Thermoacoustic range verification using a clinical ultrasound array provides perfectly co-registered overlay of the Bragg peak onto an ultrasound image.

The potential of particle therapy due to focused dose deposition in the Bragg peak has not yet been fully realized due to inaccuracies in range verification. The purpose of this work was to correlate the Bragg peak location with target structure, by overlaying the location of the Bragg peak onto a standard ultrasound image. Pulsed delivery of 50 MeV protons was accomplished by a fast chopper installed between the ion source and the cyclotron inflector. The chopper limited the train of bunches so that 2 Gy were delivered in [Formula: see text]. The ion pulse generated thermoacoustic pulses that were detected by a cardiac ultrasound array, which also produced a grayscale ultrasound image. A filtered backprojection algorithm focused the received signal to the Bragg peak location with perfect co-registration to the ultrasound images. Data was collected in a room temperature water bath and gelatin phantom with a cavity designed to mimic the intestine, in which gas pockets can displace the Bragg peak. Phantom experiments performed with the cavity both empty and filled with olive oil confirmed that displacement of the Bragg peak due to anatomical change could be detected. Thermoacoustic range measurements in the waterbath agreed with Monte Carlo simulation within 1.2 mm. In the phantom, thermoacoustic range estimates and first-order range estimates from CT images agreed to within 1.5 mm.

Allelic variation in the cagA gene of Helicobacter pylori obtained from Korea compared to the United States.

OBJECTIVE: Helicobacter pylori is an important factor in the development of duodenal ulcer disease and has been implicated in the pathogenesis of gastric adenocarcinoma. It has been suggested that the cagA gene is a marker for more virulent strains of H. pylori. METHODS: We determined the prevalence of the cagA gene in 60 clinical isolates [34 from gastric carcinoma patients (CA), 26 from duodenal ulcer patients (DU)] from Korea, a country with a high incidence and mortality from gastric cancer. Genomic DNA was polymerase chain reaction-amplified by using two different primer sets for the cagA gene. The first cagA primer set amplifies a 297-bp product from the midregion of the cagA gene. The second primer set, which was previously established in a patient population from the Houston area (21 DU patients, 20 from individuals with asymptomatic gastritis) amplified a 1.4-kb region further downstream in the cagA gene. RESULTS: The expected 297 bp polymerase chain reaction amplicon for cagA was identified in 59/60 (98.3%) H. pylori isolates from Korea (33/34 CA, 26/26 DU), and in 36/41 (88%) isolates from the Houston area (20/21 DU, 16/20 asymptomatic gastritis) (NS). Using the second cagA primer set, the expected 1.4-kb product was found in only 1/60 (1.7%) H. pylori isolates from Korea (1/34 CA, 0/26 DU), and in 36/41 (88%) of isolates from the Houston area (20/21 DU, 16/20 GST) (p < 0.001). Western blot analysis showed that all Korean H. pylori isolates expressed cagA. CONCLUSIONS: The high prevalence of the cagA gene in H. pylori isolates from Korean patients with gastric adenocarcinoma or duodenal ulcers indicates that the cagA gene is common in H. pylori strains, and therefore, is not reliable as a single marker for the discrimination of H. pylori strains with respect to a specific disease. Our data further suggest that allelic variations in the genome of H. pylori strains may exist and that distinct H. pylori populations may circulate in different geographic regions.

Response of parotid gland organ culture to radiation.

Organ cultures of rhesus parotid tissue in medium enriched with homologous serum and supplemented with low levels of isoproterenol were irradiated with single photon doses of 2.5, 5.0, 7.5, 10.0, 12.5, or 15.0 Gy. Following irradiation, the tissue was incubated while being agitated for 24 h; then it was fixed in formalin. Microscopically, death of serous acinar cells was seen in areas unaltered by autolysis. Based on the numbers of nuclear aberrations, the dose response did not differ significantly from that observed at 24 h in parotid gland irradiated in vivo. The similar rapid response under the two conditions shows that apoptosis of irradiated parotid serous cells is a direct expression of interphase cell death.

Tumoricidal effect of interleukin-2-activated killer cells in canines.

We investigated the effect of both partially purified (TCGF) and recombinant interleukin-2 (rIL-2) on the tumor-directed cytotoxic activity of canine peripheral blood mononuclear cells (PBMC) using three normal canines. No cytotoxic activity was displayed by unstimulated effector cells at 3 h of incubation; however, the cytotoxic effect was observed in a 16-h assay. PBMC of all canines displayed significant levels of lytic activity after stimulation for 4 to 7 days with both types of IL-2 against a variety of allogeneic and xenogeneic neoplastic cells in 3-h 51Cr release assay. The cytotoxic activity of cultured cells increased proportionally in the 16-h assays. Morphological examination of the May-Grünwald and Giemsa stained cytocentrifuged slides of cultured cells on each day of assay showed an increase in large granular lymphocytes (LGLs) beginning on day 4 and reaching a peak on day 7 of culture.

Recertification of psychiatrists: the time to act is now.

Because of the predictions of partial obsolescence for psychiatry as a profession and because of the increasing pressures of government, third-party payers, and a patient population that will no longer blindly follow physicians, psychiatrists must face the demands for professional accountability. The author suggests that to maintain high-quality care and continuing self-governance, psychiatrists must participate actively in self-assessment and continuing education programs.

Limitations and values of evaluation techniques in psychiatric education.

The author presents a summary of the major evaluation techniques now available and discusses the values and limitations of each. He concludes that only by the use of many evaluation instruments during the resident's period of training can some estimate of clinical competence be approached. Even with this multiplicity of testing instruments, the validity of predictions of a psychiatrist's performance can be determined only in terms of probabilities.