Tomoyoshi Kondo

Retrograde dopaminergic neuron degeneration following intrastriatal proteasome inhibition

Recent studies have suggested that defects in the ubiquitin-proteasome system (UPS) contribute to the etiopathogenetic mechanisms underlying dopaminergic neuronal degeneration in Parkinsons disease. The present study aims to study the effects of proteasome inhibition in the nerve terminals of nigrostriatal dopaminergic neurons in the substantia nigra pars compacta (SNpc). Following a unilaterally intrastriatal injection of lactacystin, a selective proteasome inhibitor, dopaminergic neurons in the ipsilateral SNpc progressively degenerated with alpha-synuclein-immunopositive intracytoplasmic inclusions. When lactacystin was administered at a high concentration, the striatum was simultaneously involved, and alpha-synuclein-immunopositive extracytoplasmic granules appeared extensively within the SN pars reticulata (SNpr). In addition, during the retrograde neuron degeneration in SN, the level of heme oxygenase-1 immunopositivity, an oxidative stress marker, was markedly increased in SNpc neurons. These results reveal that intrastriatal proteasome inhibition sufficiently induces retrograde dopaminergic neuronal degeneration with abundant accumulation of alpha-synuclein in the SN.

Changes in the incidence of amyotrophic lateral sclerosis in Wakayama, Japan

In the 1960s, the incidence of amyotrophic lateral sclerosis (ALS) in the Kozagawa and Koza areas in Wakayama prefecture was much higher than that in other areas of the world. However, between 1980 and 1993, a gradual decrease in the incidence of the disease in these areas was reported. To ascertain whether the decreased incidence has persisted, we conducted a retrospective epidemiological study, and determined the average annual incidence of ALS in Wakayama prefecture from 1998 to 2002. The number of ALS cases encountered during the period was 134 (male 79, female 55). The crude average annual incidence in Wakayama prefecture in total was 2.50 (male 3.08, female 1.99) per 100,000. In the Kozagawa and Koza areas in Wakayama prefecture, where the senility rate rapidly increased in recent years, the average annual incidence of ALS in the present research was 10.56 (male 14.14, female 7.66). When the crude rate was standardized for both age and sex to the Japanese population in 1990, the expected value was 5.24 (male 7.34, female 3.18), which was lower than that of our previous survey. The prevalence in Wakayama prefecture at 31 December 2002 was 11.31 (male 14.40, female 8.53). In Kozagawa and Koza areas, the crude prevalence was 52.81 (male 70.70, female 38.28). These results indicated that the incidence of ALS in Wakayama prefecture, especially for females, steadily decreased compared to that in previous reports. However, a high incidence of ALS persisted among males in Wakayama prefecture, especially in the Kozagawa and Koza areas. Some environmental factors and gender specificity may be related to the decreased incidence of ALS in focus areas.

Nutritional status and risk of amyotrophic lateral sclerosis in Japan

Only a few human studies have reported the relationship between dietary factors and the risk of amyotrophic lateral sclerosis (ALS). We therefore analyzed the relationship between macronutrients (carbohydrate, protein and fat) and the risk of ALS using a case‐control study in Japan. The study comprised 153 ALS patients diagnosed by the El Escorial World Federation of Neurology criteria, and 306 gender‐ and age‐ matched controls randomly selected from the general population. A self‐administered food frequency questionnaire was used to estimate pre‐illness intakes of food groups and nutrients. The strength of association between ALS and a potential risk factor was assessed by calculating odds ratios (ORs) and 95% confidence intervals (CIs). A high intake of carbohydrate was significantly associated with an increased risk of ALS (adjusted OR = 2.14, 95% CI 1.05–4.36; the highest versus the lowest tertile). ORs for the second and third tertile of total fat were 0.57 and 0.41 (95% CI 0.21–0.80), respectively. ORs for the highest tertile of intake versus the lowest were 0.41 (95% CI 0.21–0.80) for total fat, 0.30 (95% CI 0.16–0.5) for saturated fatty acids (SFAs), 0.35 (95% CI 0.18–0.69) for monounsaturated fatty acids (MUFAs) and 0.58 (95%CI 0.40–0.96) for polyunsaturated fatty acids (PUFAs). Our findings suggest that high intakes of carbohydrate and low intakes of fat and some kinds of fatty acids may, when combined, increased the risk of ALS.

Oxidative stress and microglial activation in substantia nigra following striatal MPP

The present study aims to study sequential alterations occurring in both dopaminergic neurons and microglia in substantia nigra (SN) following intrastriatal injection of 1-methyl-4-phenylpridium ion (MPP+) in rats. Heme oxygenase-1 (HO-1), a marker of oxidative stress, first appeared in dopaminergic neurons in SN at 1 day post-lesion. Subsequently, microglia in SN exhibited morphological changes indicative of activation. At 7 days post-lesion, those findings increased severity and 7a significant reduction in the number of dopaminergic neurons was observed. The present finding suggests that extensive oxidative stress and secondary-induced neuroinflammation play a relevant role in MPP+-induced retrograde dopaminergic neuron degeneration. We hope that this model will be useful in developing a disease modifying therapy of Parkinsons disease.

Ropinirole is effective on motor function when used as an adjunct to levodopa in Parkinson's disease: STRONG study

We report the results of a randomized, double‐blind, placebo‐controlled, 16‐week study to evaluate the efficacy and safety of ropinirole, 0.75 to 15.0 mg/day, as an adjunct to levodopa. A total of 243 patients were randomly assigned into placebo or ropinirole groups. The mean (standard deviation) dose of ropinirole at endpoint was 7.12 (2.88) mg/day. The primary endpoint—the mean reduction in the Unified Parkinsons Disease Rating Scale (UPDRS) total motor score—was significantly greater for the ropinirole group than the placebo group (−9.5 vs. −4.5, P = 0.00001). The mean reduction in the UPDRS total activities of daily living (ADL) score was also significantly greater for ropinirole than for placebo (−2.7 vs. −1.0, P = 0.0002). The percentage of patients showing at least a 20% reduction in the percentage of time spent “off” was significantly greater for the ropinirole group than for the placebo group (58.7% vs. 38.6%, P = 0.030). A total of 84.3 and 65.6% of the patients experienced adverse events while receiving ropinirole or placebo, respectively. The results showed that ropinirole was more effective than placebo in improving motor function and ADL when used as an adjunct to levodopa in patients with advanced Parkinsons disease.

Placebo-controlled, double-blind dose-finding study of entacapone in fluctuating Parkinsonian patients

We conducted a multicenter randomized, placebo‐controlled double‐blind parallel‐group study in Japanese Parkinsons disease (PD) patients with wearing‐off motor fluctuations to determine the clinical efficacy and safety of entacapone as an adjunct to concomitant treatment with levodopa and a dopa decarboxylase inhibitor (DCI). We randomized 341 patients to receive entacapone 100 or 200 mg or placebo per dose of levodopa/DCI for 8 weeks. The primary efficacy variable was on time change while awake, determined by patients diaries. Mean baseline on time in each group was approximately 8 hours. Mean on time change at final assessment was 1.4 hours each for entacapone 100‐mg and 200‐mg groups and by 0.5 hours for the placebo group (P < 0.05). The two entacapone doses were equally efficacious. Adverse events occurred in 79 patients (69.9%) in placebo, 82 (72.6%) in 100 mg, and 98 (86.0%) in 200 mg. The most common adverse event with entacapone was an increase in dyskinesias. The overall safety profile was satisfactory in both entacapone groups. In conclusion, both entacapone 100 and 200 mg were equally effective in increasing on time of PD patients with wearing‐off fluctuations, although the safety and tolerability profile appeared more favorable for the 100‐mg dose.

Nuclear localization of glyceraldehyde‐3‐phosphate dehydrogenase is not involved in the initiation of apoptosis induced by 1‐Methyl‐4‐phenyl‐pyridium iodide (MPP+)

Nuclear localization of glyceraldehyde‐3‐phosphate dehydrogenase (GAPDH) is implicated in the process of apoptosis. To study the function of GAPDH, we expressed GAPDH C‐terminally fused with or without nuclear localization signal (NLS) in SH‐SY5Y and NB41A3 cells using a retrovirus expression system. GAPDH carrying NLS (GAPDH‐NLS) was expressed mainly in the nucleus. However, expression of GAPDH‐NLS did not cause any difference in cell survival rate as compared to that of the vector alone or GAPDH without NLS. Treatment with 1‐Methyl‐4‐phenyl‐pyridium iodide (MPP+) caused no difference in the cell survival rate or in the pattern or extent of apoptosis among the three transductants. In the cells expressing GAPDH without NLS, MPP+ did not cause visible translocation of GAPDH into nucleus before the onset of apoptosis. Since GAPDH is known to comprise a CRM1‐mediated nuclear export signal, we blocked the nuclear export of GAPDH by treatment with leptomycin B, an inhibitor of CRM1‐mediated nuclear export. The treatment did not cause any difference in apoptosis among the three transductants. An additional treatment with MPP+ induced no apoptotic difference in these cells. Thus, we have concluded that a simple nuclear localization of GAPDH does not induce apoptosis, and that MPP+‐induced apoptosis is not caused by nuclear translocation of GAPDH.

Survival rate of patients with amyotrophic lateral sclerosis in Wakayama Prefecture, Japan, 1966 to 2005

To investigate longitudinal changes in the survival rate of patients with amyotrophic lateral sclerosis in Wakayama Prefecture, Japan, we made a retrospective hospital-based study of 454 patients diagnosed with motor neuron disease (MND) at Wakayama Medical University (WMU) Hospital between 1966 and 2005. Of the 454 patients, 240 who were born and who lived in Wakayama Prefecture were diagnosed with definite or probable ALS during this period, according to the El Escorial criteria. The clinical data of the 240 patients, including sex, birth date, birthplace, address, age at onset, initial symptoms, date when respiratory support was applied (tracheostomy, noninvasive positive pressure ventilation, or mandatory artificial ventilation), and date of death were reviewed retrospectively. The age at onset of patients who developed initial symptoms before 1990 was 53.4+/-10.6 (mean+/-S.D.) and that in 1990 or thereafter was 64.8+/-10.3, respectively, showing a significant difference (p<0.0001). Clinical duration was determined from onset to either date of death or initiation of respiratory support in this study. Survival rate was compared using the Kaplan-Meier method according to age at onset, sex, initial symptoms and year of onset. Mean age at onset shifted towards older age according to a later year of onset, due to the overwhelming senility rate in Wakayama Prefecture. Older onset patients had a significantly poorer survival rate than younger onset patients when it was compared based on 10-year age groups (log rank, p<0.0001). Male patients had a poorer survival rate than female patients (p<0.0001). ALS patients with bulbar palsy onset showed shorter clinical durations than those with lower leg onset (p<0.0071, Breslow-Gehan-Wilcoxon test). Patients over 70 years old more frequently showed bulbar palsy onset compared to those younger than 69 (p=0.003). In a comparison of year of onset before and after 1990, ALS patients after 1990 had characteristics of older age onset and shorter clinical duration, and more frequently showed bulbar palsy onset compared with those before 1990. These findings indicated that younger onset patients with ALS decreased after 1990 in Wakayama Prefecture and this might partly explain the recent decline of ALS incidence in Wakayama Prefecture. The shift of the mean age at onset to older age might be due to exogenous factors, including changes in lifestyle, food, and drinking water in this area. Bulbar palsy onset and age at onset were expected as predictors of the survival rate.

Expression of FKBP12 and ryanodine receptors (RyRs) in the spinal cord of MND patients.

We investigated the FKBP12 and ryanodine receptor (RyR) immunoreactivity (IR) in the spinal cords of neurological controls and patients with motor neuron disease (MND). In the neurological controls, the cytoplasm of the spinal anterior horn neurons was stained with anti‐FKBP12 antibodies and anti‐RyR (type 1 and type 2) antibodies. In the MND cases, the residual neurons in the anterior horn of the spinal cord showed IR for RyR (type 1 and 2) antibodies, while weak IR for anti‐FKBP12 antibodies was comparable to that of controls. The numbers of neurons recognized with the anti‐FKBP 12 or anti‐RyR (type 1 and 2) antibodies were counted in the anterior horn of spinal cords from the MND cases and neurological controls. Frequency of neurons stained with anti‐FKBP 12 antibody was significantly decreased in the MND cases compared to that in controls (48.7±23.2%, 71.0±18.5%, respectively, mean±SD, p<0.0005). In the MND cases, numbers of normal‐appearing, chromatolytic neurons showing IR to anti‐FKBP12 (N19) antibody were significantly decreased compared to those in the controls. Immunoreactivities to anti‐RyR antibodies (type 1and 2) in MND cases were present and there was no difference compared to those of the controls. Neurons in the spinal cord anterior horn of Kii‐ALS cases with prolonged clinical duration were immunostained with both anti‐FKBP12 and anti‐RyR (type 1 and 2) antibodies similar to that in the controls. The anterior horn neurons of MND cases of short clinical duration showed absent IR to FKBP 12 antibody but present IR to RyR (type 1 and 2) antibodies. The present result suggests that FKBP12 IR was decreased in the MND cases with short clinical duration. RyR (type 1 and 2) is a major component of the intracellular calcium channel, which mediates calcium‐induced calcium release. FKBP12, which is an endogenous ligand for RyR, stabilizes the calcium channels preventing calcium leakage in the absence of receptor activation. Imbalance between FKBP12 and RyR IR may play an important role in degeneration due to MND. Further study of the correlation between RyR and FKBP12 should contribute to clarifying the mechanisms of neurodegeneration in MND, including calcium‐induced neuronal loss.

Alteration of eating behaviors in patients with Parkinson's disease: Possibly overlooked?

Patients with Parkinsons disease (PD) occasionally show food cravings and/or compulsive eating that result in significant, undesired weight gain. Dopamine replacement therapy may be the cause of this type of eating disorder. We evaluated 60 consecutive patients to see if they had any alteration of eating patterns after starting levodopa. Among them, five (8.3%) patients exhibited characteristic alterations of food preference following the start of dopamine replacement therapy. One patient showed an undesirable weight gain. Of the five patients exhibiting food preference alterations, all showed increased preference to consume sweet snacks, although this alteration was not always associated with hyperphagia (eating too much). This type of dietary alteration was not related to a specific antiparkinsonian drug, and could be observed in patients undergoing dopamine agonist monotherapy. Alteration of eating behavior may not be uncommon in PD patients, and is possibly overlooked. Since dopamine is closely involved in acquisition of food preferences, dietary changes with/without compulsive eating may be a manifestation of an alteration of appetitive behaviors due to excessive dopaminergic neurotransmission.