Citations

The present series of experiments was undertaken in an effort to delineate those aspects of ultrasonic irradiation that might be destructive to malignant tumors of bone. The experiments were performed on rabbits having Vx-2 carcinoma implanted within the tibias. In preliminary, experiments, it was shown that the destructive effect of ultrasound on normal bone and on the circulation through normal bone was probably primarily due to heat. In the current series of experiments, it was shown that the heating of the bone was critically dependent on the exact location of the focus of the ultrasonic transducer within the rabbit leg. Our experiments suggested that (1) exposure of Vx-2 carcinoma to a temperature of 50°C for at least 10 min is sufficient to destroy the transmissible characteristics of this tumor, (2) exposure of Vx-2 carcinoma to ultrasonic fields with intense cavitation (applied in the absence of heat) has an effect that is far less than that of heating to 50°C for 10 min, and (3) controlled ultrasonic heating can increase the temperature of a bone to levels sufficient to destroy tumor growth within the bone.

Direct measurements were made of the displacement of the guinea-pig eardrum when acted upon by acoustic pressures (200–6000 cps). The mechanical nonlinearities of the ear were studied by introducing a static pressure (0 to ±3000 dyn/cm2) in the middle-ear cavity. Below 1000 cps, the ratio of the tympanum displacement to the sound pressure was frequency-independent, with a value of about 4×10−7 cm3/dyn. Above 1000 cps, this ratio exhibited a series of maxima and minima. A static-pressure difference across the tympanum changed the frequency at which the maximum occurred and generally decreased the displacement/pressure ratio. It was concluded (1) for low frequencies, the lumped-parameter description of the ear as a cavity was valid; (2) the tympanum acts as a flexible, conical plate under slight tension; (3) the measurements were best explained in terms of two nonlinearities: hysteresis and a nonlinearity of the elastic properties of the ear.

Dilute suspensions of canine erythrocytes were exposed to 1 Mc focused ultrasonic fields with maximum acoustic pressures estimated at 10 atm. In standing wave patterns in which circulation was inhibited, the cells clumped rapidly at the nodes and no changes were found. With a free surface, fountaining and stirring occurred. Exposure at 1 atm ambient pressure then resulted in rapid lysis. Erythrocytes exposed briefly in isotonic Rous-Turner mixture and controls were both diluted with sodium chloride solutions of varying concentration. The optical density at 650 mμ was plotted as a function of salt concentration. The exposed samples showed a greater fractional decrease in optical density at low sodium chloride concentrations than did the controls. Other samples exposed in hypotonic solutions showed both the greater sensitivity to low sodium chloride concentrations and a smaller change in optical density as the sodium chloride was varied from isotonic to 70% isotonic. It has not been possible to demonstrate that any factor other than cavitation was responsible for the observed changes in osmotic fragility.

By use of a high-power, corona type loudspeaker we have been able to demonstrate behavioral and endocrine responses of laboratory rodents to measured high sound-pressure levels at the frequencies at which their hearing is most sensitive, namely, 10 to 40 kc. The corona type loudspeaker behaves in the fashion predicted by the theoretical analysis reviewed in this paper. It is limited by extremely low efficiency (2.5%) and high production of ozone. At high frequencies it is limited by the volume of the corona, and at low frequencies by the failure of the quasi-adiabatic condition within the corona. Despite these limitations its performance has not been equaled by other types of loudspeakers; it is a unique tool for studying the responses of laboratory rodents to sound fields.

AbstractBackground: Positive control materials for clinical diagnostic molecular genetic testing are in critically short supply. High-quality DNA that closely resembles DNA isolated from patient specimens can be obtained from Epstein–Barr virus (EBV)–transformed peripheral blood lymphocyte cell lines. Here we report the development of a process to (a) recover residual blood samples with clinically important mutations detected during routine medical care, (b) select samples likely to provide viable lymphocytes for EBV transformation, (c) establish stable cell lines and confirm the reported mutation(s), and (d) validate the cell lines for use as positive controls in clinical molecular genetic testing applications.Methods: A network of 32 genetic testing laboratories was established to obtain anonymous, residual clinical samples for transformation and to validate resulting cell lines for use as positive controls. Three panel meetings with experts in molecular genetic testing were held to evaluate results and formulate a process that could function in the context of current common practices in molecular diagnostic testing.Results: Thirteen laboratories submitted a total of 113 residual clinical blood samples with mutations for 14 genetic disorders. Forty-one EBV-transformed cell lines were established. Thirty-five individual point and deletion mutations were shown to be stable after 20 population doublings in culture. Thirty-three cell lines were characterized for specific mutations and validated for use as positive controls in clinical diagnostic applications.Conclusions: A process for producing and validating positive control cell lines from residual clinical blood samples has been developed. Sustainable implementation of the process could help alleviate the current shortage of positive control materials.

OBJECTIVE To review the characteristics and determine treatment outcomes of pediatric dermoid cysts. STUDY DESIGN AND SETTING Retrospective review of the presentation, diagnosis, treatment, and outcomes of all pediatric dermoid cysts of the head and neck examined between 1980 and 2002 at Mayo Clinic. RESULTS Forty‐nine patients (59% girls) had a dermoid cyst of the head and neck. The median age at diagnosis was 22 months. The most common presenting sign was a palpable mass, noted in 100% of patients. During evaluation, approximately 25 patients (51%) had imaging studies. The most common location of the cysts was periorbital (61%), followed by the neck (18%; including 1 submental cyst). Various surgical approaches were chosen. In 2 patients (4%), the dermoid cyst had an intracranial extension. Only 1 patient experienced recurrence. The median pathologic diameter of the cysts was 1.2 cm. CONCLUSIONS Dermoid cysts are unusual neoplasms that often present in childhood, with the orbit being the area most commonly affected in the head and neck region. Imaging studies help rule out an intracranial or intraorbital extension. With complete excision, recurrence is unusual. SIGNIFICANCE Our review will assist both primary care physicians and subspecialists in diagnosing and treating dermoid cysts.