Continuous Levodopa Delivery with an Intraoral Micropump System: An Open-Label Pharmacokinetics and Clinical Study

BACKGROUND

Double-blind studies have demonstrated that motor complications in Parkinson's disease (PD) can be reduced with continuous delivery of levodopa. The DopaFuse system is a novel, intraoral micropump that attaches to a retainer and uses a propellant to deliver levodopa/carbidopa (LD/CD) continuously into the mouth.

OBJECTIVES

Evaluate the safety, pharmacokinetics, and efficacy of LD/CD delivered via the DopaFuse system compared to treatment with intermittent doses of standard oral LD/CD in PD patients with motor fluctuations.

METHODS

This was a 2-week, open-label study (NCT04778176) in 16 PD patients treated with ≥4 levodopa doses/day and experiencing motor fluctuations. On Day 1 (clinic setting) patients received their usual dose of standard LD/CD; DopaFuse therapy was initiated on Day 2, and on Day 3 patients received DopaFuse plus a morning oral LD/CD dose. Patients returned home on Days 4-14 and returned for in-clinic assessment on Day 15.

RESULTS

Continuous DopaFuse delivery of LD/CD was associated with reduced variability in plasma levodopa levels compared to oral LD/CD (mean ± SD levodopa Fluctuation Index reduced from 2.15 ± 0.59 on Day1 to 1.50 ± 0.55 on Day 2 (P = 0.0129) and to 1.03 ± 0.53 on Day 3 (P < 0.0001)). This pharmacokinetic improvement translated into significantly reduced OFF time with DopaFuse therapy (reduction of -1.72 ± 0.37 h at Day 15; P = 0.0004) and increased ON time without severe dyskinesias (increase of 1.72 ± 0.37 h at Day 15; P = 0.0004) versus oral LD/CD administration. DopaFuse therapy was not associated with any clinically significant adverse events.

CONCLUSIONS

Continuous delivery of LD/CD using the DopaFuse system was associated with significantly less variability in plasma levodopa concentrations and reductions in OFF time compared to treatment with standard oral LD/CD therapy and was well tolerated. © 2024 International Parkinson and Movement Disorder Society.

ICARUS at the Fermilab Short-Baseline Neutrino program: initial operation

The ICARUS collaboration employed the 760-ton T600 detector in a successful 3-year physics run at the underground LNGS laboratory, performing a sensitive search for LSND-like anomalous ν e appearance in the CERN Neutrino to Gran Sasso beam, which contributed to the constraints on the allowed neutrino oscillation parameters to a narrow region around 1 eV2 . After a significant overhaul at CERN, the T600 detector has been installed at Fermilab. In 2020 the cryogenic commissioning began with detector cool down, liquid argon filling and recirculation. ICARUS then started its operations collecting the first neutrino events from the booster neutrino beam (BNB) and the Neutrinos at the Main Injector (NuMI) beam off-axis, which were used to test the ICARUS event selection, reconstruction and analysis algorithms. ICARUS successfully completed its commissioning phase in June 2022. The first goal of the ICARUS data taking will be a study to either confirm or refute the claim by Neutrino-4 short-baseline reactor experiment. ICARUS will also perform measurement of neutrino cross sections with the NuMI beam and several Beyond Standard Model searches. After the first year of operations, ICARUS will search for evidence of sterile neutrinos jointly with the Short-Baseline Near Detector, within the Short-Baseline Neutrino program. In this paper, the main activities carried out during the overhauling and installation phases are highlighted. Preliminary technical results from the ICARUS commissioning data with the BNB and NuMI beams are presented both in terms of performance of all ICARUS subsystems and of capability to select and reconstruct neutrino events.

Therapeutic education for empowerment and engagement in patients with Parkinson's disease: A non-pharmacological, interventional, multicentric, randomized controlled trial

Background

In 1997 the European Parkinson's Disease Associations launched the Charter for People with Parkinson's disease that stated the right of patients to be informed and trained on the disease, its course, and treatments available. To date, few data analyzed the effectiveness of education program on motor and non-motor symptoms of PD.

Objective

The aim of this study was to evaluate the efficacy of an education program as it was a pharmacological treatment, thus choosing as the primary endpoint the change in daily OFF hours, the most widely used outcome in pharmaceutical clinical trials on PD patients with motor fluctuations. Secondary outcomes were change in motor and non-motor symptoms, quality of life and social functioning. The long-term efficacy of the education therapy was also evaluated by analyzing data collected at 12- and 24-weeks follow-up outpatient visits.

Methods

One hundred and twenty advanced patients and their caregivers were assigned to the intervention or control group in a single-blind, multicentric, prospective, randomized study evaluating an education program structured in individual and group sessions over a 6-weeks period.At the end of study, the intervention group showed a significant reduction in daily OFF hours compared to control patients (-1.07 ± 0.78 vs. 0.09 ± 0.35, p < 0.0001) and a significant improvement was also reported in most secondary outcomes. Patients retained significant medication adherence and daily OFF hours reduction at 12- and 24-weeks follow-up.

Conclusion

The results obtained demonstrated that education programs may translate in a notable improvement in motor fluctuations and non-motor symptoms in advanced PD patients.Clinical Trial Registration:Clinicaltrials.gov, identifier NCT04378127.

Scintillation light detection in the 6-m drift-length ProtoDUNE Dual Phase liquid argon TPC

DUNE is a dual-site experiment for long-baseline neutrino oscillation studies, neutrino astrophysics and nucleon decay searches. ProtoDUNE Dual Phase (DP) is a 6  ×  6  ×  6 m 3 liquid argon time-projection-chamber (LArTPC) that recorded cosmic-muon data at the CERN Neutrino Platform in 2019-2020 as a prototype of the DUNE Far Detector. Charged particles propagating through the LArTPC produce ionization and scintillation light. The scintillation light signal in these detectors can provide the trigger for non-beam events. In addition, it adds precise timing capabilities and improves the calorimetry measurements. In ProtoDUNE-DP, scintillation and electroluminescence light produced by cosmic muons in the LArTPC is collected by photomultiplier tubes placed up to 7 m away from the ionizing track. In this paper, the ProtoDUNE-DP photon detection system performance is evaluated with a particular focus on the different wavelength shifters, such as PEN and TPB, and the use of Xe-doped LAr, considering its future use in giant LArTPCs. The scintillation light production and propagation processes are analyzed and a comparison of simulation to data is performed, improving understanding of the liquid argon properties.

Prospects for beyond the Standard Model physics searches at the Deep Underground Neutrino Experiment: DUNE Collaboration

The Deep Underground Neutrino Experiment (DUNE) will be a powerful tool for a variety of physics topics. The high-intensity proton beams provide a large neutrino flux, sampled by a near detector system consisting of a combination of capable precision detectors, and by the massive far detector system located deep underground. This configuration sets up DUNE as a machine for discovery, as it enables opportunities not only to perform precision neutrino measurements that may uncover deviations from the present three-flavor mixing paradigm, but also to discover new particles and unveil new interactions and symmetries beyond those predicted in the Standard Model (SM). Of the many potential beyond the Standard Model (BSM) topics DUNE will probe, this paper presents a selection of studies quantifying DUNE's sensitivities to sterile neutrino mixing, heavy neutral leptons, non-standard interactions, CPT symmetry violation, Lorentz invariance violation, neutrino trident production, dark matter from both beam induced and cosmogenic sources, baryon number violation, and other new physics topics that complement those at high-energy colliders and significantly extend the present reach.

An evaluation of the efficacy and value of CVT-301 for the treatment of Parkinson's disease

Introduction: Levodopa is the most effective drug in the treatment of Parkinson's disease, but its chronic treatment is linked to the occurrence of motor complications with fluctuations of motor performance and dyskinesia. Unpredictable OFF episodes can be severe and disabling and current rescue medications cannot always be used safely. Rescue therapy is characterized by a rapid and predictable ON response and the safety profile of levodopa will represent a major advantage for patients affected by unresponsive OFF episodes.Areas covered: CVT-301 is a new inhaled formulation of LD recently developed as a self-administered treatment for OFF periods. Herein, the pharmacodynamic and pharmacokinetic properties, efficacy, and safety of CVT-301 are reviewed.Expert opinion: CVT-301 may offer several potential advantages including increased systemic bioavailability through pulmonary absorption, rapid onset of action, avoidance of first-pass drug metabolism, and less plasma level variability. It should be noted that the delivery device used has been described as relatively simple to use, but the few steps required to prepare and self-administer the dose can be challenging for PD patients during their OFF state. Additionally, resolution of an OFF episode requires the administration of two capsules of CVT-301, which further complicates the use of the device.

Effect of family history, occupation and diet on the risk of Parkinson disease: A case-control study

BACKGROUND

The aetiology of Parkinson's disease (PD) is still very controversial, with a peculiar lack of established risk factors or protective behavior.

METHODS

We carried out a case-control study of 634 idiopathic PD patients admitted from 2011 to 2015 to two hospitals located in central Italy and 532 controls matched by hospital, gender and age (± 5 years). The study questionnaire included questions on host factors, family history, residence, occupation and lifestyle. Odds ratios (ORs) for PD and 95% confidence intervals (CIs) were estimated with logistic regression, adjusting for actual and potential confounders.

RESULTS

A lower OR was observed in females (0.74; 95%CI:0.58-0.96), while older age classes showed a constantly increased risk for PD (p<0.005) starting from the class 65-69 years. Subjects who reported a first degree relative affected by PD showed a borderline increase which was more evident in those enrolled in the urban center of Rome (OR = 1.65; 95%CI: 1.09-2.50). Significant reduction of the risk was associated to current smoking (OR = 0.48; 95%CI: 0.24-0.54), and to vegetables consumption (p<0.03), while borderline increases were associated to meat and cold cut consumption. Occupational activities classified according to ISCO-08 categories did not show increased risk, while higher ORs' were found for pilots and physicians.

CONCLUSIONS

The results from this study confirmed the higher risk of PD in males and in elderly, and the inverse association with smoking habit. The possible etiological role of familial clustering, dietary habit, and some job tasks is suggested.

Overnight switch from rasagiline to safinamide in Parkinson's disease patients with motor fluctuations: a tolerability and safety study

BACKGROUND AND PURPOSE

When switching between monoamine oxidase type B (MAO-B) inhibitors, a 15-day suspension period is a precautionary measure to avoid a serotonin syndrome and hypertensive crisis. However, this indication results in a major inconvenience for parkinsonian patients because of the worsening of their clinical condition. In routine clinical practice, neurologists often perform a substitution of these two drugs without solution of continuity (i.e. overnight), to avoid worsening of fluctuations and prolonged OFF periods. Therefore, a safety open label study was performed to investigate the possible risks of switching overnight from rasagiline to safinamide.

METHODS

The study population included 20 advanced patients with Parkinson's disease on stable treatment with rasagiline and levodopa (alone or in combination with other anti-parkinsonian medication). The possible occurrence of serotonin syndrome and hypertension was monitored through a strict clinical observation and a 24-h Holter recording (ABPM) performed twice, whilst subjects were on rasagiline and immediately after switching to safinamide.

RESULTS

No cases of serotonin syndrome or hypertensive crisis occurred during the study. Changes that were not significant occurred in the primary end-point: 24-h mean blood pressure (BP) had a mild +4.4% increase in the ABPM2 versus ABPM1 (P = 0.17), 24-h systolic and diastolic BP values were slightly higher at ABPM2 compared to ABPM1 (respectively +3.3%, P = 0.13; and 5.4%, P = 0.08) and 24-h systolic BP variability was unchanged between the two ABPM evaluations (from 8.6 ± 2.9 to 8.9 ± 1.8; P = 0.27).

CONCLUSION

The results of the present study confirm that the overnight switch from rasagiline to safinamide is safe and well tolerated by patients.

The impact of intestinal microbiota on weight loss in Parkinson's disease patients: a pilot study

Background: There is increasing evidence of the association between microbiome dysfunction and Parkinson's disease (PD). Moreover, some PD patients suffer from unintentional weight loss (WL) which may precede the motor manifestations of the disease. Materials & methods: Gut microbiota profiling by 16S rRNA gene sequencing was performed in PD patients with an unintended WL, in steady weight patients (non-WL [NWL]) and in matched normal subjects. KEGG functional predictions were carried out. Results: Microbiota profiles revealed a dissimilarity between WL and NWL. Moreover, WL pathways were characterized by fatty acid biosynthesis, while NWL by inflammation pathways. Conclusion: The gut microbiota could participate in weight alteration observed in PD by the presence of bacteria involved in weight gain and inflammation, or conversely by bacteria implicated in energy expenditure.

Safety considerations when using non-ergot dopamine agonists to treat Parkinson's disease

INTRODUCTION

Nonergot dopamine agonists (NEDA) represent an excellent treatment option for Parkinson's disease (PD) patients, in both early and advanced stages of the disease. The post-marketing phase of NEDA has highlighted, though, the occurrence of important long-term adverse events.

AREAS COVERED

This review reports recent updates on NEDA adverse events, analyzing neurobiological bases and risk factors of these complications. A literature search has been performed using Medline and reviewing the bibliographies of selected articles.

EXPERT OPINION

NEDA represents a very important option in the treatment of PD. Criticisms on their use can be overcome through a better knowledge of these molecules and of the risk factors for adverse events which allow specialists to prevent the occurrence of undesired complications and consent a tailor-based approach. Abbreviations: PD: Parkinson's disease, DA: dopamine agonists, NEDA: non-ergot dopamine agonists, ICD: impulse control disorders, DAWS: dopamine agonist withdrawal syndrome, CYP: Cytochrome P, PK: pharmacokinetic, AUC: area under the curve, HRT: hormone replacement therapy, AV: atrioventricular, HF: heart failure, OH: orthostatic hypotension, RBD: REM behavior disorders, PDP: Parkinson's disease psychosis, DRT: dopamine replacement therapy, DDS: dopamine dysregulation syndrome, MMSE: Mini-Mental state examination, EDS: excessive daytime somnolence.

P286 Inverse relation between systolic blood pressure variability and global longitudinal strain in patients with Parkinson"s disease and autonomic dysfunction

Background

Parkinson"s disease (PD) patients often present cardiac blood pressure (BP) derangement as a result of autonomic dysfunction. However their echocardiography pattern have been poorly investigated yet . Study aim: to evaluate the correlation between indices of left ventricular function ad 24/h blood pressure pattern in patients with PD

Methods We evaluated 20 patients with diagnosed PD and autonomic dysfunction and 15 hypertensive age-matched subjects. All patients performed 24/h blood pressure monitoring (ABPM) and echocardiography. Left ventricular systolic function was evaluated through ejection fraction (EF), tissue doppler S wave and global longitudinal strain (GLS). BP variability (BPV) was evaluated through average real variability.

Results

GLS (17.6 vs 22.8; p = 0.04) was reduced in the PD group compared to hypertensive patients. Conversely EF and S wave was similar between the two groups. Patients with PD had an inverse significant correlation between GLS and 24/h systolic BPV (r= -0.64; p = 0.003) and a trend through significance between S wave and systolic BPV (r= -0.31; p = 0.07). sNocturnal diastolic BP was inversely related to GLS (r= -0.44; p = 0.001) . There were no correlation between GLS and BPV and values in hypertensive patients.

Conclusions

In PD patients GLS is related to indices of poor BP control. GLS appears to be an early detector of LV dysfunction in patients with PD and autonomic dysfunction.

Clinical and pharmacokinetics equivalence of multiple doses of levodopa benserazide generic formulation vs the originator (Madopar)

AIMS

While several generic preparations of levodopa/carbidopa and levodopa/benserazide (LBD) are currently available, pharmacokinetic (PK) equivalence and therapeutic equivalence studies with levodopa generics are not available in Italy. Lack of data on generic formulations is a critical factor for their limited use in this country and often lead patients to refuse the generic version of the branded drug.

METHODS

An experimental, 2-centre, randomized, double-blind, 2-sequence, noninferiority cross-over study was designed to evaluate both the PK equivalence and clinical equivalence of multiple doses of the generic preparation of LDB, Teva Italia, compared to the originator (Madopar). Forty-three out-patients with a diagnosis of idiopathic Parkinson's disease on LDB, were recruited and randomly assigned to 1 of 2 study sequences: generic-originator or originator-generic. Clinical evaluations were performed at the end of each study period. A PK study with an LDB fixed dose (100 + 25 mg) was performed in a subpopulation of 14 subjects.

RESULTS

Clinical data showed a reduction of 0.49 and 1.54 in the mean UPDRS III scores for the LDB and the originator, respectively. The 95% CIs [-2.21: 0.11] of the mean difference original vs LDB are smaller than the clinically significant difference of 3 UPDRS III points, supporting the conclusion that the treatment with LDB is not inferior to the originator. No statistically significant differences were found with respect to area under the curve to last dose, half-life, maximum concentration, time to maximum concentration and last observed concentration.

CONCLUSION

These findings prove the therapeutic clinical equivalence as well the PK equivalence of the generic LDB and the originator (Madopar).

Continuous versus intermittent oral administration of levodopa in Parkinson's disease patients with motor fluctuations: A pharmacokinetics, safety, and efficacy study

BACKGROUND

Laboratory and clinical evidence indicate that continous delivery of levodopa is associated with reduced motor complications compared to standard intermittent levodopa.

OBJECTIVE

To assess the pharmacokinetics and efficacy of continuous oral delivery of l-dopa/carbidopa in PD patients with motor fluctuations.

METHODS

Eighteen PD patients with motor fluctuations were enrolled in an open-label study comparing pharmacokinetics and efficacy measures between standard intermittent oral l-dopa/carbidopa and "continuous" oral l-dopa/carbidopa. Continuous treatment was operationally defined as sips of an l-dopa dispersion at 5- to 10-minute intervals. On day 1, patients received their usual oral l-dopa/carbidopa doses. On day 2, patients received l-dopa/carbidopa dose by "continuous" oral administration. On day 3, patients received a single dose of oral l-dopa/carbidopa followed by continuous administration of l-dopa/carbidopa. Each study period was 8 hours, and the total l-dopa/carbidopa dose administered was the same on each day. Analyses of variability were primarily-based samples drawn between 4 and 8 hours when subjects were in a relative steady state.

RESULTS

There was less variability in plasma l-dopa concentration with continuous versus intermittent oral l-dopa/carbidopa treatment (fluctuation index was 0.99 ± 0.09 vs. 1.38 ± 0.12 [P < 0.001] and coefficient of variation was 0.35 ± 0.03 vs. 0.49 ± 0.04 [P < 0.001]). Mean OFF time was decreased by 43% (P < 0.001) with continuous oral l-dopa therapy. No safety or tolerability issues were observed.

CONCLUSIONS

Continuous oral delivery of l-dopa/carbidopa was associated with less plasma variability and reduced off time in comparison to standard intermittent oral l-dopa/carbidopa therapy. © 2019 International Parkinson and Movement Disorder Society.

Non motor symptoms in progressive supranuclear palsy: prevalence and severity

NMSs have been extensively studied in PD patients but not in other forms of parkinsonism such as Progressive Supranuclear Palsy (PSP). The primary objective of this study was to analyze the frequency, severity and the type of non-motor symptoms (NMS) in PSP patients using the non-motor symptoms scale (NMSS). The secondary objective was to differentiate NMS between PSP and Parkinson’s disease (PD). We enrolled in this cross-sectional study 50 consecutive PSP and 100 matched Parkinson’s disease (PD) patients, in the proportion PSP/PD = 1/2, matched in age, sex, and disease duration. Motor and Non Motor symptoms (different scales for each disease) were evaluated at baseline using PSP scale, SCOPA Motor, Montreal Cognitive Assessment (MOCA), HADS, Hamilton, and Non Motor Symptom scale (NMSS). Comparative analysis was done using chi-squared test, Mann-Whitney test and Fisher’s exact test. Fifty PSP (56% female) and 100 PD (59% female) patients completed the study protocol and were included for statistical analysis. The NMSS total domains score in the PSP group was 77.58 ± 42.95 (range 14–163) with NMS burden grade: 4, very severe, and the in the PD group was 41.97 ± 35.45 (range: 0–215) with NMS burden grade: 3, severe. The comparative analysis showed that NMS total score (p < 0.0001), Sleep/Fatigue (p = 0.0007), Mood/Apathy (p = 0.0001), Gastrointestinal (p < 0.0001), and Urinary dysfunction (p = 0.0001) domains were significantly more severe in PSP patients than in PD. This observational study reports that NMSs are very frequent in PSP patients hence the higher burden of NMS in PSP specifically related to mood/apathy, attention/memory, gastrointestinal, urinary disturbances compared to PD.

Non-motor symptoms are more frequent and severe in patients with Progressive Supranuclear Palsy (PSP) than in those with Parkinson’s disease (PD). An international team led by Fabrizio Stocchi at the Institute for Research and Medical Care IRCCS in Rome used the Non-motor Symptoms Scale (NMSS) to compare the symptoms experienced by 50 PSP patients and 100 PD patients. They found that patients with PSP suffered worse and more frequent gastrointestinal and urinary disturbances, as well as more severe dysfunctions in attention and memory compared with PD patients. Moreover, the reported lack of motivation and sleep disturbances were more burdensome in PSP patients. These findings will not only contribute to diagnose PSP earlier and more accurately, but also help to increase awareness of the impact of non-motor symptoms on patients’ quality of life.

Constipation in Parkinson's Disease

Constipation is one of the main and disabling nonmotor symptoms in Parkinson's disease (PD), with a prevalence ranging from 24.6% to 63% according to the different diagnostic criteria used to define chronic constipation. Constipation is currently recognized as a risk factor of PD in relation to the number of evacuation per week and its severity. Moreover, several studies have demonstrated that constipation may precede the occurrence of motor symptoms underlying an earlier involvement of the enteric nervous system and the dorsal motor nucleus of the vagus in the α-synuclein pathology. In PD, constipation is mainly due to slower colonic transit or puborectalis dyssynergia, but the concomitant use of antiparkinsonian, pain, and antidepressant medications may worsen it. An accurate diagnosis and an adequate treatment of constipation it is pivotal to prevent complications such as intestinal occlusion and to ensure an optimal clinical response to levodopa.

Advances in dopamine receptor agonists for the treatment of Parkinson's disease

INTRODUCTION

Dopamine agonists (DA) are a class of agents which directly stimulate dopamine receptors mimicking the endogenous neurotransmitter dopamine. At first used as adjunctive therapy in the advanced phases of the disease, over the years a significant role was found for DA monotherapy as a first approach in the initial stage of Parkinson's disease (PD). Several reviews have already reported efficacy and safety of DA in PD and differences between DA and levodopa. Therefore the objective of this review is to gather recent updates in DA therapy. A thorough knowledge of recent literature evidences, would help clinician in the management of treatment with DA.

AREAS COVERED

Our review investigates recent updates on DA therapy, the role of these compounds in controlling non-motor symptoms (NMS) as well as new formulations under clinical evaluation and newly emerged post-marketing safety considerations. A literature search has been performed using Medline and reviewing the bibliographies of selected articles.

EXPERT OPINION

DA represents a very important option in the treatment of PD, even though there are still some criticisms and unmet needs. A better knowledge of dopamine receptors could lead to identification of new compounds able to better balance clinical efficacy and side effects.

Adjuvant therapies for Parkinson's disease: critical evaluation of safinamide

Safinamide (SAF) is a new drug developed for the treatment of Parkinson’s disease (PD). It is a benzylamino derivative with multiple mechanisms of action and antiparkinsonian, anticonvulsant, and neuroprotective properties. SAF inhibits monoamine oxidase B and dopamine reuptake and glutamate release, blocks voltage-dependent sodium channels, and modulates calcium channels. Although the antiparkinsonian effect can be ascribed in part to the inhibition of the monoamine oxidase B, which is complete at 50 mg, the enhanced benefit seen at the 100 mg dose is probably due to nondopaminergic mechanisms. SAF will represent an important option for patients with both early and advanced PD. In early PD patients, the addition of SAF to dopamine agonists may be an effective treatment strategy to improve motor function, prolong the use of dopamine agonists, and/or delay the introduction of levodopa. In advanced parkinsonian patients, SAF has been demonstrated to significantly increase on time with no, or nontroublesome dyskinesias. All studies performed have demonstrated its efficacy in benefiting both short-term and long-term quality-of-life outcomes in both early and advanced PD patients. SAF has been investigated in long-term (24 months), double-blind, placebo-controlled studies, where it showed a very good safety profile. SAF has not been studied in de novo PD patients, and its potential positive effect on dyskinesia deserves further dedicated studies.

The Lee Silverman Voice Treatment (LSVT®) speech therapy in progressive supranuclear palsy

BACKGROUND

The Lee Silverman Voice Treatment (LSVT®) was specifically created and tested to comply with the needs of individuals with Parkinson's disease (PD) and other neurological problems. This is a high effort intensive treatment that aims at increasing vocal intensity through the increase of subglottal air pressure, i.e. respiratory effort, for a better cordal adduction and vibration, following the motto "think loud".

AIM

The main goal of this study is to inspect the efficacy of LSVT® treatment in progressive supranuclear palsy (PSP) patients.

DESIGN

Longitudinal study.

SETTING

Rehabilitative inpatient unit.

POPULATION

Sixteen patients with PSP and 23 patients with idiopathic PD as control were enrolled in the study.

METHODS

All patients underwent a training consisting in16 sessions of speech therapy following the LSVT® protocol. Initially the two groups of patients had similar voice problems, i.e. low volume and bad articulation of speech.

RESULTS

A statistically significant improvement was found among the data collected before and after treatment in the PSP and Parkinson groups. Increase in maximum phonation duration and volume of voice in reading were similar in the two groups. Improvement in quality of voice and articulation were more significant in the PD group as compared to the PSP group.

CONCLUSION

These results, along with previous findings, add further support to the generalized therapeutic impact of intensive voice treatment on respiratory and laryngeal functions in individuals with PSP.

CLINICAL REHABILITATION IMPACT

The positive results, the absence of dropout and collateral effect following this clinical treatments with LSVT technique encouraged to use this technique in PSP patients.

A systems medicine clinical platform for understanding and managing non- communicable diseases

Non-Communicable Diseases (NCDs) are among the most pressing global health problems of the twenty-first century. Their rising incidence and prevalence is linked to severe morbidity and mortality, and they are putting economic and managerial pressure on healthcare systems around the world. Moreover, NCDs are impeding healthy aging by negatively affecting the quality of life of a growing number of the global population. NCDs result from the interaction of various genetic, environmental and habitual factors, and cluster in complex ways, making the complex identification of resulting phenotypes not only difficult, but also a top research priority. The degree of complexity required to interpret large patient datasets generated by advanced high-throughput functional genomics assays has now increased to the point that novel computational biology approaches are essential to extract information that is relevant to the clinical decision-making process. Consequently, system-level models that interpret the interactions between extensive tissues, cellular and molecular measurements and clinical features are also being created to identify new disease phenotypes, so that disease definition and treatment are optimized, and novel therapeutic targets discovered. Likewise, Systems Medicine (SM) platforms applied to extensively-characterized patients provide a basis for more targeted clinical trials, and represent a promising tool to achieve better prevention and patient care, thereby promoting healthy aging globally. The present paper: (1) reviews the novel systems approaches to NCDs; (2) discusses how to move efficiently from Systems Biology to Systems Medicine; and (3) presents the scientific and clinical background of the San Raffaele Systems Medicine Platform.

Drug safety evaluation of ropinirole prolonged release

INTRODUCTION

The need for multiple administrations and a difficult titration schedule has always represented a limit in the use of dopamine agonists in the treatment of early Parkinson's disease. To avoid these problems, Ropinirole prolonged release (RPR), a non-ergoline dopamine receptor agonist that can be taken once a day, has been formulated. The prolonged release formulation has higher patient compliance due to a simpler and fastest titration schedule; the once-a-day administration makes this molecule especially suitable for young Parkinsonian patients who are still working and having an active lifestyle.

AREAS COVERED

In this paper, we will review ropinirole's mechanism of action including pharmacokinetics and pharmacodynamic data and the results of the main clinical studies in early and advanced PD patients. We will also discuss safety data shown during the experimental phase and after RPR commercialization. This article reviews the use of RPR in early and advanced Parkinsonian patients. Medical literature on the use of RPR in Parkinson's disease was identified using MEDLINE and the reference lists of published articles.

EXPERT OPINION

RPR is effective in the treatment of patients with early Parkinson's disease; in advanced Parkinsonian patients, the amount of daily off-time significantly decreases, improving the mean on time. RPR has also demonstrated to be effective in ameliorating the quality of sleep without increasing the occurrence of daily sleepiness and nocturnal psychosis. RPR was generally well tolerated in both early and advanced Parkinsonian patients.

The proline-rich tyrosine kinase Pyk2 regulates platelet integrin αIIbβ3 outside-in signaling

BACKGROUND

The proline-rich tyrosine kinase Pyk2 is a focal adhesion kinase expressed in blood platelets, and is activated downstream of G-protein coupled receptors as well as integrin α2β1.

OBJECTIVE

In this study we have investigated the involvement of Pyk2 in integrin αIIbβ3 outside-in signaling in human and murine platelets.

METHODS

We analyzed the stimulation of intracellular signaling pathways in platelets from Pyk2 knockout mice adherent to immobilized fibrinogen.

RESULTS

Pyk2 was rapidly phosphorylated and activated in human and murine platelets adherent to fibrinogen through integrin αIIbβ3. Activation of Pyk2 was Src-dependent, but did not require phospholipase Cγ2 activity. Platelets from Pyk2 knockout mice showed a defective ability to adhere and spread on fibrinogen, in association with a dramatic reduction of phosphatidylinositol 3-kinase (PI3K) activation and Akt phosphorylation. Pharmacological and genetic analysis demonstrated that integrin αIIbβ3 engagement selectively stimulated the β-isoform of PI3K (PI3Kβ), and that, as for Pyk2, PI3Kβ activation required Src family kinases activity, but not phospholipase Cγ2. In fibrinogen-adherent platelets, both Pyk2 and PI3Kβ were necessary for stimulation of the small GTPase Rap1b, a regulator of cell adhesion and spreading. Integrin αIIbβ3 engagement triggered the association of the PI3Kβ regulatory subunit p85 with the adaptor protein c-Cbl, which was mediated by the p85 SH3 domain, and was independent of c-Cbl tyrosine phosphorylation. However, p85-associated c-Cbl was tyrosine phosphorylated by activated Pyk2 in fibrinogen adherent platelets.

CONCLUSIONS

These results identify a novel pathway of integrin αIIbβ3 outside-in signaling and recognize the tyrosine kinase Pyk2 as a major regulator of platelet adhesion and spreading on fibrinogen.

Integrin alpha2beta1 induces phosphorylation-dependent and phosphorylation-independent activation of phospholipase Cgamma2 in platelets: role of Src kinase and Rac GTPase

BACKGROUND

Platelet adhesion promoted by integrin alpha2beta1 induces integrin alpha(IIb)beta3 activation through the phospholipase C (PLC)-dependent stimulation of the small GTPase Rap1b.

OBJECTIVE

To analyze the mechanism of PLC activation downstream of alpha2beta1 that is required for regulation of Rap1b and alpha(IIb)beta3.

METHODS

Human and murine platelets were allowed to adhere to immobilized type I monomeric collagen through alpha2beta1. Tyrosine phosphorylation of PLCgamma2, PLC activation, accumulation of GTP-bound Rap1b and fibrinogen binding were measured and compared.

RESULTS

Integrin alpha2beta1 recruitment induced an evident PLC activation that was concomitant with robust tyrosine phosphorylation of PLCgamma2, and was suppressed in platelets from PLCgamma2-knockout mice. Moreover, PLCgamma2(-/-) platelets were unable to accumulate active Rap1b and to activate alpha(IIb)beta3 upon adhesion through alpha2beta1. Inhibition of Src kinases completely prevented tyrosine phosphorylation of PLCgamma2 in adherent platelets, but did not affect its activation, and both Rap1b and alpha(IIb)beta3 stimulation occurred normally. Importantly, alpha(IIb)beta3-induced phosphorylation and activation of PLCgamma2, as well as accumulation of active Rap1b, were totally suppressed by Src inhibition. Integrin alpha2beta1 recruitment triggered the Src kinase-independent activation of the small GTPase Rac1, and activation of Rac1 was not required for PLCgamma2 phosphorylation. However, when phosphorylation of PLCgamma2 was blocked by the Src kinase inhibitor PP2, prevention of Rac1 activation significantly reduced PLCgamma2 activation, GTP-Rap1b accumulation, and alpha(IIb)beta3 stimulation.

CONCLUSIONS

Src kinases and the Rac GTPases mediate independent pathways for PLCgamma2 activation downstream of alpha2beta1.

Proplatelet formation in heterozygous Bernard-Soulier syndrome type Bolzano

BACKGROUND

Although mutations of GPIb alpha are among the most frequent causes of inherited platelet disorders, the mechanisms for the onset of thrombocytopenia and platelet macrocytosis are still poorly defined.

OBJECTIVE

In this work we analyzed in vitro megakaryocyte differentiation and proplatelet formation in six subjects heterozygous for the Ala156Val mutation in the GPIb alpha (Bolzano mutation).

METHODS

Human megakaryocytes were obtained by differentiation of patient cord blood-derived CD34(+) cells and peripheral blood-derived CD45(+) cells. Proplatelet formation was evaluated by phase contrast and fluorescence microscopy.

RESULTS

Megakaryocyte differentiation from both cord blood (one patient) and peripheral blood (five patients) was comparable to controls. However, proplatelet formation was reduced by about 50% with respect to controls. An identical defect of proplatelet formation was observed when megakaryocytes were plated on fibrinogen, von Willebrand factor or grown in suspension. Morphological evaluation of proplatelet formation revealed an increased size of proplatelet tips, which was consistent with the increased diameters of patients' blood platelets. Moreover, alpha-tubulin distribution within proplatelets was severely deranged.

CONCLUSIONS

Megakaryocytes from patients carrying a Bolzano allele of GPIb alpha display both quantitative and qualitative abnormalities of proplatelet formation in vitro. These results suggest that a defect of platelet formation contributes to macrothrombocytopenia associated to the Bolzano mutation, and indicate a key role for GPIb alpha in proplatelet formation.

Adhesive receptors, extracellular proteins and myosin IIA orchestrate proplatelet formation by human megakaryocytes

BACKGROUND

Megakaryocytes release platelets from the tips of cytoplasmic extensions, called proplatelets. In humans, the regulation of this process is still poorly characterized.

OBJECTIVE

To analyse the regulation of proplatelet formation by megakaryocyte adhesion to extracellular adhesive proteins through different membrane receptors.

METHODS

Human megakaryocytes were obtained by differentiation of cord blood-derived CD34(+) cells, and proplatelet formation was evaluated by phase contrast and fluorescence microscopy.

RESULTS

We found that human megakaryocytes extended proplatelets in a time-dependent manner. Adhesion to fibrinogen, fibronectin or von Willebrand factor (VWF) anticipated the development of proplatelets, but dramatically limited both amplitude and duration of the process. Type I, but not type III or type IV, collagen totally suppressed proplatelet extension, and this effect was overcome by the myosin IIA antagonist blebbistatin. Integrin alphaIIbbeta3 was essential for megakaryocyte spreading on fibrinogen or VWF, but was not required for proplatelet formation. In contrast, proplatelet formation was prevented by blockade of GPIb-IX-V, or upon cleavage of GPIbalpha by the metalloproteinase mocarhagin. Membrane-associated VWF was detected exclusively on proplatelet-forming megakaryocytes, but not on round mature cells that do not extend proplatelets.

CONCLUSIONS

Our findings show that proplatelet formation in human megakaryocytes undergoes a complex spatio-temporal regulation orchestrated by adhesive proteins, GPIb-IX-V and myosin IIA.

The endocannabinoid 2-arachidonoylglycerol activates human platelets through non-CB1/CB2 receptors

BACKGROUND

The endocannabinoid 2-arachidonoylglycerol (2-AG) is an endogenous lipid that acts through the activation of G-protein-coupled cannabinoid receptors and plays essential roles in many physiological contexts. In the cardiovascular system 2-AG is generated by both activated endothelial cells and platelets, and participates in the regulation of inflammation and thrombosis. Although human platelets actively metabolize endocannabinoids, 2-AG also binds to platelet surface and leads to cell activation.

OBJECTIVE

To investigate the biological consequence of 2-AG interactions with human platelets and to clarify the role of cannabinoid receptors.

METHODS

Gel-filtered platelets were stimulated with 2-AG in the presence or absence of various inhibitors. Platelet aggregation and secretion were measured in a lumiaggregometer. Calcium ion movements were measured in FURA-2 loaded platelets. Thromboxane A(2) (TxA(2)) generation was evaluated as Thromboxane B(2) accumulation with a commercial EIA assay.

RESULTS

2-AG induced platelet shape change, aggregation and secretion with a dose-dependent mechanism that required engagement of platelet TxA(2) receptors. 2-AG caused also cytosolic calcium increase; however, it was totally dependent on availability of TxA(2). Indeed 2-AG was able to induce a robust generation of TxA(2) through the cyclooxygenase pathway. Treatment of platelets with inhibitors of monoacylglycerol lipase and fatty acid amide hydrolase did not affect the activation induced by 2-AG. Moreover, neither CB(1) and CB(2) proteins nor CB(1)/CB(2) mRNAs were detected in platelets.

CONCLUSIONS

2-AG can be considered a new physiologic platelet agonist able to induce full platelet activation and aggregation with a non-CB(1)/CB(2) receptor-mediated mechanism.

Intraplatelet signaling mechanisms of the priming effect of matrix metalloproteinase-2 on platelet aggregation

OBJECTIVE

Platelets contain and release some matrix metalloproteinases (MMPs), enzymes involved in the degradation of extracellular matrix, and one of these (MMP-2) exerts a proaggregatory effect. We explored the signal transduction mechanisms activated by MMP-2 in human blood platelets.

METHODS AND RESULTS

Recombinant, human MMP-2, added before stimulation with subthreshold doses of different agonists, potentiated platelet activation, calcium influx, IP3 formation, and pleckstrin phosphorylation. Wortmannin and LY29400, two PI3-K inhibitors, suppressed the potentiating effects of MMP-2 and preincubation with MMP-2 enhanced the thrombin-induced association of the p85alpha PI3-K subunit with the cytoskeleton and increased the phosphorylation of PKB. Protein tyrosine kinase inhibitors, MAP kinase inhibitors, PLA2 inhibitors, cyclooxygenase inhibitors and antagonists of the P2Y1 and P2Y12 receptors did not affect the potentiating activity of MMP-2 on platelets.

CONCLUSION

Our data show that MMP-2, at a concentration released by activated platelets, facilitates platelet activation acting at the level of a second messenger system common to different agonists and related to the activation of PI3-K. Platelet-released MMP-2 may contribute to platelet activation in vivo.

Altered cytoskeleton organization in platelets from patients with MYH9-related disease

MYH9-related disease (MYH9-RD) is an autosomal dominant disorder deriving from mutations in the MYH9 gene encoding for the heavy chain of non-muscle myosin IIA, and characterized by thrombocytopenia and giant platelets. Isoform IIA of myosin is the only one expressed in platelets, but the possibility that MYH9 mutations affect the organization of contractile structures in these blood elements has never been investigated. In this work we have analyzed the composition and the agonist-induced reorganization of the platelet cytoskeleton from seven MYH9-RD patients belonging to four different families. We found that an increased amount of myosin was constitutively associated with actin in the cytoskeleton of resting MYH9-RD platelets. Upon platelet stimulation, an impaired increase in the total cytoskeletal proteins was observed. Moreover, selected membrane glycoproteins, tyrosine kinases, and small GTPases failed to interact with the cytoskeleton in agonist-stimulated MYH9-RD platelets. These results demonstrate for the first time that mutations of MYH9 result in an alteration of the composition and agonist-induced reorganization of the platelet cytoskeleton. We suggest that these abnormalities may represent the biochemical basis for the previously reported functional alterations of MYH9-RD platelets, and for the abnormal platelet formation from megakaryocytes, resulting in thrombocytopenia and giant platelets.

Activation of the small GTPase Rap2B in agonist-stimulated human platelets

The activation of the small GTPase Rap2B in resting and agonist-stimulated human platelets was investigated. Both thrombin, that stimulates heterotrimeric G-protein-coupled receptors, and the GPVI ligand convulxin, that activates a tyrosine-kinase based signaling pathway, were able to induced the rapid and sustained binding of GTP to Rap2B. Similarly, a number of other agonists tested, previously known to activate the highly related protein Rap1B, were also able to stimulate Rap2B. In contrast, platelet antagonists that increase the intracellular concentration of cAMP did not signal to Rap2B. Thrombin- and convulxin-induced activation of Rap2B was not dependent on thromboxane A2, did not require the interaction of the protein with the cytoskeleton, and was not regulated by integrin alphaIIbbeta3-dependent outside-in signaling. When secreted ADP was neutralized, activation of Rap2B induced by thrombin, but not by convulxin, was significantly reduced. ADP itself was found to induce the rapid and sustained binding of GTP to Rap2B, and this effect was predominantly mediated by stimulation of the Gi-coupled P2Y12 receptor. Activation of Rap2B promoted by both thrombin and convulxin was regulated by intracellular Ca2+, while protein kinase C was found to be involved in convulxin- but not in thrombin-induced activation of Rap2B. Moreover, Rap2B activation induced by thrombin, but not by convulxin, was totally dependent on phosphatidylinositol 3-kinase activity. These results demonstrate that the small GTPase Rap2B is involved in platelet activation, and outline some important differences between the regulation of highly related GTPases Rap2B and Rap1B in human platelets.

Platelet activation by von Willebrand factor requires coordinated signaling through thromboxane A2 and Fc gamma IIA receptor

Interaction of von Willebrand Factor with glycoprotein Ib-IX-V induces platelet activation through a still poorly defined mechanism. Previous studies have suggested a possible role for the low affinity receptor for immunoglobulin, Fc gamma RIIA, in GPIb-IX-V signaling. Here we show that binding of vWF to platelets induces the tyrosine phosphorylation of Fc gamma RIIA by a Src kinase. Treatment of platelets with the anti-Fc gamma RIIA monoclonal antibody IV.3 specifically inhibits vWF-induced but not thrombin-induced pleckstrin phosphorylation and serotonin secretion. Moreover, vWF fails to induce pleckstrin phosphorylation in mouse platelets, lacking Fc gamma RIIA, and serotonin secretion is impaired. Pleckstrin phosphorylation and serotonin secretion in human platelets stimulated with vWF are blocked by the cyclooxygenase inhibitor acetylsalicylic acid. However, release of arachidonic acid and synthesis of TxA(2) induced by vWF are not affected by the anti-Fc gamma RIIA monoclonal antibody IV.3. Similarly, vWF-induced tyrosine phosphorylation of Fc gamma RIIA, as well as of Syk and PLC gamma 2, occurs normally in aspirinized platelets. Inhibition of the tyrosine kinase Syk by piceatannol does not affect vWF-induced tyrosine phosphorylation of Fc gamma RIIA but prevents phosphorylation of PLC gamma 2. Pleckstrin phosphorylation and platelet secretion induced by vWF, but not by thrombin, are also inhibited by piceatannol. Pleckstrin phosphorylation is also sensitive to the phosphatidylinositol 3-kinase inhibitor wortmannin. These results indicate that PLC gamma 2 plays a central role in platelet activation by vWF and that the stimulation of this enzyme requires coordinated signals through endogenous TxA(2) and Fc gamma RIIA.

Anorectal function in multiple system atrophy and Parkinson's disease

This study was designed to investigate anorectal function in Parkinson's disease and multiple system atrophy (MSA). After a standardized interview, 17 patients with Parkinson's disease (PD) and 16 patients with multiple system atrophy (MSA) underwent anorectal manometry with a continuously perfused multi-lumen catheter, located to record pressures from the anal canal, and a balloon for rectal distension. Data were analyzed by observers blind to the neurologic diagnosis. Disease duration was shorter in the MSA than in the PD group (6+/-4 versus 10+/-5 yrs, p<0.05). Most patients reported a bowel frequency of less than three evacuations per week and some patients had fecal incontinence. Most manometric recordings disclosed an abnormal pattern during straining (a paradoxic contraction or lack of inhibition) in 13 patients with MSA and 11 patients with PD. Mean anal pressures and rectal sensitivity threshold were not significantly higher in the MSA group, whereas the inhibitory anal reflex and rectal compliance thresholds were within the normal range in both groups. Manometric patterns did not differentiate patients with MSA from patients with PD. Most patients in both groups showed an abnormal straining pattern, decreased anal tone, or both dysfunctions. In conclusion, our findings suggest that although bowel and anorectal dysfunctions do not differentiate MSA from PD, both abnormalities occur earlier and develop faster in MSA than in PD.

The platelet cytoskeleton regulates the aggregation-dependent synthesis of phosphatidylinositol 3,4-bisphosphate induced by thrombin

Pretreatment of intact platelets with cytochalasin D prevented actin polymerization and cytoskeleton reorganization induced by thrombin, but did not affect platelet aggregation. Under these conditions, synthesis of phosphatidylinositol 3,4-bisphosphate (PtdIns(3,4)P2) stimulated by thrombin was strongly inhibited, while production of phosphatidic acid was unaffected. The inhibitory effect of cytochalasin D was not observed when platelet aggregation was prevented by the RGDS peptide. We also found that cytochalasin D did not affect PtdIns(3,4)P2 synthesis induced by concanavalin A (ConA), which is known to occur through an aggregation-independent mechanism. Moreover, thrombin, but not ConA, induced the translocation of phosphatidylinositol 3-kinase to the cytoskeleton. This process was equally inhibited by both the RGDS peptide and cytochalasin D. These results demonstrate that the cytoskeleton represents a functional link between thrombin-induced aggregation and synthesis of PtdIns(3,4)P2.

Anorectal function in multiple system atrophy and Parkinson's disease

This study was designed to investigate anorectal function in Parkinson's disease and multiple system atrophy (MSA). After a standardized interview, 17 patients with Parkinson's disease (PD) and 16 patients with multiple system atrophy (MSA) underwent anorectal manometry with a continuously perfused multi-lumen catheter, located to record pressures from the anal canal, and a balloon for rectal distension. Data were analyzed by observers blind to the neurologic diagnosis. Disease duration was shorter in the MSA than in the PD group (6+/-4 versus 10+/-5 yrs, p<0.05). Most patients reported a bowel frequency of less than three evacuations per week and some patients had fecal incontinence. Most manometric recordings disclosed an abnormal pattern during straining (a paradoxic contraction or lack of inhibition) in 13 patients with MSA and 11 patients with PD. Mean anal pressures and rectal sensitivity threshold were not significantly higher in the MSA group, whereas the inhibitory anal reflex and rectal compliance thresholds were within the normal range in both groups. Manometric patterns did not differentiate patients with MSA from patients with PD. Most patients in both groups showed an abnormal straining pattern, decreased anal tone, or both dysfunctions. In conclusion, our findings suggest that although bowel and anorectal dysfunctions do not differentiate MSA from PD, both abnormalities occur earlier and develop faster in MSA than in PD.

Interaction of the low-molecular-weight GTP-binding protein rap2 with the platelet cytoskeleton is mediated by direct binding to the actin filaments

The interaction of the low-molecular-weight GTP-binding protein rap2 with the cytoskeleton from thrombin-aggregated platelets was investigated by inducing depolymerization of the actin filaments, followed by in vitro-promoted repolymerization. We found that the association of rap2 with the cytoskeleton was spontaneously restored after one cycle of actin depolymerization and repolymerization. Exogenous rap2, but not unrelated proteins, added to depolymerized actin and solubilized actin-binding proteins, was also specifically incorporated into the in vitro reconstituted cytoskeleton. The incorporation of exogenous rap2 was also observed when the cytoskeleton from resting or thrombin-activated platelets was subjected to actin depolymerization-repolymerization. Moreover, such interaction occurred equally well when exogenous rap2 was loaded with either GDP or GTPgammaS. We also found that polyhistidine-tagged rap2 immobilized on Ni(2+)-Sepharose and loaded with either GDP or GTPgammaS, could specifically bind to cytoskeletal actin. Moreover, when purified monomeric actin was induced to polymerize in vitro in the presence of rap2, the small G-protein specifically associated with the actin filaments. Finally, rap2 loaded with either GDP or GTPgammaS was able to bind to purified F-actin immobilized on a plastic surface. These results demonstrate that rap2 interacts with the platelet cytoskeleton by direct binding to the actin filaments and that this interaction is not regulated by the activation state of the protein.

Hydrolysis of NADP+ by platelet CD38 in the absence of synthesis and degradation of cyclic ADP-ribose 2'-phosphate

CD38 is a multifunctional cell surface ectoenzyme that catalyzes both the synthesis of cyclic ADP-ribose from NAD+ and its hydrolysis to ADP-ribose. In this work, we investigated the metabolism of NADP+ by CD38 expressed on human platelets. Incubation of either platelet membranes or intact cells with NADP+ resulted in the rapid and time-dependent accumulation of ADP-ribose 2'-phosphate that paralleled the consumption of the substrate. However, under the same conditions, synthesis of cyclic ADP-ribose 2'-phosphate was not observed. By immunoprecipitation experiments, we identified CD38 as the enzyme responsible for the observed NADP+ glycohydrolase activity. The lack of detection of cyclic ADP-ribose 2'-phosphate was not due to its rapid hydrolysis, since direct incubation of platelet membranes with cyclic ADP-ribose 2'-phosphate did not result in the formation of ADP-ribose 2'-phosphate. By contrast, the same membrane samples expressed a significant ability to hydrolyze cyclic ADP-ribose to ADP-ribose. The absence of cyclic ADP-ribose 2'-phosphate hydrolase activity was also confirmed using high concentrations of substrate and by analysing both intact Jurkat T-lymphocytes and immunoprecipitated CD38. These results indicate that CD38, which is a multifunctional enzyme towards NAD+, displays exclusively a NADP+ glycohydrolase activity and is unable to catalyze both the synthesis and the hydrolysis of cyclic ADP-ribose 2'-phosphate.

Rap1B and Rap2B translocation to the cytoskeleton by von Willebrand factor involves FcgammaII receptor-mediated protein tyrosine phosphorylation

Stimulation of human platelets with von Willebrand factor (vWF) induced the translocation of the small GTPases Rap1B and Rap2B to the cytoskeleton. This effect was specifically prevented by an anti-glycoprotein Ib monoclonal antibody or by the omission of stirring, but was not affected by the peptide RGDS, which antagonizes binding of adhesive proteins to platelet integrins. Association of Rap2B with the cytoskeleton was very rapid, while translocation of Rap1B occurred in a later phase of platelet activation and was totally inhibited by cytochalasin D. vWF also induced the rapid tyrosine phosphorylation of several proteins that was prevented by the tyrosine kinases inhibitor genistein and by cAMP-increasing agents. Under these conditions, also the association of Rap1B and Rap2B with the cytoskeleton was prevented. Translocation of Rap proteins to the cytoskeleton induced by vWF, but not by thrombin, was inhibited by a monoclonal antibody against the FcgammaII receptor. The same antibody inhibited vWF-induced tyrosine phosphorylation of selected substrates with molecular masses of about 75, 95, and 150 kDa. Three of these substrates were identified as the tyrosine kinase pp72(syk), the phospholipase Cgamma2, and the inositol 5-phosphatase SHIP. Our results indicate that translocation of Rap1B and Rap2B to the cytoskeleton is regulated by tyrosine kinases and suggest a novel role for the FcgammaII receptor in the mechanism of platelet activation by vWF.

Clustering of integrin alphaIIb-beta3 differently regulates tyrosine phosphorylation of pp72syk, PLCgamma2 and pp125FAK in concanavalin A-stimulated platelets

Tyrosine phosphorylation of the non-receptor tyrosine kinases pp72syk and pp125FAK and of the gamma2 isoform of phospholipase C (PLCgamma2) in human platelets stimulated with the lectin Concanavalin A was investigated. Concanavalin A induced the rapid tyrosine phosphorylation of pp72syk and PLCgamma2 with a similar kinetics, while tyrosine phosphorylation of pp125FAK occurred in a later phase of platelet activation. When compared with other platelet agonists, Concanavalin A revealed to be at least as potent as collagen in inducing tyrosine phosphorylation of PLCgamma2 and pp125FAK, while tyrosine phosphorylation of pp72syk induced by the lectin was much stronger than that induced by thrombin or collagen. Concanavalin A-induced tyrosine phosphorylation of pp72syk, PLCgamma2 and pp125FAK was not dependent on platelet aggregation as it occurred normally even in the absence of sample stirring and when fibrinogen binding to integrin alphaIIb-beta3 was inhibited by the peptide RGDS. Tyrosine phosphorylation of pp72syk, PLCgamma2 and pp125FAK required the binding of the lectin to the platelet surface, but was not observed in platelets treated with succinyl-Concanavalin A, a derivative of the lectin that interacts with the same receptors but does not promote clustering of membrane glycoproteins. Moreover, the aggregation-independent tyrosine phosphorylation of pp125FAK and pp72syk induced by Concanavalin A required the expression of integrin alphaIIb-beta3 on the platelet surface as it was strongly inhibited in platelets from patients affected by Glanzmann thrombasthenia. By contrast, tyrosine phosphorylation of PLCalpha2 occurred normally also in thrombasthenic platelets stimulated with Concanavalin A. These results demonstrate that, even in the absence of aggregation, the clustering of integrin alphaIIb-beta3 induced by Concanavalin A on the platelet surface directly promotes tyrosine phosphorylation of pp72syk and pp125FAK and provide further evidence that the oligomerization of the fibrinogen receptor promoted by its natural ligand during platelet aggregation may be responsible for the tyrosine phosphorylation of these proteins induced by physiological agonists.

Cytoskeleton-dependent inhibition of the ADP-ribosyl cyclase activity of CD38 in thrombin-stimulated platelets

Stimulation of human platelets with thrombin caused a 42% inhibition of the ADP-ribosyl cyclase activity of membrane CD38. This effect was mediated by the activation of the platelet thrombin receptor rather than by proteolysis of CD38, and was not due to a different distribution of the synthesised nucleotide or to a reduced accessibility of CD38 to the substrate. The inhibitory effect of thrombin required actin polymerisation and was not observed when interaction of CD38 with the cytoskeleton was prevented by cytochalasin D. Finally, we analysed whether cADPR could play a role as a Ca2+-mobilising agent in human platelets. Using saponin-permeabilised cells, we found that unlike IP3, cADPR did not induce any release of Ca2+ from intracellular stores. These results indicate that the enzymatic activity of membrane CD38 can be modulated by platelet activation, and that the function of this glycoprotein is probably not related to Ca2+ mobilisation.

Arachidonic acid mediates angiotensin II effects on p21ras in renal proximal tubular cells via the tyrosine kinase-Shc-Grb2-Sos pathway

In kidney epithelial cells, an angiotensin II (Ang II) type 2 receptor subtype (AT2) is linked to a membrane-associated phospholipase A2 (PLA2) and the mitogen-activated protein kinase (MAPK) superfamily. However, the intervening steps in this linkage have not been determined. The aim of this study was to determine whether arachidonic acid mediates Ang II's effect on p21ras and if so, to ascertain the signaling mechanism(s). We observed that Ang II activated p21ras and that mepacrine, a phospholipase A2 inhibitor, blocked this effect. This activation was also inhibited by PD123319, an AT2 receptor antagonist but not by losartan, an AT1 receptor antagonist. Furthermore, Ang II caused rapid tyrosine phosphorylation of Shc and its association with Grb2. Arachidonic acid and linoleic acid mimicked Ang II-induced tyrosine phosphorylation of Shc and activation of p21ras. Moreover, Ang II and arachidonic acid induced an association between p21ras and Shc. We demonstrate that arachidonic acid mediates linkage of a G protein-coupled receptor to p21ras via Shc tyrosine phosphorylation and association with Grb2/Sos. These observations have important implications for other G protein-coupled receptors linked to a variety of phospholipases.

Thrombin induces the association of cyclic ADP-ribose-synthesizing CD38 with the platelet cytoskeleton

The effect of platelet stimulation on the subcellular localization of CD38, a membrane glycoprotein that catalyses the synthesis of cyclic ADP-ribose from beta-NAD+ was investigated. Treatment of human platelets with thrombin caused the association of about 40% of the total ADP-ribosyl cyclase activity with the cytoskeleton, through the translocation of the CD38 molecule from the Triton X-100-soluble to the insoluble fraction. The interaction of CD38 with the cytoskeleton was a specific and reversible process, mediated by the binding to the actin-rich filaments and was inhibited by treatment of platelets with cytochalasin D. This event was regulated by integrin alphaIIb beta3 and platelet aggregation as it was prevented by the inhibition of fibrinogen binding and was not observed in platelets from a patient affected by Glanzmann thrombasthenia. These results demonstrate that the subcellular localization of CD38 can be influenced by platelet stimulation with physiological agonists, and that membrane CD38 can interact with intracellular proteins.

Agonist-induced actin polymerization is required for the irreversibility of platelet aggregation

Cytochalasin D was used to investigate the role of intracellular cytoskeleton in the stabilization of platelet aggregation induced by strong platelet agonists. Incubation of gel-filtered platelets with increasing concentrations of cytochalasin D resulted in a dose-dependent inhibition of actin polymerization and association of actin-binding proteins with the Triton X-100-insoluble material induced by the thromboxane analogue, U46619, and the thrombin receptor activating peptide, TRAP. The same concentrations of cytochalasin D did not significantly inhibit platelet aggregation promoted by the two agonists. The addition of the chelating agent EDTA to fully aggregated platelets, that had been treated with cytochalasin D, resulted in the rapid and almost complete disaggregation. EDTA did not cause disaggregation of control, solvent-treated, aggregated platelets. The degree of platelet disaggregation induced by EDTA was dependent on the dose of cytochalasin D used, and was correlated with the inhibition of the cytoskeletal reorganization. Aggregation of cytochalasin D-treated platelets stimulated with U46619 or TRAP was also reverted by the addition of the tetrapeptide RGDS or the fibrinogen gamma-chain dodecapeptide, which competitively interfere with fibrinogen binding to the glycoprotein IIb-IIIa complex. These results indicate that the intracellular cytoskeleton plays an essential role in the stabilization of the fibrinogen-platelet interaction, and is necessary for the irreversibility of platelet aggregation induced by strong agonists.

Expression of cyclic ADP-ribose-synthetizing CD38 molecule on human platelet membrane

CD38 is a cell surface molecule widely used as a marker for immature and activated lymphocytes. It has been recently shown that CD38 displays three enzymatic activities: hydrolysis of NAD+ to ADP-ribose, synthesis of cyclic ADP-ribose from NAD+, and hydrolysis of cyclic ADP-ribose to ADP-ribose. Thus, CD38 plays a key role in the synthesis of cyclic ADP-ribose, a calcium-mobilizing compound. We investigate here the expression and cellular localization of CD38 in human platelets using a specific monoclonal antibody. Results showed that CD38 is expressed by human platelet membranes. Moreover, we show that platelet CD38 possesses NAD glycohydrolase, ADP-ribose cyclase, and cyclic ADP-ribose hydrolase activities. This finding indicates that the calcium-mobilizing agent cyclic ADP-ribose can be synthetized by human platelets and raises the question about the possible role of CD38 expression and enzymatic activities in the signal transduction pathways leading to platelet activation.

Activation of human platelets by lysophosphatidic acid

The biochemical mechanisms of platelet activation by lysophosphatidic acid were investigated. Lysophosphatidic acid interacts with a membrane receptor coupled to the inhibitory GTP-binding protein Gi and produces a rapid decrease of the intracellular concentration of cAMP. Aggregation of gel-filtered platelets by lysophosphatidic acid requires the presence of extracellular CaCl2, as this phospholipid does not induce secretion of platelet dense granules. Platelet activation by lysophosphatidic acid in the absence of extracellular CaCl2 does not involve phospholipase C activation, as evaluated by measuring mobilization of Ca2+ from internal stores and pleckstrin phosphorylation, but causes the rapid tyrosine phosphorylation of several intracellular proteins. Our results indicate that activation of intracellular tyrosine kinases is not secondary to Ca2+ mobilization and protein kinase C activation in lysophosphatidic acid-stimulated platelets.

Evidence for a glycoprotein IIb-IIIa- and aggregation-independent mechanism of phosphatidylinositol 3',4'-bisphosphate synthesis in human platelets

The synthesis of phosphatidylinositol 3',4'-bisphosphate (PtdIns(3,4)P2) in 32P-labeled human platelets induced by the tetrameric lectin concanavalin A and the physiological agonist thrombin were compared. Like thrombin, concanavalin A stimulated a time-dependent accumulation of PtdIns(3,4)P2, which reached maximal levels after 5 min of stimulation. However, while synthesis of PtdIns(3,4)P2 induced by thrombin was dependent on platelet aggregation, the production of PtdIns(3,4)P2 induced by concanavalin A was unchanged when aggregation was prevented by the omission of stirring or when fibrinogen binding to platelets was inhibited by the tetrapeptide RGDS. Accumulation of PtdIns(3,4)P2 was not observed in platelets stimulated with succinyl-concanavalin A, a dimeric derivative of the lectin that binds to the same receptors on the platelet surface but does not promote clustering of membrane glycoproteins. The synthesis of PtdIns(3,4)P2 induced by concanavalin A was also independent of the membrane glycoprotein IIb-IIIa, as normal accumulation of this lipid was observed in platelets from two patients affected by Glanzmann thrombasthenia. In contrast, thrombin showed a strongly reduced ability to stimulate PtdIns(3,4)P2 production in thrombasthenic platelets. Although concanavalin A was able to induce association of the regulatory subunit of the phosphatidylinositol 3-kinase with tyrosine-phosphorylated proteins, the tyrosine kinase inhibitor tyrphostin AG-213 did not inhibit the lectin-induced synthesis of PtdIns(3,4)P2. These results demonstrate the existence of a novel mechanism of PtdIns(3,4)P2 synthesis in human platelets, which is independent of glycoprotein IIb-IIIa and aggregation, but requires clustering of membrane glycoproteins. As clustering events occur during platelet aggregation promoted by physiological agonists, this new mechanism may also be involved in the aggregation-dependent production of PtdIns(3,4)P2 in thrombin-stimulated platelets.

Dual mechanism of protein-tyrosine phosphorylation in concanavalin A-stimulated platelets

Treatment of human platelets with the lectin Concanavalin A (Con A) resulted in the tyrosine phosphorylation of several proteins with molecular masses 65, 80, 85, 95, 120, 135, and 150 kDa. These proteins were divided in two groups: the first group included the 65-, 85-, 95-, and 120-kDa bands, which were tyrosine phosphorylated also in thrombin-stimulated platelets; the second group (80-, 135-, and 150-kDa bands) included proteins whose tyrosine phosphorylation was exclusively promoted by Con A, but not by thrombin. Members of the second group were rapidly dephosphorylated when the lectin was displaced from the cell surface by methyl alpha-D-mannopyranoside. Pretreatment of intact platelets with the prostacyclin analog iloprost, inhibited Con A-induced tyrosine phosphorylation of the first group of proteins, but had no effect on the tyrosine phosphorylation of the proteins of the second group. Succinyl-Con A, a dimeric derivative of the lectin, which binds to the platelet surface but does not promote clustering of the receptor, did not induce tyrosine phosphorylation of the second group of proteins, although phosphorylation of some members of the first group was observed. Our results demonstrate the presence of two different mechanisms leading to protein-tyrosine phosphorylation in Con A-stimulated platelets, and identify a new signal transduction pathway, promoted by the clustering of membrane glycoproteins, that produces tyrosine phosphorylation of specific substrates. This new pathway may be activated by platelet interaction with multivalent ligands, such as adhesive proteins, during adhesion, spreading, and aggregation.

Activation of poly(ADP-ribose)polymerase in apoptotic human cells

We have studied the effect of the chemotherapeutic drug VP-16 (etoposide) on the metabolism of HeLa cells by analysing different cellular parameters considered as markers of apoptosis. Typical features such as chromatin condensation and internucleosomal DNA cleavage are visible in HeLa cells exposed to VP-16. We investigated whether the appearance of small-sized DNA fragments could regulate the ADP-ribosylation process. To this purpose, we have analysed, by means of the activity gel technique; the structural and catalytical properties of poly(ADP-ribose)polymerase. In extracts from cells where etoposide-induced DNA fragmentation occurred, we have shown that the label of the autoribosylated form of the enzyme is greatly increased even if the amount of the protein remains constant. This phenomenon is completely abolished in cells preincubated with poly(ADP-ribose)polymerase inhibitor, 3-aminobenzamide. After VP-16 administration, we have observed that the level of NAD is not heavily decreased. It is widely agreed that zinc exerts an inhibitory effect on the endonuclease(s) responsible for the fragmentation of DNA during apoptosis. After incubation of cells with zinc/VP-16 we have found the occurrence of apoptotic parameters even in the absence of internucleosomal DNA cleavage. The inhibition of DNA fragmentation prevents the activation of poly(ADP-ribose)polymerase activity. These results indicate that the activation of the enzyme towards the automodification reaction is strictly dependent on the appearance of DNA internucleosomal fragments and could represent a way to control enzyme activity.