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Biomedical subjects

R F Meredith

Publications and source records attributed to R F Meredith.

At least 55 records · Page 3Linked to original sources
PubMed1989

Ferromagnetic thermoseeds: suitable for an afterloading interstitial implant.

Previous studies have shown implantable ferromagnetic thermoseeds to be a promising hyperthermia method. However, migration from the implant site and chemical toxicity caused by corrosion of the thermoseed alloy have proven to be potential hazards. These problems could be overcome by placing the thermoseeds into removable catheters similar to those used for afterloading interstitial brachytherapy. As an additional merit, the method would allow convenient combination of heat and radiation therapy. To test the clinical performance of this method, we compared temperature distributions and biologic effects in canine muscle and transmissible venereal tumors for bare thermoseeds and thermoseeds contained within catheters. We found no significant difference in the heating patterns and similar tissue changes when all implants were removed immediately after heating. More severe tissue changes were present around bare thermoseeds that were retained. This suggests that catheters provide a safe and reliable method for thermoseed hyperthermia which would allow convenient combination with interstitial radiation.

Alloys↗
PubMed1989

Practical aspects of ferromagnetic thermoseed hyperthermia.

Thermoseeds are needle-shaped devices that are interstitially placed into tumors, similar to brachytherapy implants. Heating is accomplished by an externally applied electromagnetic induction field, requiring no connections to an external power source. Thermoseeds made of special alloys provide automatic temperature control. Therapeutic efficacy has been demonstrated in initial clinical applications.

Brachytherapy↗
PubMed1987

1986 Association of Residents in Radiation Oncology Survey.

Two simultaneous surveys were conducted by the Association of Residents in Radiation Oncology (ARRO). A survey of all residents in Radiation Oncology was conducted to obtain information on trends in residency training. A simultaneous survey of Chief Residents was obtained to determine more specific information on current training programs. Over one-half of residents responded. Eighty-eight percent of respondents were graduates of a North American medical school. Most did at least an internship prior to entering Radiation Oncology and 3/4 of those who did not do a separate internship rotated through other areas at a later time to broaden their knowledge. One-half are Board certified or Board eligible in another specialty or hold a Masters or Ph.D. degree. Three-quarters of all residents had authorship of at least one paper during training and one-half were primary authors. Eighty percent felt adequately prepared for practice after residency. One-half plan at least an initial post-residency affiliation with an academic center. Many were concerned that Radiation Oncologists are not afforded respect equivalent to that of other specialties. Ninety-eight percent favored departmental status for Radiation Oncology. Resident recommendations for improving the image of Radiation Oncology are presented.

Education, Medical, Continuing↗
PubMed1986

An excess of uterine sarcomas after pelvic irradiation.

The Ohio State University Registry recorded 1208 uterine corpus malignancies between 1940 and 1983. Thirty cases occurred in women with a history of pelvic irradiation. Eight patients had previously been irradiated for pelvic malignancy, four of whom presented with advanced stage sarcomas and died of their disease within 14 months. This represents an increase over the expected sarcoma prevalence which is less than 5%. In contrast, the majority of women (20 of 22) previously irradiated for benign conditions were diagnosed with endometrial adenocarcinoma. In 18, the adenocarcinoma was diagnosed as Stage I, and the prognosis was only slightly less favorable than for nonirradiated women. No significant effect of age at the time of irradiation was apparent. This study of women with a history of pelvic irradiation who later developed uterine cancer demonstrates a tendency for patients previously irradiated for pelvic malignancy to present with advanced stage, extremely aggressive uterine tumors compared to those previously irradiated for benign conditions.

Adenocarcinoma↗
PubMed1986

Beta-chain human chorionic gonadotropin-producing leiomyosarcoma of the small intestine.

A 22-year-old patient with primary leiomyosarcoma of the small bowel presented with symptoms including nausea and vomiting, a symptom complex similar to hyperemesis gravidarum in the pregnant female. She was found to have elevated levels of serum beta-HCG which were localized to the leiomyosarcoma cells utilizing an immunoperoxidase staining technique. Thus, this patient presents evidence that beta-HCG may be produced by sarcoma cells and, therefore, that beta-HCG may be used as a tumor marker in some sarcoma patients.

Adult↗
PubMed1983

Possibility of graft-vs-leukemia determinants independent of the major histocompatibility complex in allogeneic marrow transplantation.

The role of major histocompatibility (MHC) versus non-MHC determinants in the antileukemic effect exerted by engrafted normal marrow (graft-vs-leukemia, GvL) was studied in Rauscher leukemic SJL/J mice. The marrow donor strains included normal syngeneic SJL/J (H-2s), allogeneic C57BL/10 and 129/J (H-2b), congenic B10.S (H-2s, but otherwise genetically identical to the C57BL/10), and also F1 hybrid mice of the SJL/J and B10.S or C57BL/10 strains. Prior to transplant the recipients were exposed to a dose of total body irradiation that was large, but lower than that required to eliminate all hematopoietic precursors, such that GvL activity of the donor marrow would be necessary to avoid leukemic relapse. Total relapse within 60 days was observed when the syngeneic SJL/J donors were used. Transplantation either of the H-2b C57BL/10 or the H-2s B10.S marrow resulted in approximately 50% unrelapsed survival at 4 months. In contrast, only 26% unrelapsed survival was obtained with H-2b 129/J marrow. Marrow from (SJL/J X B10.S)F1 hybrids yielded a survival curve that was intermediate between those for the two parental strains; a similar but somewhat improved pattern was seen with (SJL/J X C57BL/10)F1-hybrid donors. The results suggest that although MHC genetic differences between the donor and recipient may produce a GvL effect in marrow transplantation therapy, other non-MHC determinants may also be capable of exerting an independent GvL effect of at least equivalent strength.

Animals↗
PubMed1981

Fatal response suggestive of graft-versus-host reaction following transplantation of spleen cells from allogeneic athymic (nude) donors.

Normal female SJL/J mice were exposed to 950 R of total body irradiation (TBI) and transplanted with allogeneic spleen or marrow cells from normal or nude (athymic) C57BL/10 donors. With nude mouse donor marrow, no evidence of graft-versus-host (GVH) response was seen and all SJL/J recipients survived for more than 75 days. In contrast, when spleen cells taken from the same nude C57BL/10 donors were engrafted into SJL/J mice the incidence of fatalities among the recipients was 70% by 60 days. Furthermore, all of the recipients of nude mouse spleen cells showed signs strongly suggestive of GVH response. Comparative fatalities among the recipients of cells from normal donors were 27% for marrow at 60 days and 100% for spleen at 11 days, and these were accompanied by the characteristic signs of GVH response usually seen after transplantation of cells from normal allogeneic donors. Transplantation of normal C57BL/10 marrow mixed with small numbers at normal spleen cells resulted in an increase in the number of fatalities among the SJL/J recipients, and an increase in the severity of the signs of GVH response as compared to that seen following engraftment of normal C57BL/10 marrow alone. However, no such increases in fatalities or severity were observed when similar amounts of nude C57BL/10 spleen cells were engrafted along with normal marrow cells into SJL/J recipients. The results suggest that a factor may exist in nude mouse spleen which in allogeneic transplantation can lead to a fatal response suggestive of GVH reaction, but that nude mouse spleen lacks the T cell-related ability to enhance GVH response that has been previously demonstrated following allogeneic transplantation using normal spleen and marrow donors.

Animals↗
PubMed1981

Histocompatibility influence in allogeneic marrow transplantation therapy of murine viral leukemia. I.--Studies of the relative influence of major versus minor histocompatibility determinants.

The anti-leukemic effectiveness (GvL activity) and anti-host response (GvH response) of several allogeneic donor marrows were compared in lethally irradiated normal and Rauscher leukemia SJL/J recipients. Although both types of effects could be demonstrated, the degree of GvL activity did not parallel the severity of GvH response. The level of GvL activity of the donor marrow also appeared to be independent of sensitivity of the donors to the leukemia inducing Rauscher virus (RLV), as a high level of leukemia recurrence was found using marrow from RLV-resistant RF/J donors, while a lesser degree of recurrence occurred with the use of RLV-sensitive DBA-2J marrow. Analysis of the possible influence of major (MHC) and Minor (MiHL) histocompatibility loci suggested that GvL activity may be independent of the H-2 locus, and that the "a" alleles of the H-4 and H-13 loci may not be contributing to GvL effect. Likewise the "a" alleles of the H-7 and H-12 loci did not appear to affect the severity of GvH response. The possibly that GvL activity may be independent of th MHC, but governed by MiHL possibility different from those regulating GvH response might explain why in this and previous studies GvL activity could only be demonstrated following allogeneic marrow transplantation but did not appear to correlate with severity of GvH response.

Alleles↗
PubMed1981

Graft-vs-leukemia and moderation of graft-vs-host reaction in transplantation therapy of viral leukemia.

In transplantation studies of Rauscher leukemic SJL/J mice longer median survival times (MST) were obtained with spleen cells from syngeneic donors than with marrow. These could be further extended by immunization of the donors to Rauscher virus (RLV) and Rauscher leukemia cells. This suggests that spleen cells exert a greater graft-vs-leukemia effect than marrow. Nevertheless, with syngeneic cells all recipients eventually died of leukemia relapse. In contrast, the use of RLV-resistant C57BL/10J allogeneic marrow cells resulted in a substantial number of long-term survivors and a low incidence of GvH disease, while the use of pure allogeneic spleen cells resulted in early and fatal GvH response in all recipients. To determine if allogeneic spleen cells might have any demonstrably beneficial effect on survival of leukemic mice various small quantities of C57BL/10J spleen cells were mixed with marrow from the same donors and engrafted into normal and leukemic SJL/J recipients. Among the normal mice MST decreased as a function of spleen cell concentration. However, with the leukemics the use of 2.5 or 5% spleen cells resulted in later deaths than that found when leukemic mice were given only marrow. Also, for all allogeneic spleen/marrow mixtures tested, survival of leukemic recipients exceeded that of normal recipients given the same cell mixtures. These data suggest a possible beneficial effect of small amounts of allogeneic spleen cells in transplantation therapy for leukemia, and a possible competitive interaction of anti-host and anti-leukemic activities of the transplanted cells leading to a moderation of the GvH response.

Animals↗