Tardive dyskinesia (TD) is a common side effect of long-term medication with typical neuroleptics. TD presents itself by abnormal involuntary movements and may lead to a potentially disabling and ...chronic clinical course. A vast majority of patients suffering from schizophrenia are smokers. Smoking has been reported to induce the activity of the CYP1A2 enzyme, which is an established metabolic pathway within the disposition of antipsychotics. Recently, a C-->A genetic polymorphism in the first intron of the CYP1A2 gene was reported to influence CYP1A2 activity in smokers. Subsequently, a pharmacogenetic study in 85 U.S. patients with schizophrenia (44 smokers, 41 individuals with unknown smoking status) showed the C/C genotype to be associated with higher TD severity (measured by the Abnormal Involuntary Movement Scale, AIMS) than the A/C or A/A genotype. This finding prompted us to investigate whether this effect was also present in a larger German sample of 119 patients with schizophrenia (82 smokers, 37 individuals with unknown smoking status). However, we could not replicate the reported association. The median AIMS scores did not differ between individuals with the A/A, A/C, or C/C genotypes. In an additional analysis, we compared the genotypic and allelic distribution among individuals grouped according to the criteria established by Schooler and Kane 1982: Arch Gen Psychiatry 39:486-487 (persistent TD vs. absent TD). We did not observe a differential genotypic or allelic distribution between the two diagnostic groups. Thus, our results do not support the hypothesis that the C-->A polymorphism in the CYP1A2 gene is involved in the etiology of TD in the German population.
In the search for genetic factors contributing to tardive dyskinesia, dopamine receptor genes are considered major candidates. The dopamine D3 receptor is of primary interest as dopamine D3 receptor ...knock-out mice show locomotor hyperactivation resembling extrapyramidal side-effects of neuroleptic treatment. Furthermore, Steen and colleagues (1997) recently reported an association between tardive dyskinesia and a dopamine D3 receptor gene variant. In the present study we tried to replicate this finding. We investigated 157 patients with schizophrenia or schizoaffective disorder receiving long-term neuroleptic medication who never or persistently displayed tardive dyskinesia. As advanced age is a main risk factor for tardive dyskinesia, we also compared older patients with a long duration of schizophrenia not displaying tardive dyskinesia to younger patients with a shorter duration of the illness displaying tardive dyskinesia. However, we found no evidence that the dopamine D3 receptor gene is likely to confer susceptibility to the development of tardive dyskinesia.
This letter presents the realization of a high-efficiency, high-temperature Continuous Class-E Sub-Waveform Solution power amplifier using for the first time GaN technology. The recently introduced ...Continuous Class-E PA mode theory has revealed new and various impedance solutions for which high efficiency switch mode PAs can be realized. The investigation carried out in this work clearly shows that very high efficiency is still delivered despite the smaller voltage waveform peak when compared to standard Class-E, leading to more reliable PAs. The Continuous Class-E Sub-Waveform Solution PA prototype shows efficiency as high as 80% while delivering output power of 4 W and gain > 10 dB at 2 GHz of frequency and ambient temperature. The PA module has also been tested at high temperature T=150 ° C revealing targeted performance with efficiency up to 71% while delivering 3.5 W of output power. Reliability measurements also show satisfactory results in the time frame up to 1500 hours.
Affective symptomatology has repeatedly been suggested to confer susceptibility to tardive dyskinesia (TD). In our sample of 174 schizophrenic patients a history of depressive symptoms was not ...associated with the occurrence of TD, whereas manic symptomatology was significantly associated with the absence of TD. Thus, our data suggest that affective symptomatology cannot unambiguously be considered to predispose to TD.
Five different versions of grounded coplanar waveguide (GCPW) branch-line couplers on GaAs were EM simulated, processed and investigated for operation in G-band (140-220 GHz), based on different ...layer structures (including 2 or 3 metallization layers) and layouts. The best results have been obtained with the structures based on a continuous galvanic metal in the central conductor line and ohmic connections between top ground planes, reducing the insertion losses by 0.8 dB. A measured amplitude imbalance less than 0.5 dB from 160 to 200 GHz (22%), with a coupler insertion loss lower than 1.3 dB was achieved for a 3 metallization layer branch-line coupler.
Dual-Gate GaN MMICs for MM-Wave Operation Quay, R; Tessmann, A; Kiefer, R ...
IEEE microwave and wireless components letters,
02/2011, Letnik:
21, Številka:
2
Journal Article
Recenzirano
This letter describes the millimeter-wave operation of III-N dual-gate MMICs based on a complete mm-wave MMIC technology suitable for operation up to 110 GHz. The GaN HEMTs have a gate length of 100 ...nm, yield high maximum transconductance, and very low parasitic capacitances. The cutoff frequency f T is above 80 GHz at an operation bias of 15 V in a fully passivated device. Dual-gate devices were developed for high gain at high gate widths and for substantial improvements in gain per stage on MMIC level. Complete III-N MMICs in grounded coplanar passive technology were designed. A single-stage dual-gate MMIC at 60 GHz yields 150 mW (840 mW/mm) of output power. A second MMIC shows a linear gain of greater than 10 dB at 94 GHz. It further yields an output power of 22.8 dBm (190 mW or 520 mW/mm) in CW-operation to a 50 Ω load with a maximum PAE of 7% at 94 GHz. The letter demonstrates the advantage of GaN dual-gate devices in power gain over common-source devices while maintaining essential improvements in power density.
A high power broadband switch-mode core MMIC has been developed for an application in digital switch-mode power amplifiers, e.g., class S, for mobile communications. The three-stage design can be ...flexibly used at any frequency operating in UHF band up to a maximum digital bit rate of 3 Gbps, equal to a square wave frequency of 1.5 GHz. At 0.9 Gbps a maximum broadband output power of 20.5 W was measured at a drain efficiency of 76% and a power added efficiency of 70%. Controlled by a digital signal with a peak-to-peak amplitude of 3.5 V, a large signal gain of 25.3 dB was achieved.
An inverter-based digital switch-mode driver circuit, highly-integrated with a GaN power transistor is presented. The layout is fully scalable in output power and therefore suitable for amplifiers ...with power levels of higher than 10 W. The circuit enables a switch-mode operation from DC to 3 GHz. A consistent analysis of digital switching measurements and active harmonic load-pull results is performed. Measurements at 2 GHz and 30 V yield a drain efficiency of 82 % and 6 W of output power, while a gain up to 35 dB and more than 76 % overall circuit efficiency were achieved.
A high efficiency digital MMIC amplifier for mobile communication switch-mode concepts was designed by utilizing a 0.25 mum GaN HEMT technology with f tau of 32 GHz. A comparative investigation of ...two different driver concepts for a 1.2 mm GaN HEMT PA is shown. The MMICs were on-wafer evaluated for class-D and class-S operation. A drain efficiency of 70% for an output power of 4.4 W for a band pass delta-sigma (BPDS) class-S input signal at a bit rate of 3.6 Gbps equivalent to a 0.9 GHz fundamental was obtained. For the first time the operating mode up to 8 Gbps (2 GHz) is shown with an efficiency of 62%, demonstrating the prospect of future use of GaN HEMTs for switch mode amplifier concepts.
