on chondrocytes. SAMPLE POPULATION: Articular cartilage from humeral heads of 6 dogs. PROCEDURE: Chondrocytes from harvested specimens were cultured in 3-dimensional (3-D) agarose at 10(6) cells/mL. We prepared 3-D constructs exposed to only tumor necrosis factor (TNF)-alpha (50 ng/mL). Recombinant human TIMP-1 (255nM), -2 (285nM), or -3 (250nM) was added to liquid media bathing 3-D constructs cultured with TNF-alpha. Chondrocytes cultured without TIMP or TNF-alpha served as control samples. Samples of liquid media were collected on days 6, 9, 15, and 21 of culture for evaluation of glycosaminoglycan (GAG) and nitric oxide concentrations. The 3-D constructs were collected on days 9, 15, and 21 for evaluation of GAG, hydroxyproline (HP), and DNA contents. RESULTS: GAG content in control samples increased significantly during the study, whereas GAG content in 3-D constructs cultured with TNF-alpha or TNF-alpha plus TIMP did not increase. On day 9, GAG release from 3-D constructs cultured with TNF-alpha was significantly higher than that in other constructs. The HP content in control samples increased during the study and was significantly higher than that in all other constructs on day 21. Concentrations of nitric oxide were significantly lower in control samples on day 6, compared with concentrations for all other constructs. CONCLUSIONS AND CLINICAL RELEVANCE: Addition of TIMPs did not counteract suppression of GAG and HP accumulation in 3-D constructs exposed to TNF-alpha. Apparently, adverse effects on chondrocytes exposed to TNF-alpha cannot be prevented by addition of TIMP alone.     

Effects of lipoxygenase inhibitors in a model of lens-induced uveitis in dogs

Uveitis was induced in dogs by intracameral injection of canine lens protein. The lipoxygenase inhibitors phenidone and norhydroguaiaretic acid, and dimethyl sulfoxide decreased fibrin production at 0.5 and 1 hour after induction of uveitis. Phenidone and norhydroguaiaretic acid also inhibited the initial increase in intraocular pressure early in the course of inflammation. Leukotriene B4 in the aqueous was measured by use of radioimmunoassay at 1 hour after inflammation. In control dogs, 230 to 1,700 pg of leukotriene B4/ml was measured; in dogs treated with phenidone, leukotriene B4 was not measured.