Autophagy is involved in oral rAAV/Aβ vaccine-induced Aβ clearance in APP/PS1 transgenic mice

The imbalance between β-amyloid(Aβ) generation and clearance plays a fundamental role in the pathogenesis of Alzheimer 's disease(AD). The sporadic form of AD is characterized by an overall impairment in Aβ clearance. Immunotherapy targeting Aβ clearance is believed to be a promising approach and is under active clinical investigation. Autophagy is a conserved pathway for degrading abnormal protein aggregates and is crucial for Aβ clearance. We previously reported that oral vaccination with a recombinant AAV/Aβ vaccine increased the clearance of Aβ from the brain and improved cognitive ability in AD animal models, while the underlying mechanisms were not well understood. In this study, we first demonstrated that oral vaccination with rAAV/Aβ decreased the p62 level and up-regulated the LC3BII/LC3B-I ratio in APP/PS1 mouse brain, suggesting enhanced autophagy. Further, inhibition of the Akt/m TOR pathway may account for autophagy enhancement. We also found increased anti-Aβ antibodies in the sera of APP/PS1 mice with oralvaccination, accompanied by elevation of complement factors C1 q and C3 levels in the brain. Our results indicate that autophagy is closely involved in oral vaccination-induced Aβ clearance, and modulating the autophagy pathway may be an important strategy for AD prevention and intervention.     

MiR-206 decreases brain-derived neurotrophic factor levels in a transgenic mouse model of Alzheimer＇s disease

MicroRNA alterations have been reported in patients with Alzheimer＇s disease （AD） and AD mouse models. We now report that miR-206 is upregulated in the hippocampal tissue, cerebrospinal fluid, and plasma of embryonic APP/PS1 transgenic mice. The increased miR-206 downregulates the expression of brain-derived neurotrophic factor （BDNF）. BDNF is neuroprotective against cell death after various insults, but in embryonic and newborn APP/PS1 mice it is decreased. Thus, a specific microRNA alteration may contribute to AD pathology by downregulating BDNF.     

Ratanasampil reduced levels of Aβ1-40 and Aβ1-42 and Aβ42/Aβ40 ratio in brains of Tg2576 mouse model of Alzheimer's disease

Objective To investigate the effect of ratanasampil (RNSP) which is traditional Chinese Tibet-Medicines on the β-amyloid peptide as a therapeutic target in Alzheimer's disease.Methods Thirteen female mice of 13-14 months old with Tg2576 transgene and ten BL6 × SJL mice as control were used in drug test All mice sacrificed after 8 weeks of RNSP treatment at 15-16 months of age.Open field activity and Y-maze tests were performed for animal behavioral change and memory ability.The β-amyloid peptides (Aβ1-40 and Aβ1-42) and β-amyloid precursor protein (APP) in Tg2576 mice brain were measured with western blot and enzyme linked immunosorbent assay (ELISA).Immunostaining with 1 E8 ( 1: 25 ) was carried out on brain sections of RNSP and vehicle-treated mice.Results The training times of Y-maze test decreased in RNSP-treated Tg2576 mice (P ＜0.01 ).After 2 months of RNSP treatment, a decrease in open field behavior was seen in Tg2576 mice ( P ＜ 0.05 ).The level of Aβ1-40 and Aβ1-42 in the brain was significantly decreased after RNSP treatment ( P ＜ 0.05 ).The Aβ42/Aβ40 ratio was significantly decreased after RNSP treatment as compared to vehicle-treated mice ( P ＜ 0.05 ) .But levels of APP in brain unchanged.Preliminary plaque counting of the sections showed reduced plaque numbers in the drug-treated mice in brain.Conclusions These results suggest that ratanasampil may reduce β-amyloid peptide production in brain to improve the learning and memory ability of Tg2576 mice of Alzheimer's disease.     

Ratanasampil reduced levels of Aβ1-40 and Aβ1-42 and Aβ42/Aβ40 ratio in brains of Tg2576 mouse model of Alzheimer's disease

Objective To investigate the effect of ratanasampil (RNSP) which is traditional Chinese Tibet-Medicines on the β-amyloid peptide as a therapeutic target in Alzheimer's disease.Methods Thirteen female mice of 13-14 months old with Tg2576 transgene and ten BL6 × SJL mice as control were used in drug test All mice sacrificed after 8 weeks of RNSP treatment at 15-16 months of age.Open field activity and Y-maze tests were performed for animal behavioral change and memory ability.The β-amyloid peptides (Aβ1-40 and Aβ1-42) and β-amyloid precursor protein (APP) in Tg2576 mice brain were measured with western blot and enzyme linked immunosorbent assay (ELISA).Immunostaining with 1 E8 ( 1: 25 ) was carried out on brain sections of RNSP and vehicle-treated mice.Results The training times of Y-maze test decreased in RNSP-treated Tg2576 mice (P ＜0.01 ).After 2 months of RNSP treatment, a decrease in open field behavior was seen in Tg2576 mice ( P ＜ 0.05 ).The level of Aβ1-40 and Aβ1-42 in the brain was significantly decreased after RNSP treatment ( P ＜ 0.05 ).The Aβ42/Aβ40 ratio was significantly decreased after RNSP treatment as compared to vehicle-treated mice ( P ＜ 0.05 ) .But levels of APP in brain unchanged.Preliminary plaque counting of the sections showed reduced plaque numbers in the drug-treated mice in brain.Conclusions These results suggest that ratanasampil may reduce β-amyloid peptide production in brain to improve the learning and memory ability of Tg2576 mice of Alzheimer's disease.     

Comparative study of histopathology changes between the PS1/APP double transgenic mouse model and Aβ_(1-40)-injected rat model of Alzheimer disease

Objective To identify the genetype of the PS1/APP double transgenic mouse model, then to analyse the histopathological changes in the brain and compare the differences between the transgenic mice models and Aβ_(1-40)-injected rats models of Alzheimer disease. Methods The modified congo red staining, Nissl's staining and immunohistology staining was used to observe the Aβ deposits, activation of astrocyte respectively. Results ①The PS1/APP transgenic mouse extensively displayed Aβ deposits in the cortex and hippocampal structures, and GFAP positive cells were aggregated in mass and surrounded the congo red-positive plaque. ②The Aβ_(1-40)-intrahippocampal-injected rat model showed the Aβ plaque deposits in the dentate gyrus of the hippocampus, with the astrocyte surrounded. The neurons loss was significant in the injection point and pin hole of injection with Nissl's staining methods. GFAP-positive cells increased significantly compared with the uninjected lateral of the hippocampus. Conclusion Although Aβ_(1-40)-injected rat models could simulate some characteristic pathological features of human Alzheimer diseases, Aβ deposits and neurons loss in partial hippocampal, it would not simulate the progressive degenenration in the brain of AD. The double transgenie PS1/APP mice could simulate the specific pathogenesis and progressive changes of AD, mainly is Aβ deposits and the spongiocyte response, while no neurons loss were observed in this model.     

Glymphatic imaging and modulation of the optic nerve

Optic nerve health is essential for proper function of the visual system.However,the pathophysiology of certain neurodegenerative disease processes affecting the optic nerve,such as glaucoma,is not fully understood.Recently,it was hypothesized that a lack of proper clearance of neurotoxins contributes to neurodegenerative diseases.The ability to clear metabolic waste is essential for tissue homeostasis in mammals,including humans.While the brain lacks the traditional lymphatic drainage system identified in other anatomical regions,there is growing evidence of a glymphatic system in the central nervous system,which structurally includes the optic nerve.Named to acknowledge the supportive role of astroglial cells,this perivascular fluid drainage system is essential to remove toxic metabolites from the central nervous system.Herein,we review existing literature describing the physiology and dysfunction of the glymphatic system specifically as it relates to the optic nerve.We summarize key imaging studies demonstrating the existence of a glymphatic system in the optic nerves of wild-type rodents,aquaporin 4-null rodents,and humans;glymphatic imaging studies in diseases where the optic nerve is impaired;and current evidence regarding pharmacological and lifestyle interventions that may help promote glymphatic function to improve optic nerve health.We conclude by highlighting future research directions that could be applied to improve imaging detection and guide therapeutic interventions for diseases affecting the optic nerve.     

Degenerative alterations in noradrenergic neurons of the locus coeruleus in Alzheimer’s disease

Mice carrying mutant amyloid-β precursor protein and presenilin-1 genes (APP/PS1 double transgenic mice) have frequently been used in studies of Alzheimer’s disease; however, such studies have focused mainly on hippocampal and cortical changes. The severity of Alzheimer’s disease is known to correlate with the amount of amyloid-β protein deposition and the number of dead neurons in the locus coeruleus. In the present study, we assigned APP/PS1 double transgenic mice to two groups according to age: young mice (5-6 months old) and aged mice (16-17 months old). Age-matched wild-type mice were used as controls. Immunohistochemistry for tyrosine hydroxylase (a marker of catecholaminergic neurons in the locus coeruleus) revealed that APP/PS1 mice had 23% fewer cells in the locus coeruleus compared with aged wild-type mice. APP/PS1 mice also had increased numbers of cell bodies of neurons positive for tyrosine hydroxylase, but fewer tyrosine hydroxylase-positive fibers, which were also short, thick and broken. Quantitative analysis using unbiased stereology showed a significant age-related increase in the mean volume of tyrosine hydroxylase-positive neurons in aged APP/PS1 mice compared with young APP/PS1 mice. Moreover, the mean volume of tyrosine hydroxylase-positive neurons was positively correlated with the total volume of the locus coeruleus. These findings indicate that noradrenergic neurons and fibers in the locus coeruleus are predisposed to degenerative alterations in APP/PS1 double transgenic mice.     

Comparative study of histopathology changes between the PS1/APP double transgenic mouse model and Aβ1-40 -injected rat model of Alzheimer disease

Objective To identify the genetype of the PS1/APP double transgenie mouse model, then to analyse the histopathological changes in the brain and compare the differences between the transgenie mice models and Aβ1-40-injeeted rats models of Alzheimer disease. Methods The modified congo red staining, Nissl＇s staining and immunohistology staining was used to observe the Aβ deposits, activation of astrocyte respectively. Results ①The PS1/APP transgenic mouse extensively displayed Aβ deposits in the cortex and hippocampal structures, and GFAP positive cells were aggregated in mass and surrounded the congo red-positive plaque. ②The Aβ1-40-intrahippocmnpal-injeeted rat model showed the Aβ plaque deposits in the dentate gyrus of the hippocampus, with the astrocyte surrounded. The neurons loss was significant in the injection point and pin hole of injection with Nissl＇s staining methods. GFAP-positive cells increased significantly compared with the uninjected lateral of the hippocampus. Conclusion Although Aβ1-40-injected rat models could simulate some characteristic pathological features of human Alzheimer diseases, Aβ deposits and neurons loss in partial hippocampal, it would not simulate the progressive degenenration in the brain of AD. The double transgenie PS1/APP mice could simulate the specific pathogenesis and progressive changes of AD, mainly is Aβ deposits and the spongiocyte response , while no neurons loss were observed in this model.     

Sex Differences in Neuropathology and Cognitive Behavior in APP/PS1/tau Triple-Transgenic Mouse Model of Alzheimer’s Disease

Alzheimer's disease(AD) is the most common form of dementia among the elderly, characterized by amyloid plaques, neurofibrillary tangles, and neuroinflammation in the brain, as well as impaired cognitive behaviors.A sex difference in the prevalence of AD has been noted,while sex differences in the cerebral pathology and relevant molecular mechanisms are not well clarified. In the present study, we systematically investigated the sex differences in pathological characteristics and cognitive behavior in12-month-old male and female APP/PS1/tau triple-transgenic AD mice(3×Tg-AD mice) and examined the molecular mechanisms. We found that female 3×Tg-AD mice displayed more prominent amyloid plaques, neurofibrillary tangles, neuroinflammation, and spatial cognitive deficits than male 3×Tg-AD mice. Furthermore, the expression levels of hippocampal protein kinase A–cAMP response element-binding protein(PKA-CREB) and p38–mitogen-activated protein kinases(MAPK) also showed sex difference in the AD mice, with a significant increase in the levels of p-PKA/p-CREB and a decrease in the p-p38 in female, but not male, 3×Tg-AD mice. We suggest that an estrogen deficiency-induced PKA-CREB-MAPK signaling disorder in 12-month-old female 3×Tg-AD mice might be involved in the serious pathological and cognitive damage in these mice. Therefore, sex differences should be taken into account in investigating AD biomarkers and related target molecules, and estrogen supplementation or PKA-CREBMAPK stabilization could be beneficial in relieving the pathological damage in AD and improving the cognitive behavior of reproductively-senescent females.     

Adipose-derived mesenchymal stem cell transplantation promotes adult neurogenesis in the brains of Alzheimer’s disease mice

In the present study,we transplanted adipose-derived mesenchymal stem cells into the hippocampi of APP/PS1 transgenic Alzheimer’s disease model mice.Immunofluorescence staining revealed that the number of newly generated(BrdU+)cells in the subgranular zone of the dentate gyrus in the hippocampus was significantly higher in Alzheimer’s disease mice after adipose-derived mesenchymal stem cell transplantation,and there was also a significant increase in the number of BrdU+/DCX+neuroblasts in these animals.Adipose-derived mesenchymal stem cell transplantation enhanced neurogenic activity in the subventricular zone as well.Furthermore,adipose-derived mesenchymal stem cell transplantation reduced oxidative stress and alleviated cognitive impairment in the mice.Based on these findings,we propose that adipose-derived mesenchymal stem cell transplantation enhances endogenous neurogenesis in both the subgranular and subventricular zones in APP/PS1 transgenic Alzheimer’s disease mice,thereby facilitating functional recovery.     

The behavioral and neuroanatomical effects of IB4-saporin treatment in rat models of nociceptive and neuropathic pain

One distinguishing feature of primary afferent neurons is their ability to bind the lectin IB(4). Previous work suggested that neurons in the inner part of lamina II (IIi), onto which IB(4)-positive sensory neurons project, facilitate nociceptive transmission following tissue or nerve injury. Using an IB(4)-saporin conjugate (IB(4)-SAP), we examined the contribution of IB(4)-positive neurons to nociceptive processing in rats with and without nerve injury. Intrasciatic injection of IB(4)-SAP (5 mug/5 mul) significantly decreased IB(4)-labeling and immunoreactive P(2)X(3) in the spinal cord and delayed the behavioral and neuroanatomical consequences of L5 spinal nerve ligation (SNL) injury. In the absence of injury, thermal and mechanical nociceptive thresholds increased 2 weeks post-treatment only in IB(4)-SAP-treated, but not control (saline or saporin only), rats. Acute NGF-induced hyperalgesia was also attenuated following IB(4)-SAP treatment. In the SNL model, mechanical allodynia failed to develop 1 and 2 weeks post-injury, but was fully established by 4 weeks. Moreover, neuropeptide Y immunoreactivity (NPY-ir), which increases in the spinal cord after nerve injury, was unchanged in IB(4)-SAP-treated animals whereas immunoreactive PKCgamma decreased 2, but not 4, weeks post-injury. Quantitative RT-PCR revealed a reduction in P(2)X(3) mRNA in L4 DRG of IB(4)-SAP-treated animals, but no change in TrkA expression. Our results suggest that IB(4)-positive neurons in L4 are required for the full expression of NGF-induced hyperalgesia and participate in the behavioral and anatomical consequences that follow injury to the L5 spinal nerve.     

Structure-function relationships for analogues of L-2-amino-4-phosphonobutanoic acid on the quisqualic acid-sensitive AP4 receptor of the rat hippocampus.

Hippocampal CA1 pyramidal cell neurons are sensitized to depolarization by L-2-amino-4-phosphonobutanoic acid (L-AP4) following exposure to L-quisqualic acid (QUIS). We have examined the interaction of 43 structural analogues of L-AP4 with both the 'induction' site and the QUIS-sensitive AP4 site in rat hippocampus. The synthesis of cis- and trans-4-phosphonoxy-L-proline, 3-(RS)-amino-5-phosphonopentanoic acid and 2(RS)-amino-5-phenyl-4(RS)-phosphonopentanoic acid (gamma-benzyl AP4) are described. None of the test compounds interact with the induction site; thus L-QUIS remains the only compound known to induce this effect. However, one compound (L-2-amino-3-(5-tetrazolyl)-propanoic acid (L-aspartate tetrazole) 'pre-blocked' and reversed the effects of QUIS. In addition, the potency of 16 analogues increased more than 4-fold following exposure of slices to L-QUIS. Among these, L-AP4, L-AP5, 2-amino-4-(methylphosphino)butanoic acid (AMPB), and E-1(RS)-amino-3(RS)-phosphonocyclopentanecarboxylic acid (E-cyclopentyl AP4) displayed IC50 values of less than 0.100 mM after QUIS. The results presented here suggest that the QUIS-sensitive AP4 site requires a spatial configuration of functional groups similar to that present in E-cyclopentyl AP4. The presence of a primary amino group and a phosphorus-containing group (either monoanionic or dianionic) appear to be required, however, a carboxyl group is not essential for interaction. The pharmacology of the QUIS-sensitive AP4 site suggests that it is distinct from other known binding sites for L-AP4 in the central nervous system (CNS).     

Quantitative mRNA analysis of five C-terminal splice variants of the human 5-HT4 receptor in the central nervous system by TaqMan real time RT-PCR

5-HT4 receptors mediate several physiological effects of 5-HT, particularly in the central nervous system (CNS), heart and gut. Recently, several C-terminal splice variants of the human 5-HT4 (h5-HT4) receptor have been described, namely h5-HT4(a), h5-HT4(b), h5-HT4(c), h5-HT4(d) and h5-HT4(g). Previous tissue distribution data suggest some degree of specificity in the mRNA expression patterns of the different h5-HT4 receptor splice variants. However, comparison of the mRNA expression profiles of these splice variants is difficult due to the non-quantitative methods used, and in addition, there is very limited data on the expression of each splice variant in human CNS subregions. In the present study we used a single technique, TaqMan real time quantitative RT-PCR, to investigate the mRNA distribution of 5-HT4 receptor C-terminal splice variants in multiple human CNS and peripheral tissues. Using a primer/probe set that amplified all 5-HT4 splice variants (5-HT4pan), the highest CNS expression of 5-HT4 receptor mRNA was observed in basal ganglia, amygdala and hippocampus, consistent with previous studies. h5-HT4(a), h5-HT4(b), h5-HT4(c) and h5-HT4(g) were predominantly expressed in various CNS tissues, compared to most peripheral tissues, but there were differences in expression levels and distribution patterns of each variant. The distribution profile and expression levels observed for the 5-HT4(b) splice variant were virtually identical to that obtained with the 5-HT4pan primer/probe set, whilst the other splice variants were expressed at much lower levels and with different expression patterns obtained with both 5-HT4(b) and 5-HT4pan primer/probe sets. Highest levels of 5-HT4(g) were observed in the hypothalamus and cortex, whilst the 5-HT4(a) variant was highest in the amygdala. 5-HT4(c) expression was highest in the pituitary gland whilst 5-HT4(d) mRNA was only detected in the small intestine at very low levels and not in the CNS. In conclusion, we have shown quantitative differences in the mRNA distribution profiles of the 5-HT4 receptor C-terminal splice variants in human CNS subregions as well as peripheral tissues. In addition, our data suggests that the h5-HT4(b) variant is the most predominant form of the 5-HT4 receptor in humans.     

Stimulation of transient receptor potential vanilloid 4 channel suppresses abnormal activation of microglia induced by lipopolysaccharide

Microglia are intrinsic immune cells in the brain. In response to neurodegenerative events, excessively activated microglia change their shapes and release various cytokines leading to the pathogenesis of central nervous system (CNS) disease. Because the intracellular mechanisms of this process are still unclear, we have evaluated the functional roles of transient receptor potential vanilloid 4 (TRPV4) channel expressed in the microglia. Robust microglial activation after an injection of lipopolysaccharide (LPS) into the mouse cerebral ventricle was suppressed by concurrent administration of a selective TRPV4 agonist, 4α-phorbol 12,13-didecanoate (4α-PDD). When the mechanism was further investigated using cultured rat microglia intrinsically expressing functional TRPV4, release of tumor necrosis factor-α (TNF-α) and expression of galectin-3 were both increased by LPS. These increases were significantly suppressed by cotreatment with 4α-PDD, and the inhibitory effects of 4α-PDD were abolished by knockdown of TRPV4 or TRPV4 antagonists. The amplitude of voltage-dependent K(+) current, which is augmented during microglial activation, was also suppressed by 4α-PDD treatment. Opening of TRPV4 channels with 4α-PDD induced membrane depolarization mainly by increasing Na(+) influx. In addition, mimicking depolarization with a high-K(+) solution suppressed LPS-induced TNF-α release and galectin-3 upregulation. Both depolarizing treatments with 4α-PDD and high-K(+) solution decreased store-operated Ca(2+) influx caused by thapsigargin. These results suggest that depolarization in response to opening of the TRPV4 channel attenuates the driving force for extracellular Ca(2+) and suppresses microglial activation.     

水通道蛋白4抗体检测对视神经脊髓炎的诊断价值

目的:探讨水通道蛋白4(AQP4)抗体检测对视神经脊髓炎(NMO)的诊断价值.方法:采用表达人AQP4基因的人胚肾(HEK)293细胞株分别对35例NMO患者(NMO组)、14例NMO高危综合征患者(HRS组)、37例多发性硬化患者(MS组)、23例其他脱髓鞘疾病患者(ODD组)及75例其他神经系统疾病患者(MD组)的血标本进行AQP4抗体检测,比较各组抗体的阳性率.结果:NMO组中31例患者(88.6%)及HRS组中6例患者(42.9%n)AQP4抗体检测为阳性;MS组、ODD组和MD组患者AQP4抗体检测均为阴性.NMO组AQP4抗体检测阳性的敏感性为88.6%,95%CI,73.11%-96.79%;HRS组AQP4抗体检测阳性的敏感性为42.9%,95%CI:16.97%-68.83%;NMO患者AQP4抗体检测阳性的特异性为100%.结论:AQP4抗体检测对NMO及其疾病谱早期确诊有重要意义,且具有较高的敏感性和特异性.     

Prevalence of health anxiety problems in medical clinics

Objectives

To determine the prevalence of significant health anxiety (hypochondriasis) in patients aged 16–75 in cardiology, respiratory medicine, neurological, endocrine and gastrointestinal clinics in general hospitals in London, Middlesex and North Nottinghamshire.

Method

The Health Anxiety Inventory (HAI) (short form) was administered to patients attending the five clinics over a 21 month period and all those who scored 20 or more invited to take part in a further assessment for a randomised controlled trial.

Results

Of 43,205 patients attending the clinics 28,991 (67.1%) were assessed and of these, after exclusion of ineligible patients 5747 (19.8%) had significant health anxiety. 444 subsequently agreed to take part in a randomised controlled trial of treatment. The prevalence levels varied by clinic with neurology (24.7%) having the highest prevalence followed by respiratory medicine (20.9%), gastroenterology (19.5%), cardiology (19.1%), and endocrinology (17.5%).

Conclusion

Abnormal health anxiety is common and a significant problem in those attending medical clinics and deserves greater awareness.     

Isolation and characterization of a heparin with low antithrombin activity from the body of Styela plicata (Chordata-Tunicata). Distinct effects on venous and arterial models of thrombosis

INTRODUCTION: A heparin preparation with low antithrombin activity and different disaccharide composition than mammalian heparin was isolated from the body of the ascidian Styela plicata (Chordata-Tunicata). The disaccharide composition and the effect of the invertebrate glycan on venous and arterial models of thrombosis was investigated. METHODS AND RESULTS: High performance liquid chromatography of the products formed by a mixture of heparin lyases showed that the ascidian heparin is composed mainly by delta UA(2SO4)-1-->4-beta-d-GlcN(SO4) (47.5%), delta UA(2SO4)-1-->4-beta-d-GlcN(SO4)(6SO4) (38.3%) disaccharides and smaller amounts of the disaccharides delta UA(2SO4)-1-->4-beta-d-GlcN(SO4)(3SO4)(6SO4) (2.8%) and delta UA(2SO4)-1-->4-beta-d-GlcN(SO4)(3SO4) (8.0%). The invertebrate heparin has an aPTT activity of 18 IU/mg and an antithrombin-mediated antithrombin and anti-factor Xa activities 10-fold lower than that of mammalian heparin. In a venous model of thrombosis in the vena cava, S. plicata heparin inhibits only 80% of thrombosis at a dose 10-fold higher than that of the mammalian heparin that inhibits 100% of thrombosis. However, in an arterio-shunt model of arterial thrombosis, both S. plicata and mammalian heparin possess equivalent antithrombotic activities. It is also shown that at equivalent doses, ascidian heparin has a lower bleeding effect than mammalian heparin. CONCLUSION: The antithrombin-mediated anticoagulant activity of heparin polymers is not directly related to antithrombotic potency in the arterio-venous shunt. The results of the present work suggest that heparin preparations obtained from the body of S. plicata may have a safer therapeutic action in the treatment of arterial thrombosis than mammalian heparin.     

Lack of allelic association of dopamine D4 receptor gene polymorphisms with Parkinson's disease in a Chinese population.

Parkinson's disease (PD) is a neurodegenerative disease caused by a multitude of environmental, neurochemical, and genetic factors. The gene for human dopamine D4 receptor (DRD4) has been considered as a plausible candidate for the pathogenesis of PD. Different dopamine D4 receptor allelic forms have variable affinity toward certain neuroleptics such as clozapine, suggesting a role for dopamine D4 receptors in neurologic disorders. To test the hypothesis that the DRD4 polymorphism is associated with the susceptibility to Parkinson's disease, we have examined differences in allele frequencies of different DRD4 polymorphisms in 101 Chinese patients with PD and in 105 age-matched control subjects in Hong Kong. The DRD4 gene was analyzed by a non-radioactive polymerase chain reaction-based Southern hybridization with chemiluminescence detection. The number of polymorphic 48 base pair tandem repeats in exon 3 was identified in each study subject. The DRD4 alleles with high frequencies in the control subjects are 4-repeat allele (72.4%), 2-repeat allele (21.4%), and 7-repeat allele (3.8%) which accounted for over 97% of the total alleles in the elderly Chinese population. The most prevalent genotype in the control subjects is the 4/4 (47.6%), followed by 4/2 (38.6), 4/7 (7.6%), and 2/2 (3.0%). None of the variable number tandem repeat polymorphism showed evidence for genetic association with Parkinson's disease.     

Abnormal expression of CTLA-4 by T cells from patients with myasthenia gravis: effect of an AT-rich gene sequence

Cytolytic T lymphocyte-associated antigen-4 (CTLA-4) plays a critical role in the down-regulation of antigen-activated immune responses. The aberrant CTLA-4 expression is characterized by low surface and intracellular levels of CTLA-4 protein, impaired up-regulation of CTLA-4 in T cells in response to ConA stimulation and high levels of soluble CTLA-4 (sCTLA-4) in serum. The serum levels of sCTLA-4 are positively correlated with the serum concentration of antibodies against the acetylcholine receptor. The (AT)(n) polymorphism in the 3'-untranslated region contributes to decreased mRNA stability and, hence, to reduced expression of CTLA-4.