Optimization of the Thin Waveguide for Double-Parabolic-Reflectors Ultrasonic Transducers (DPLUS) for Thermal Ablation.

OBJECTIVE: Interstitial and intracavitary ultra- sound applicators had been developed and studied for minimally invasive treatments (MIT). However, the acoustic outputs are limited by the small-size PZT. We therefore studied the acoustic waveguide (AW) applicator which enables the use of a large-size PZT, and we aimed to advance AW applicators towards thermal ablation applications. METHODS: Double parabolic reflectors wave-guided ultrasonic transducer (DPLUS) was introduced which has two parabolic reflectors for enhancing the acoustic output. Theoretical modeling was conducted for optimizing the DPLUS thin waveguide. RESULTS: Modeling results showed that optimal a/Λ (thin waveguide radius/wavelength) can be found and the optimal a depends on the excitable vibration amplitude in the thin waveguide. A local optimal a/Λ= 0.2392 was considered the best choice, which results in the optimal frequency of 2.2 MHz at the radius a of 0.6 mm. To verify this optimal frequency, experiments under two working frequencies of 1.0282 MHz and 2.2579 MHz were conducted. Temperature rise curves in the chicken breast tissue showed good agreements between experiments and modeling results, which proved the effectiveness of the modeling. In addition, experiments showed an ablated area with a diameter of 1.03±0.12 mm under continuous excitation of 2.2579 MHz and 5 s. CONCLUSION: The developed DPLUS advanced the AW applicators towards thermal ablation applications. SIGNIFICANCE: This study provides the evidence for recognizing AW applicators as a technique for thermal ablation.

High-Power Ultrasonic Transducer for Effective Hemolysis.

To realize compact and portable hemolysis devices, an ultrasonic transducer with a blood channel is proposed in this study. Ultrasound waves are focused by a parabolic reflector to generate high sound pressure inside the channel for hemolysis. The hemolysis performance of the transducer is evaluated using simulations and experiments. Experiments are performed with various voltages and flow rates to verify the feasibility of hemolysis. The hemolysis rate is more than 93% at an applied voltage of 80 Vp-p, a flow rate of 0.25 mL/min, and a driving frequency of 1.28 MHz.

High-power piezoelectric vibration model considering the interaction between nonlinear vibration and temperature increase.

For high-power piezoelectric devices, nonlinear vibrations and related increases in temperature are critical problems produced by large internal stress and strain. Such nonlinear vibrations have been studied by some researchers; however, the related increase in temperature has not been taken into consideration, because it is a complicated phenomenon. In this study, the mechanism underlying the interaction between nonlinear vibration and temperature increase in a piezoelectric transducer under high-power conditions was clarified. For this purpose, cubic terms of the mechanical strain, the nonlinear transfer matrix method, and the heat conduction equation were combined. Additionally, it is necessary to utilize the distributed parameter model because the temperature increase is not uniform. The calculation results obtained using the measured temperature dependence of material constants verified that the temperature increase significantly degrades the piezoelectric vibration. It is expected that the proposed model will prove indispensable in the development of piezoelectric materials for high-power piezoelectric devices.

Microseizures Induced by Topiramate.

A 22-year-old Japanese male with trisomy 21 was diagnosed with West syndrome at 4 months old. After the suppression of epileptic spasms using adrenocorticotropic hormone therapy, he had complex partial seizures and bilateral frontal epileptic discharges on EEG. Although the introduction of topiramate (TPM) decreased the seizures during wakefulness, frequent episodes of brief eye-opening appeared during sleep while the patient was taking TPM (400 mg/day). EEG showed fast activity at the times of eye-opening. The episodes of eye-opening during sleep and the fast activities disappeared upon TPM discontinuation. This is the first report of TPM-induced microseizures similar to benzodiazepine-induced microseizures.

A screening test for the prediction of Dravet syndrome before one year of age.

PURPOSE: Our aim was to develop a screening test to predict Dravet syndrome before the first birthday based on the clinical characteristics of infants and the SCN1A mutation analysis. METHODS: Ninety-six patients who experienced febrile seizures before the age of one were enrolled. The patients were divided into two groups-the Dravet syndrome group (n = 46) and the non-Dravet syndrome group (n = 50). We compared the clinical characteristics before one year of age of the two groups. We analyzed all coding exons of the SCN1A gene by the direct sequencing method. Scores from 0 to 3 were assigned to each risk factor based on the odds ratio and p-value. RESULTS: An age of onset of febrile seizure or= 5, and prolonged seizures lasting more than 10 min. were regarded as significant risk factors for Dravet syndrome. Other factors highly predictive of this syndrome were hemiconvulsions, partial seizures, myoclonic seizures, and hot water-induced seizures. A total clinical score of six or above was the cutoff value indicating a high risk of Dravet syndrome. SCN1A missense and truncated mutations were detected significantly more often in the Dravet syndrome group than in the non-Dravet syndrome group. DISCUSSION: This simple screening test was designed to be used by general pediatricians. It could help to predict Dravet syndrome before one year of age. If the sum of the clinical risk score is >or= 6, then the performance of an SCN1A mutation analysis is recommended.

Novel mutation of gene coding for glial fibrillary acidic protein in a Japanese patient with Alexander disease.

We report the mutation analysis of a Japanese patient diagnosed with infantile-type Alexander disease. The genetic analysis revealed a new missense mutation, an A to G transition at nucleotide position 1026 in exon 6, leading to the substitution of glycine for glutamic acid at amino acid position 371(E371G). This mutation was not detected in 50 Japanese controls using denaturing high-performance liquid chromatography.

[A case of hypereosinophilic syndrome associated with paraplegia].

We report a 3-year-old girl with idiopathic hypereosinophilic syndrome. She was admitted to our hospital because of fever, cough, significant eosinophilia (16,500/microliter) and an elevated serum IgE level (114,685 u/ml). After wheezes continued for several days, paraplegia, dysuria and dyschezia developed. CSF, chest roentgenogram and spinal MRI were normal, as well as motor and sensory conduction velocities of the median and tibial nerves. Flaum's hematologic score was 4. Treatment with prednisolone resulted in remission of neurological symptoms and a rapidly normalization of the eosinophil count. During the following months, eosinophilia reappeared with tapering the medication, but there was no recurrence of neurological signs. Glucocorticoid therapy was discontinued after 21 months.

The productive and reproductive biology of flowering plants X. Reproductive energy allocation and propagule output of five congeners of the genus Setaria (Gramineae).

The energy allocation patterns to reproductive structures (RA) and the propagule output (PN) of five annual weedy or ruderal fox-tail species (Gramineae)-Setaria viridis (2x) (including var. pachystachys (2x)), S. X pycnocoma (2x), S. faberi (4x), S. glauca (4x, 8x), and S. pallide-fusca (8x)-were studied in relation to their biomass on the materials from ten different wild populations in Toyama and Fukui Prefectures, Japan. In addition, the relationship between the RA and PN was also critically examined.For all five fox-tail species, proportional partitioning of dry matter into total reproductive structures (caryopses, bristles, inflorescence axis and other persistent floral organs at the fruiting stage) (RA) shows considerable overlaps, but more or less constant within each taxon and independent of the biomass. On the other hand, the number of propagules produced per plant (PN) is remarkably dependent on the size of plants and thus a function of the biomass. This high efficiency of energy allocation to propagules is evidently determined by the breeding system (i.e., predominant inbreeding) of these weedy annual species. However, the relationship between the RA and PN showed no conspicuous trend, and thus the reproductive output is also independent of RA. The reproductive strategy found in Setaria is perhaps typical in such weedy annuals which grow chiefly in frequently disturbed, unpredictable environments. Another notable discovery was that, in spite of differences in ploidy levels (from 2x to 8x), all five species showed a very similar reproductive strategy, although slight but clear decrease was noted in the RA in response to the increase in ploidy levels, ranging from 49.52% (in diploids) to 27.53% (in tetraploids and octoploids). Seed weight (per gram), on the contrary, clearly increases in response to the increase in ploidy levels, i.e., ranging from 7.09×10-4 g (in diploids) to 41.87×10-4g (in octoploids).