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Biomedical subjects

R Simon

Publications and source records attributed to R Simon.

At least 433 records · Page 24Linked to original sources
PubMed1980

Length biased sampling in etiologic studies.

The problem of estimating and comparing the frequency of a characteristic in newly diagnosed patients based upon a length biased sample of living patients is described in this paper. This problem is of considerable importance in immunogenetics for determining whether a characteristic is related to disease etiology, or whether, instead, it is of prognostic importance for individuals who have already developed the disease. Maximum likelihood estimation of the proportion of newly diagnosed patients having a characteristic is outlined. The estimator and its variance depend upon the proportion of living patients having the characteristic and upon the survivals of patients with and without the characteristic in the length biased sample.

Antigens↗
PubMed1980

The Rappaport classification of non-Hodgkin's lymphomas: a closer look using other proposed classifications.

An essential purpose of a pathologic classification of non-Hodgkin's lymphomas is to supply guidance in the clinical management of patients. Ideally, an optimal subclassification should also be scientifically accurate, highly reproducible, and readily teachable. Such a system, when used in conjunction with uniform staging, should enable relatively homogeneous groups of patients to be defined. In the present study, we have evaluated four new systems for possible additions to the traditional Rappaport classifcation. In response to specific questions the following tentative conclusions could be drawn: (1) Within the Rappaport nodular lymphomas, there are no differences in survival between lymphomas that are totally nodular verusus those that are nodular and diffuse. (2) In lymphomas composed of small cleaved follicular center cells of the Lukes-Collins system, survival appears to be independent of pattern (follicular, follicular and diffuse, or diffuse). In contrast, in tumors classified as centroblastic-centrocytic in the Kiel classification or those classified as large cleaved or large noncleaved in the Lukes-Collins system, a totally or partially follicular pattern confers a better prognosis than its diffuse counterpart. (3) The numbers are small but there is no apparent difference in survival between cases of Rappaport's difuse well differentiated lymphocytic lymphomas with or without plasmacytoid differentiation. (4) Within the original Rappaport DPDL there were at least two distinct types of lymphomas: (1) a convoluted lymphoblastic that occurs in younger patients has a high frequency of B symptoms and carries a poor prognosis; and (2) a diffuse lymphoma that is cytologically identical to nodular PDL, occurs in older patients, and has a relatively good prognosis. In August of 1976 Rappaport modified his classification to recognize these lymphoblastic lymphomas as a distinct clinicopathologic entity. (5) In this 22-yr retrospective review, neither the Kiel nor the Lukes-Collins system could identify any relatively favorable subsets within Rappaport's category of diffuse histiocytic lymphoma. Prospective studies applying the same approach to large numbers of patients subjected to modern uniform staging and aggressive combination chemotherapy may provide data upon which to base an optimal subclassification of DHL.

Adolescent↗
PubMed1980

A proposed model for the prediction of response to endocrine therapy in breast cancer from the estrogen receptor status of one site and the number of metastatic sites.

A mathematical model for prediction of response to endocrine therapy of breast cancer has been developed based on a clonal concept of metastatic spread. The model includes an expression of the likelihood of response of an estrogen receptor-positive site and an expression of the concordance of receptor assays when multiple sites are assayed. Both of these are raised to a power function based on the number of sites of metastases to yield a predicted response rate. An excellent fit of the predictions of this mathematical model and response data from a series of patients receiving endocrine therapy was observed. This model provides a worthwhile insight into the biology of response to endocrine therapy. The model may be extended and refined through additional analyses.

Binding Sites↗
PubMed1980

Influence of mitral valve surgery on tricuspid incompetence concomitant with mitral valve disease.

Twenty adult patients with predominant mitral valve disease and variable degrees of tricuspid incompetence (TI) were reinvestigated 6-28 months after mitral valve operation. Postoperatively, 10 of the 20 patients were in sinus rhythm, compared with four of 20 preoperatively. Right ventricula peak systolic pressure decreased from 48 to 33 mm Hg (p less than 0.005), pulmonary vascular resistance declined from 234 to 141 dyn-sec-cm-5 (p less than 0.05), and cardiac index increased from 2.4 to 3.0 l/min/m2 (p less than 0.01) after operation, but right ventricular end-diastolic pressure and right atrial pressure failed to improve. TI, as graded by semiquantitative criteria from right ventricular angiocardiograms taken in the right anterior oblique projection, was decreased unequivocally in only six patients, unchanged in degree in 13 patients, and worse in one. Improvement in TI was associated with an enhancement of systolic shortening of the tricuspid annulus (24 vs 15%, p less than 0.02), whereas in patients with unchanged TI, tricuspid annulus shortening was also unchanged. These data suggest that TI associated with mitral disease is not invariably decreased after mitral surgery, despite improved hemodynamics. A depressed extent of shortening of the tricuspid annulus in systole seems to be important in the pathogenesis of TI.

Adult↗
PubMed1979

Estrogen receptor values in patients with benign breast disease.

Tissue specimens from 55 female patients with benign breast disease were assayed for estrogen receptor. Twenty-one of 55 patients (38%) had tumors which contained significant amounts of estrogen receptor (greater than 10 femtomoles/mg protein). Fibroadenomas possessed estrogen receptor more frequently than fibrocystic disease or other benign breast tumors. Estrogen receptor positivity did not correlate with laterality of the tumor; location or size of the largest nodule. Patients with estrogen receptor positive tumors had a mean age of 26.9 years compared to 36.4 years for patients with estrogen receptor negative tumors (p less than 0.01). Twenty of 46 (43%) premenopausal patients had benign tumors which were estrogen receptor positive compared to zero of 8 postmenopausal patients (p less than 0.05).

Adenofibroma↗
PubMed1979

Recommendations for the analysis of the effect of treatment on the development of second malignancies.

Use of the person-years method for evaluating the association between treatment of a primary cancer and subsequent development of a second malignancy is reviewed. For this type of analysis, the risk of developing a second malignancy is implicitly assumed to remain constant during each patient's follow-up period; this assumption is shown to be inappropriate. When the oncogenic potential of two or more treatments is compared, results are biased unfavorably against the use of intensive treatments that prolong life. Misinterpretation of the oncogenic potential of such treatment regimens can therefore occur, and two alternative statistical techniques are proposed, each for use in a commonly encountered experimental situation. These fairly classic methods of survival analysis are recommended to ascertain the relationship between treatment and development of a second cancer.

Antineoplastic Agents↗
PubMed1979

Purification of alpha-fetoprotein from mouse amniotic fluid by gel-entrapped antibody filtration.

A one-step immunospecific affinity chromatographic method for purification of mouse alpha-fetoprotein (AFP) directly from amniotic fluid is described. The procedure employed a rabbit anti-AFP immunoglobulin-G entrapped in a polyacrylamide gel matrix prepared as a gel slurry. The presence of impurities could not be demonstrated in the eluted fraction and the recovery of AFP was approximately 26%. Sufficient quantities of AFP were readily purified for raising antibodies and for purity studies.

Albumins↗
PubMed1979

Prolonged disease-free survival in Hodgkin's disease with MOPP reinduction after first relapse.

Thirty-two patients with Hodgkin's disease who relapsed after a first complete remission induced by nitrogen mustard, vincristine, procarbazine, and prednisone (MOPP) were retreated with MOPP chemotherapy. Nineteen patients achieved a second complete remission. Median duration of the second complete remission was 21 months. The likelihood of achieving a second complete response could be predicted by the duration of the first response. Fourteen of 15 patients whose first complete remission was longer than 12 months achieved a second complete response in contrast to five of 17 patients whose initial complete remission lasted less than 12 months (P less than 0.001). Median survival of all patients in this study who were re-treated with MOPP was longer than 4 years after their first relapse. We conclude that patients with Hodgkin's disease who relapse after a first complete remission induced by MOPP are not necessarily resistant to further MOPP therapy and can achieve long-term survival with MOPP reinduction.

Adolescent↗