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Biomedical subjects

R Simon

Publications and source records attributed to R Simon.

At least 415 records · Page 23Linked to original sources
PubMed1982

Patient subsets and variation in therapeutic efficacy.

1 The determination of what treatment is best for what kinds of patients is a general objective of clinical research. We consider here the extent to which this objective can be accomplished reliably in a single clinical trial. 2 The reliability of subset analyses is often poor due to problems of multiplicity and limitations in numbers of patients studied. Implications for the design of clinical trials are presented. 3 Statistical approaches to subset analysis are reviewed in a general manner. In order to obtain the degree of reliability usually demanded of clinical therapeutic evaluations, "statistically significant' interactions between relative treatment efficacy and subsets should be demonstrated. Exploratory analyses of subset differences are important but should be reported as hypotheses to be tested in separate studies.

Clinical Trials as Topic↗
PubMed1982

Blood velocity, flow and dimensions of aortocoronary venous bypass grafts in the postoperative state.

Intraoperative measurements have suggested an interrelation between the diameter of aortocoronary venous bypass (ACVB) grafts and the hemodynamic properties that may influence the functional results and long-term graft patency. We therefore studied the function of 35 nonobstructed ACVB grafts in 34 patients 1-59 months after bypass grafting. The mean blood velocity and flow were assessed using the roentgen videodensitometric technique. Graft diameters were obtained by morphometry from 35- or 70-mm cineangiograms taken in two orthogonal projections. The regional resistance of the graft-dependent area was calculated as mean aortic pressure/ACVB flow. The average graft diameter was 3.67 mm, the average graft-to-host vessel diameter ratio 1.5, the average ACVB blood velocity 8.5 cm/sec, the average flow 55 ml/min, and the average regional resistance 2.8 mm Hg/ml/min. No significant differences were observed for different graft locations or for different postoperative time intervals. Neither ACVB blood velocity nor flow correlated convincingly with graft size, but there was a significant inverse relation between graft diameter and the resistance of the graft-dependent area. We conclude that ACVB hemodynamics generally cannot be predicted by the dimensions of the graft in the postoperative state. Our data suggest that venous bypass grafts may adjust in size to the needs of the myocardial region supplied by the graft after operation.

Adult↗
PubMed1981

Bereavement art.

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Adult↗
PubMed1981

Composite randomization designs for clinical trials.

This paper proposes a new design for the augmentation of a randomized clinical trial through the participation of private physicians who do not randomize individual patients. Each private physician is randomly assigned a study treatment which he or she uses consistently for all eligible patients. A statistically rigorous method of analysis is described, the efficiency of this design is evaluated, and its limitations discussed.

Clinical Trials as Topic↗
PubMed1980

Estradiol affinity chromatography: application to purification of murine alpha-fetoprotein.

A one-step batch procedure is described for purification of murine alpha-fetoprotein (AFP) by estradiol affinity chromatography. Various ratios of carbodiimide (C), diaminononame (D) and estradiol hemisuccinate (E) were tested to determine optimal conditions for AFP purification. Although yields of AFP ranged from 15 to 44% depending on the reagent ratio employed, AFP isolates free of other protein contaminants were achieved at C:D:E ratios of 10:10:1 with a 29% yield. Both estrone and estradiol proved efficient as elution agents to free AFP bound to the estradiol-Sepharose beads, but higher yields were produced with estrone. After isolation the estrogen-eluted AFP preparations were analyzed by (1) estradiol-binding assays, (2) third-party radiocoprecipitation, (3) inhibition of radioimmunoassay for estrone and estradiol and (4) exchange of unlabeled for radiolabeled estradiol. These results indicated that the steroid remained attached to the eluted AFP molecule.

Animals↗
PubMed1980

Haemopoietic recovery in Ewing's sarcoma after intensive combination therapy and autologous marrow infusion.

After the completion of combination therapy designed to achieve local control of Ewing's sarcoma, 13 patients with either truncal primary lesions or proven metastases were given 150 rad of total body irradiation over 5 weeks followed by cyclophosphamide, doxorubicin, imidazole carboxamide, and vincristine. 11 patients received autologous cryopreserved marrow infusions. In 2 patients marrow collections were not attempted. Two patterns of haemopoietic recovery were observed: 8 patients, who had received marrow infusions, showed leucocyte, granulocyte, and platelet recovery by 27, 28, and 30 days. 5 patients, 3 of whom had also received marrow, showed more delayed recovery with leucocyt, granulocyte, and platelet recovery at 45, 53, and 77+ days. Delayed recovery in patients receiving marrow seemed to correlate with aberrations in marrow freezing-rate during phase change, and these aberrations could be shown to diminish post-freeze recovery of marrow granulocyte-monocyte precursor cells.

Adolescent↗
PubMed1980

Statistical methods for evaluating pregnancy outcomes in patients with Hodgkin's disease.

This report presents a review of difficulties in the analysis of case-control studies in which multiple binary responses are observed for each individual and the number of controls per case varies. These statistical considerations are described in the context of a previously reported analysis of the influence of treatment of Hodgkin's disease on pregnancy outcomes.

Abnormalities, Drug-Induced↗
PubMed1980

Prognostic factors in Burkitt's lymphoma: importance of total tumor burden.

In 42 patients with African Burkitt's lymphoma, we have studied biochemical and clinical correlations with prognosis. Clinical stage and anti-EA titer were the best predictive factors, but lactic dehydrogenase (LDH) and uric acid (UA) concentrations also correlated with stage and prognosis, whereas lactic acid (LA), which was significantly elevated in Stage D, did not significantly correlated with prognosis or with LDH and UA levels. All of these factors with the possible exception of LA reflect the total body burden of tumor. We conclude that the tumor burden is the single most important prognostic factor in Burkitt's lymphoma, and that this is reflected directly by LDH and UA concentrations, and probably indirectly by anti-EA titer.

Adolescent↗