Small soluble α-synuclein aggregates are the toxic species in Parkinson's disease.

Soluble α-synuclein aggregates varying in size, structure, and morphology have been closely linked to neuronal death in Parkinson's disease. However, the heterogeneity of different co-existing aggregate species makes it hard to isolate and study their individual toxic properties. Here, we show a reliable non-perturbative method to separate a heterogeneous mixture of protein aggregates by size. We find that aggregates of wild-type α-synuclein smaller than 200 nm in length, formed during an in vitro aggregation reaction, cause inflammation and permeabilization of single-liposome membranes and that larger aggregates are less toxic. Studying soluble aggregates extracted from post-mortem human brains also reveals that these aggregates are similar in size and structure to the smaller aggregates formed in aggregation reactions in the test tube. Furthermore, we find that the soluble aggregates present in Parkinson's disease brains are smaller, largely less than 100 nm, and more inflammatory compared to the larger aggregates present in control brains. This study suggests that the small non-fibrillar α-synuclein aggregates are the critical species driving neuroinflammation and disease progression.

Soluble amyloid beta-containing aggregates are present throughout the brain at early stages of Alzheimer's disease.

Protein aggregation likely plays a key role in the initiation and spreading of Alzheimer's disease pathology through the brain. Soluble aggregates of amyloid beta are believed to play a key role in this process. However, the aggregates present in humans are still poorly characterized due to a lack of suitable methods required for characterizing the low concentration of heterogeneous aggregates present. We have used a variety of biophysical methods to characterize the aggregates present in human Alzheimer's disease brains at Braak stage III. We find soluble amyloid beta-containing aggregates in all regions of the brain up to 200 nm in length, capable of causing an inflammatory response. Rather than aggregates spreading through the brain as disease progresses, it appears that aggregation occurs all over the brain and that different brain regions are at earlier or later stages of the same process, with the later stages causing increased inflammation.

Soluble aggregates present in cerebrospinal fluid change in size and mechanism of toxicity during Alzheimer's disease progression.

Soluble aggregates of amyloid-ß (Aß) have been associated with neuronal and synaptic loss in Alzheimer's disease (AD). However, despite significant recent progress, the mechanisms by which these aggregated species contribute to disease progression are not fully determined. As the analysis of human cerebrospinal fluid (CSF) provides an accessible window into the molecular changes associated with the disease progression, we characterised soluble aggregates present in CSF samples from individuals with AD, mild cognitive impairment (MCI) and healthy controls using a range of sensitive biophysical methods. We used super-resolution imaging and atomic force microscopy to characterise the size and structure of the aggregates present in CSF and correlate this with their ability to permeabilise lipid membranes and induce an inflammatory response. We found that these aggregates are extremely heterogeneous and exist in a range of sizes, varying both structurally and in their mechanisms of toxicity during the disease progression. A higher proportion of small aggregates of Aß that can cause membrane permeabilization are found in MCI CSF; in established AD, a higher proportion of the aggregates were larger and more prone to elicit a pro-inflammatory response in glial cells, while there was no detectable change in aggregate concentration. These results show that large aggregates, some longer than 100 nm, are present in the CSF of AD patients and suggest that different neurotoxic mechanisms are prevalent at different stages of AD.

Optimization of Tetrapolar Impedance Electrodes in Microfluidic Devices for Point of Care Diagnostics using Finite Element Modeling.

Electrophoresis is widely applied in the field of biochemistry and molecular biology. Tetrapolar electrical impedance sensing (TEIS) has been shown capable of replacing the conventional detection technology in order to develop a point of care electrophoretic analyzer. Besides the advantages of reduced influence of electrode polarization, TEIS is affected by sensitivity distribution depending on the electrode design. A well reported practice outside of electrophoresis, systematic investigation of the effects of sensitivity distribution on the TEIS in microfluidic devices has not been conducted. Here we utilize finite element modeling, backed by experimental results, to optimize the sensor design within an electrophoretic separation device. Numerous sensor designs were validated regarding detectability, sensitivity and spatial resolution. The results show, that minimizing the distance between the central/pick-up electrodes increases sensitivity and spatial resolution whereas the distance between the central electrodes and the outer electrode do not influence sensitivity and spatial resolution.

Synapse loss in the prefrontal cortex is associated with cognitive decline in amyotrophic lateral sclerosis.

In addition to motor neurone degeneration, up to 50% of amyotrophic lateral sclerosis (ALS) patients present with cognitive decline. Understanding the neurobiological changes underlying these cognitive deficits is critical, as cognitively impaired patients exhibit a shorter survival time from symptom onset. Given the pathogenic role of synapse loss in other neurodegenerative diseases in which cognitive decline is apparent, such as Alzheimer's disease, we aimed to assess synaptic integrity in the ALS brain. Here, we have applied a unique combination of high-resolution imaging of post-mortem tissue with neuropathology, genetic screening and cognitive profiling of ALS cases. Analyses of more than 1 million synapses using two complimentary high-resolution techniques (electron microscopy and array tomography) revealed a loss of synapses from the prefrontal cortex of ALS patients. Importantly, synapse loss was significantly greater in cognitively impaired cases and was not due to cortical atrophy, nor associated with dementia-associated neuropathology. Interestingly, we found a trend between pTDP-43 pathology and synapse loss in the frontal cortex and discovered pTDP-43 puncta at a subset of synapses in the ALS brains. From these data, we postulate that synapse loss in the prefrontal cortex represents an underlying neurobiological substrate of cognitive decline in ALS.

Ventricular arrhythmias and antioxidative medication: experimental study.

INTRODUCTION: Reperfusion arrhythmias could be due to free radicals, while contraction excitation feedback is the cause of arrhythmias generated by blood pressure elevation (BPE). The aim of this study was to test the antiarrhythmic effects of an antioxidant (vitamin C [vit C], 1.5 g), an iron-binding agent (deferoxamine [Def], 1 g), and their combination in an experimental model of arrhythmia based on these 2 mechanisms. METHODS: Thirty anaesthetised sheep were divided into 4 groups, depending on the infused agent: saline (8 sheep), combination of vit C and Def (8), Def (6), and vit C (8). Induction of ventricular arrhythmias was attempted in all animals using both ischaemia-reperfusion (phase I) and a combination of ischaemia and BPE (phase II). In all cases ischaemia was caused by ligating the left anterior descending coronary artery distally to the origin of the 1st diagonal artery, while reperfusion was achieved by releasing the ligation 45 min later. BPE was achieved by obstructing the ascending aorta or by administering intravenous metaraminol. All agents were infused intravenously for 15 min and their administration was started 30 min after the first ligation. Phases I and II lasted 50 and 20 min, respectively. RESULTS: Ventricular tachycardia/fibrillation (VT/VF) was induced in all animals in the control group (8/8) and in the Def group (6/6). VT/VF appeared in 6/8 of the animals in the vit C group (75%) and in only 3/8 of the animals in the combination therapy group (37.5%). The difference between the combination and control groups was statistically significant (p < 0.03). CONCLUSIONS: The intravenous administration of vit C and Def in combination protects against VT/VF induced by ischaemia-reperfusion and/or BPE. Administration of Def alone does not appear to help, while the action of vit C alone is not clear.

Apoptosis bcl-2 and nitrotyrosine expression in an angioplasty-restenosis rabbit: an experimental model.

Apoptosis has been suggested to have an important role in the pathogenesis of restenosis in addition to cell migration and proliferation. The aim of the present study was to investigate in an experimental in vivo model the occurrence of apoptosis postangioplasty and its relation to bcl-2 and peroxynitrite detection. Eighteen hypercholesterolemic rabbits underwent transluminal angioplasty of the right iliac artery. The rabbits were sacrificed on the 1st, 2nd, 3rd, 7th, 15th, and 28th day postangioplasty (3 animals per time point) and both the angioplasted and non-injured arteries were studied. Apoptosis was assessed by the terminal uridine nick-end labeling method (TUNEL). Bcl-2 and peroxynitrite were detected by immunochemistry using anti-bcl-2 and anti-nitrotyrosine antibodies. In the angioplasted arteries the number of apoptotic cells was

Long-term clinical outcome of patients treated with beta-brachytherapy in routine clinical practice.

BACKGROUND: Only limited data exist regarding the long-term efficacy of beta-brachytherapy (beta-VBT) in routine clinical practice and the impact of the prolonged (>6 months) combined antiplatelet therapy after beta-VBT. Our aim is to examine the long-term clinical efficacy of routine beta brachytherapy (beta-VBT) followed by indefinite administration of combined antiplatelet therapy in patients at high restenotic risk. METHODS: Sixty-one patients with 65 lesions [de novo: 41, in-stent restenotic (ISR): 24] underwent intracoronary beta-VBT and were followed prospectively. All patients received indefinite administration of aspirin and clopidogrel, underwent routine angiography 6 months later and were followed-up clinically for 43.7 months (range: 32 to 52 months). RESULTS: Acute success was achieved in 60/61 (98.4%) patients. Lesion length was 36.1 (+/-17.6) mm for the de novo and 22.0 (+/-9.8) mm for the ISR (p=0.001). Stents were implanted in 35/41 de novo and 7/24 ISR lesions (p<0.01). Six-month binary restenosis after successful beta-VBT was 35.9% (23/64). During follow-up patients with de-novo lesions who received a new stent during index procedure had a higher incidence of major cardiac events than patients with ISR lesions without a new stent (log rank test, p=0.02). Acute and late thrombotic events were reported at 6 patients, all with de novo lesions and stent implantation. CONCLUSIONS: Beta-VBT plus stenting in de novo lesions is related to an unacceptable high rate of thrombotic complications and clinical restenosis despite prolonged administration of combined antiplatelet therapy. Brachytherapy remains a reasonable option for patients with ISR lesions until full data from large randomized trials comparing drug eluting stents with brachytherapy are available.

Transient complete atrioventricular block associated with herb intake.

We report a case of transient complete atrioventricular block in a 38-year-old man, after intake of a mixture of herbs, intended to aid cigarette smoking cessation. Since all other causes of conduction disturbances were excluded, a side-effect of the herbal remedy was identified as the most likely diagnosis. Given that most patients are unaware of the potential risks of the intake of various herbs, we would urge that their usage be regulated.

Rare association of diffused coronary ectasia and anomalous origin of left circumflex coronary artery in a man with heterozygous familial hypercholesterolemia: a case report.

Coronary artery ectasia (CAE) is an uncommon form of coronary artery disease. It has been reported in association with a variety of pathological conditions, such as isolated congenital heart disease and Kawasaki disease. CAE is more relevant in young adults with multiple predisposing risk factors, especially familial hypercholesterolemia, and is usually considered a form of atherosclerotic coronary artery disease. A case of CAE is reported with familial hypercholesterolemia and diffuse ectasia of the coronary vessels in association with anomalous origin of the left circumflex coronary artery, which lacked ectatic segments. This combination has not been reported previously.

Intrapericardial drug delivery: pharmacologic properties and long-term safety in swine.

BACKGROUND: Intrapericardial drug delivery is a promising new technique, but the pharmacologic properties of various agents delivered via this route are not known. Furthermore, the long-term safety of intrapericardial catheters has not been previously examined. METHODS: Using a pericardial access device, a catheter connected to a drug-delivery system was implanted in five pigs. Plasma levels and electrocardiographic measurements were obtained after intravenous and intrapericardial administration of digoxin and procainamide. Histological examination was performed after the device had been implanted for a total of 6 months. RESULTS: The QTc interval did not change significantly after digoxin or procainamide intravenous administration. QTc decreased by 47+/-23 ms (p=0.046) 8 h after digoxin intrapericardial administration and increased by 128+/-60 ms (p=0.002) 1 h after procainamide intrapericardial administration. The QRS duration did not change significantly after intravenous administration of either agent, but it increased by 17+/-9 ms (p=0.004) 1 h and by 15+/-4 ms (p=0.01) 8 h after procainamide intrapericardial administration. After intravenous procainamide the RR interval decreased, but it did not change significantly after intrapericardial administration of either agent. Histology showed moderate inflammatory infiltration and fibrosis adjacent to the catheter. CONCLUSIONS: Intrapericardial delivery of digitalis and procainamide produces unique electrophysiological properties. In contrast to satisfactory success of the implantation technique, long-term dwell of the catheter in the pericardium induces moderate, albeit probably clinically significant, fibrosis.

Mapping the binding domains of the alpha(IIb) subunit. A study performed on the activated form of the platelet integrin alpha(IIb)beta(3).

alpha(IIb)beta(3), a member of the integrin family of adhesive protein receptors, is the most abundant glycoprotein on platelet plasma-membranes and binds to adhesive proteins via the recognition of short amino acid sequences, for example the ubiquitous RGD motif. However, elucidation of the ligand-binding domains of the receptor remains controversial, mainly owing to the fact that integrins are conformationally labile during purification and storage. In this study, a detailed mapping of the extracellular region of the alpha(IIb) subunit is presented, using overlapping 20-peptides, in order to identify the binding sites of alpha(IIb) potentially involved in the platelet-aggregation event. Regions alpha(IIb) 313-332, alpha(IIb) 265-284 and alpha(IIb) 57-64 of alpha(IIb)beta(3) were identified as putative fibrinogen-binding domains because the corresponding peptides inhibited platelet aggregation and antagonized fibrinogen association, possibly by interacting with this ligand. The latter is further supported by the finding that the above peptides did not interfere with the binding of PAC-1 to the activated form of alpha(IIb)beta(3). Furthermore, alpha(IIb) 313-332 was found to bind to fibrinogen in a solid-phase binding assay. It should be emphasized that all the experiments in this study were carried out on activated platelets and consequently on the activated form of this integrin receptor. We hypothesize that RAD and RAE adhesive motifs, encompassed in alpha(IIb) 313-332, 265-284 and 57-64, are capable of recognizing complementary domains of fibrinogen, thus inhibiting the binding of this ligand to platelets.

Aortic dissection with aorto-left atrial fistula formation soon after aortic valve replacement: A lethal complication diagnosed by transthoracic and transesophageal echocardiography.

Fistulas between the aorta and left atrium are a rare manifestation of aortic dissection and are infrequently diagnosed premortem. We report the case of a 70-year-old man who exhibited this condition soon after aortic valve replacement and eventually died from rapidly developing refractory congestive heart failure. The diagnosis was indicated by transthoracic echocardiography and was ultimately made with transesophageal echocardiography and color flow Doppler imaging. Transesophageal echocardiography is the procedure of choice for establishing the correct diagnosis and leading to prompt surgical repair of this lethal condition.

Sudden death due to an unrecognized cardiac hydatid cyst.

Echinococcosis is an endemic disease, most common in sheep-raising communities, usually caused by the larval or cyst stage of the tapeworm Echinococcus granulosus. Isolated cardiac hydatid cyst is uncommon at any age, occurs through the coronary circulation, and accounts for less than 3% of all hydatid disease. We describe a case of an 1%-year-old female, who died suddenly. The post-mortem examination revealed an isolated cyst in the left ventricle of the heart with intact wall. The cytologic examination of the cyst fluid demonstrated the presence of the characteristic scolices and hooklets and established the diagnosis of cardiac hydatid cyst. The present case is of special interest because of the rare primary localization and the onset of sudden death in a young person as the initial manifestation of the disease.

Vibrational angioplasty in the treatment of chronic infrapopliteal arterial occlusions: preliminary experience.

PURPOSE: To evaluate the safety and efficacy of vibrational angioplasty in chronic infrapopliteal arterial occlusions. METHODS: Twelve patients (9 men, aged 54 to 90 years) with 13 below-knee arterial chronic total occlusions were treated percutaneously using vibrational angioplasty. The occlusions were located in the anterior tibial artery (n=5), the tibioperoneal trunk (n=4), the peroneal artery (n=1), the posterior tibial artery (n=1), and in both the tibioperoneal trunk and peroneal artery (n=2). The length of the lesions ranged from 5 to 14 cm. RESULTS: Recanalization was successful in 12 (92.3%) lesions. In 1 case, the wire perforated the arterial wall; the procedure was abandoned without clinical sequelae. The time to cross the occlusions with the wire ranged from 6 to 19 minutes. No other complications were observed. Clinical follow-up ranged to 18 months. Ten patients with ulceration or gangrene demonstrated good wound healing, and pain was alleviated in all successfully treated patients. CONCLUSIONS: Vibrational angioplasty appears feasible as a means of safely recanalizing chronic total occlusions of the infrapopliteal arteries. Further experience should be acquired to assess its short- and long-term effects on this vascular territory.