bluuebunny/crossref_metadata_2025 huggingface dataset:
Mixture of ammonia and helium as a carrier gas for capillary gas chromatography
Authors: Abdel‐Rehim Mohamed , Zhang Lin , Hassan Moustapha , Ehrsson Hans
Published: May 2005

A mixture of ammonia and helium was used as a carrier gas for capillary gas chromatographic analysis of aliphatic amines and dichlorophenols. The peak symmetry for aliphatic amines was drastically improved when the percentage of ammonia was 5–30%. The symmetry continued to improve, although less drastically, between 30–100%ammonia. The capacity factors of the amines decreased with increasing ammonia content up to 100%. 2,5‐Dichlorophenol and 2,6‐dichlorophenol could not be resolved when helium alone was used as the mobile phase with a column of intermediate polarity (cyanopropylmethylphenylsilicone). Complete separation was, however, achieved by increasing the ammonia content in the carrier gas to 50%. The ratio of the capacity factors (k'NH3/k'He) for the dichlorophenols increased linearly with increasing ammonia percentage up to 100% on the methylsilicone and cyanopropylmethylphenylsilicone columns.
Shape selectivity assessment of stationary phases in gas chromatography
Authors: Sander Lane C. , Schneider Manfred , Wise Stephen A.
Published: May 2005

Column selectivity is examined for a series of smectic liquid crystalline columns and is compared with methyl and C18 polysiloxane columns for the separation of polycyclic aromatic hydrocarbon (PAH) isomers. A set of extended and condensed solute probes is described that provides a sensitive indication of variations in column shape selectivity. Examples of shape selectivity differences are presented for smectic liquid crystalline columns and 5% phenyl polysiloxane columns using various PAH isomer sets. Variations in selectivity have been observed among different smectic liquid crystalline columns, and this problem appears more significant than for methyl polysiloxane columns. The selectivity ration for tetraphenylmethane and p‐terphenyl provides a sensitive indication of column shape selectivity, with a change in elution order occurring between ordered (smectic liquid crystalline) columns and non‐ordered (methyl polysiloxane) columns. Shape selectivity differences indicated by this test mixture are apparent for more complex PAH isomer mixtures. Despite stationary phase selectivity variability, smectic liquid crystalline columns offer considerable potential for solving difficult separation problems involving structured solutes.
Performance of silica‐bonded quinolinol as a selective stationary phase for packed capillary supercritical fluid chromatography
Authors: Hägglund Ingela , Demirbüker Mustafa , Blomberg Lars G.
Published: May 2005

Selective stationary phases are of crucial importance in packed column supercritical fluid chromatography (SFC), and a potentially powerful selective stationary phase, silica‐bonded 8‐quinolinol, has been evaluated. Its performance was compared with that of an aminopropyl modified silica. The 8‐quinolinol columns could be used at temperatures up to 150°C, while the aminopropyl columns were degraded above 90°C. The general performance of the quinolinol column was very good when utilizing a mobile phase containing a polar modifier. Reduced plate heights of 4.8 to 3.8 and symmetrical peaks were obtained. Further, the quinolinol phase showed excellent selectivities under supercritical conditions. This was demonstrated by the separation of fatty acid methylesters and azaarenes. In addition, changes in selectivity could readily be made by loading with metal ions.
Capillary gel electrophoresis
Authors: Dolník Vladislav
Published: May 2005

Capillary gel electrophoresis (CGE) is a new rapidly developing method for biopolymer separations. It has been used successfully for separations of oligonucleotides, oligosaccharides, polyamino acids, and even for SDS electrophoresis of polypeptides. Shrinkage of the gel during polymerization, with resulting void formation as the main technological problem when making capillary gels, was overcome by several procedures. More recently, a modification of gel electrophoresis, using replaceable linear polymer solutions has gained popularity, especially for SDS electrophoresis of proteins and electrophoresis of DNA.
Capillary supercritical fluid chromatography with nitro‐ and nitroso‐specific chemiluminescence detection
Authors: Francis Eric S. , Eatough Delbert J. , Lee Milton L.
Published: May 2005

The thermal energy analyzer (TEA), a gas‐phase chemiluminescence detector which is specific for nitro and nitroso compounds, was evaluated as a detector for use with capillary supercritical fluid chromatography. The potential use of the TEA for thermally labile compounds and environmental samples was demonstrated. The TEA showed good sensitivity and broad linear dynamic range; minimum detectable quantities (MDQ) were below 20 pg for pentaerythritol tetranitrate (PETN) with a dynamic range of over 4 orders of magnitude. The analysis of cyclotetramethylene tetranitramine (HMX) was accomplished by using modified (CO2) with a corresponding MDQ of 67 pg. The selectivity of the TEA for nitro and nitroso compounds can be adjusted by changing the pyrolysis temperature. The SFC/TEA system was applied to a variety of nitro and nitroso compounds, and evaluated more extensively for routine analysis of propellant and explosive residues.
Solvent‐free sample introduction for supercritical fluid chromatography using polymer coated fibers
Authors: Hirata Yukio , Pawliszyn Janusz
Published: May 2005

A solvent‐free sample introduction method for supercritical fluid chromatography that uses polymer coated fused silica fibers results in very stable baseline and high efficiency separations. The method has two steps: first, a fiber is exposed to a prepared mixture of target analytes or a sample so that the polymeric coating absorbs analytes, and second, the fiber is placed inside a piece of tubing connected to the column of a supercritical fluid chromatograph. The supercritical fluid carrier extracts analytes from the coating and transfers them onto the head of the column. Pressure programmed separation follows. The method was tested on high molecular weight and polar analytes using 100 and 50 μm i.d. capillary columns. Fibers with a polydimethylsiloxane coating were used to extract hydrophobic analytes, and fibers with a polyacrylate coating were used to extract more polar compounds.
Functional group selectivity using fluoroform as a mobile phase for supercritical fluid chromatography
Authors: Blackwell John A. , Schallinger Luke E.
Published: May 2005

The eluotropic strenght and chromatographic selectivity of fluoroform is compared to that of carbon dioxide and methanol‐modified carbon dioxide. Naphthalene derivatives were used as probe solutes in capillary supercritical fluid chromatography to determine the effects of fluid type, pressure, and temperature on selectivity and retention. Fluoroform is much stronger in eluotropic strengh than carbon dioxide or methanol‐modified carbon dioxide at the same temperature and pressure. Under the same reduced conditions, fluoroform is lower in eluotropic strength than carbon dioxide. Specific interactions between hydrogen bond accepting functional groups and fluoroform are observed. Functional groups capable of accepting hydrogen bonds contribute less of an increase in retention when using fluoroform while those capable of dispersive interactions contribute less of an increase in retention when using carbon dioxide.
Rapid separation of DNA restriction digests using size selective capillary electrophoresis with application to DNA fingerprinting
Authors: Clark Brian K. , Nickles Christine L. , Morton Ken C. , Kovac Jeffrey , Sepaniak Michael J.
Published: May 2005

Capillary electrophoresis (CE) using running buffers containing a water soluble polymer (methylcellulose, MC) was employed for the rapid size‐selective separation and identification of plasmid DNA (pBR322 and pBR328). The two plasmid samples were distinguished based on differences in CE elution patterns resulting from injections of their Hinfl enzyme digests. The restriction fragments in the digests were detected by incorporating the DNA intercalation dye, ethidium bromide (EB), in the running buffer and utilizing laser fluorimetry. Short separation times were achieved by increasing the applied field, but with a concomitant decrease in fragment resolution. This behavior was attributed to three main effects: (i) a reduction in efficiency due to problems with Joule heating, (ii) a decrease in selectivity as the fragments elongate and align with the high fields, and (iii) a general reduction in system retention due to the fragment elongation and increased capillary temperature. The deleterious effects of Joule heating were minimized by employing small diameter capillaries and low buffer concentrations. The molecular weight of the MC polymer primarily influenced separation efficiency. Conversely, MC concentration influenced both selectivity and system retention. High efficiency (106 plates m−1) and good resolution of the fragments in the different restriction digests were achieved using running buffers containing 100,000 MW methyl cellulose at high fields. Under optimized conditions, the test plasmid sample digest provided reproducible and unique elution profiles with 120 s separation times.
Fused silica packed capillary columns in supercritical fluid chromatography
Authors: Li Wenbao , Malik Abdul , Lee Milton L.
Published: May 2005

Packed capillary columns provide advantages of low flow rates, moderate sample capacities and loadabilities, short analysis times, high detectabilities, and the possibility of using a wide variety of commercially available stationary phases. This type of column is finding increasingly more applications in a variety of fields. In this paper, we report detailed studies using relatively long (0.5 to 10 m) packed capillary columns in SFC. Characteristics such as packing density and column stability are reported, as well as efficiency, resolution, and pressure drop for the different columns. It was found that densely packed capillary columns prepared using supercritical CO2 as the slurry fluid are more stable and generally have better performance than conventional solvent slurry packed columns.
Polyacrylamide‐modified polypropylene hollow fibers for capillary electrophoresis
Authors: Liu Peter Z. , Malik Abdul , Kuchar Marvin C. J. , Lee Milton L.
Published: May 2005

Surface treatment methods were developed for bonding of a polyacrylamide layer on the inside surface of polypropylene hollow fiber columns for capillary electrophoresis. Details of different modification procedures involving surface activation and in situ polymerization, using dynamic and static coating of reagents, are described. Both linear and cross‐linked polyacrylamide modified surfaces greatly improved the electrophoretic performance of the capillaries. The column efficiencies for model proteins reached as high as 370,000 theoretical plates on an 85 μm i.d. polyacrylamide surfacetreated polypropylene hollow fiber column. A variety of applications, including the separation of several very polar compounds at a pH of 10.6, were demonstrated. Reproducibility measurements were used to illustrate the performance and high pH stability of the resultant columns.
Optimization of resolution of 13 diuretics in CZE by controlling capillary length and electroosmotic flow velocity
Authors: Jumppanen Juho Hermanni , Riekkola Marja‐Liisa , Haario Heikki
Published: May 2005

The separation of diuretics in CZE can be further improved by controlling the capillary length and the analysis times independently, while other parameters are kept constant. This can be done by using a modifier in the electrolyte solution which has a strong effect on the electroosmosis, but negligible effect on the selectivity of the electrolyte system.

In this work, [Cu(NH3)4]2+ was used at low concentration (0 – 140 μM) to control the electroosmotic flow velocity (veo) and hence the analysis time, determined as the migration time of the last migrating compound (tfin). With other parameters, especially V, kept constant, the use of shorter capillaries enables the use of high electric field strength for the separation.

The use of quadratic regression models proved to be an effective way to study the effect of Ltot and tfin on the Rs of each analyte pair. The theoretical values for the separation of peak maxima correlated well with the values predicted by the empirical regression models. The actual band broadening was much stronger, however, than what was predicted by the overly simplified theoretical calculations based on the electrophoretic mobilities as well as the self diffusion coefficients of the diuretics, determined by the two marker technique. Further study is needed on theoretical modelling of the band broadening, while the use of regression models and desirability functions provided a convenient way to determine the optimal conditions.

The results showed that independent control of Ltot and tfin offers an effective way to further optimize capillary electrophoretic separation. This method should prove important in cases where sufficient separation is difficult to achieve.
Calculation of statistical attributes in small regions of separations: Variation of overlap probability along the separation coordinate
Authors: Davis Joe M.
Published: May 2005

Theory based on the extended statistical model of overlap (SMO) is proposed to predict the numbers of components in small regions of separations and the likelihood of overlap along the separation coordinate. The extended SMO is an expansion of theory begun a decade ago and, unlike its predecessor, allows one to estimate statistical parameters from separations containing peaks of variable density. These estimations are made possible by frequencies that scale the relative density of peaks. Using a frequency determined from a complex separation, one can critique overlap in small regions of the separation containing as few as five components. The ability to quantify overlap in small regions allows one to characterize local overlap patterns that would be obscured by interpretation of large regions. Furthermore, with the frequency, the probability of forming singlet and multiplet peaks can be calculated along the separation coordinate. Unlike with earlier theory, the frequency allows the values of these probabilities to change continuously throughout the separation. Applications of theory are made to four gas chromatograms of lime oil, which were developed by different temperature programs to vary the peak density therein.
Low concentration drug analysis by semi‐microcolumn liquid chromatography with a polymer‐coated mixed‐function precolumn
Authors: Shirota Osamu , Suzuki Ayako , Kanda Taketoshi , Ohtsu Yutaka , Yamaguchi Michihiro
Published: May 2005

The construction and performance of dual‐and triple‐column systems for the analysis of dilute drug samples are described. The systems are based on the following two separation processes: (1) deproteinization and analyte fractionation using a short polymer‐coated mixed‐function (PCMF) phase (10 mm × 4.0 mm i.d. column) and, (2) final separation using a C18 semi‐microcolumn (1.5 to 2.0 mm i.d.). The surface structure of the MF phase and the geometry of the packed column for the primary separation made it possible to inject hundreds of microliters of serum samples into the system. Analytes separated in the primary chromatography are transferred to the main column with or without an intermediate column (35 mm × 1.0 mm i.d.). A system using an intermediate column was designed to save time of analysis when a 1.5‐mm i.d.(and smaller) main column was used. The systems showed an increased concentration sensitivity for drug molecules, such as diazepam, carbamazepine, and phenobarbital, without any loss in chromatographic efficiency. Carbamazepine and phenobarbital at 12.5 ppb and 50 ppb, respectively, in human serum were detected with good S/N ratio.
Structural characteristics of pendant and copolymeric cyclodextrin polysiloxane stationary phases and their influence on chiral selectivity and resolution in capillary gas chromatography
Authors: Malik Abdul , Yun Hao , Yi Guoliang , Bradshaw Jerald S. , Rossiter Bryant E. , Markides Karin E. , Lee Milton L.
Published: May 2005

The dependence of gas chromatographic properties on stationary phase structural characteristics was evaluated for three different types of cyclodextrin‐bonded polysiloxanes: small‐rim‐tethered, large‐rim‐tethered, and copolymeric. Separation efficiency, chiral selectivity, and resolution were investigated as functions of stationary phase structural features such as length and chemical composition of the connecting arms, chemical composition of the substituent groups on the small rim of the cyclodextrin toroid, and the position(s) of connecting arm attachment(s) on the cyclodextrin rims. For all of the solutes and experimental conditions used in this study, the small‐rim‐tethered cyclodextrin phases were found to provide superior chromatographic performances compared to the other two types of cyclodextrin phases. The chiral selectivities of the investigated phases were found to depend both on chemical composition and length of the connecting arm(s). Shorter connecting arms were found to provide improved chiral selectivities. Stationary phases having a four‐carbon connecting arm with an etheric oxygen linkage in the chain provided higher chiral selectivities compared to stationary phases with hydrocarbon or phenoxy group‐containing connecting arm(s). The chiral selectivities of the studied phases did not change when the substituents at the C‐6 positions were changed from ‐CH2OCH2 to ‐CH3. Efficiency values of up to 5,000 theoretical plates per meter were obtained using 200 μm i.d. columns. Column efficiency was found to be independent of structural features of the cyclodextrin toroid and the connecting arms.
Enantioselective separations by capillary gas chromatography on derivatized cyclodextrins. Part IV: Enantioselective interaction model of 2,2‐dialkyl‐4‐alkoxycarbonyl‐1,3‐dioxolane derivatives on some substituted cyclodextrins
Authors: Jaques K. , Buda W. M. , Venema A. , Sandra P.
Published: May 2005

An evaluation of the effects of differently derivatized cyclodextrins and analyte geometry for a series of 2,2‐dialkyl‐4‐alkoxycarbonyl‐1,3‐dioxolane derivatives on enantioselectivity has been performed. It was shown that changes in the cyclodextrin cavity size, caused by either the choice of type (α‐, β‐ or γ‐cyclodextrin) or substitution pattern, strongly affect the selectivity of the chiral separation of the substituted dioxolanes. The geometry of the analyte also appears to be very important to the selectivity. A model of the inclusion complex is proposed.
Pore size influence in chiral packed column micro‐LC
Authors: Svensson Lars A. , Karlsson Karl‐Erik
Published: May 2005

Fused silica capillary columns containing α‐chymotrypsin‐modified silica were used to separate the enantiomers of naproxen. The separation was followed with a fluorescence detector that could be moved to several positions along the column. The interest was focused on the effect of the pore size of the original unmodified diol‐silica‐gel. The results indicate that the large pore material yields more efficient columns. It was also noted that the van Deemter plot reached a plateau value at higher flow rates for this large pore material. © 1995 John Wiley & Sons, Inc.
On‐line sample enrichment–capillary gas chromatography of aqueous samples using geometrically deformed open‐tubular extraction columns
Authors: Mol Hans G. J. , Janssen Hans‐Gerd , Cramers Carel A. , Brinkman Udo A. Th.
Published: May 2005

The effect of geometrical deformation of open‐tubular extraction columns on peak dispersion of retained solutes is evaluated. By coiling or stitching of the columns peak dispersion is decreased, with a factor of two and more than five, respectively, due to secondary flow enhanced radial dispersion. This enables the increase of sampling flow rates in on‐line extraction‐GC using open‐tubular extraction columns up to 4 mL/min while still obtaining quantitative trapping of the analytes. © 1995 John Wiley & Sons, Inc.
Cyclodextrin derivatives in GC separation of racemic mixtures of volatiles. Part IX. The influence of the different polysiloxanes as diluting phase for 2,3‐di‐O‐acetyl‐6‐O‐t‐butyldimethylsilyl‐β‐cyclodextrin on the separation of some racemates
Authors: Bicchi C. , D'Amato A. , Manzin V. , Galli A. , Galli M.
Published: May 2005

The results of a series of experiments concerning the GC enantioseparation of some racemates on columns coated with 2,3‐di‐O‐acetyl‐6‐O‐t‐butyldimethylsilyl‐β‐cyclodextrin diluted in two different polysiloxanes (PS‐086 and OV‐1701) are reported. The investigation is centered on the influence of the diluting phase on the separations of the racemates investigated [δ‐heptalactone, linalyl acetate, and an homologous series of cis‐2‐(2‐alkyl‐cyclopropyl)‐ethanol (alkyl from ethyl to heptyl)] because one of the two polysiloxanes separated them, whereas the other did not. Column retention and efficiency characteristics were investigated as a function of the diluting phase. Retention increase (RI) and Gibbs–Helmholtz parameter (ΔR,SΔG) were determined for each of the above racemates, analyzed by different mixtures of the CDD selector with the two diluting phases. © 1995 John Wiley & Sons, Inc.
Analysis of fumonisin B1 in corn by capillary electrophoresis with fluorescence detection of the FMOC derivative
Authors: Holcomb Manuel , Thompson Harold C.
Published: May 2005

A new method has been developed for the analysis of fumonisin B1 in corn using capillary electrophoresis. Fumonisin B1 is the major fumonisin metabolite produced by the fungus Fusarium moniliforme and has been implicated in human and animal diseases. Fumonisin B1 was extracted from corn with acetonitrile/water (50/50) and cleaned up with a Waters C18 Sep‐Pak Vac cartridge. Fumonisin B1 was quantitated after elution from the C18 Sep‐Pak column using capillary electrophoresis (CE) with a 25 mM sodium borate buffer (pH 9.0) containing 10% acetonitrile and fluorescence detection of the FMOC derivative. The minimum detectable amount in corn was 0.5 ppm. Recovery values in spiked corn averaged over 96% over the range 1–20 ppm. © 1995 John Wiley & Sons, Inc.
Application of peralkylated β‐CDs capillary columns for the GC separation of positional isomers of industrial chemicals
Authors: Dai Rongji , Fu Ruonong , Zhou Wei
Published: May 2005

Peralkyiated β‐cyclodextrins were used as stationary phases to separate positional isomers of industrial chemicals. Their selectivity was measured using isomers of dimethylphenols. Among the peralkylated β‐cyclodextrins, permethylated β‐cyclodextrins possess the highest selectivity. Finally, they were used to separate some positional isomers such as disubstituted benzene and so on. The results show that peralkylated β‐CDs were excellent GC stationary phases in industrial analysis.
Capillary electrophoresis/electrospray ionization ion trap mass spectrometry using a sheathless interface
Authors: Ramsey Roswitha S. , McLuckey Scott A.
Published: May 2005

The sensitivity that can be obtained with the quadrupole ion trap for on‐line CE analysis using a sheathless electrospray interface and gold‐tipped columns is examined. Capillaries of different i.d. are compared in continuous infusion experiments and the effects of sheath solvents on the signal for some peptides and proteins are illustrated. The sheathless CE/ITMS system using 20 μm i.d. columns is shown to provide mid‐attomole detection levels for leucine enkephalin in total ion electropherograms under full scan conditions. Good quality MS/MS spectra are also obtained for low femtomole injections of this peptide.
Modification of the inner capillary surface by the sol‐gel method: Application to open tubular electrochromatography
Authors: Guo Yong , Colón Luis A.
Published: May 2005

The sol‐gel procedure was used to prepare an organically modified silica glass coating material which was used as the stationary phase for reversed‐phase open tubular electrochromatography. The unique column preparation scheme is simplified by combining the synthesis of the stationary phase and the attachment of the supporting porous glass matrix in a single‐step procedure. This approach significantly increases surface area which results in a higher phase ratio. Controlling the amount of the precursor materials used in the sol‐gel solution provides a means to adjust the carbon content in the stationary phase. The column performance was evaluated using a test mixture of polycyclic aromatic hydrocarbons; under certain experimental conditions, efficiencies around 500,000 theoretical plates per meter were obtained for some test solutes.
High temperature liquid chromatography on packed capillary columns with nonaqueous mobile phases
Authors: Trones Roger , Iveland Asbjorn , Greibrokk Tyge
Published: May 2005

The need for a high resolution chromatographic technique for analyzing compounds that are heavy, relatively polar, have low water solubility, and are not adequately separated by regular HPLC methods, has led to the development of a high temperature liquid chromatography system. The increased diffusion coefficients and reduced viscosity at higher temperatures resulted in high separation velocities and allowed long columns to be used. The HTLC system contained 70 cm columns and nonaqueous mobile phases. Packed capillary columns prevented radial temperature gradients which otherwise would reduce the efficiency. The capillary columns were packed with a reversed phase material (ODS) using supercritical carbon dioxide as the slurry fluid. A new method for preparing a ceramic frit inside the column was developed. The frit withstood pressures of at least 600 bar. The robustness of the columns in a nonaqueous environment with elevated temperature was tested and found satisfactory for 150 injections with a temperature program at each injection. Isothermal elution or temperature programming in the 50–150°C range reduced the analysis time significantly. Compounds which were completely retained at room temperature eluted with good peak shape at elevated temperature.
Evidence of peripheral axonal neuropathy in primary restless legs syndrome
Authors: Iannaccone Sandro , Zucconi Marco , Marchettini Paolo , Ferini‐Strambi Luigi , Nemni Raffaello , Quattrini Angelo , Palazzi Stefano , Lacerenza Marco , Formaglio Fabio , Smirne Salvatore
Published: May 2005

Restless legs syndrome (RLS) is a well‐defined clinical entity characterized by an unpleasant creeping sensation arising in the legs with an irresistible need to move them. The trouble is more pronounced when the affected people lie in a prolonged rest position and try to fall asleep. It is known that RLS may be consequent to systemic disorders and to diseases affecting the central or peripheral nervous system. The International Classification of Sleep Disorders states that peripheral neuropathy should be ruled out by medical history and clinical grounds before diagnosing primary RLS (pRLS). The present study extended peripheral nerve investigation in eight consecutive pRLS patients with normal neurological examination results and showed that all patients exhibited two or more electrical, psychophysiological, and/or morphological features of peripheral axonal neuropathy. Morphometric analysis of sural nerve showed a significant reduction in myelinated fiber density and g ratio (axon diameter/fiber diameter) in the pRLS group compared with eight control biopsy specimens. These results suggest that axonal neuropathy is often present in patients with RLS. A comprehensive peripheral nerve investigation should be considered in RLS patients.
Striatal dihydroxyphenylalanine decarboxylase and tyrosine hydroxylase protein in idiopathic Parkinson's disease and dominantly inherited olivopontocerebellar atrophy
Authors: Zhong Xiao‐Hui , Haycock John W. , Shannak Kathleen , Robitaille Yves , Fratkin Jonathan , Koeppen Arnuf H. , Hornykiewicz Oleh , Kish Stephen J.
Published: May 2005

We measured the levels of dopamine, tyrosine hydroxylase (TH) protein, and dihydroxyphenylalanine (DOPA) decarboxylase (DDC) protein in the striatum of 10 patients with idiopathic Parkinson's disease (PD) and 23 patients with dominantly inherited olivopontocerebellar atrophy (OPCA). The levels of dopamine were markedly reduced (2% of control) in the striatum of the patients with PD, whereas striatal dopamine in the patients with OPCA ranged from normal (<60% of control) to moderately reduced (20–60% of control) to severely depleted (<20% of control). Both TH and DDC protein levels were significantly lower than those of the controls in the striatum of all of the patients with PD and in the subgroup of patients with OPCA having severely depleted dopamine. In contradistinction, TH but not DDC protein levels were reduced in those patients with OPCA having moderately reduced dopamine levels. This suggests that in the early stage of nigrostriatal dopamine neurone degeneration, DDC levels may be less susceptible to neurodegenerative influences than is TH synthesis or, alternatively, DDC synthesis may be more aggressively upregulated. Unexpectedly, from the blot immunolabeling analysis an additional DDC‐immunoreactive band of slightly lower apparent molecular mass was detected in two of the patients with PD and in 12 of the patients with OPCA. This additional DDC band, which was not present in any of the control subjects, may reflect posttranslational modification(s) of DDC related to the neurodegenerative process.
Gonadal sex hormones and dystonia: Experimental studies in genetically dystonic hamsters
Authors: Löscher Wolfgang , Blanke Thomas , Richter Angelika , Hoppen Hans‐Otto
Published: May 2005

In some kinds of idiopathic dystonia, including paroxysmal dystonia, a role of sex hormones has been suggested because of female predominance and onset, recurrence, or exacerbation of dystonic symptoms with pregnancy. Similar effects of pregnancy have recently been reported in a model of paroxysmal dystonia, the genetically dystonic hamster. Dystonia in mutant hamsters of both genders is transient, i. e., exhibits spontaneous remission at around puberty, strongly suggesting involvement of gonadal sex hormones. For exploration of the role of sex hormones in dystonia, we undertook a series of ontogenetic experiments in male and female dystonic hamsters. Mutant animals of both genders exhibited the same postnatal development of dystonia with maximum severity of dystonic attacks between weaning and ∼40 days of age and spontaneous remission thereafter. As shown by plasma sex hormone determinations and, in females, vaginal cytology, spontaneous improvement of the movement disorder coincided with puberty in both genders. Male and female hamsters had about the same plasma levels of progesterone. Compared with nondystonic hamsters, onset of puberty was significantly retarded in both male and female dystonic hamsters. Furthermore, body weight gain was lower in dystonic animals, indicating retarded postnatal development. Gondectomy at time of weaning did not alter the age‐dependent development and remission of dystonia, suggesting that gonadal sex hormones are not critically involved in the disease in hamsters. We propose that transient paroxysmal dystonia in mutant hamsters is caused by postnatal retardation of brain development resulting in a temporary impairment of brain functions with spontaneous remission independent of gonadal sex hormones. In view of the fact that the brain can synthesize steroids such as progesterone independent of peripheral glands in both genders, such neurosteroids might be involved in the postnatal brain maturation that leads to remission of dystonia at around puberty in mutant hamsters.
Tremor as a factor in prolonged reaction times of Parkinsonian patients
Authors: Staude G. , Wolf W. , Ott M. , Oertel W. H. , Dengler R.
Published: May 2005

Prolonged reaction times and tremor are symptoms of Parkinson's disease (PD). Recently, we showed the existence of a systematic phase relationship between tremor‐at‐rest and the onset of voluntary motor responses in PD patients. In the present study we investigated whether this phase relationship contributes to the prolongation of reaction time in PD. Eight PD patients with prominent tremor‐at‐rest and five age‐matched controls performed rapid stimulus‐evoked index finger abductions under isometric conditions. Force and surface electromyogram (EMG) signals from first dorsal interosseus muscle were recorded and analyzed off‐line by means of automatic routines. Reaction times of PD patients exhibited a significant dependence of mean values and variability on the current tremor phase at the onset of the voluntary motor response. Responses with an onset of contraction during the beginning of an EMG tremor burst were substantially delayed (on average 50 ms) and showed more variability in comparison to responses initiated at later times in the tremor cycle. This effect can be modeled by a simple gating process splitting the tremor cycle into two different system states that supports and inhibits the initiation of voluntary motor responses, respectively. We conclude that attraction of voluntary motor initiation to the tremor oscillator clearly contributes to prolongation of reaction time in PD.
Platelet mitochondrial respiratory chain function in Parkinson's disease
Authors: Blake C. I. , Spitz E. , Leehey M. , Hoffer B. J. , Boyson S. J.
Published: May 2005

Reports on mitochondrial respiratory chain (MRC) complex I (CI) dysfunction in the substantia nigra in Parkinson's disease (PD) support the oxidative stress hypothesis in the neuropathogenesis of PD. Studies in peripheral tissue have found variable decreased CI and occasionally other complex activity suggestive of systemic impairment of MRC function in PD; however, MRC activity may be influenced by numerous variables. We conducted spectrophotometric measurements of MRC function in platelet mitochondrial preparations in 13 individuals with PD and 9 age‐matched controls (CON) and have identified additional variables that may affect MRC activity. Mean CI, CIII, CIV, and citrate synthase (CS) activities were similar between PD and CON. CIII and CIV, specific and CS‐corrected, activities were significantly positively correlated with CI in combined and individual group data, with the exception of CIII CS‐corrected and CIV specific activities in CON and PD, respectively. CIII and CS specific activities were negatively correlated with age in CON, but varied randomly in PD. In PD, CIII specific activity was 1.4‐fold higher in those with a history of environmental risk factors for PD and CIV specific activity was lower in those with a positive family history of PD [8.34 ± 0.74 (n = 4) vs. 12.4 ± 1.1 (SEM) min−1 mg−1; p = 0.046]. Group heterogeneity, variables affecting enzyme activity, and intrinsic properties of cells may thus contribute to conflicting data in studies of MRC function in platelets and other tissues.
The characterization and outcome of stereotypic movements in nonautistic children
Authors: Tan Adrian , Salgado Miran , Fahn Stanley
Published: May 2005

Stereotypies are patterned, repetitive, purposeless movements that are performed the same way each time. They are commonly seen in individuals with autism, schizophrenia, or mental retardation, and also occur as a feature of tardive dyskinesia and as movements in those with akathisia. We studied 10 children who had stereotypies but were not autistic or mentally retarded. Although most had an uneventful delivery, seven had mild to moderately delayed developmental milestones. Five had hyperactive behavior or attention‐deficit problems. All appeared to be of normal intelligence. The median age of onset of stereotypies was 12 months. The stereotypies included arm flapping, arm and hand posturing, finger wiggling, body rocking, leg shaking, facial grimacing, involuntary noises, neck extension, and eye blinking. Of the 10 children, only two stopped having stereotypies eventually without medications.
Comparison of clinical rating scales in treatment of cervical dystonia with botulinum toxin
Authors: Tarsy Daniel
Published: May 2005

Seventy‐six consecutive patients with cervical dystonia (CD) treated with botulinum toxin were assessed with the Tsui rating scale, the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS), and a global scale of improvement. Tsui, TWSTRS, and TWSTRS subscale scores all showed significant improvement. Tsui and TWSTRS score reduction rates correlated significantly with each other, and each correlated with the global scale. Analysis of these scales and TWSTRS subscales indicates that an objective scale of severity such as either the Tsui rating scale or TWSTRS severity subscale used in conjunction with the TWSTRS pain subscale adequately assesses improvement of CD following treatment with botulinum toxin.
Reduced Gs protein function and Gαs levels in leukocytes of patients with Parkinson's disease
Authors: Avissar Sofia , Barki‐Harrington Liza , Herishanu Yuval , Schreiber Gabriel
Published: May 2005

Early events in signal information transduction beyond dopamine, β‐adrenergic, and muscarinic receptors, involving receptor‐coupled G‐protein function and Gα subunit immunoreactive levels were measured in mononuclear leukocytes (MNLs) of 12 never‐treated patients with Parkinson's disease in comparison with 10 age‐ and sex‐matched healthy control subjects. Both β‐adrenergic and dopamine receptor‐coupled Gs protein function as measured by cholera toxin‐sensitive, isoproterenol‐ and dopamine‐induced increases in Gpp(NH)p‐binding capacity, in MNLs of patients with Parkinson's disease were found to be significantly reduced in comparison with those in the control group. Muscarinic receptor‐coupled non‐Gs (Gi or Go) protein function: pertussis toxin‐sensitive, carbamylcholine‐induced increase in Gpp(NH)p‐binding capacity, was not found to be significantly different between patients with Parkinson's disease and control subjects. G protein α subunits were measured through immunobloting analyses with specific polyclonal antibodies against Gαs, Gαi, and Gαq subunits. MNL levels of the 45‐kDa species of Gαs were found to be significantly reduced in patients with Parkinson's disease in comparison with control subjects. Other non‐Gs proteins (Gi, Gq) did not show any significant quantitative differences between patients with Parkinson's disease and control subjects. The reductions in Gαs, levels in MNLs of patients with Parkinson's disease may explain the β‐adrenergic and dopamine receptor–coupled Gs, protein hypofunction detected in MNLs of these patients. As previous studies have failed to observe significant changes in receptor levels in MNLs of patients with Parkinson's disease, our findings of reduced dopa‐minergic and β‐adrenergic receptor–coupled Gs function and of Gαs immunoreactive levels in MNLs of Parkinson's patients point to alterations distal to these receptors at the level of the signal‐transducing Gs protein.
The effects of early selegiline therapy on long‐term levodopa treatment and parkinsonian disability: An interim analysis of a norwegian–danish 5‐year study
Authors: Larsen Jan P. , Boas Jette ,   Norwegian‐Danish Study Group
Published: May 2005

In this study, we investigated the effects of selegiline on levodopa treatment and parkinsonian disability over several years of treatment in patients with early Parkinson's disease (PD). The 163 patients were randomized to receive either selegiline or placebo in addition to levodopa in a double‐blind, parallel‐group study design, and the patients were to be followed up until a defined termination point or for 5 years. All patients had previously either never (two thirds) or for <6 months (one third) received levodopa. After 1 year of treatment or at withdrawal from study or both, the patients were divided according to specified diagnostic criteria into groups of definite, probable, possible, or unlikely PD. The efficacy parameters were levodopa therapy, Unified Parkinson's Disease Rating Scale (UPDRS) with subscales, and the time to develop wearing‐off fluctuations or reaching the termination point. Evaluation of efficacy was performed for all patients with PD and for patients with a definite and probable disease. The results of this study are based on an interim analysis when 80% of the 163 randomized patients had been followed up for ≥3 years. Nine patients were excluded from the study because of protocol violations or because the patients were diagnosed as unlikely PD. At the time of interim analysis, 39 patients had been withdrawn from the study because of adverse effects or their own wish. Eighteen patients had reached the termination point, and 97 patients (observation time, 30–54 months) were still in the study. Among the patients receiving selegiline, we found a rather stable daily levodopa dose during 54 months of therapy, compared with an anticipated increase among patients with levodopa monotherapy. Concurrently, patients in the selegiline group showed a trend to develop less severe parkinsonian disability and a lower frequency of motor fluctuations and need for additional antiparkinsonian medication. The results of this study indicate that early combination therapy of selegiline and levodopa compared with levodopa monotherapy has an increasingly favorable impact on the long‐term daily levodopa dose and may possibly delay the development of disability in PD.
Phenotypic heterogeneity and disease course in three murine strains with mutations in genes encoding for α1 and β glycine receptor subunits
Authors: Simon Ely S.
Published: May 2005

Impaired glycinergic inhibition causes human hyperekplexia, and may be involved in the pathogenesis of movement disorders associated with uremia, spinal cord lesions, DDT poisoning, and tetanus. Three autosomal recessive mutant mouse strains with single‐gene mutations affecting either the α1 (spasmodic and oscillator) or β (spastic) subunits of the glycine receptor were studied. Serial videotaped examinations assessed the severity of hyperkinetic features. Homozygote oscillator mice appeared normal until postnatal day (P) 11–14, when decreased exploratory movements, spastic gait, stimulus‐induced myoclonic bouts, rigidity, and tremor were noticeable. All symptoms gradually worsened until death by P21–P23. In contrast, spastic and spasmodic mice were most severely affected by the 3rd–5th week of life and had a lessening of symptom severity in adulthood. Within each mutant strain, there was marked interanimal variation of severity of the other motor abnormalities, possibly because of stochastic variability in developmental processes. These mutants represent good animal models for elucidation of molecular and cellular issues regarding the glycine receptor and for the study of pathogenetic mechanisms of movement disorders.
Motor fluctuations during continuous levodopa infusions in patients with Parkinson's disease
Authors: Nutt John G. , Carter Julie H. , Lea Eric S. , Woodward William R.
Published: May 2005

The cause of motor fluctuations occurring during constant‐rate levodopa infusions is unknown. We examined whether known pharmacokinetic factors could explain the fluctuations and looked for clues to pharmacodynamic causes. Eleven subjects with stage III–V Parkinson's disease (PD) and a fluctuating response to levodopa underwent constant‐rate infusions for 36–110 h. Levodopa, 3‐O‐methyldopa (3‐OMD), and plasma large neutral amino acids (LNAAs) were measured at 2‐ to 6‐h intervals and PD was monitored hourly from 07:00 to 22:00 h with tapping speed. Ten subjects had motor fluctuations during the infusions. Zero to 68% of the variability of tapping speed could be explained by variation in plasma LNAA concentrations in individual subjects. Flutuations occurred more commonly later in the day, which may be related to the tendencey fo LNAAs to increase during the day. Motor fluctuations were not associated with minor variations in levodopa or 3‐OMD concentrations. Fluctuations during constant infusions were more marked in patients using larger daily doses of oral levodopa; severity of PD did not predict fluctuations during the infusions. There was no trend for fluctuations or dyskinesia to decrease or increase during several days of constant‐rate levodopa infusion. A portion of motor fluctuations occurring during constant levodopa infusions can be explained by peripheral pharmacokinetic mechanisms. Fluctuations are more prominent in subjects who have taken larger daily doses of levodopa, implicating pharmacodynamic factors as well.
Movement disorders cochrane collaborative review group
Authors: Clarke C. E. , Sampaio C.
Published: May 2005

Evidence‐based medicine is the process of sytematically finding, appraising, and applying contemporaneous research findings as the basis for clinical decisions. The individual clinician is too busy to perform this long and arduous task across the whole of their specialty, so they must rely on the highest quality reviews available in the literature. The Cochrane Collaboration is an international network of individuals preparing, maintaining, and disseminating systematic reviews of trials of all health care interventions. We examine the work of the Collaboration and the major method it uses to dissmisnate systematic reviews through the Cochrane Libray. The rationale for the Cochrane Movement Disorders Group is discussed, and its management structure outlined.
Perception of spatial orientation in spasmodic torticollis part I: The postural vertical
Authors: Anastasopoulos D. , Bhatia K. , Bisdorff A. , Bronstein A. M. , Gresty M. A. , Marsden C. D.
Published: May 2005

Estimates of points of entering and exiting from upright posture were obtained from 25 seated, restrained patients with idiopathic spasmodic torticollis (ST) and matched normal subjects exposed to cycles of 1.5°/s tilts in a flight simulator. Estimates were obtained for displacements in roll and pitch about upright and for yaw tilts about a rostrocaudal, “barbecue,” axis with the subjects supinated. For both pitch and roll, normal subjects estimated entering upright when they were still ∼1° from machine upright and perceived themselves to be upright through a mean arc of 6°. In barbecue tilt, entering upright was estimated at 0.2° for an arc of 6°. Patients estimated entering upright at 2.8° in roll and 3° in pitch but estimated exiting upright at the same tilt as normal subjects; that is, they were less specific in detecting verticality. Patients were normal in barbecue tilt. No relationship between tilt estimates and head deviation was found. There were no differences between normal subjects when tested with their head in normal posture and with an assumed tilt of 20°. Normal subjects probably based their estimates on combined vestibularsomatosensory signals, whereas torticollis patients appeared to derive more from a vestibular signal. However, patients referred the vestibular signals to the trunk long axis when asked to indicate the whole‐body vertical. The findings suggest disruption of the normal combined vestibuloproprioceptive mechanism for detecting body uprightness in ST.