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Biomedical subjects

Amos D Korczyn

Publications and source records attributed to Amos D Korczyn.

At least 19 recordsLinked to original sources
PubMed2006

Management of sleep problems in Parkinson's disease.

Patients with Parkinson's disease (PD) frequently complain of sleep problems. These can be due to several factors, and the approach to their management depends on careful consideration of the various possible factors in each case. 1. Older people, in general, require less sleep. After retirement, people may also engage in less physical activity, and this factor is of course even more pronounced in patients with PD because of their illness. 2. Daytime naps, either spontaneous or due to drugs, reduce the need for nocturnal sleep. Explanation of these physiological and circumstantial changes may help those PD patients who manifest these consequences. 3. The existence of a severe progressive disease as well as social isolation have psychologic consequences, such as anxiety and depression, that may manifest as insomnia. Furthermore, depression is part of the disease, frequently antedating the motor manifestations, and may manifest as insomnia. 4. In advanced disease, patients may be immobile and have difficulty in getting up or even turning in bed. This causes great inconvenience, and may impair sleep. Long acting anti-Parkinson drugs such as cabergoline or rotigotine patch may help. 5. In some cases, unpleasant hallucinations may appear which prevent the patient from falling asleep. These may respond to atypical neuroleptics. Clozapine and quetiapine are particularly useful, but require attention to possible adverse effects.

Humans↗
PubMed2006

Dementia with Lewy bodies.

Advanced Parkinson's disease (PD) is frequently associated with dementia. The pathogenesis of this dementia is complex, related to deficiency of several biogenic amines and cortical Lewy body deposition, as well as co-existent age-related brain changes, both of the Alzheimer type and vascular. However, degeneration of the cholinergic neurons in the nucleus basalis of Meynert may have an important contribution to the cognitive decline. The dementia of PD has a grave effect on the quality of life of the patients and their caregivers, as well as a negative effect on their survival. The treatment of dementia associated with PD with cholinesterase inhibitors produced gratifying (although limited) results. Future studies should define the exact role of these agents in the treatment of the dementia of PD. Another major problem presented by demented PD patients is the occurrence of delusions and hallucinations, which make the life of patients and caregivers miserable. Classical neuroleptics are of course contra-indicated in these patients but recent data increase concern about the safety of novel derivatives, leaving a void in the pharmacological armamentarium available when these manifestations appear.

Brain Chemistry↗
PubMed2006

Cerebral vasomotor reactivity in Parkinson's disease, multiple system atrophy and pure autonomic failure.

Parkinson's disease (PD), multiple system atrophy (MSA) and pure autonomic failure (PAF) are neurodegenerative disorders frequently associated with orthostatic hypotension and syncope, though with different underlying mechanisms. Cerebral hemodynamic responses in these three neurodegenerative diseases are still incompletely studied and it is possible that they would be differentially affected. We measured blood flow velocity (BFV) in the middle cerebral artery (MCA) and vertebral artery (VA) in patients with these disorders and investigated whether cerebral vasomotor reactivity (VMR) differs in these three disorders. Twenty-four patients (9 with PD, 10 with MSA and 5 with PAF) were studied. VMR was assessed in the MCA and VA, using transcranial Doppler (TCD) and Diamox test (injection of 1 g acetazolamide i.v.) with the patients in a recumbent position. The percent difference between BFV before and after acetazolamide injection was defined as VMR% and the results were compared by ANOVA. The mean MCA and VA blood flow velocities were similar in the three disorders and within normal limits for our laboratory. The mean MCA VMR values were 37.5+/-24.0%, 27.9+/-28.0% and 38.0+/-33.9% in PD, MSA and PAF, respectively. The VA VMR values were 22.9+/-23.6%, 32.4+/-38.0% and 18.9+/-18.3%, respectively, with no significant differences between the groups. We conclude that BFV is normal in PD, MSA and PAF and that the VMR, as investigated by TCD and the Diamox test, did not disclose differences in cerebral vasomotor responses between these conditions.

Acetazolamide↗
PubMed2006

Effect of rivastigmine on tremor in patients with Parkinson's disease and dementia.

The purpose of this study was to assess whether rivastigmine, a cholinergic agent, affects tremor features when given to improve cognition in demented Parkinson's disease (PD) patients. Demented PD patients (n = 26; Mini-Mental State Examination score, 13-25; age, 75.2 +/- 4.9 yr) were given rivastigmine (mean dose, 8.0 mg/day) for 12 weeks. They underwent tremor assessment before and during treatment. Global Tremor Score (GTS) was based on eight items specific to tremor in the Unified Parkinson's Disease Rating Scale. Tremor amplitude was also measured using accelerometers during the ON state in both hands in 19 patients. Drug therapy for other PD symptoms was unchanged. The mean group baseline GTS was 1.2 +/- 1.6 points, increasing to 1.6 +/- 2.4 points after treatment (mean increase, 0.4 +/- 1.2 points; P > 0.05). The GTS increased by 3.2 +/- 1.9 points (range, 1-5) in 7 patients (26.9%) and decreased by 1 +/- 0 points in 3 patients (11.5%). Accelerometric assessment showed a significant increase of the average tremor amplitude in the right hand (0.08 +/- 0.03 xg at baseline; 0.12 +/- 0.02 xg at Week 12 of treatment, P = 0.02). Left-hand tremor amplitude did not change. Rivastigmine caused only slight worsening of tremor in demented PD patients, while improving cognition.

Activities of Daily Living↗
PubMed2006

Development of dyskinesias in a 5-year trial of ropinirole and L-dopa.

A 5-year trial of ropinirole and levodopa in early Parkinson's disease showed that ropinirole is associated with reduced incidence of dyskinesias. This post hoc analysis investigated whether the dyskinesia-sparing benefit of ropinirole is lost when levodopa is added to the regimen and evaluated other risk factors for developing dyskinesias. Patients receiving levodopa had a significantly higher risk of dyskinesias than those taking ropinirole monotherapy (hazard ratio [HR], 6.67; 95% confidence interval [CI], 3.23-14.29; P < 0.001). When patients randomized to ropinirole were treated with supplementary levodopa, the development of dyskinesias was not significantly different from that in those receiving levodopa from the start (HR, 0.80; 95% CI, 0.48-1.33; P = 0.39). However, the onset of dyskinesias was delayed by around 3 years compared with levodopa monotherapy. Adjusted analyses taking into account baseline and on-treatment factors that influenced use of supplementary levodopa or the development of dyskinesias produced similar results. In conclusion, the risk of developing dyskinesias during maintained initial ropinirole monotherapy is very low. Only once levodopa is added does the risk substantially change. Early use of ropinirole postpones the onset of dyskinesias, but these benefits decline when levodopa therapy is started, with no evidence of a subsequent rapid "catch-up" or a persisting preventive effect.

Antiparkinson Agents↗
PubMed2006

[Mild cognitive impairment (MCI): characteristics, risk factors and prevention].

Mild cognitive impairment (MCI) is a term describing the individual's cognitive state, ranging from normal aging to dementia. Since the term MCI was only recently introduced, there are still controversies regarding its definition, frequency and characteristics. Despite ambiguity in the clinical definitions, MCI is strongly considered as representing enhanced risk for the development of dementia. Therefore, MCI seems to be an important target phase for clinical intervention aimed at inhibiting deterioration to dementia. Despite the controversies regarding the diagnosis of MCI and its exact definition, great progress has been achieved in identifying brain changes, genetic risk factors and prevention factors associated with MCI.

Aged↗
PubMed2005

Increased thrombin inhibition in experimental autoimmune encephalomyelitis.

Multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE), are inflammatory diseases of the central nervous system (CNS). Activated coagulation factors are associated with inflammation and are elevated in the plasma of animals with EAE. Thrombin is a key coagulation factor and its major endogenous inhibitors are antithrombin III (ATIII) in the plasma and protease nexin 1 (PN-1) in the brain. We measured the capacity of brain homogenates to inhibit exogenous thrombin and the CNS levels of ATIII and PN-1 during the course of EAE. Acute EAE was induced in SJL/J mice by immunization with mouse spinal cord homogenates. On Days 8, 13, and 22 post-immunization, inhibition of exogenous thrombin activity was measured by a recently developed fluorimetric assay. PN-1 and ATIII were assayed both by immunohistochemistry and by immunoblots in the brain and spinal cord. Total brain thrombin inhibitory activity increased (32%) in EAE mice at the peak of clinical disease (Day 13, P=0.04 compared to controls). Brain ATIII also increased at the peak of disease (2.5-fold higher than controls, P=0.0001), and correlated significantly with clinical scores at all stages of disease (r=0.72, P=0.0068). In contrast, PN-1 elevations were more pronounced at the preclinical stage on Day 8 (3-fold higher than controls, P=0.01) than on Day 13 (1.4-fold higher, P=0.005). Increased brain thrombin inhibition at the clinical peak of EAE probably reflects increased influx of plasma thrombin inhibitors. Early PN-1 changes represent a potential target for thrombin modulating drugs in EAE and MS.

Amyloid beta-Protein Precursor↗
PubMed2005

Hidden function of neuronal nicotinic acetylcholine receptor beta2 subunits in ganglionic transmission: comparison to alpha5 and beta4 subunits.

Neuronal nicotinic acetylcholine receptors (nAChR), which modulate fast excitatory postsynaptic potentials (f-EPSP), are located on both pre- and postganglionic sites in the autonomic nervous system (ANS). The receptor subunits alpha3, alpha5, alpha7, beta2 and beta4 are present in autonomic ganglia in various combinations and modulate acetylcholine (ACh) transmission. In the present study, autonomic functions were systemically examined in mice lacking beta2 subunits (beta2-/-) to further understand the functional role of beta2 subunits in modulating ganglionic transmission. The results show normal autonomic functions, both under physiological conditions and in perturbed conditions, on thermoregulation, pupillary size, heart rate responses and ileal contractile reactions. This suggests that the function of beta2-containing receptors in ganglionic transmission is hidden by the predominant beta4 containing receptors and confirms previous studies which suggest that alpha3alpha5beta4 nAChRs are sufficient for autonomic transmission. On the other hand, beta2-containing receptors have only a minor function on postsynaptic responses to ACh, but may modulate ACh release presynaptically, although there is no evidence for this.

Acetylcholine↗
PubMed2005

The underdiagnosis of the vascular contribution to dementia.

The existence of vascular dementia (VaD) was first identified by Marie, who described the etat lacunaire, and by Binswanger, who identified white matter lesions in the brain subcortical areas. Alois Alzheimer, when defining the disease now bearing his name, did so in a patient with a presenile onset. The majority of demented elderly people were then believed to have cerebral arteriosclerosis underlying their cognitive decline. The role of cortical vascular lesions, while clear to clinicians, was highlighted only later, by the pathological studies of Tomlinson et al. and the clinical demonstrations of Hachinski et al. who have defined multi-infarct dementia. Lately, the emphasis shifted to pathogenic mechanisms for vascular brain disease with the identification of a multitude of processes, such as lipohyalinosis, cardiac dysfunction and genetic causes, to name only a few. Epidemiologic studies have demonstrated the high frequency of vascular lesions in brains of demented individuals, as well as the fact that vascular factors can contribute to Alzheimer's disease (AD). Moreover, many factors, which were identified as contributing to cerebrovascular disease in general and VaD in particular, are frequently suspected as predisposing to AD as well. All these considerations converge to the realization that vascular components are extremely important in the pathogenesis of old-age dementia and that prevention and perhaps treatment of dementia are within reach. These surprising findings highlight the importance of mixed vascular-degenerative dementia as a disorder that has to be properly defined.

Dementia, Vascular↗
PubMed2005

A new clinical and molecular form of Unverricht-Lundborg disease localized by homozygosity mapping.

Progressive myoclonus epilepsy (PME) has a number of causes, of which Unverricht-Lundborg disease (ULD) is the most common. ULD has previously been mapped to a locus on chromosome 21 (EPM1). Subsequently, mutations in the cystatin B gene have been found in most cases. In the present work we identified an inbred Arab family with a clinical pattern compatible with ULD, but mutations in the cystatin B gene were absent. We sought to characterize the clinical and molecular features of the disorder. The family was studied by multiple field trips to their town to clarify details of the complex consanguineous relationships and to personally examine the family. DNA was collected for subsequent molecular analyses from 21 individuals. A genome-wide screen was performed using 811 microsatellite markers. Homozygosity mapping was used to identify loci of interest. There were eight affected individuals. Clinical onset was at 7.3 +/- 1.5 years with myoclonic or tonic-clonic seizures. All had myoclonus that progressed in severity over time and seven had tonic-clonic seizures. Ataxia, in addition to myoclonus, occurred in all. Detailed cognitive assessment was not possible, but there was no significant progressive dementia. There was intrafamily variation in severity; three required wheelchairs in adult life; the others could walk unaided. MRI, muscle and skin biopsies on one individual were unremarkable. We mapped the family to a 15-megabase region at the pericentromeric region of chromosome 12 with a maximum lod score of 6.32. Although the phenotype of individual subjects was typical of ULD, the mean age of onset (7.3 years versus 11 years for ULD) was younger. The locus on chromosome 12 does not contain genes for any other form of PME, nor does it have genes known to be related to cystatin B. This represents a new form of PME and we have designated the locus as EPM1B.

Adolescent↗
PubMed2005

Inhibition of Ras attenuates the course of experimental autoimmune neuritis.

EAN induced in Lewis rats by immunization with peripheral bovine myelin was treated by the Ras inhibitor farnesylthiosalicylate (FTS). Treatment from day 0 with FTS (5 mg/kg intraperitoneally twice daily) attenuated peak clinical scores (mean+/-S.E., 2.5+/-0.5 compared to 4.1+/-0.5 in saline treated controls, p=0.018, t-test) but not recovery. Treatment from day 10 with FTS attenuated peak disability (2.5+/-0.6, p=0.032 compared to saline treated controls) and improved recovery (0.84+/-0.42, untreated controls 2.4+/-0.6, p=0.028 by repeated measures ANOVA). Effects were confirmed by rotarod and nerve conduction studies. An inactive analogue, geranylthiosalicylate, had no clinical effect. Inhibition of Ras is of potential use in the treatment of inflammatory neuropathies.

Analysis of Variance↗
PubMed2005

White matter changes in multiple sclerosis: correlation of q-space diffusion MRI and 1H MRS.

OBJECTIVE: To explore the diagnostic usefulness of high b-value diffusion magnetic resonance brain imaging ("q-space" imaging) in multiple sclerosis (MS). More specifically, we aimed at evaluating the ability of this methodology to identify tissue damage in the so-called normal-appearing white matter (NAWM). DESIGN: In this study we examined the correlation between q-space diffusion imaging and magnetic resonance spectroscopy (MRS)-based two-dimensional 1H chemical shift imaging. Eight MS patients with different degree of disease severity and seven healthy subjects were scanned in a 1.5-T magnetic resonance imaging (MRI) scanner. The MRI protocol included diffusion tensor imaging (DTI) (with bmax of 1000 s/mm2), high b-value diffusion-weighted imaging (with bmax of 14,000 s/mm2) and 2D chemical shift imaging. The high b-value data set was analyzed using the q-space methodology to produce apparent displacement and probability maps. RESULTS: We found that the q-space diffusion displacement and probability image intensities correlated well with N-acetylaspartate levels (r=.61 and .54, respectively). Furthermore, NAWM that was abnormal on MRS was also found to be abnormal using q-space diffusion imaging. In these areas, the q-space displacement values increased from 3.8+/-0.2 to 4.6+/-0.6 microm (P<.02), the q-space probability values decreased from 7.4+/-0.3 to 6.8+/-0.3 (P<.002), while DTI revealed only a small, but still significant, reduction in fractional anisotropy values from 0.40+/-0.02 to 0.37+/-0.02 (P<.05). CONCLUSION: High b-value diffusion imaging can detect tissue damage in the NAWM of MS patients. Despite the theoretical limitation of this method, in practice it provides additional information which is clinically relevant for detection of tissue damage not seen in conventional imaging techniques.

Adult↗
PubMed2005

Autonomic impairment in amyotrophic lateral sclerosis.

PURPOSE OF REVIEW: Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder characterized by progressive loss of motor neurones, but it is increasingly recognized to be a more disseminated disease. The autonomic nervous system may also be involved. Here we review the literature with specific emphasis on autonomic functions in ALS. RECENT STUDIES: Ample evidence exists for subclinical dysfunction of cardiovascular, sudomotor, gastrointestinal, salivary and lacrimal regulation, even in early ALS cases. Autonomic disturbances may lead to circulatory collapse or sudden death in respirator dependent patients. Several studies suggest the existence of sympathetic hyperactivity in ALS. We discuss some possible pathophysiological mechanisms of the subtle abnormalities and some clinical and treatment implications. SUMMARY: The wide range of autonomic involvement, together with results suggesting cognitive and extrapyramidal dysfunction, supports the view that ALS is a multisystem degenerative disease.

Amyotrophic Lateral Sclerosis↗
PubMed2005

Analysis of genetic polymorphisms in acetylcholinesterase as reflected in different populations.

Acetylcholinesterase (AChE) plays a crucial physiological role in termination of impulse transmission at cholinergic synapses through rapid hydrolysis of acetylcholine. In addition, it was implicated in amyloid plaque formation, a hallmark of Alzheimer's disease (AD), and most of the drugs used in AD treatment are AChE inhibitors. Thus ACHE is an obvious candidate gene for pharmacogenetic study of AD treatment. However, AChE is a highly conserved molecule, and only a few naturally occurring genetic polymorphisms have been reported in the human gene. The goals of this study were to make a systematic effort to identify natural single nucleotide polymorphisms (SNPs) in the human ACHE gene, and to reveal their population specific architecture. To this end, the genomic coding sequences for AChE of 96 unrelated control individuals from three distinct ethnic groups, African Americans, Ashkenazi Jews and Israeli Arabs, were analyzed. Thirteen ACHE SNPs were identified, ten of which are newly described, and five of which should produce amino-acid substitutions (Arg34Gln, Gly57Arg, Glu344Gly, His353Asn and Pro592Arg). Population frequencies of 11 of the 13 SNPs were established in four different populations, African Americans, Ashkenazi Jews, Sephardic Jews and Israeli Arabs; 17 haplotypes and 5 ethno-specific alleles were identified, and a cladogram of ACHE haplotypes was constructed. Among the SNPs resulting in an amino-acid substitution, three are within the mature protein, mapping on its external surface; they are thus unlikely to affect its catalytic properties, yet could have antigenic consequences or affect putative protein-protein interactions. Furthermore, the newly identified SNPs open the door to a study of the possible association of AChE with deleterious phenotypes - such as adverse drug responses to AChE inhibitors employed in treatment of AD patients and hypersensitivity to pesticides.

Acetylcholinesterase↗
PubMed2004

Neuropsychological evaluation of late-onset post-radiotherapy encephalopathy: a comparison with vascular dementia.

It is known that radiotherapy (RT) may cause cerebral injury. The most frequent neurotoxic effect of RT at any age is diffuse cerebral injury. Brain injury by therapeutic irradiation has traditionally been classified according to its time of onset into acute, early delayed, and late forms. The latter is not reversible. The neurocognitive sequelae of cranial irradiation can be mediated through vascular injury. Because the pathologic changes are most profound in the white matter, we compared a group of patients treated by RT (n=34) with a group of patients affected by subcortical vascular dementia (sVaD, n=34). Patients with a total radiation does <35 cGy did not show any sign of cognitive impairment. All the patients with a total irradiation dose >45 cGy did show profound cognitive and behavioural alteration. The patients who received a total dose of brain radiation comprised between 35 and 45 cGy did show slowness of executive function, and profound alterations of frontal functions, such as attention focusing, mentation control, analogical judgement and insight. The patients who suffered from the consequences of RT had slowness of executive functions, and profound alterations of frontal functions, such as attention focusing, mentation control, analogical judgement and insight, similar to those obtained by the patients suffering from subcortical vascular dementia. High dose RT might result in a severely demented, bedridden patient, who "has been cured" from his primary disease, the brain tumour. This constellation demands serious consideration before RT is given.

Adult↗
PubMed2004

Nicotinic acetylcholine receptor alpha5 subunits modulate oxotremorine-induced salivation and tremor.

Neuronal nicotinic acetylcholine receptors (nAChRs) are composed of 12 subunits (alpha2-alpha10 and beta2-beta4). alpha5 Subunits, expressed throughout the central nervous system (CNS) and the autonomic nervous system (ANS), possess unique pharmacological properties. The effects of oxotremorine (OXO) on autonomic functions and tremor were examined in mice lacking alpha5 nAChR subunits (alpha5-/-) and compared with those in wild-type (WT) control mice. The alpha5-/- mice showed significantly increased salivation and tremor responses to OXO. The hypothermia, bradycardia and defecation induced by OXO were of similar magnitudes in the two mouse strains. The enhanced OXO effects in alpha5-/- mice indicate inhibitory effects of alpha5 subunits in autonomic ganglia, and support the participation of these subunits in cholinergic transmission in autonomic ganglia.

Acetylcholine↗