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Biomedical subjects

F A Gibbs

Publications and source records attributed to F A Gibbs.

69 records · Page 4Linked to original sources
PubMed1967

The enzymatic preparation of isolated intact parenchymal cells from rat liver.

Suspensions of isolated parenchymal cells were prepared from rat liver by incubation with collagenase and hyaluronidase followed by mechanical treatment. Utilization of 0.15% collagenase together with 0.15% hyaluronidase yielded adequate numbers of cells for experimental purposes. As shown by light and electron microscopy, approximately 75% of the isolated cells retain their structural integrity. The cell suspensions are capable of maintaining endogenous respiration in the presence of 1% albumin for periods of time up to 8 hr. These cell preparations consist almost entirely of parenchymal cells and offer a unique tissue preparation for the study of hepatic metabolism.

Animals↗
PubMedDate not supplied

Localized hyperthermia and X-irradiation of murine jejunum in situ: a new method.

In C3H mice, preparative surgery apposed a 15 mm length of jejunum to the peritoneal surface of the ventral abdominal wall. After the mice healed, manipulation of the abdominal wall made possible selective hyperthermic treatment and X-irradiation of the immobilized jejunal segment (IJS) while it remained within the peritoneal cavity and in continuity with the rest of the intestines. For hyperthermia, the ventral abdominal wall and attached IJS was flattened between two aluminium plates immersed in a standard water bath. The temperature at the mesenteric attachment of the IJS was within 0.5 degrees C of a 44 degrees C bath 100 s after immersion and within 0.3 degrees C at steady-state. Xenon-133 washout studies showed that the treatment technique did not compromise blood flow to the IJS. The preparative surgery left the IJS normally responsive to X-irradiation as determined by crypt microcolony assay. Hyperthermia treatment by itself at 44 degrees C for up to 20 min caused no loss of crypts or villi; however, adjuvant 5-15 min 44 degrees C hyperthermia displaced the X-ray crypt-survival curves towards lower doses without changing their slopes. Nevertheless, formal statistical analyses admitted both additive and multiplicative interpretations of the effects of X-irradiation and adjuvant hyperthermia on intestinal crypt survival. After adjuvant hyperthermia, the surviving crypts were preferentially clustered near the mesenteric attachment to a greater extent than was expected from the asymmetry of the heat dose.

Animals↗
PubMedDate not supplied

Phase I evaluation of hyperthermia equipment--University of Utah institutional report.

At the University of Utah Medical Center the thrusts of the effort with respect to the NCl Hyperthermia Equipment Evaluation Contract have been threefold. The first objective was the development of a reliable thermometry system for collecting temperature information as a function of space as well as time. The second objective was the evaluation and comparison of a number of hyperthermia devices, particularly with respect to deep-heating devices, and specifically as pertains to the BSD annular phased array system (AA) and its various configurations. The third objective was to develop methodology for analysing hyperthermia data which could be easily adapted toward device comparison. In the period from 10/81-1/86, a total of 137 patients were treated with one or more of 10 devices, totalling 199 device evaluations at the University of Utah Medical Center or the subcontracting institution, LDS Hospital. Of these, 132 device evaluations involved deep-seated tumours. The AA was found to be feasible for deep pelvic regional hyperthermia, although the frequency of reversible acute toxicity was high, and achievement of desired temperatures was frequently limited by one of several factors. The radiative electromagnetic wave applicators which were evaluated for treatment of superficial tumours were found to be mostly feasible for tumours of the thoracic and extremities regions, although the heating patterns were frequently too shallow or too small in area, when compared with the size of the lesion.

Equipment Design↗
PubMedDate not supplied

Myonecrosis following deep pelvic hyperthermia.

A case report is presented in which severe myonecrosis of the inferior anterior abdominal wall followed treatment of a recurrent pelvic tumour with an annular phased array (AA) deep heating device. This unusual complication has not been observed at this institution in 107 patients previously treated with deep pelvic or abdominal hyperthermia, who had undergone a total of 368 hyperthermia sessions. The injury was confirmed radiographically and histopathologically, and was associated with serum enzymatic elevations characteristic of muscular injury. The implications for clinical trials employing the AA or similar devices are discussed.

Abdominal Muscles↗
PubMedDate not supplied

Adjuvant pelvic hyperthermia in advanced cervical carcinoma. I. Feasibility, thermometry and device comparison.

From 1981 to 1989, a total of 26 women with locally or regionally advanced carcinoma of the uterine cervix were treated with radiotherapy (RT) and pelvic regional hyperthermia (HT), in the Divisions of Radiation Oncology at the University of Utah Medical Center (UU) and the Kenneth Norris Jr Cancer Hospital of the University of Southern California (USC). HT was produced by the BSD-1000 HT system and the annular phased array (AA) applicator usually driven at 60-65 MHz, or the BSD-2000 HT system and the Sigma-60 (S60) applicator usually driven at 70-85 MHz. During the HT sessions acute toxicity was common, particularly because of pain within or outside the applicator, which was power-limiting in 43% of the patients overall. Pain was more easily manipulated, but more commonly power-limiting with the S60. Systemic stress was power-limiting in 22% of patients treated with the AA, but in no patients with the S60. Detailed thermal mapping and temperature analysis were performed on 26 patients. The mean overall average intratumour temperature achieved was 41 +/- 1.1 degrees C for 30 min; 5% and 35% of the monitored intratumour loci exceeded 43 degrees C and 42 degrees C, respectively. Temperatures recorded in the cervical os and proximal vagina appeared lower relative to the monitored normal structures in the region. Subacute treatment related toxicities occurred in five patients and included protracted pain (three) and superficial second degree burns (one), all of which resolved with supportive non-surgical therapy.

Adenocarcinoma↗
PubMedDate not supplied

Finite element simulation of Sigma 60 heating in the Utah phantom: computed and measured data compared.

An initial series of comparisons are made between finite element computations and laboratory measurements obtained during heterogeneous phantom heating with the Sigma 60 applicator. The phantom is a relatively complex, though still idealized, rendering of the pelvic area which has been used to study the deep heating characteristics of the Sigma 60 in this anatomy. Direct electric field measurements as well as inferred SAR through transient temperature analysis are plotted against computed results along 11 one-dimensional tracks through the phantom. Quantitative comparisons provided through the track-by-track analysis show generally good agreement between computation and measurement. The finite element method is found to predict well the jumps in the electric field when polarized perpendicularly to a muscle/fat interface. Visualizations of the complete three-dimensional distributions are also highlighted and correlate well with physical reasoning about the expected behaviour of the fields produced. Some discrepancies in the data persist and are discussed and analysed in depth. They underscore the difficulties that can arise in performing comparisons between measured and computed results and stress the need for careful and thorough investigations when attempting these types of model validation studies.

Biophysical Phenomena↗