Network


Latest external collaboration on country level. Dive into details by clicking on the dots.

Hotspot


Dive into the research topics where Michael Rentzos is active.

Publication


Featured researches published by Michael Rentzos.


Clinical Neurology and Neurosurgery | 2009

Serum uric acid levels in patients with Parkinson's disease: their relationship to treatment and disease duration.

Elisabeth Andreadou; Chryssoula Nikolaou; Filippos Gournaras; Michael Rentzos; Fotini Boufidou; Anthoussa Tsoutsou; Christos Zournas; Vassilis Zissimopoulos; Demetrios Vassilopoulos

UNLABELLED There is evidence to support that oxidative stress is increased in Parkinsons disease (PD) and contributes to degeneration of dopaminergic neurons. Uric acid (UA), a natural antioxidant in blood and brain tissue, scavenging superoxide, peroxynitrite and hydroxyl radical, was found reduced in the serum of PD patients. In addition low plasma uric acid (UA) levels have been associated with an increased risk of PD. OBJECTIVES The aim of our study was to investigate serum UA levels in PD patients compared with age-matched healthy controls and their possible relationship with several clinical parameters of PD and pharmaceutical treatment. PATIENTS AND METHODS We measured serum UA levels in 43 PD patients and 47 healthy volunteers, age and sex-matched. UA levels were correlated with disease duration, severity and treatment. RESULTS Low UA levels were observed in PD patients compared with controls (p=0.009). Age, Body Mass Index (BMI) and UPDRS III score did not significantly affect serum UA concentrations, whereas gender was found to contribute significantly to UA level (p<0.000). Strong and significant inverse correlations of UA with disease duration (R(s)=-0.397, p=0.009) and daily levodopa dosage (R(p)=-0.498, p=0.026) were observed. These associations were significant for men (R(s)=-0.441, p=0.04 and R(s)=-0.717, p=0.03 respectively), but not for women (R(s)=-0.221, p=0.337 and R(s)=-0.17, p=0.966 respectively). CONCLUSION Our results suggest that there may be increased consumption of UA as a scavenger in PD, possibly heightened by dopaminergic drug treatment. Given the antioxidant properties of UA, manipulation of its concentrations should be investigated for potential therapeutic strategies of the disease.


Journal of the Neurological Sciences | 2006

IL-15 is elevated in serum and cerebrospinal fluid of patients with multiple sclerosis.

Michael Rentzos; C. Cambouri; Antonis Rombos; Chryssoula Nikolaou; Maria Anagnostouli; Anthousa Tsoutsou; A. Dimitrakopoulos; N. Triantafyllou; D. Vassilopoulos

UNLABELLED Interleukin-15 (IL-15) is a novel proinflammatory cytokine having similar biological activities to IL-2 which is implicated in the pathogenesis of multiple sclerosis. It is produced by activated blood monocytes, macrophages and glial cells. There is little information about the involvement of IL-15 in the development of multiple sclerosis (MS). The objective of our study was to measure IL-15 serum and cerebrospinal fluid (CSF) levels in MS patients and to correlate serum and CSF IL-15 concentrations with clinical parameters of the disease. CSF IL-15/Serum IL-15 ratio (c/s IL-15 ratio) was introduced to assess the origin of elevated IL-15 levels. MATERIALS AND METHODS We measured serum and CSF IL-15 levels in 52 patients with MS and 36 age and gender matched patients with inflammatory (IND) and non-inflammatory neurological diseases (NIND) studied as control groups. IL-15 levels were correlated with clinical parameters as duration, disability, MRI activity and clinical subtypes of the disease. RESULTS MS patients were found to have significantly higher serum IL-15 levels compared with IND (p=0.00016) and NIND patients (p=0.00045). Elevated levels of IL-15 were also found in CSF samples from MS patients compared with patients with IND (p=0.00034) and NIND (p=0.0003). Among MS subgroups there were no statistically different IL-15 serum and CSF concentrations. No significant correlation of serum and CSF IL-15 concentrations with MRI activity, disability assessed by EDSS score and duration of the disease were also found. C/S IL-15 ratio was found lower in MS patients compared with IND (p=0.01) and not significantly different compared with NIND patients (p=0.14) suggesting that systemic activation might be the source of high CSF IL-15 levels in MS patients. CONCLUSIONS Our findings suggest a possible role of IL-15 in the immunopathogenetic mechanisms of MS.


Amyotrophic Lateral Sclerosis | 2007

RANTES levels are elevated in serum and cerebrospinal fluid in patients with amyotrophic lateral sclerosis

Michael Rentzos; Chryssoula Nikolaou; Antonis Rombos; Fotini Boufidou; Margarita Zoga; Antonis Dimitrakopoulos; Anthousa Tsoutsou; Demetrios Vassilopoulos

Immunological disturbances have been implicated in the pathogenesis of amyotrophic lateral sclerosis (ALS). Chemokines are involved in the recruitment of immune cells. Regulated upon activation, normal T‐cell expressed and secreted (RANTES) is a C‐C beta‐chemokine with strong chemo‐attractant activity for T‐lymphocytes and monocytes. We examined serum levels of RANTES in 20 patients with amyotrophic lateral sclerosis (ALS), 14 patients with non‐inflammatory neurological disorders (NIND) and 13 control subjects (CTRL) and cerebrospinal fluid (CSF) levels of RANTES in ALS and NIND group patients in order to investigate whether RANTES as index of immune activation is present in ALS patients. Patients with ALS had higher RANTES levels compared with the NIND patients and CTRL subjects (p = 0.005 and p = 0.02, respectively). CSF RANTES levels were also higher compared with the NIND patients (p = 0.007). No correlation of serum and CSF RANTES levels with disease duration was found. These results may suggest an activated microglia induced recruitment of peripheral inflammatory cells to sites of inflammation in ALS patients.


Annals of clinical and translational neurology | 2014

LRP4 antibodies in serum and CSF from amyotrophic lateral sclerosis patients

John Tzartos; Paraskevi Zisimopoulou; Michael Rentzos; Nikos Karandreas; Vasiliki Zouvelou; Panagiota Evangelakou; Anastasios Tsonis; Thomas Thomaidis; Giuseppe Lauria; Francesca Andreetta; Renato Mantegazza; Socrates J. Tzartos

Amyotrophic lateral sclerosis (ALS) and myasthenia gravis (MG) are caused, respectively, by motor neuron degeneration and neuromuscular junction (NMJ) dysfunction. The membrane protein LRP4 is crucial in the development and function of motor neurons and NMJs and LRP4 autoantibodies have been recently detected in some MG patients. Because of the critical role in motor neuron function we searched for LRP4 antibodies in ALS patients.


Amyotrophic Lateral Sclerosis | 2011

Prevalence of major depression in ALS: Comparison of a semi-structured interview and four self-report measures

Panagiotis Ferentinos; Thomas Paparrigopoulos; Michael Rentzos; Vassiliki Zouvelou; Theodoros Alexakis; Ioannis Evdokimidis

Abstract This study aimed to compare prevalence estimates of current major depression obtained with a semi-structured interview and four frequently used self-report depression severity measures in a sample of amyotrophic lateral sclerosis (ALS) patients. Thirty-seven ALS patients (56.8% males) aged 37–80 years (mean 62.0 ± 10.7) without respiratory insufficiency or dementia were studied during hospitalization or on a follow-up visit. SCID-IV interview as well as self-report Hospital Anxiety and Depression Scale (HADS), ALS Depression Inventory (ADI), Center for Epidemiological Studies-Depression scale (CES-D) and Beck Depression Inventory (BDI-I) were administered. Kappa coefficients of diagnostic agreement between various instruments were calculated. Results showed that 37.8% of patients had a lifetime diagnosis of depression and in 13.5% depression followed ALS onset. Percentages of patients ‘diagnosed’ with current major depression were: 21.6% (SCID-IV), 16.7% (HADS-D ≥ 11), 16.2% (ADI ≥ 29), 25% (CES-D ≥ 24) and 24.3% (BDI-I ≥ 16). High kappa values were recorded between CES-D, BDI-I and SCID-IV as well as between HADS-D and ADI. CES-D, BDI-I and SCID-IV gave the highest prevalence estimates of current major depression in ALS patients and were in poor agreement with estimates based on HADS and ADI; it is suggested that this is possibly because the former give a far greater emphasis on physical symptoms of depression than the latter.


Journal of the Neurological Sciences | 2006

Interleukin-12 is reduced in cerebrospinal fluid of patients with Alzheimer's disease and frontotemporal dementia

Michael Rentzos; George P. Paraskevas; Elisabeth Kapaki; Chryssoula Nikolaou; Margarita Zoga; Antonis Rombos; Anthousa Tsoutsou; Demetris Vassilopoulos D

UNLABELLED Interleukin-12 is a heterodimeric cytokine produced by activated blood monocytes, macrophages and glial cells. It enhances differentiation and proliferation of T cells and increases production of proinflammatory cytokines, such as Interferon-gamma and Tumor Necrosis Factor-alpha. There is little information about the involvement of IL-12 in the pathophysiology of Alzheimers disease (AD) and other tauopathies. OBJECTIVES The objective of our study was to assess the role of IL-12 as a potential marker of immune reactions in patients with AD and frontotemporal dementia (FTD). PATIENTS AND METHODS We measured by immunoassay cerebrospinal fluid (CSF) IL-12 levels in 19 patients with AD and 7 patients with FTD in comparison with CSF IL-12 levels in 30 patients with non-inflammatory neurological diseases served as neurological control patients (NCTRL). IL-12 levels were correlated with age, age of disease onset, disease duration, MMSE score, and rate of dementia progression. Abeta42 and Total tau (tau(T)) levels in CSF were also measured. RESULTS Patients with AD had significantly lower CSF IL-12 levels compared with NCTRL patients (p<0.001). Patients with FTD had also lower CSF IL-12 levels compared with NCTRL patients (p<0.05). Age, sex, disease duration and MMSE score did not affect IL-12 levels in any of the groups. In AD a significant positive correlation was noted between IL-12 levels and tau(T) levels (Rs=0.46, p=0.048). CONCLUSIONS Our findings may suggest a reduced inflammatory reaction during the course of AD and FTD. A neurotrophic role of IL-12 and other proinflammatory cytokines cannot be excluded.


Journal of the Neurological Sciences | 2005

The role of soluble intercellular adhesion molecules in neurodegenerative disorders.

Michael Rentzos; M. Michalopoulou; Chryssoula Nikolaou; C. Cambouri; Antonis Rombos; A. Dimitrakopoulos; D. Vassilopoulos

UNLABELLED Immunological disturbances have been implicated in the pathogenesis of some neurodegenerative disorders like Alzheimers disease (AD) and amyotrophic lateral sclerosis (ALS). Adhesion molecules are markers of activated endothelial cells upregulated by action of cytokines. MATERIALS AND METHODS To investigate the activation or not of the vascular cells in AD and ALS, serum soluble intercellular adhesion molecule-1 (ICAM-1) and soluble E-selectin were evaluated (enzyme-like immunosorbent assay, ELISA) in 22 patients with Alzheimers disease (AD), 20 patients with amyotrophic lateral sclerosis (ALS), 34 patients with non-inflammatory neurological diseases (NIND) and 15 control subjects. RESULTS Patients with AD had higher s-ICAM-1 levels compared to NIND patients and control subjects (p<0.0027 and p<0.04, respectively). Patients with ALS had not higher s-ICAM-1 levels compared to NIND patients and control subjects (p<0.21 and p<0.31, respectively). Soluble-E-selectin levels in AD and ALS patients were not statistically different compared to NIND patients and controls (p<0.4, p<0.9 and p<0.3, p<0.19, respectively). CONCLUSIONS The presence of high s-ICAM values may be related to immunological processes involved in pathogenetic mechanisms of AD. The not statistically significant values of s-E selectin, a glycoprotein considered an exclusive marker of endothelial activation, seem to suggest the neural rather than the endothelial s-ICAM origin in patients with AD. The low values of s-ICAM-1 and sE-selectin in the serum of ALS patients do not exclude the presence of an unconventional immunological abnormality in this disorder.


European Neurology | 2010

Interleukin-15 and Interleukin-12 Are Elevated in Serum and Cerebrospinal Fluid of Patients with Amyotrophic Lateral Sclerosis

Michael Rentzos; Antonis Rombos; Chryssoula Nikolaou; Margarita Zoga; Vassiliki Zouvelou; Antonis Dimitrakopoulos; Theodoros Alexakis; Anthousa Tsoutsou; Anastasia Samakovli; Maria Michalopoulou; Ioannis Evdokimidis

Background: There is evidence that immunological factors may be involved in pathogenic mechanisms of amyotrophic lateral sclerosis (ALS). Interleukin (IL)-15 and IL-12 are proinflammatory cytokines produced by activated blood and glial cells. They promote T cell differentiation and proliferation. Patients and Methods: We measured by ELISA serum and cerebrospinal fluid (CSF) levels of IL-15 and IL-12 in 21 patients with ALS and 19 patients with other noninflammatory neurological disorders (NIND) studied as a control group. IL-15 and IL-12 serum and CSF levels were also correlated with duration of the disease, the disability level determined using the revised ALS Functional Rating Scale and the clinical subtype of the disease onset in patients with ALS. Results: IL-15 and IL-12 serum levels were higher in patients with ALS as compared with patients with NIND (p = 0.014 and p = 0.011, respectively). IL-15 and IL-12 CSF levels were also increased in patients with ALS (p = 0.011 and p = 0.005, respectively). IL-15 and IL-12 levels were not correlated with disease duration, disability scale or clinical subtype of the disease onset in ALS patients. Conclusions: Our findings suggest that these molecules may be involved in the pathogenic mechanisms acting as potential markers of immune activation in ALS.


Neuromuscular Disorders | 2013

Double seronegative myasthenia gravis with anti-LRP 4 antibodies

Vasiliki Zouvelou; Paraskevi Zisimopoulou; Michael Rentzos; Nikos Karandreas; Panagiota Evangelakou; Eleftherios Stamboulis; Socrates J. Tzartos

About 10% of patients with generalized myasthenia gravis do not have detectable antibodies to acetylcholine receptor or muscle specific kinase (double seronegative myasthenia). The presence of anti-low density lipoprotein receptor-related protein 4 antibodies (LRP4 Abs) has recently been reported in variable proportion of double seronegative cases. We report the presenting characteristics of two double seronegative myasthenic patients from Greece with anti-LRP4 antibodies shortly after disease onset. The first patient, a 52-year-old male, presented with a one month history of isolated neck extensor weakness; the second patient is a 52-year-old female with three months history of ocular-bulbar-cervical myasthenic weakness. Both patients presented with mild severity and responded promptly and adequately to pyridostigmine. In the female patient thymic residual tissue was detected on CT of the mediastinum. She underwent thymectomy, and histological examination revealed follicular hyperplasia. This is the first clinical report of the presenting features of newly diagnosed myasthenia with anti-LRP4 antibodies. The clinical and therapeutic implications of the anti-LRP4 antibody positivity remain to be clarified.


Journal of Neuroimaging | 2011

MRI Evidence of Early Muscle Atrophy in MuSK Positive Myasthenia Gravis

Vasiliki Zouvelou; Michael Rentzos; Panagiotis Toulas; Ioannis Evdokimidis

Muscle atrophy, particularly of facial and bulbar muscles, seems to be a relatively common long‐term consequence of musclespecific tyrosine kinase‐myasthenia gravis (MuSK‐MG), perhaps reflecting the chronic state of disease or long‐term therapy with corticosteroids. We performed magnetic resonance imaging (MRI) to assess muscle wasting in the facial and bulbar muscles in two female MuSK‐MG patients, with short duration of symptoms prior to diagnosis and prior to commencement of steroid therapy. The study revealed marked atrophy of temporalis, masseters, and lingual muscles with fatty replacement. MRI evidence of early muscle atrophy in MuSK‐MG may indicate that MuSK antibodies per se may predispose to muscle atrophy.

Collaboration


Dive into the Michael Rentzos's collaboration.

Top Co-Authors

Avatar

Chryssoula Nikolaou

National and Kapodistrian University of Athens

View shared research outputs
Top Co-Authors

Avatar

Ioannis Evdokimidis

National and Kapodistrian University of Athens

View shared research outputs
Top Co-Authors

Avatar

Vasiliki Zouvelou

National and Kapodistrian University of Athens

View shared research outputs
Top Co-Authors

Avatar

Margarita Zoga

National and Kapodistrian University of Athens

View shared research outputs
Top Co-Authors

Avatar

Vassiliki Zouvelou

National and Kapodistrian University of Athens

View shared research outputs
Top Co-Authors

Avatar

Eleftherios Stamboulis

National and Kapodistrian University of Athens

View shared research outputs
Top Co-Authors

Avatar

Nikos Karandreas

National and Kapodistrian University of Athens

View shared research outputs
Top Co-Authors

Avatar

Theodoros Alexakis

National and Kapodistrian University of Athens

View shared research outputs
Top Co-Authors

Avatar

Demetrios Vassilopoulos

National and Kapodistrian University of Athens

View shared research outputs
Top Co-Authors

Avatar

George P. Paraskevas

National and Kapodistrian University of Athens

View shared research outputs
Researchain Logo
Decentralizing Knowledge