The aim of establishment of animal models is to replicate human diseases in the animals and serve studies on causes, symptoms, pathogenesis, diagnosis and treatment, etc. of those diseases. Up to now, there is no ideal animal model of Alzheimer's disease(AD). The lag of animal models of Alzheimer's disease (AD) has greatly restricted the studies on of AD-related drug development. Regarding the causes and mechanisms of AD, some more desirable AD animal models have been developed. In recent years, some transgenic AD animal models have emerged and much facilitate the studies on etiology and pathogenesis of AD. However, this model can not replicate all the features of AD. The most striking distinction is a lack of neurofibrillary tangles (NFTs), and in some types of transgenic models (especially single transgenic models), no extensive neuronal loss is observed. Although tau protein has been detected in those models by immunohistochemical methods, paired helical filaments (PHF) have never been found. In this article, we are trying to review on some hot topics of development and application of transgenic mouse models in AD research.

BACKGROUND: D-galactose-induced aging animal model is similar tohuman natural aging. Whether the expression of protein phosphatase-1(PP-1) in the brain of D-galactose-induced aging mice is related to cerebralaging process or not should be researched further. OBJECTIVE: To investigate the effect of the APP17 peptide and theliquid extract ofjiunao yizhi capsule on regulating the expression of PP-1 inhippocampal neurons of the aging mice induced by the D-galactose (D-gal). DESIGN: A random controlled study. SETTING: Department of Pathology, College of Basic Medical Sciences, Capital University of Medical Sciences and Beijing Research Laboratory forBrain Aging, Xuanwu Hospital of Capital University of Medical Sciences. MATERIALS: The study was completed between July 2003 and July2004 in the Experimental Center of Capital University of Medical Sciences. Forty male Kunming mice (SPF grade) with a body mass fron 28 g to 32 gwere purchased from Chinese Academy of Medical Sciences Institute ofMaterial Medical.METHODS: Kunming mice were randomly divided into 5 groups: control group, D-gal group, APP17 peptide treatment group, low dose herb treatment group, and high dose herb treatment group with 8 mice in each group. In Dgal group, APP17 peptide treatment group, low dose herb treatment group and high dose herb treatment group, galactose was injected subcutaneously (50 nmg/kg). Meanwhile, 0.1 mL normal saline containing 0.35 μg of APP17 peptide was injected subcutaneously into the mice in APP17 peptide treatment group, once a day for 3 months; liquid extract of jiunao yizhi capsule (provided by Beijing Chaoyangmen Hospital and Shanxi Quwo Traditional Medical Institute; the main component: dangshen, baizhu, guijia and chuanshanjia, etc.) was perfused by stomach (0.3 g/kg and 1.0 g/kg respectively) in low dose herb treatment group and high dose herb treatment group, once a day. And equivalent normal saline was injected and perfused in the two control groups. After 3 months of survival, the mice were killed and their brains were cut into sections. The immunohistochemical staining of these sections was then performed with PP-1 antibody.MAIN OUTCOME MEASURES: The results of immunohistochemical staining analysis of PP-1.RESULTS: Forty mice entered the final analysis without any loss. PP-1 positive cells in the hippocampus were poorly stained in the D-gal mice. In contrast, PP-1 positive neurons were widely distributed in the hippocampus of those normal mice, the APP17 peptide-treated D-gal mice and the high liquid extract of raw herb-treated D-gal mice. These cells were darkly stained in cytoplasm. The unexpected result was that in the low liquid extract of raw herb-treated D-gal mice the number of PP-1 positive neurons did not increase to normal.CONCLUSION: The results demonstrated that the expression of PP-1 decreased in the hippocampus of D-gal mice. The APP17 and low dose liquid extract of raw herbs can regulate the distribution of PP-1 in the brain of D-gal mice and make them recover to normal situation.

BACKGROUND: In brain insulin does its work through the insulin receptor substrate (IRS). Amyloid beta protein precursor 17 (APP17) peptide has the neurotrophic function, which may improve diabetic encephalopathy resulted from insulin deficiency by affecting insulin receptor substrate.OBJECTIVE: The mouse diabetic model was produced to observe the effect of APP17 peptide on the distribution of IRS-1 in brain tissues.DESIGN: Randomized control animal experiment.SETTING: Staff Room of Pathology, College of Basic Medical Sciences,Capital University of Medical Sciences; Beijing Research Laboratory for Brain Aging of Xuanwu Hospital.MATERIALS: The experiment was performed in Staff Room of Pathology,College of Basic Medical Sciences, Capital University of Medical Sciences and Beijing Research Laboratory for Brain Aging of Xuanwu Hospital from September to October 2003. Totally 18 male kunming mice were employed,and randomly assigned into control group, diabetic group and APP17 peptide treatment group with 6 mice in each group.METHODS: ①The mice were subjected to intraperitoneal injection of streptozotocin (STZ, Sigma) by 200 mg/kg, and 3 days later, the tail blood was sampled to examine non-fasting blood glucose, and the blood glucose over 15 mmol/L was set as the criteria for successful diabetic model establishment. ②In APP17 + diabetes mellitus group, the mice received subcutaneous injection of 0.35 μg APP17 peptide once daily for 2 weeks. The mice in the normal control group were not interfered. ③Then brain was removed and crystat sections were prepared. Immunohistochemical staining was done for IRS-1 at four weeks after giving streptozotocin.MAIN OUTCOME MEASURES: Pattern and distribution of IRS-1 positive cells of mice in each group.RESULTS: Totally 18 mice were involved in the result analysis. ①In the brains of diabetic mice the IRS-1 immunohistochemical positive cells distributed at cortex, hippocampus, thalamus, hypothalamus and so on, while the positive cells distributed only at cortex and hippocampus in the normal control group and APP17 peptide treatment group, lightly stained. ②Numbers of immunohistochemical positive cells of IRS-1 of cerebral hippocampus in the diabetic group, normal control group and APP17 peptide treatment group were (28.7±1.5), (9.2±1.5), (10.1±1.4) piece per 10 power object lens, and that in the diabetic group was higher than that in the other two groups (P ＜ 0. 001 ). CONCLUSION: Neurons in many regions of brains of diabetic mice have plenty of IRS-1 positive cells. APP17 peptide can make part and quantity of IRS-1 positive cells normality so as to ameliorate the degeneration of hippocampal neurons of diabetic mice.

Objective To establish a paraspinal neural pathway of quadriceps femoris by end-to-end anastomoses between the spinal ventral root after spinal cord injury(SCI) in rats. Methods Twenty-fourweek old SD rats, with the weight of 120 g to 150 g, were included. The left side was the experimental side, while the right side served as a control. Electrostimulating of L1-L5 ventral root was done respectively to decide the predominant nerve of quadriceps femoris. The lumbar 1 ventral root was reveal to little innervation of quadriceps femoris, and the lumbar 3 ventral root was predominant innervation. End-to-end anastomosis between the left L1 and L3 ventral root was done. After axona regeneration, the new paraspinal neural pathway of quadriceps femoris was established. At 6 months postoperatively, the early function of the new pathway was observed by electrophysiological examinations, hindlimb locomotion and BBB (basso, beattie and bresnahan)scale at 1,3,7, 14,21,28 d after SCI. Results Sixteen rats survived for 6 months after operation and only ten rats got good results because of tissue adhesion postoperatively. Single stimuli (2.5 mA,0.2 ms, 1 Hz) of the left anastomoses nerve resulted in action potential recorded from the left quadriceps femoris before and after the spinal cord hemisection horizontally between L2 segmental levels. The amplitudes of the action potentials were (7.63 ± 1.86) mV and (6.00 ± 1.92)mV, respectively, and there was no significant difference (P ＞ 0.05). The left quadriceps femoris contraction was initiated by single stimuli (2.5mA, 0.2 ms, 1 Hz) of the left anastomoses nerve. After paraplegia, when the right L3 ventral root was stimulated, the amplitude of the action potential was (15.87 ± 1.16) mV. Locomotion of the left hindlimb was partially restored after spinal cord hemisection while creeping and climbing. According to BBB scale, there was significant difference at 1, 3, 7 d, and little difference at 14, 21, 28 d after SCI. Conclusion Spinal ventral roots cross-ananstomosis to reconstruct the paraspinal pathway of quadriceps femoris after SCI is efficient reinnervation of hindlamb muscles in a rat model and may have potential in clinical application.

Objective To investigate the effect of insulin signaling pathway on neuronal survival and the effect of the peptide App17 on regulating the expression of some apoptosis-related proteins in neurons of the hippocampus through intracerebrorentricular injection of streptozotocin in rats. Methods The rats were injected with App17 peptide subcutaneously three weeks after the model group was established by intracerebrorentricular injection of streptozotocin.After the four-week treament,the expressions of the apoptosis-related proteins,such as Bcl-2,Bax,CytoC in neurons of the hippocampus were tested with immunohistochemical staining and Western blotting.Results Bax,CytoC positive neurons were widely distributed in the hippocampus of the model group,and the cytoplasm was darkly stained.In contrast,the positive neurons for Bax,CytoC in hippocampus were poorly stained in the control group and the treated group,and appeared significant difference in cell counting as compared with model group.Bcl-2 positive neurons were widely distributed in the hippocampus in the control group and the treated group,and the cytoplasm was darkly stained while its positive neurons were poorly stained in the model group,and appeared significant difference in cell counting as compared with the model group.From the Western blotting clear bars could be seen in the three groups and there was a significant difference between them.Conclusions The expression of Bax,CytoC increased in the hippocampus in the rats with intracerebrorentricular injection of streptozotocin while the expression of Bcl-2 decreased.The App17 peptide could promote the rehabilitation of the abnormal expression of the three proteins to some extent.The insulin signaling pathway could affect the survival of the neurons in rats' hippocampus.

Objective To identify the factors related to prognosis of diabetic foot ulcer (DFU).Methods A total of 186 patients with type Ⅱ DFU from a single diabetic foot center was included in this prospective study.Follow-up of the final outcome (healing,major amputation or death) was made in 6 months.Influence of patient demographics and clinical data on outcome was detected using multivariate Logistic regression analysis.Results Follow-up was performed in 172 patients,of whom 147 were cured (55 cases cured after minor amputations),3 underwent major amputations,6 died,and 16 were not yet cured at the final follow-up.In multivariate Logistic regression analysis,the outcome was independently correlated with ischemia (P ＜0.01),infection (P ＜ 0.05),ulcer number (P ＜ 0.01) and peripheral neuropathy (P ＜ 0.05) ; the risk of poor outcome increased with ischemia [odds ratio (OR) =10.8],infection (OR =211.4),ulcer number (OR =39.5),and peripheral neuropathy (OR =181.1).Conclusion Prognosis of DFU is associated with ischemia,infection,ulcer number,and peripheral neuropathy.

BACKGROUND: Overexpression of phosphorylated Tau protein is a factor of dementia, and scholars abroad find that APP17 peptide may have effect on it.OBJECTIVE: To observe changes of phosphorylated Tau protein Ser202/Thr205 of mice with diabetes mellitus (DM) after injection of APP17 peptide.DESIGN: Randomized control study.SETTING: Department of Pathology, Capital University of Medical Sciences; Department of Brain Aging, Xuanwu Hospital, Capital University of Medical Sciences.MATERIALS: The experiment was carried out in the Pathological Department of Capital University of Medical Sciences and Brain Aging Department of Beijing Xuanwu Hospital. A total of 18 male Kunming mice of 8 weeks old and weighing 28-32 g were randomly divided into control group, DM group and APP17 peptide group with 6 in each group.METHODS: DM models were induced by streptozotocin (STZ) through selectively destroying β-islet cells; meanwhile, APP17 peptide was intraperitoneally injected into mice. Four weeks later, brain tissue underwentimmunohistochemical staining with AT-8 (Ser202/Thr205, a special monoclonal antibody).MAIN OUTCOME MEASURES: ① Morphological observation; ② AT-8 distribution; ③ quantitative analysis of immunohistochemical staining.RESULTS: Positive AT-8 cells in DM group were distributed in retrosplenial cortex, hippocampus, thalamus, hypothalamus, etc.; however, those incontrol and APP17 peptide groups were only distributed in retrosplenial cortex and hippocampus, and poorly stained.CONCLUSION: Positive AT-8 cells may be widely distributed in neurons of brains of DM mice; however, APP17 peptide may normalize the expression of positive AT-8 cells.

Objective Using Morris water maze test to evaluate the effects of guanosine and curcumin on cognitive function of APPswe/PS1dE9 double transgenic mice .Methods 3-month old APPswe/PS1dE9 dtg mice were randomly di-vided into model group , donepezil HCL group , guanosine group , curcumin group , curcumin and guanosine group ( n=12), with age-matched Wild C57BL/6J mice of the same genetic background as normal control group .Medication was giv-en once a day for 1 month.Using Morris water maze to test the spatial learning and memory ability of mice .Results Guanosine and curcumin could improve spatial learning and memory disorders of AD mice , particularly in the group of cur-cumin.Conclusion Guanosine and curcumin improve the cognitive ability of APPswe /PS1dE9 double transgenic mice with early cognitive impairment .

Objective To investigate the effect of the peptide APP17 on regulating the expression of Bcl\|2,Bax,cAMP response element binding Protein(CREB),Ser\|Thr kinase B/protein kinase B(Akt/PKB),apoptosis inducing factor(AIF) in neurons of the hippocampus from the D\|gal mouse. Methods D\|gal mouse models were established by injection of D\|gal.In experimental group,these models were injected with APP17 petide subcutaneously and their brain sections were taken after 3 months of survival.The immunohistochemical staining of these sections was then performed with Bcl\|2,Bax,CREB,Akt,AIF antibody. Results Bax,AIF positive neurons were widely distributed in the hippocampus of the D\|gal mice,and the cytoplasm was darkly stained.In contrast,positive cells in the hippocampus were poorly stained in those normal mice and the APP17 peptide\|treated D\|gal mice.But Bcl\|2,CREB,AKt positive neurons were widely distributed in the hippocampus of those normal mice and the APP17 peptide\|treated D\|gal mice,and the cytoplasm was darkly stained.In contrast,positive cells in the hippocampaus were poorly stained in the D\|gal mice.Conclusion\ The expression of Bax and AIF could be increased in the hippocampus of D\|gal mice.But the expression of Bcl\|2,CREB,AKt decreased in the hippocampus of D\|gal mice.The APP17 can regulate the distribution of Bcl\|2,Bax,CREB,Akt,AIF in the brain of D\|gal mice and return them to normal situation.\;[

Objective Through the observation on the distribution of hyperphosphorylated Tau,to investigate the connection between hyperphosphorylated Tau and learning, memory tasks. Furthermore, the treatment of App17 on brain tissues of diabetic mice. Methods Diabetic model mouse was produced in the use of streptozotion and App17 peptide as a curative was injected subcutaneously. Four weeks later, removed the brains. Immunohistochemical stainning was done with AT\|8, Tau\|1, again with Tau\|1 antibody after dephosphorylation. Results In the brains of diabetic mice positive AT\|8 reacting neurons were widely distribution in retrosplenial granular cortex, hippocampas, thalamus et al, the cytoplasm was darkly stained, while in normal mice and App17 peptide\|treated diabetic mice positive cells were localized in retrosplenial granular cortex, however, in hippocampas and RSG area, the cytoplasm were poorly stained. Conclusion Hyperphosphorylated Tau is widely expressed in brains of diabetic mice. App17 peptide can improve the hyperphosphorylated Tau in brains of diabetic mice, therefore, it may improve learning ability and memory.\;