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Biomedical subjects

F M Stewart

Publications and source records attributed to F M Stewart.

At least 91 records · Page 5Linked to original sources
PubMed1988

Esthesioneuroblastoma: a comparison of two treatment eras.

This paper is a retrospective review of 30 patients with esthesioneuroblastoma, an uncommon malignancy of the upper nasal cavity, treated at a single institution from 1959 through 1986. Over the period of study, there has been a gradual evolution of treatment policy and technique with the introduction of craniofacial resections and complex field megavoltage radiation, as well as for Stage C disease, the addition of chemotherapy to radiotherapy and surgery. The 25 patients with a 2 year minimum follow-up are divided into 2 groups depending upon treatment era to determine the impact of modern aggressive therapy upon treatment results. Two-year survival for Group I (1959-1975) was 70% as compared with 87% for Group II (1976-85). For Stage C disease, there was a definite improvement in survival in the later era (88% versus 50%), although relapses did not appear to be circumvented. Salvage therapy has an important role in prolonging survival in this disease.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1988

Synergistic interactions between hematopoietic growth factors as detected by in vitro mouse bone marrow colony formation.

We have investigated the proliferative effects of several combinations of hematopoietic growth factors in agar cultures of murine bone marrow cells. Granulocyte-macrophage colony-stimulating factor (GM-CSF) synergized with granulocyte colony-stimulating factor (G-CSF), while G-CSF also synergized with macrophage colony-stimulating factor (CSF-1) and interleukin 3 (IL3), resulting in colony numbers greater than the sum of the numbers of colonies formed with each factor alone. In addition, these combinations resulted in increased colony sizes, with the formation of day-14 colonies with diameters greater than 0.5 mm. The combination of GM-CSF plus IL3 showed an increase in numbers of colonies that approximated the sum of that seen with each factor alone, however, the size of the colonies was increased with a number of day-14 and day-21 colonies having diameters greater than 0.5 mm. These data add to the list of hematopoietic factors known to synergistically stimulate myeloid progenitors and suggest that some of these interactions may be on early progenitor cells with high proliferative potentials.

Animals↗
PubMed1987

Sinonasal undifferentiated carcinoma: a distinctive and highly aggressive neoplasm.

Eleven cases of sinonasal undifferentiated carcinoma were treated between 1975 and 1986. This distinctive neoplasm involved the orbital cavity in 6 of 11 patients (55%) and the cranial cavity in 7 of 11 patients (64%) at the time of presentation. Of the eight patients (73%) who died of disease, six died within 13 months after the diagnosis. One patient has no evidence of disease 10 months after therapy, and two are alive with disease after 15 and 22 months.

Adult↗
PubMed1986

Interstitial lung disease associated with vindesine and radiation therapy for carcinoma of the lung.

Diffuse interstitial lung disease and pulmonary fibrosis occurred after the use of vindesine and radiation therapy in a patient with squamous cell carcinoma of the lung. Clinical improvement occurred after the drug was discontinued and corticosteroid therapy was initiated. Review of the literature reveals no previously reported cases of pulmonary toxicity due to vindesine when used alone or in combination with other therapeutic modalities.

Aged↗
PubMed1985

Residual tumor masses following treatment for advanced histiocytic lymphoma. Diagnostic and therapeutic implications.

Forty percent or more of patients with advanced diffuse histiocytic (large cell) lymphoma will achieve prolonged disease-free survival with the use of intensive combination chemotherapy. These results are obtained only if complete resolution of all viable tumor is documented prior to the cessation of chemotherapy. Residual tumor masses at the time of re-staging usually are excised or biopsied to confirm the presence or absence of viable tumor. Three patients are reported who had with advanced histiocytic (large cell) lymphoma, and who demonstrated residual intra-abdominal tumor masses on CT scan following four courses of COPP chemotherapy. After two additional courses of a non-cross-resistant regimen and/or supplemental radiotherapy failed to reduce the size of the masses, abdominal exploration with removal of the tumors including splenectomy in one patient was performed, and in each instance no viable tumor was found. The patients have remained disease-free for periods ranging from 24 to 48 months. The various options available to evaluate such patients are presented, and a systematic approach which should avoid the unnecessary prolongation of potentially harmful chemotherapy or radiotherapy is proposed.

Abdominal Neoplasms↗
PubMed1985

Mitomycin and fluorouracil with concomitant radiotherapy in head and neck cancer.

Forty-two previously untreated patients with predominantly stage IV (35) head and neck squamous cell carcinoma were treated preoperatively with mitomycin and fluorouracil and concomitant radiotherapy with 5,000 to 6,000 rad using a split-course technique. Toxic reactions were acceptable. Five patients developed severe mucositis. The white blood cell count fell to 1,500/cu mm in two patients; the platelet count fell to 100,000/cu mm in three. Other complications occurred in three patients. Eighty-six percent of patients completed advised treatment. Complete response, assessed clinically and with histologic correlation, was 79% at primary sites and 69% at nodal sites. Twenty-seven patients had a complete response (64%). Follow-up currently is between ten and 24 months. Though analysis of disease-free intervals and survival data is premature, the high complete response rates in this study are encouraging.

Carcinoma, Squamous Cell↗
PubMed1984

The population biology of bacterial viruses: why be temperate.

A model of the interactions between populations of temperate and virulent bacteriophage with sensitive, lysogenic, and resistant bacteria is presented. In the analysis of the properties of this model, particular consideration is given to the conditions under which temperate bacteriophage can become established and will be maintained in bacterial populations. The effects of the presence of resistant bacteria and virulent phage on these "existence" conditions for temperate viruses are considered. It is demonstrated that under broad conditions temperate phage will be maintained in bacterial populations and will coexist with virulent phage. Extrapolating from this formal consideration of the population biology of temperate bacteriophage, a number of hypotheses for the conditions under which temperate, rather than virulent, modes of phage reproduction are to be anticipated and the nature of the selective pressures leading to the evolution and persistence of this "benign" type of bacterial virus are reviewed and critically evaluated. Two hypotheses for the "advantages of temperance" are championed: (1) As a consequence of the allelopathic effects of diffusing phage, in physically structured habitats, lysogenic colonies are able to sequester resources and, in that way, have an advantage when competing with sensitive nonlysogens. (2) Lysogeny is an adaptation for phage to maintain their populations in "hard times," when the host bacterial density oscillates below that necessary for phage to be maintained by lytic infection alone.

Bacteriophages↗
PubMed1983

Acute nonlymphocytic leukemia and acute aplastic anemia. The simultaneous occurrence in marital partners.

A young husband and wife couple presented simultaneously with aplastic anemia and acute myelomonocytic leukemia, respectively. No etiologic agent or exposure was identified. With appropriate therapy, the wife achieved a complete remission and the husband has had a good response. Potential etiologic environmental factors known to cause both disorders are discussed. A single causative agent may induce stem-cell changes in genetically dissimilar persons and produce a spectrum of pathologic features ranging from aplastic anemia to acute leukemia.

Adult↗
PubMed1980

The population biology of bacterial plasmids: a priori conditions for the existence of mobilizable nonconjugative factors.

A mathematical model for the population dynamics of nonconjugative plasmids that can be mobilized by conjugative factors is presented. In the analysis of the properties of this model, primary consideration is given to the conditions under which these nonself-transmissible extrachromosomal elements could become established and would be maintained in bacterial populations. The results of this analysis demonstrate the existence of conditions where, as a consequence of infectious transmission via mobilization, nonconjugative plasmids could become established and be maintained even when the bacteria carrying them have lower reproductive fitnesses than plasmid-free members of the population. However, these existence conditions are stringent and suggest therefore, that it is highly unlikely that plasmids of this type would become established and maintained without some direct selection favoring their carriage. The general implications of these results and limitations of the model are discussed. Brief consideration is also given to the implications of these theoretical findings to the problems of the spread of multiple antibiotic resistance plasmids (R-factors) and the risk of contaminating natural populations of bacteria with chimeric plasmids produced by work with recombinant DNA.

Conjugation, Genetic↗
PubMed1977

Probability of establishing chimeric plasmids in natural populations of bacteria.

Formulas for estimating the probability that chimeric plasmids carried by disarmed hosts will become established in natural populations of bacteria are presented and their use illustrated with a series of realistic numerical examples. The implications of these a priori probability estimates for the problem of containment for recombinant DNA research is discussed.

Conjugation, Genetic↗
PubMed1977

Regions of stable equilibria for models of differential selection in the two sexes under random mating.

The equilibrium structure of models of differential selection in the sexes is investigated. It is shown that opposing additive selection leads to stable polymorphic equilibria for only a restricted set of selection intensities, and that for weak selection intensities must be of approximately the same magnitude in the sexes. General models of opposing directional selection, with arbitrary dominance, are investigated by considering simultaneously the stability properties of the trivial equilibria and the curve along which multiple roots appear. Numerical calculations lead us to infer that the average degree of dominance determines the equilibrium characteristics of models of opposing selection. It appears that if the favored alleles are, on the average, recessive, there may be multiple polymorphic equilibria, whereas only a single polymorphic equilibrium can occur when the favored alleles are, on the average, dominant. The principle that the average degree of dominance controls equilibrium behavior is then extended to models allowing directional selection in one sex with overdominance in the other sex, by showing that polymorphism is maintained if and only if the average fitness in heterozygotes exceeds one.

Animals↗