Subthalamic deep brain stimulation at individualized frequencies for Parkinson disease.

OBJECTIVES: The oscillation model of Parkinson disease (PD) states that, in the subthalamic nucleus (STN), increased θ (4-10 Hz) and ß (11-30 Hz) frequencies were associated with worsening whereas γ frequencies (31-100 Hz) were associated with improvement of motor symptoms. However, the peak STN frequency in each band varied widely from subject to subject. We hypothesized that STN deep brain stimulation (DBS) at individualized γ frequencies would improve whereas θ or ß frequencies would worsen PD motor signs. METHODS: We prospectively studied 13 patients with PD. STN local field potential (LFP) was recorded after electrode implantations, in the OFF and then in ON dopaminergic medication states while patients performed wrist movements. Six individual peak frequencies of the STN LFP power spectra were obtained: the greatest decrease in θ and ß and greatest increase in γ frequencies in the ON state (MED) and during movements (MOVE). Eight DBS frequencies were applied including 6 MED and MOVE frequencies, high frequency (HF) used for chronic stimulation, and no stimulation. The patients were assessed using the motor Unified Parkinson's Disease Rating Scale (mUPDRS). RESULTS: STN DBS at γ frequencies (MED and MOVE) and HF significantly improved mUPDRS scores compared to no stimulation and both γ frequencies were not different from HF. DBS at θ and ß frequencies did not worsen mUPDRS scores compared to no stimulation. CONCLUSION: Short-term administration of STN DBS at peak dopamine-dependent or movement-related γ frequencies were as effective as HF for reducing parkinsonian motor signs but DBS at θ and ß frequencies did not worsen PD motor signs. CLASSIFICATION OF EVIDENCE: This study provides Class III evidence that STN DBS at patient-specific γ frequencies and at usual high frequencies both improved mUPDRS scores compared to no stimulation and did not differ in effect.

Involvement of the human pedunculopontine nucleus region in voluntary movements.

OBJECTIVE: The pedunculopontine nucleus region (PPNR) is being investigated as a target for deep brain stimulation (DBS) in Parkinson disease (PD), particularly for gait and postural impairment. A greater understanding of how PPNR activities and oscillations are modulated with voluntary movements is crucial to the development of neuromodulation strategies. METHODS: We studied 7 patients with PD who underwent DBS electrode implantations in the PPNR. PPNR local field potential and EEG were recorded while patients performed self-paced wrist and ankle movements. RESULTS: Back-averaging of the PPNR recording showed movement-related potentials before electromyography onset. Frequency analysis showed 2 discrete movement-related frequency bands in the theta (6- to 10-Hz) and beta (14- to 30-Hz) ranges. The PPNR theta band showed greater event-related desynchronization with movements in the ON than in the OFF medication state and was coupled with the sensorimotor cortices in the ON state only. Beta event-related desynchronization was observed in the PPNR during the premovement and movement execution phases in the OFF state. In contrast, premovement PPNR beta event-related synchronization occurred in the ON state. Moreover, beta band coherence between the PPNR and the midline prefrontal region was observed during movement preparation in the ON but not the OFF state. CONCLUSIONS: Activities of PPNR change during movement preparation and execution in patients with PD. Dopaminergic medications modulate PPNR activities and promote the interactions between the cortex and PPNR. Beta oscillations may have different functions in the basal ganglia and PPNR, and may be prokinetic rather than antikinetic in the PPNR.

Prenatal exposures to LTP-patterned magnetic fields: quantitative effects on specific limbic structures and acquisition of contextually conditioned fear.

Weak (<1 microT) complex magnetic fields (CMFs) may exert their behavioral influences through the hippocampus by resonating by accident or design with intrinsic electrical patterns. Rats were exposed prenatally to one of four intensities of a CMF (either <5 nanoTesla [nT], 10-50 nT, 50-500 nT, or 500-1000 nT) designed to interact with the process of Long-Term Potentiation (LTP) in the hippocampus. Rats then underwent testing in the forced swim, open field, and fear-conditioning procedures. The cell densities of all amygdaloid nuclei, specific hypothalamic structures, and the major regions of the hippocampus were quantified. Results showed that acquisition of conditioned fear was strongly inhibited in animals exposed to LTP-CMFs. Rats exposed to intensities above 10 nT showed decreased cell density in the CA2 fields of the hippocampus; more neurons were present in the CA1 fields of rats exposed to the 10-50 nT intensities compared to all other groups. A decrease in cell density in the medial preoptic nucleus was linearly dependent on field intensity. In the forced-swim test, swimming was decreased in rats that had been exposed to low (10-50 nT) and medium intensity (50-500 nT) LTP-CMFs in a manner consistent with monoamine modulation. In the open field, exposed rats were indistinguishable from controls. These findings support the hypothesis that continuous exposure during prenatal development to CMFs designed to simulate intrinsic LTP within the hippocampus can affect adult behaviors specific to this structure and produce quantitative alterations in neuronal density.

Electrophysiological and quantitative electroencephalographic measurements after treatment by transcerebral magnetic fields generated by compact disc through a computer sound card: the Shakti treatment.

Quantitative electroencephalographic activity over the left and right frontal, temporal, parietal, and occipital lobes was obtained on 4 successive weeks in 12 subjects before they were exposed cerebrally for 30 min to one of two configurations of weak complex magnetic fields or to a sham-field condition. The two configurations were Shakti (c Todd Murphy) and the set of 4 solenoids (Koren boxes) generating a burst-firing magnetic field through the temporal lobes. Compared to baseline measurements there were no statistically significant differences in treatments for relative changes in power over these regions within the delta, theta, low alpha, beta, or gamma ranges. However within the high alpha range (10.5 Hz to 13 Hz), there was a significant interaction between session and type of treatment that was due primarily to the Shakti treatment. These changes were congruent with the subjective experiences reported by some users of the technology.

Power increases within the gamma range over the frontal and occipital regions during acute exposures to cerebrally counterclockwise rotating magnetic fields with specific derivatives of change.

A total of 11 men and women were exposed for 5 min each to six different temporal configurations of pulsed magnetic fields that were delivered through serial activation of 8 solenoids in a counterclockwise direction around the head within the horizontal plane above the ears. Twenty-second samples of quantitative electroencephalographic activity within the delta, theta, lower alpha, upper alpha, beta, and gamma regions were collected after each configuration had been activated for 2.5 min. Only the circumcerebral presentation of the first pulse for 25 ms followed by an acceleration of +2 ms to each of the other 7 solenoids (the last duration = 11 ms) resulted in a significant increase in power within the gamma range (35 Hz to 45 Hz) over both frontal and occipital lobes but not over the parietal or temporal lobes. These results suggest topical application of specific spatial-temporal configurations of magnetic fields may affect the recursive creation of the rostral-caudal waves of cohesive fields that might produce consciousness.

Enhanced power within a specific band of theta activity in one person while another receives circumcerebral pulsed magnetic fields: a mechanism for cognitive influence at a distance?

Four pairs of adult siblings served once as either the stimulus or the response person in two sessions separated by one week. While the brain of the stimulus person, who was seated in a closed chamber, was exposed successively to six different complex magnetic fields for 5 min. each quantitative monopolar electroencephalographic measurements over the frontal, temporal, parietal, and occipital lobes were collected by computer for the response person who was seated in another room. The six configurations of fields served as different stimulus patterns and had been designed to affect consciousness. As predicted theoretically, a significant increase in electroencephalographic power within the 5.0-Hz to 6.0-Hz band over the frontal and occipital lobes was noted for the response persons when the stimulus persons received one of the six specific patterns of weak (1 microTesla range) magnetic fields. This magnetic stimulus was presented for 100 msec. with changes in rate of 20 msec. to each of the eight solenoids that were equally spaced in the horizontal plane around the head of the stimulus person. Derivatives within this narrow frequency band had been hypothesized to be a source of the "binding factor" for the cohesive cerebrogenic electromagnetic fields producing consciousness. The results suggest that an appropriate altered state of one brain can effect specific predictable frequencies of the electroncephalographic activity of another distant brain which is genetically related.

An example of intron junctional sliding in the gene families encoding squalene monooxygenase homologues in Arabidopsis thaliana and Brassica napus.

Sequences of three Arabidopsis thaliana and two Brassica napus cDNAs encoding squalene monooxygenase homologues (Sqp1 and Sqp2) are reported. Southern analysis confirmed that these cDNAs are derived from small gene families in both species. Expression analysis indicates that Sqp1 genes in B. napus are strongly expressed in leaves but not roots or developing seeds. Comparison of cDNA and genomic sequences indicate that the 3' splice site of an intron in these genes has undergone junctional sliding. The evolutionary significance of this phenomenon is discussed.

Transformation of white spruce (Picea glauca) somatic embryos by microprojectile bombardment.

Cotyledonary somatic embryos of white spruce [Picea glauca (Moench) Voss] were subjected to microprojectile bombardment with a gene construct containing a gus::nptll fusion gene. Somatic embryos were used to re-induce the embryogenic tissue after bombardments. Histochemical assay using X-gluc as a substrate showed that all the embryos (100%) were GUS positive 48 h after bombardment. However, only thirteen out of 605 embryos (2.2%) remained GUS positive after two months in culture. Three of those thirteen (23%) embryo-derived tissues consistently showed GUS activity for eight months in culture. These putatively transfomed embryogenic tissues were subjected to Southern blot analysis and the results suggested integration of the gus::nptll gene expression cassette in the white spruce genome.

Microprojectile-DNA delivery in conifer species: factors affecting assessment of transient gene expression using the ß-glucuronidase reporter gene.

The Biolistic(®) microprojectile DNA-delivery method was used to test the usefulness in conifers of eight gene constructs based on the 35S promoter, the AMV translational enhancer, and gene fusion between the P-glucuronidase and the neomycin phosphotransferase II genes. The evaluation was done with embryogenic cells of Picea glauca, where the relative strengths of the promoters were 35S-35S-AMVE>35S-AMVE>35S-35S>35S as evaluated by transient gene expression. The fusion gene of GUS and NPT II gave lower levels of transient gene expression than the unfused GUS gene as detected by X-GLU histochemical assays. Experiments comparing the EM promoter of wheat and the 35S-35S-AMVE promoter (with and without fusion between GUS and NPT II) were done in Picea rubens, P. mariana, P. glauca, and Larix x eurolepis. The unfused gene with the 35S-35S-AMVE promoter gave higher levels of transient gene expression than the fused GUS-NPT II gene. The fluorescent MUG assay was more sensitive than the histochemical X-GLU assay to detect the activity of the ß-glucuronidase gene.

Differential regulation of superoxide dismutases in plants exposed to environmental stress.

Superoxide dismutases (SODs) are metalloproteins that catalyze the dismutation of superoxide radicals to hydrogen peroxide and oxygen. The enzyme is ubiquitous in aerobic organisms where it plays a major role in defense against oxygen radical-mediated toxicity. In plants, environmental adversity often leads to the increased generation of reduced oxygen species and, consequently, SOD has been proposed to be important in plant stress tolerance. Here we describe the isolation of a cDNA clone encoding a cytosolic copper/zinc SOD from Nicotiana plumbaginifolia. Using this, together with previously isolated cDNAs encoding the mitochondrial manganese SOD and the chloroplastic iron SOD as probes in RNA gel blot analyses, we have studied SOD transcript abundance during different stress conditions: in response to light, during photoinhibitory conditions (light combined with high or low temperatures), and in response to a xenobiotic stress imposed by the herbicide paraquat. Evidence is presented that iron SOD mRNA abundance increases whenever there is a chloroplast-localized oxidative stress, similar to the previous finding that manganese SOD responds to mitochondria-localized events. The diverse effects of the different stress conditions on SOD mRNA abundance thus might provide an insight into the way that each treatment affects the different subcellular compartments.

Characterization of iron superoxide dismutase cDNAs from plants obtained by genetic complementation in Escherichia coli.

The inability of superoxide dismutase (SOD; superoxide:superoxide oxidoreductase, EC 1.15.1.1)-deficient mutants of Escherichia coli to grow aerobically on minimal medium can be restored by functional complementation with a heterologous SOD-encoding sequence. Based upon this property, a phenotypic selection system has been developed for the isolation of clones containing eukaryotic SOD cDNAs. cDNA expression libraries from both Nicotiana plumbaginifolia and Arabidopsis thaliana were transformed into a SOD-deficient E. coli strain by electroporation, and clones containing functional SODs were selected by growth on minimal medium. Analysis of these clones revealed the identity of cDNAs encoding the iron form of superoxide dismutase (FeSOD)--the first SODs of this type to be cloned from eukaryotes. The presence of this enzyme in these two divergent plant species challenges previous ideas that FeSOD is found in only a few plant families. In addition, these results show the potential for shotgun cloning of eukaryotic genes by complementation of bacterial mutants, particularly when it is combined with a highly efficient transformation method, such as electroporation.

Toxicity of antibiotics on zygotic embryos of white spruce (Picea glauca) cultured in vitro.

The toxicity of kanamycin, hygromycin B, geneticin, methotrexate and cefotaxime on zygotic embryos ofPicea glauca was studied. Embryos placed on bud induction medium produced approximately 20 adventitious buds per embryo under control conditions. Addition of antibiotics reduced the number of bud-forming embryos. Using the percentage of embryos with buds as an indication of antibiotic toxicity, two-day-old explants were found to be more sensitive than nine-day-old. Kanamycin toxicity was enhanced by cefotaxime and this effect increased with increases in concentration of either antibiotic. Although no morphological difference was observed after 21 days, embryos growing on medium containing 20 µg ml(-1) kanamycin showed a decrease of 73% in dry weight and 23% in protein content per embryo when compared to control embryos. Similarly, a decrease of 38% in dry weight and 40% in protein content per embryo was found in embryos on medium containing 300 µg ml(-1) cefotaxime.