Osteoprotegerin mediate RANK/RANKL signaling inhibition eases asthma inflammatory reaction by affecting the survival and function of dendritic cells.

INTRODUCTION: Asthma is a chronic inflammatory, heterogeneous airway disease affecting millions of people around the world. Dendritic cells (DCs) are considered the most important antigen-presenting cell in asthma airway inflammatory reaction. But whether osteoprotegerin (OPG) mediate RANK/RANKL signaling inhibition influences asthma development by affecting the survival and function of DCs remains unclear. In this study, we assessed the effects of OPG on DCs and asthma. MATERIAL AND METHODS: BALB/c mice immunized with ovalbumin (OVA) were challenged thrice with an aerosol of OVA every second day for eight days. Dexamethasone (1.0mg/kg) or OPG (50µg/kg) was administered intraperitoneally to OVA-immunized BALB/c mice on day 24 once a day for nine days. Mice were analyzed for effects of OPG on asthma, inflammatory cell infiltration and cytokine levels in lung tissue. The expression of RANK and ß-actin was detected by Western Blot. DCs were isolated from mouse bone morrow. Cell survival was assessed by cell counting. The content of IL-12 was detected by ELISA. RESULTS: Results showed that OVA increased the number of inflammatory factors in BALF, elevated lung inflammation scores in mice. OPG reversed the alterations induced by OVA in the asthmatic mice. OPG inhibited the survival and function of DC via inhibition of RANK/RANKL signaling. CONCLUSIONS: This research proved inhibition of RANK/RANKL signaling by OPG could ease the inflammatory reaction in asthma, providing new evidence for the application of OPG on asthma.

[Establishment of macrophage model of iron overload in vitro and the injury induced by oxidative stress on macrophage with iron overload].

OBJECTIVE: To establish macrophage iron overload model in vitro by co-culture macrophages with iron, and to explore the effect of iron overload on cell reactive oxygen species (ROS) and the impact of ROS on macrophages. METHOD: Iron overload group were treated with different concentrations (0, 5, 10, 20, 40, 80 µmol/L respectively) of ferric ammonium citrate (FAC). The control group was the group of macrophages without FAC treatment. We detected the number and state of cells, metabolic activity, the change of phagocytosis, the levels of ROS and reactive nitrogen, and changes of related oxidative stress signaling pathways in different groups. Changes in the above indexes were detected after application of deferasirox (DFX) to remove iron and the antioxidant N -acetylcysteine (NAC) to clear excess oxidative stress. RESULTS: (1)The levels of labile iron pool (LIP) in macrophages co-cultivated with iron was increased with the increase of iron concentration in a dose-dependent manner. The LIP levels was the highest in the macrophages treated with 80 µmol/L. (2)The increase of FAC concentration, the metabolic activity of macrophages in the 5 FAC-treated groups decreased to 51.58%, 40.98%, 16.23%, 3.46%, and 0.05% of the activity level of the control group (all P< 0.05). The group with the metabolic activity decreased to 16.23% (20 µmol/L) was selected as the iron overload group for the following experiments. (3)Compared with the control group, the number of macrophages in the iron overload group reduced to 32.80% (P<0.05), and the state of cells changed from adherence to partial suspension. The phagocytosis of macrophages in the iron overload group reduced to 20.40% of the control group (P<0.05). (4)Our further experiment showed that the levels of ROS and the activity nitrogen in the iron overload group increased by 7.71-and 1.45-fold compared with the control group (both P<0.05). The RT-PCR showed up-regulated mRNA expression of genes related with ROS production, i. e. nicotinamide adenine dinucleotide phosphate oxidase 4 (NOX 4) gene related with ROS production and inducible nitric oxide synthase (iNOS) gene related with reactive nitrogen production, down-regulated mRNA expression of glutathione peroxidase 1 (GPX1) gene which participated in ROS clearance. Moreover, mRNA expression of phosphatidylinositol-3-kinase (PI3K) gene involved in oxidative stress signaling pathway in the iron overload group was up-regulated, while fork head protein O3 (FOXO3) which regulated oxidative stress through negative feedback showed a down-regulation level of mRNA expression compared with the control group. (5)After iron chelation and antioxidant treatment, the above-mentioned damage in the iron overload group were partially reversed. CONCLUSIONS: The damages of iron overload on macrophages may be mediated by inducing oxidative stress and activating oxidative stress signaling pathways. Our established model provides a method to explore the mechanism of iron overload on macrophage, and may shed some new light on possible therapeutic target in treating iron overload patients.

Risk of Parkinson's disease following anxiety disorders: a nationwide population-based cohort study.

BACKGROUND AND PURPOSE: Anxiety is potentially a pre-motor symptom of Parkinson's disease (PD). Our aim was to investigate the association between anxiety and subsequent PD risk in a population-based sample. METHODS: A total of 174 776 participants, who were free of prior PD, dementia and stroke, were enrolled from Taiwan National Health Insurance Research Database between 1 January 2005 and 31 December 2005. The association between anxiety at the beginning of the study and the incidence of PD was examined using a Cox regression model. Information regarding comorbidities, especially depression, and concomitant medication use was adjusted in the proportional hazards models. RESULTS: Over an average follow-up of 5.5 years, 2258 incident PD cases were diagnosed. After adjusting for age, sex, comorbidities and concomitant medication use, patients with anxiety were more likely to develop PD than subjects without anxiety [adjusted hazard ratio (HR) 1.38; 95% confidence interval (CI) 1.26-1.51]. Anxiety severity was dose-dependently associated with increased likelihood of PD: crude HR 1.27 (95% CI 1.11-1.44) for mild anxiety, 1.35 (95% CI 1.19-1.53) for moderate anxiety and 2.36 (95% CI 2.13-2.62) for severe anxiety (P < 0.0001). Results were similar after adjustment for age, sex, comorbid depression and other PD risk factors, and in the sensitivity analyses excluding participants with comorbid depression or with a PD diagnosis <3 years after anxiety diagnosis, and controlling for Charlson's scores. CONCLUSIONS: The likelihood of developing PD was greater amongst patients with anxiety than patients without anxiety, and the severity of anxiety correlated with risk of PD.

Restless legs syndrome is associated with cardio/cerebrovascular events and mortality in end-stage renal disease.

BACKGROUND AND PURPOSE: Earlier studies suggested an association between idiopathic restless legs syndrome (RLS) and cardiovascular diseases. However, the risk of cardiovascular events in patients with secondary RLS due to end-stage renal disease (ESRD) is unclear. Our aim was to examine whether ESRD patients with RLS had an increased risk of cardio/cerebrovascular events and mortality. METHODS: In all, 1093 ESRD patients were recruited between 2009 and 2010. The diagnosis and severity of RLS were assessed in a face-to-face interview. The occurrence of cardio/cerebrovascular events and death were confirmed by medical record review. The association between RLS and the outcomes of interest was examined using an adjusted multivariate Cox regression model. RESULTS: After a mean follow-up period of 3.7 ± 0.8 years, ESRD patients with RLS had a significantly higher risk of developing cardiovascular events and strokes [adjusted hazard ratio (aHR) 2.82, 95% confidence interval (CI) 2.02-4.11, and aHR 2.41, 95% CI 1.55-3.75, respectively] compared with patients without RLS. Increasing RLS severity was associated with an increasing likelihood of cardiovascular events [mild RLS severity, aHR 1.71 (95% CI 1.02-2.87); moderate, 2.79 (1.64-4.66); severe, 2.85 (1.99-4.46)] and strokes [mild, 1.89 (0.87-4.16); moderate, 2.42 (1.50-3.90); severe, 2.64 (1.49-4.91)] in a dose-dependent manner. RLS also increased the risk of total mortality in patients with ESRD [aHR 1.53 (95% CI 1.07-2.18), P = 0.02]; this association attenuated slightly after stratification by individual RLS severity category [mild RLS severity, aHR 1.44 (95% CI 0.78-2.67); moderate, 1.49 (0.98-2.55); severe, 2.03 (0.93-4.45)]. CONCLUSIONS: ESRD patients with RLS demonstrated an increased likelihood of cardio/cerebrovascular events and mortality.

Association of candidate genetic variants with restless legs syndrome in end stage renal disease: a multicenter case-control study in Taiwan.

BACKGROUND AND PURPOSE: Recent genome-wide association studies have shown associations between multiple genetic variants and primary restless legs syndrome (RLS). Their roles in end stage renal disease (ESRD) related secondary RLS are not clear and studies in Asian populations are scarce. The association between candidate genetic variants and uremic RLS was investigated in a large cohort of Taiwanese dialysis patients. METHODS: Sixteen RLS-related genetic variants at six loci, including MEIS1, BTBD9, MAP2K5/SKOR1, PTPRD, TOX3/BC034767 and the intergenic region of chromosome 2p14, in a total of 993 ESRD patients (259 subjects with and 734 subjects without RLS) were genotyped using TaqMan genotyping assays. Multivariate logistic regression analysis was used to test for associations between the genotypes and RLS in ESRD. Power calculations were completed using the CATs Genetic Power Calculator with settings of a multiplicative genetic model. RESULTS: A modest association between the PTPRD variant rs4626664 and uremic RLS (odds ratio 1.52, 95% CI 1.03-2.23, P = 0.03) and a trend that TOX3/BC034767 variant rs3104767 may associate with the occurrence of RLS were observed in our dialysis population (odds ratio 1.74, 95% CI 0.97-3.11, P = 0.06). No associations between other genetic variants and risk and severity of RLS were observed in our ESRD cohort. CONCLUSIONS: The genetic variants of primary RLS candidate genes did not play a major role in our uremic RLS populations. The ethnic difference and heterogeneous etiologies underlying renal failure may partly explain the minor genetic contribution to uremic RLS in our populations. Further studies for other ethnicities will be of worth.

Preceding pain symptoms and Parkinson's disease: a nationwide population-based cohort study.

BACKGROUND AND PURPOSE: Painful sensations are recently reported to be a non-motor feature of Parkinson's disease (PD). The non-steroidal anti-inflammatory drug ibuprofen is a common painkiller and was reported to be associated with a decreased risk of PD. The aim of the present study was to examine the relationship amongst preceding pain symptoms, use of ibuprofen and risk of PD in a nationwide population-based cohort. METHODS: The data of participants who were free of PD at baseline were obtained from two large National Health Interview Surveys (NHIS) in Taiwan, conducted in 2001 and 2005. The information regarding pain status included severity and location of pain. Information regarding pain status, use of ibuprofen, comorbidity of depression and PD-associated risk/protective behaviors was adjusted using proportional hazards models. RESULTS: Amongst 33 388 participants, 32 cases of incident PD were identified after a mean follow-up of 3 years. After adjusting for the use of ibuprofen and other PD risk factors, subjects with preceding pain symptoms had a higher incidence of PD than those without pain at baseline, and the hazard ratio was 1.79 (95% CI: 0.71-4.51, P = 0.21) for mild pain and 2.88 (95% CI: 1.05-7.86, P = 0.04) for moderate or severe pain. The PD risk increased by 34% with each additional increment in pain score [hazard ratio = 1.34 (1.03-1.75), P = 0.03], showing a dose-response relationship. CONCLUSIONS: These findings support the hypothesis that pain is associated with PD in the pre-motor stage of the disease. Further research is needed to clarify the role of sensory system involvement in the pre-motor phase of PD.

Restless legs syndrome in end-stage renal disease: a multicenter study in Taiwan.

BACKGROUND AND PURPOSE: Restless legs syndrome (RLS) is an underestimated movement disorder in patients with end-stage renal disease (ESRD). Several clinical and laboratory factors were inconsistently reported to associate with RLS. We aim to perform a large-scale multicenter study to investigate the possible associated risk factors of RLS in patients with ESRD in Taiwan, a country with the highest incidence of uremia in the world. METHODS: From October 2009 to October 2011, we constitutively recruited 1130 patients with ESRD from 17 hemodialysis centers. Demographic, laboratory data, presence and severity of RLS were collected. Odds ratios (ORs) were estimated by logistic regression models. RESULTS: We found the prevalence of RLS to be 25.3% in patients with ESRD. Having type 2 diabetes [OR = 3.61 (2.27-5.77), P < 0.01], low serum transferrin saturation [OR = 1.42 (1.01-2.03), P < 0.05] and duration of dialysis [OR = 1.09 (1.03-1.14), P < 0.01] were associated with RLS. In contrast, high serum hemoglobin level was inversely associated with RLS [OR = 0.61 (0.40-0.89), P < 0.05]. RLS has a significant impact on sleep quality in dialysis patients. Among patients with RLS, history of type 2 diabetes [OR = 4.04 (1.65-10.79), P < 0.05], low serum hemoglobin level [OR = 5.41 (2.43-13.12), P < 0.01] and duration of dialysis [OR = 1.01 (1.01-1.02), P < 0.01] were associated with increased severity of RLS. CONCLUSIONS: Our findings demonstrated that RLS is common in Taiwanese dialysis patients. Clinicians should have a high suspicion for the presence of RLS symptoms in patients with ESRD, especially those with type 2 diabetes, anemia, low serum iron status and long duration of dialysis.

Death-associated protein kinase 1 variation and Parkinson's disease.

BACKGROUND AND PURPOSE: Mutations of the LRRK2 gene are now recognized as major risk factors for Parkinson's disease. The Lrrk2 protein is a member of the ROCO family, which also includes Lrrk1 and Dapk1. Functional genetic variants of the DAPK1 gene (rs4877365 and rs4878104) have been previously associated with Alzheimer's disease. METHODS: Herein, we assessed the role of DAPK1 variants (rs4877365 and rs4878104) in risk of Parkinson's disease with Sequenom iPLEX genotyping, employing one Taiwanese series (391 patients with Parkinson's disease, 344 controls) and five separate Caucasian series' (combined sample size 1962 Parkinson's disease patients, 1900 controls). RESULTS: We observed no evidence of association for rs4877365 and rs4878104 and risk of Parkinson's disease in any of the individual series or in the combined Caucasian series under either an additive or recessive model. CONCLUSION: These specific DAPK1 intronic variants do not increase the risk of Parkinson's disease. However, further functional studies are required to elucidate the potential therapeutic implications with the dimerization of the Dapk1 and Lrrk2 proteins.

Deep brain stimulation therapy for Parkinson's disease using frameless stereotaxy: comparison with frame-based surgery.

BACKGROUND AND PURPOSE: Deep brain stimulation (DBS) surgery has been performed using frame-based stereotaxy traditionally; however, in recent years, it has also been performed using frameless stereotaxy. The purpose of this study was to compare the experience at our centre in performing DBS surgery using frameless surgery for patients with Parkinson's disease with that of using frame-based surgery. METHODS: Twenty-four patients with advanced Parkinson's disease underwent DBS surgery, 12 with frameless and 12 with frame-based stereotaxy. After identifying the subthalamus by microelectrode recording (MER), the DBS electrodes were implanted and connected to an implanted programmable generator in all patients. Programming was started 1 month after the operation and the outcome of the patients was followed up regularly for at least 12 months. RESULTS: After 1 year of follow-up, the patients who received frameless surgery showed no difference in the degree of improvement in clinical motor function compared with the patients who received frame-based surgery (P = 0.819); the average improvement was 60.9% and 56.9%, respectively, in the stimulation alone/medication-off state, as evaluated by the Unified Parkinson's Disease Rating Scale-III motor subscore. However, the frameless group had significantly shorter total MER time (P = 0.0127) and a smaller number of trajectories (P = 0.0096) than the frame-based group. CONCLUSIONS: Our data indicate that frameless DBS surgery has a similar outcome when compared with frame-based surgery; however, frameless surgery can decrease the operation time, MER time, and MER trajectory number.

Plasma calcitonin gene-related peptide in diagnosing and predicting paediatric migraine.

To investigate the role of plasma calcitonin gene-related peptide (CGRP) in paediatric migraine, we prospectively collected 134 blood samples during or between attacks from 66 migraine, 33 non-migraine headache (non-migraine) and 22 non-headache patients, aged 4-18 years. Plasma CGRP concentrations were measured by enzyme-linked immunosorbent assay and disability by Pediatric MIgraine Disability ASsessment (PedMIDAS) questionnaire. Migraineurs had higher plasma CGRP levels than non-migraine patients (P = 0.007). The attack level was higher than the non-attack level in migraine (P = 0.036), but not in non-migraine, patients. This was also revealed in paired comparison (n = 9, P = 0.015 vs. n = 4, P = 0.47). Using a threshold of 55.1 pg/ml, the sensitivity of the attack level in predicting migraine was 0.81, and specificity 0.75. The PedMIDAS score tended to be higher in the high CGRP (> 200 pg/ml, n = 7) group than in the low (< 200 pg/ml, n = 33) group (26.07 vs. 19.32, P = 0.16) using Mann-Whitney test. Plasma CGRP is useful for diagnosis in paediatric migraine.

Acute disseminated encephalomyelitis: a follow-up study in Taiwan.

BACKGROUND: Acute-disseminated encephalomyelitis (ADEM) is a demyelinating disorder of the central nervous system, whose epidemiology, clinical presentations and functional outcome are incompletely understood in Asian populations. OBJECTIVE: To assess the clinical presentations, predisposing factors and functional outcome of ADEM in Taiwan. METHODS: 50 patients initially diagnosed with ADEM (male, 19; female, 31) were enrolled from 1991 to 2005. Diagnosis of ADEM or multiple sclerosis was established during a follow-up period of 2-120 months. 8 adult patients were noted to have taken the immunomodulatory drug, levamisole, within 3 months before onset of symptoms. The remaining 42 patients (male, 17; female, 25) were categorised by age as children (<16 years, n = 12), young adults (16-49 years, n = 21) and elderly adults (> or =50 years, n = 9). The clinical manifestations, predisposing factors and radiological findings were compared between different age groups and adult patients with or without levamisole use. Functional outcome was compared by a log-rank test. RESULTS: Preceding upper respiratory tract infection was evident in 21 (50%) patients and only one young-adult patient had received Rubella vaccine immunisation. The frequency of fever was higher in children (p = 0.04) and psychiatric symptoms were more prevalent in elderly patients (p = 0.03). Functional recovery was faster in children than in adults (p = 0.002). Initial Expanded Disability Status Scale score (odds ratio (OR) 1.9, p = 0.03) and no fever (OR 0.04, p = 0.06) were associated with poor outcome (modified Rankin scale > or =2). After a mean (SD) follow-up of 31.8 (9.9) months, 4 (9.5%) patients developed multiple sclerosis (3 (25%) children, 1 (4.7%) young adult, p = 0.03). The neurological disability, radiological and cerebrospinal fluid findings did not differ between patients with and without levamisole use. One elderly adult patient previously receiving levamisole developed multiple sclerosis of relapse-remitting type after a mean follow-up period of 36.9 months. CONCLUSION: The clinical presentations, functional outcome and risk of developing multiple sclerosis differed between different age groups. Functional recovery was faster in children than in adults. Poor functional outcome was related to initial high Expanded Disability Status Scale score and absence of fever.

3D simulations of hydrodynamic drag forces on two porous spheres moving along their centerline.

This paper numerically evaluates the hydrodynamic drag force exerted on two highly porous spheres moving steadily along their centerline through a quiescent Newtonian fluid over a Reynolds number ranging from 0.1 to 40. At creeping-flow limit, the drag forces exerted on both spheres were approximately identical. At higher Reynolds numbers the drag force on the leading sphere (sphere #1) was higher than the following sphere (sphere #2), revealing the shading effects produced by sphere #1 on sphere #2. At dimensionless diameter beta<2 (beta=d(f)/2k(0.5), d(f) and k are sphere diameter and interior permeability, respectively), the spheres can be regarded as "no-spheres" limit. At increasing beta for both spheres, the drag force on sphere #2 was increased because of the more difficult advective flow through its interior, and at the same time the drag was reduced owing to the stronger wake flow produced by the denser sphere #1. The competition between these two effects leads to complicated dependence of drag force on sphere #2 on beta value. These effects were minimal when beta became low.

Sleep disturbances in the Vietnam generation: findings from a nationally representative sample of male Vietnam veterans.

OBJECTIVE: This study analyzed questionnaire items that address complaints about sleep from the National Vietnam Veterans Readjustment Study, a nationally representative sample of the 3.1 million men and women who served in Vietnam. This study compared the frequency of nightmares and difficulties with sleep onset and sleep maintenance in male Vietnam theater veterans with male Vietnam era veteran and male civilian comparison subjects. It focused on the role of combat exposure, nonsleep posttraumatic stress disorder (PTSD) symptoms, comorbid psychiatric and medical disorder, and substance abuse in accounting for different domains of sleep disturbance. METHOD: The authors undertook an archival analysis of the National Vietnam Veterans Readjustment Study database using correlations and linear statistical models. RESULTS: Frequent nightmares were found exclusively in subjects diagnosed with current PTSD at the time of the survey (15.0%). In the sample of veterans who served in Vietnam (N = 1,167), combat exposure was strongly correlated with frequency of nightmares, moderately correlated with sleep onset insomnia, and weakly correlated with disrupted sleep maintenance. A hierarchical multiple regression analysis showed that in Vietnam theater veterans, 57% of the variance in the frequency of nightmares was accounted for by war zone exposure and non-sleep-related PTSD symptoms. Alcohol abuse, chronic medical illnesses, panic disorder, major depression, and mania did not predict the frequency of nightmares after control for nonsleep PTSD symptoms. CONCLUSIONS: Frequent nightmares appear to be virtually specific for PTSD. The nightmare is the domain of sleep disturbance most related to exposure to war zone traumatic stress.

The COMT L allele modifies the association between MAOB polymorphism and PD in Taiwanese.

OBJECTIVE: Reports suggest that catechol-O-methyltransferase (COMT(L/L)) (Val(158)/Met) and monoamine oxidase B (MAOB) intron 13 genotype polymorphism is associated with PD. To understand the ethnicity-specific effects of genetic polymorphism, we performed a case-control study of the association between PD susceptibility and polymorphism of MAOB and COMT, both separately and in combination, in Taiwanese. METHODS: Two hundred twenty-four patients with PD and 197 controls, matched for age, sex, and birthplace, were recruited. MAOB and COMT polymorphism genotyping was performed by using PCR-based restriction fragment length polymorphism (RFLP) analyses. chi(2), OR, and Fisher's exact tests were used to compare differences in allelic frequencies and genotypes. RESULTS: The MAOB G genotype (G in men and G:/G in women) was associated with a 2.07-fold increased relative risk of PD. COMT polymorphism, considered alone, showed no correlation with PD risk; however, a significant synergistic enhancement was found in PD patients harboring both the COMT(L) and MAOB G genotypes. CONCLUSIONS: These results suggest that, in Taiwanese, PD risk is associated with MAOB G intron 13 polymorphism, and this association is augmented in the presence of the COMT(L) genotype, indicating an interaction of these two dopamine-metabolizing enzymes in the pathogenesis of sporadic PD. However, the relatively low frequencies of these combined genotypes in our study necessitates confirmation with a larger sample size.

Effect of MAO-B inhibitors on MPP+ toxicity in Vivo.

l-Deprenyl (Selegiline), a selective and irreversible type B monoamine oxidase inhibitor, has been used as an adjunct to levodopa therapy in Parkinson's disease. Recently, it is proposed as a putative neuroprotective agent in delaying the progression of cell death based on its capability of reducing the oxidative stress derived from the MAO-B dependent metabolism of dopamine, and blocking the development of MPTP-parkinsonism. However, a variety of experimental models suggest that l-deprenyl provides neuroprotection through multiple modes of mechanism other than the inhibition of MAO-B. We have previously shown that l-deprenyl protects midbrain dopamine neurons from MPP+ toxicity by a novel antioxidant effect. In the present study we examined whether the protection against MPP+ toxicity is also shared by other reversible or irreversible MAO-B inhibitors including (+)-deprenyl, Ro16-6491 and pargyline. Our data show that non of these MAO-B inhibitors changes the dopamine loss in the striatum induced by intranigral injection of MPP+. Our result suggests that l-deprenyl may possess a unique neuroprotective action on nigral neuron against MPP+ toxicity independent of the MAO-B inhibition.

Suppression of hydroxyl radical formation and protection of nigral neurons by l-deprenyl (selegiline).

The present study clearly demonstrated that l-deprenyl confers a substantial protective effect against MPP+ in the substantia nigra zona compacta in vivo. 32.39. The protection provided by l-deprenyl may not depend on its inhibition of type B monoamine oxidase. A unique antioxidant property of l-deprenyl by suppression of cycotoxic. OH formation and associated oxidative damage induced by MPP+ in the A9 melanized nigral neurons may contribute to the protection against MPP+ toxicity in the nigrostriatal system. The likelihood that l-deprenyl may confer neuroprotection against MPP+ toxicity through antioxidant effect is further strongly supported by our recent data that U-78517F (2-methlaminochromans) a potent inhibitor of ironcatalyzed lipid peroxidation, and DMSO an effective. OH scavenger also protect nigral neurons against MPP(+)-induced severe oxidative injury in the substantia nigra. This putative antioxidant effect of deprenyl may explore another mechanism which may in part contribute to its overt neuroprotection against several toxins, including 6-OHDA, DSP-4, and MPTP, and the possible clinical effects on slowing the neuronal degeneration in early Parkinson's disease, Alzheimer's disorder and even senescent changes.

Antioxidant mechanism and protection of nigral neurons against MPP+ toxicity by deprenyl (selegiline).

The current research has demonstrated that MPP+ can induce lipid peroxidation in the nigrostriatal system of rat in vivo. Antioxidant agent U-78517F and .OH scavenger DMSO may protect against MPP+ toxicity through the inhibition of .OH radical-mediated oxidative injury in the substantia nigra. These findings indicate that the cytotoxic hydroxyl radical generated from dopamine oxidation in the iron-rich basal ganglia may contribute to the mechanism underlying the selective A9 melanized nigral degeneration in MPTP-Parkinsonism and possibly in idiopathic Parkinson's disease. In addition, the present studies also clearly demonstrate that deprenyl can substantially protect dopaminergic neurons against MPP+ toxicity in the substantia nigra zona compacta in vivo. The neuroprotective effect provided by deprenyl may not be the consequence of its inhibition of MAO-B activity or prevention of the uptake of MPP+ by dopaminergic neurons. A unique antioxidant property of deprenyl by suppressing .OH formation and associated oxidative injury induced by MPP+ may contribute to the apparent neuroprotective action. In perspective, this putative antioxidant effect of deprenyl may provide another mechanism to its overt neuroprotective effects against oxygen radical-mediated oxidative injury in some neurotoxic chemicals, such as 6-OHDA and DSP-4, and probably in Alzheimer's disease and senescent changes. Finally, based on the present data, a possible neuroprotective therapeutic window of deprenyl in the treatment of early Parkinson's disease has been proposed. It is suggested that deprenyl should be introduced as early as possible in de novo Parkinsonian patients to achieve its full neuroprotective effect on nigral degeneration. Moreover, a combination of early detection of individuals at risk of developing Parkinson's disease and early intervention of deprenyl and/or other centrally active antioxidants to these patients may provide a new preventive therapeutic strategy in the future, in addition to the current conventional levodopa treatment of Parkinson's disease.

In vivo generation of hydroxyl radicals and MPTP-induced dopaminergic toxicity in the basal ganglia.

The in vivo generation of .OH free radicals in specific brain regions can be measured by intracerebral microdialysis perfusion of salicylate, avoiding many of the pitfalls inherent in systemic administration of salicylate. Direct infusion of salicylate into the brain can minimize the hepatic hydroxylation of salicylate and its contribution to brain levels of 2,5-DHBA. Levels of 2,5-DHBA detected in the brain dialysate may reflect the .OH adduct plus some enzymatic hydroxylation of salicylate in the brain. After minimizing the contribution of enzyme and/or blood-borne 2,5-DHBA, the present data demonstrate the validity of the use of 2,3-DHBA and apparently 2,5-DHBA as indices of .OH formation in the brain. Therefore, intracranial microdialysis of salicylic acid and measurement of 2,3-DHBA appears to be a useful .OH trapping procedure for monitoring the time course of .OH generation in the extracellular fluid of the brain. These results indicate that nonenzymatic and/or enzymatic oxidation of the dopamine released by MPTP analogues in the extracellular fluid may play a key role in the generation of .OH free radicals in the iron-rich basal ganglia. Moreover, a site-specific generation of cytotoxic .OH free radicals and quinone/semiquinone radicals in the striatum may cause the observed lipid peroxidation, calcium overload, and retrograde degeneration of nigrostriatal neurons. This free-radical-induced nigral injury can be suppressed by antioxidants (i.e., U-78517F, DMSO, and deprenyl) and possibly hypothermia as well. In the future, this in vivo detection of .OH generation may be useful in answering some of the fundamental questions concerning the relevance of oxidants and antioxidants in neurodegenerative disorders during aging. It could also pave the way for the research and development of novel neuroprotective antioxidants and strategies for the early or preventive treatment of neurodegenerative disorders, such as Parkinson's disease (Wu et al., this issue), amyotrophic lateral sclerosis, head trauma, and possibly Alzheimer's cognitive dysfunction as well. In conclusion, this in vivo free-radical trapping procedure provides evidence to support a current working hypothesis that a site-specific formation of cytotoxic .OH free radicals in the basal ganglia may be one of the neurotoxic mechanisms underlying nigrostriatal degeneration and Parkinsonism caused by the dopaminergic neurotoxin MPTP. Addendum added in proof: The controversy concerning possible neurotoxic and/or neuroprotective roles of NO. in cell cultures was discussed and debated at the symposium (Wink et al., this issue; Dawson et al., this issue; Lipton et al., this issue).(ABSTRACT TRUNCATED AT 400 WORDS)

Ferrous-citrate complex and nigral degeneration: evidence for free-radical formation and lipid peroxidation.

Increased nigral iron content in the parkinsonian brain is now well documented and is implicated in the pathogenesis of this movement disorder. Free iron in the pigmented DA-containing neurons catalyze DA autoxidation and Fenton reaction to produce cytotoxic .OH, initiating lipid peroxidation and consequent cell damage. The present results clearly demonstrate that a regional increase in the levels of the "labile iron pool" can result in the degeneration of dopaminergic nigral neurons as reflected by a significant inhibition in the expression of tyrosine hydroxylase mRNA and DA depletion. Iron-complex-induced damage of dopaminergic neurons in the substantia nigra, might have resulted from a sequence of cytotoxic events including the .OH generation and lipid peroxidation as demonstrated in this study. This free-radical-induced oxidative nigral injury may be a reliable free-radical model for studying parkinsonism and may be relevant to idiopathic Parkinson's disease. This apparent nigral injury stimulated by Fe(2+)-citrate is more severe than that produced by ferric iron and its citrate complex. Moreover, these data indicate that Fe(2+)-citrate is as potent as MPP+ in causing oxidative injury to the substantia nigral neurons. However, the nigral toxicity of MPTP and its congeners are not progressive, while Fe(2+)-citrate complex may produce a progressive degeneration of the nigrostriatal neurons which is similar to the progression of ideopathic Parkinson's disease. Thus, this unique Fe(2+)-citrate complex animal model could be used for studying neuroprotective treatments for retarding or halting the progressive nigrostriatal degeneration caused by free radicals in the iron-rich basal ganglia.

CPP antagonizes hypoxia-induced changes in dopamine metabolism in the striatum of newborn rat.

Treatment with 3-(2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid (CPP), a potent and competitive N-methyl-D-aspartate antagonist, is able to reduce the hypoxia-induced increase in striatal dopamine level by 26% even after the hypoxic insult has occurred. The hypoxia-induced decrease of the striatal 3,4-dihydroxyphenylacetic acid level can also be reversed by CPP. This study demonstrates that CPP can antagonize the hypoxia-induced changes in the dopamine metabolism in the striatum of the newborn rat.