Plasma catecholamines during activation of the sympathetic nervous system in a patient with Shy-Drager syndrome.

Plasma catecholamines and circulation parameters were studied in a patient with a Shy-Drager syndrome. Basal values of free noradrenaline and dopamine were within the normal range, whereas the adrenaline level was decreased. The response of plasma catecholamines to different kinds of physical activity was pathological. The inability to maintain elevated catecholamine levels during prolonged activity corresponded to impaired circulatory regulation and may provide an additional tool for diagnosis and monitoring of the Shy-Drager syndrome

A review of neuroleptic malignant syndrome : incidence and features in Malta

This paper describes Malta’s first sample of Neuroleptic Malignant Syndrome (NMS) and reviews the current literature. A retrospective sample of all diagnosed cases of NMS was reviewed using Pope’s (1986) criteria. Twelve cases were identified yielding an incidence of 0.67%. The range of associated risk factors and complications agreed with other reports. There were also two cases of uncontrolled diabetes. Treatments commonly used were Bromocriptine and Levodopa. There were no deaths due to NMS and no recurrence on re-exposure. The sample is too small to draw any statistically significant conclusions, however, the results are mostly in line with those obtained from larger samples. Malta’s incidence is towards the lower end of the reported range of 0.02% to 3.23%, but higher than that reported in centres trying to recognise NMS early and reduce risk factors. This suggests that Malta could benefit from trying to adopt such measures. Given Malta’s small size, it would be relatively easy to disseminate such information. This study, despite its comprehensive sample, failed to reveal any other reported cases. Nor has it been demonstrated that diabetics were at higher risk of developing NMS or its complications. It would be important to explore these possibilities further in future studies.peer-reviewe

Measuring dopaminergic function in the 6-OHDA-lesioned rat: a comparison of PET and microdialysis

BACKGROUND: [(18) F]fluorodopa (FDOPA) positron emission tomography (PET) allows assessment of levodopa (LDOPA) metabolism and is widely used to study Parkinson's disease. We examined how [(18) F]FDOPA PET-derived kinetic parameters relate the dopamine (DA) and DA metabolite content of extracellular fluid measured by microdialysis to aid in the interpretation of data from both techniques. METHODS: [(18) F]FDOPA PET imaging and microdialysis measurements were performed in unilaterally 6-hydroxydopamine-lesioned rats (n = 8) and normal control rats (n = 3). Microdialysis testing included baseline measurements and measurements following acute administration of LDOPA. PET imaging was also performed using [(11)C]dihydrotetrabenazine (DTBZ), which is a ligand for the vesicular monoamine transporter marker and allowed assessment of denervation severity. RESULTS: The different methods provided highly correlated data. Lesioned rats had reduced DA metabolite concentrations ipsilateral to the lesion (p < 0.05 compared to controls), with the concentration being correlated with FDOPA's effective distribution volume ratio (EDVR; r = 0.86, p < 0.01) and DTBZ's binding potential (BP(ND); r = 0.89, p < 0.01). The DA metabolite concentration in the contralateral striatum of severely (>80%) lesioned rats was lower (p < 0.05) than that of less severely lesioned rats (<80%) and was correlated with the ipsilateral PET measures (r = 0.89, p < 0.01 for BP(ND)) but not with the contralateral PET measures. EDVR and BP(ND) in the contralateral striatum were not different from controls and were not correlated with the denervation severity. CONCLUSIONS: The demonstrated strong correlations between the PET and microdialysis measures can aid in the interpretation of [(18) F]FDOPA-derived kinetic parameters and help compare results from different studies. The contralateral striatum was affected by the lesioning and so cannot always serve as an unaffected control

Less Is More - Estimation of the Number of Strides Required to Assess Gait Variability in Spatially Confined Settings

Background: Gait variability is an established marker of gait function that can be assessed using sensor-based approaches. In clinical settings, spatial constraints and patient condition impede the execution of longer distance walks for the recording of gait parameters. Turning paradigms are often used to overcome these constraints and commercial gait analysis systems algorithmically exclude turns for gait parameters calculations. We investigated the effect of turns in sensor-based assessment of gait variability. Methods: Continuous recordings from 31 patients with movement disorders (ataxia, essential tremor and Parkinson's disease) and 162 healthy elderly (HE) performing level walks including 180° turns were obtained using an inertial sensor system. Accuracy of the manufacturer's algorithm of turn-detection was verified by plotting stride time series. Strides before and after turn events were extracted and compared to respective average of all strides. Coefficient of variation (CoV) of stride length and stride time was calculated for entire set of strides, segments between turns and as cumulative values. Their variance and congruency was used to estimate the number of strides required to reliably assess the magnitude of stride variability. Results: Non-detection of turns in 5.8% of HE lead to falsely increased CoV for these individuals. Even after exclusion of these, strides before/after turns tended to be spatially shorter and temporally longer in all groups, contributing to an increase of CoV at group level and widening of confidence margins with increasing numbers of strides. This could be attenuated by a more generous turn excision as an alternative approach. Correlation analyses revealed excellent consistency for CoVs after at most 20 strides in all groups. Respective stride counts were even lower in patients using a more generous turn excision. Conclusion: Including turns to increase continuous walking distance in spatially confined settings does not necessarily improve the validity and reliability of gait variability measures. Specifically with gait pathology, perturbations of stride characteristics before/after algorithmically excised turns were observed that may increase gait variability with this paradigm. We conclude that shorter distance walks of around 15 strides suffice for reliable and valid recordings of gait variability in the groups studied here

Relationship between L-DOPA-induced reduction in motor and exploratory activity and degree of DAT binding in the rat

Purpose: The present study assessed the influence of L-DOPA administration on neostriatal dopamine (DA) transporter (DAT) binding in relation to motor and exploratory behaviors in the rat. Methods: Rats received injections of 5 mg/kg L-DOPA, 10 mg/kg L-DOPA or vehicle. Motor and exploratory behaviors were assessed for 30 min in an open field prior to administration of [(123)I]FP-CIT. Dopamine transporter binding was measured with small animal single-photon emission computed tomography (SPECT) 2 h after radioligand administration for 60 min. Results: Both L-DOPA doses significantly reduced DAT binding and led to significantly less head-shoulder motility and more sitting relative to vehicle. Moreover, 10 mg/kg L-DOPA induced less distance traveled and ambulation than 5 mg/kg L-DOPA. Analysis of time-behavior (t-b) curves showed that L-DOPA-treated animals relative to vehicle exhibited (1) a faster rate of increase in duration of sitting; (2) a slower rate of increase in duration of head-shoulder motility; and (3) a slower rate of decrease in frequency of head-shoulder motility. Conclusions: The reductions of striatal DAT binding after L-DOPA challenges reflected elevated concentrations of synaptic DA. L-DOPA-treated animals showed less head-shoulder motility and more sitting than vehicle-treated animals, indicating an association between less behavioral activity and increased availability of striatal DA. The faster increase of sitting duration to a higher final level and the slower increase of head-shoulder motility to a lower final level relative to controls may be interpreted in terms on behavioral habituation to a novel environment

The Effects of Treadmill or Overground Walking Training Program on Gait in Parkinson's Disease

[Abstract] Background. Gait impairment in Parkinson's disease (PD) patients is characterized by the inability to generate appropriate stride length. Treadmill training has been proposed as a therapeutic tool for PD patients. However, it remains unknown whether treadmill training effects are different from overground walking training. Thus, our goal was to explore the effects of two training programs, walking on a treadmill and walking overground, in PD patients. Methods. 22 PD patients were randomly assigned to a treadmill or overground training group. The training program consisted of 5 weeks (3 sessions/week). Before and after the program we evaluated gait kinematics during walking at preferred and maximal speed; Timed Up and Go (TUG); static posturography and knee extensors strength. Gait parameters were reevaluated in the treadmill training group one month after the cessation of the training. Results. Preferred speed walking improved in both groups after the training program. The treadmill training program, but not the overground, led to an improvement in the stride length at the preferred and maximal walking speed in the PD patients. In addition, the treadmill training group showed improvement of the TUG and static posturography tests. The improvement in gait parameters was maintained one month after the cessation of the treadmill training. Conclusions. This study provides evidence of a specific therapeutic effect of treadmill training on Parkinsonian gait and balance. Walking on a treadmill may be used as an easy, effective and accessible way to improve the stride length and balance in PD patients. Background. Gait impairment in Parkinson's disease (PD) patients is characterized by the inability to generate appropriate stride length. Treadmill training has been proposed as a therapeutic tool for PD patients. However, it remains unknown whether treadmill training effects are different from overground walking training. Thus, our goal was to explore the effects of two training programs, walking on a treadmill and walking overground, in PD patients. Methods. 22 PD patients were randomly assigned to a treadmill or overground training group. The training program consisted of 5 weeks (3 sessions/week). Before and after the program we evaluated gait kinematics during walking at preferred and maximal speed; Timed Up and Go (TUG); static posturography and knee extensors strength. Gait parameters were reevaluated in the treadmill training group one month after the cessation of the training. Results. Preferred speed walking improved in both groups after the training program. The treadmill training program, but not the overground, led to an improvement in the stride length at the preferred and maximal walking speed in the PD patients. In addition, the treadmill training group showed improvement of the TUG and static posturography tests. The improvement in gait parameters was maintained one month after the cessation of the treadmill training. Conclusions. This study provides evidence of a specific therapeutic effect of treadmill training on Parkinsonian gait and balance. Walking on a treadmill may be used as an easy, effective and accessible way to improve the stride length and balance in PD patients.Ministerio de Ciencia e Innovación;DEP-2011-2246

Structural and biophysical analysis of important biomedical enzymes and nano-architectures

Dopa decarboxylase (DDC) is an important enzyme in the catecholamine biosynthesis pathways. Catecholamines, e.g., dopamine, serotonin, etc. often are the major neuromodulators or neurotransmitters. Hence, DDC plays a key role in regulation of neurodegenerative diseases like Parkinson’s disease (PD). In order to achieve a medicine for PD, a successful inhibitor for DDC, that could reduce the activity of DDC in the blood while making it more effective in brain, is required. An effective design of an inhibitor requires a detailed structural study of human DDC. It was aimed to solve the DDC structure by X-ray crystallography. In order to have enough protein the DDC encoding gene has been cloned in the pET21d vector which was later termed as pET-DDC-His. However, it required numerous trials and errors until a suitable condition for soluble DDC expression was found. Addition of additives like PLP, ethanol, a complex of sorbitol and betaine in the growth medium of the bacteria did not help bring the protein in the soluble part as it formed inclusion bodies. Several soluble protein fusions with DDC, like Thioredoxin and Glutathione-S-transferase were also not quite helpful towards achieving soluble expression of DDC. Finally, a coexpression of DDC along with bacterial chaperone proteins, e.g., GroEL and GroES (after cotransforming both the DDC and Chaperone protein encoding plasmid in the same E.coli cell, used for expression) lead to solubilization of recombinant human DDC. This enzyme was then purified to homogeneity by successively passing the crude bacterial proteins through Ni-chelate-affinity chromatography and Size Exclusion Chromatography. The purified protein (>90 % purity) did not produce a good yield (4mg/ 8L culture), but this was enough to start the initial crystallization trial. Using a scale up to a 50 L culture, quite a good amount of protein was achieved. The homogeneity of DDC was further confirmed by using Multi-Angle Light Scattering and Blue Native PAGE. The dimeric enzyme preparation was then utilized for crystallization using the Hanging Drop Vapor Diffusion method. In a particular condition of the crystal screens trigonal bipyramidal crystals formed. However, these crystals did not show good diffraction when bombarded with X-ray beams. Later, this particular crystallization condition remained irreproducible. The peptide nanoparticle, designed and produced in our lab, could possibly be a very valuable tool in biomedical applications, e.g., in designing vaccines, delivering drugs, bioimaging, serodiagnosis, etc. The design of the peptide nanoparticles is based on the application of the symmetry elements of virus icosahedral capsid on a specially designed building block peptide. The designed peptide building block contains two oligomerization motifs, i.e., a trimeric coiled coil and a pentameric coiled coil joined by a linker region. Sixty such peptide units, upon self-assembly, would produce peptide nanoparticle mimicking a small icosahedral virus particle. The peptide chains in the building block provide flexibility in the design so that an additional peptide could be attached to it at the C-terminus in order to functionalize the peptide nanoparticle for various biomedical applications. First of all, the functional peptide at the C-terminus could be an epitope for the antibody of a life threatening disease like HIV. These peptide nanoparticles can then function as the potent vaccine candidate for that particular disease. In this thesis work, I have attached the two epitopes against the two broadly neutralizing classes of antibody for HIV infection, 2F5 and 4E10, to the peptide nanoparticle. Secondly, another sequence of peptide, which proved to have the capacity of seeding gold on its surface, was attached to the building block peptide unit. The nanoparticle, functionalized with such a peptide, can decorate a gold layer surrounding it. Gold coating on the peptide nanoparticle scaffold can provide a nanostructure, called ‘nanoshells’, which could be very important in the field of therapeutics because of its ability in easy detection and quick treatment of cancer cells. Lastly, I added three peptides; those are recognized in the culture filtrates of M.tuberculosis isolated from TB patients, separately, to the basic peptide construct to form three different nanoparticles. Also, I tried to make a single nanoparticle that displays all the three peptides on its surface. Such a nanoparticle could be a very useful tool in the serodiagnosis or the antibody-based rapid detection of the deadly disease- Tuberculosis. The nanoparticle formation in each of the above-mentioned cases was more or less successful. One of the constructs could successfully even produce gold shells on the peptide nanoparticle