Note: ion source design for ion trap systems

A small plasma (glow discharge) based ion source and circuit are described in this work. The ion source works by producing a high voltage pulsed discharge between two electrodes in a pressure range of 50-100 mTorr. A third mesh electrode is used for ion extraction. The electrodes are small stainless steel screws mounted in a MACOR ionization chamber in a linear arrangement. The electrode arrangement is driven by a circuit, design for low power operation. This design is a proof of concept intended for applications on small cylindrical ion traps.

Characterization system for research on energy storage capacitors

In this work a characterization system for high energy-density capacitors is described and demonstrated. Capacitors are being designed using thin-film technology in an attempt to achieve higher energy-density levels by operating the devices at a high voltage. These devices are fabricated from layers of 100 nm aluminum and a layer of polyvinylidene fluoride-hexafluoropropylene on a polyethylene naphthalate plastic substrate. The devices have been designed to store electrical charge at up to 200 V. Characterizations of these devices focus on the measurement of capacitance vs bias voltage and temperature, equivalent series resistance, and charge/discharge cycles. For the purpose of the characterization of these capacitors, an electronic charge/discharge interface was designed and tested.

The consequences of chromosomal aneuploidy on gene expression profiles in a cell line model for prostate carcinogenesis

Here we report the genetic characterization of immortalized prostate epithelial cells before and after conversion to tumorigenicity using molecular cytogenetics and microarray technology. We were particularly interested to analyze the consequences of acquired chromosomal aneuploidies with respect to modifications of gene expression profiles. Compared with nontumorigenic but immortalized prostate epithelium, prostate tumor cell lines showed high levels of chromosomal rearrangements that led to gains of 1p, 5, 11q, 12p, 16q, and 20q and losses of 1pter, 11p, 17, 20p, 21, 22, and Y. Of 5700 unique targets on a 6.5K cDNA microarray, approximately 3% were subject to modification in expression levels; these included GRO-1, -2, IAP-1,- 2, MMP-9, and cyclin D1, which showed increased expression, and TRAIL, BRCA1, and CTNNA, which showed decreased expression. Thirty % of expression changes occurred in regions the genomic copy number of which remained balanced. Of the remainder, 42% of down-regulated and 51% of up-regulated genes mapped to regions present in decreased or increased genomic copy numbers, respectively. A relative gain or loss of a chromosome or chromosomal arm usually resulted in a statistically significant increase or decrease, respectively, in the average expression level of all of the genes on the chromosome. However, of these genes, very few (e.g., 5 of 101 genes on chromosome 11q), and in some instances only two genes (MMP-9 and PROCR on chromosome 20q), were overexpressed by > or =1.7-fold when scored individually. Cluster analysis by gene function suggests that prostate tumorigenesis in these cell line models involves alterations in gene expression that may favor invasion, prevent apoptosis, and promote growth.

In vivo determination of body composition of rats using magnetic resonance imaging

Magnetic resonance imaging (MRI) has potential as an instrument to measure body composition because it can discriminate various soft tissues in vivo. These soft tissues include adipose tissue, muscle, organs, and brain. We report on preliminary studies using a 4.2-tesla MRI for measuring body composition in the mouse and rat. We employed image segmentation methods that include an image correction method, a necessary requirement when the images are taken in the presence of nonuniform radio-frequency (RF) coil response. The software for 3-D data segmentation, quantification, correction, image manipulation, and visualization has been developed as a research tool. This method currently is being validated.

A prospective randomized evaluation of the prophylactic use of low-dose dopamine in cancer patients receiving interleukin-2

The administration of high-dose interleukin-2 (IL-2) causes tumor regression in 17-25% of patients with metastatic melanoma or renal cell carcinoma. Renal dysfunction is a common dose-limiting toxicity of IL-2 administration, limiting 26% of treatment cycles. We have conducted a prospective randomized trial to evaluate whether the prophylactic administration of low-dose dopamine (2 mg/kg/min) can minimize renal toxicity and thus affect the amount of IL-2 administered. Forty-two patients were randomly assigned to receive systemic high-dose IL-2 with standard supportive measures (group A = 21 patients) or with the addition of prophylactic dopamine (group B = 21 patients) at 2 mg/kg/min. For patients in group B, dopamine was instituted 1 h before the initiation of IL-2 administration and was discontinued 6-12 h after the maximum number of doses of IL-2 were given. There was no difference in the amount of IL-2 administered for each course of therapy for groups A and B. Despite differences in urine flow (milliliters per kilogram per day), fluid balance (liters per day), and overall weight gain, prophylactic low-dose dopamine did not significantly alter maximum plasma urea or creatinine levels in group B when compared with the control group (group A). The overall toxicity profile considering all grade 3 and 4 toxicities for patients in groups A and B was comparable. Thus, there is no evidence to support the routine use of prophylactic low-dose dopamine in patients receiving high-dose IL-2.