The median-effect equation derived from the mass-action law principle at equilibrium-steady state via mathematical induction and deduction for different reaction sequences and mechanisms and different types of inhibition has been shown to be the unified theory for the Michaelis-Menten equation, Hill equation, Henderson-Hasselbalch equation, and Scatchard equation. It is shown that dose and effect are interchangeable via defined parameters. This general equation for the single drug effect has been extended to the multiple drug effect equation for n drugs. These equations provide the theoretical basis for the combination index (CI)-isobologram equation that allows quantitative determination of drug interactions, where CI 1 indicate synergism, additive effect, and antagonism, respectively. Based on these algorithms, computer software has been developed to allow automated simulation of synergism and antagonism at all dose or effect levels. It displays the dose-effect curve, median-effect plot, combination index plot, isobologram, dose-reduction index plot, and polygonogram for in vitro or in vivo studies. This theoretical development, experimental design, and computerized data analysis have facilitated dose-effect analysis for single drug evaluation or carcinogen and radiation risk assessment, as well as for drug or other entity combinations in a vast field of disciplines of biomedical sciences. In this review, selected examples of applications are given, and step-by-step examples of experimental designs and real data analysis are also illustrated. The merging of the mass-action law principle with mathematical induction-deduction has been proven to be a unique and effective scientific method for general theory development. The median-effect principle and its mass-action law based computer software are gaining increased applications in biomedical sciences, from how to effectively evaluate a single compound or entity to how to beneficially use multiple drugs or modalities in combination therapies.

http://www.protocol-online.org/forums/uploads/monthly_09_2010/post-8165-008503000%201284677034.ipb

Theoretical Basis, Experimental Design, and Computerized Simulation of Synergism and Antagonism in Drug Combination Studies

NOTE The report of the Committee without its annexes appears as Official Records of the General Assembly, Sixty-third Session, Supplement No. 46. The designations employed and the presentation of material in this publication do not imply the expression of any opinion whatsoever on the part of the Secretariat of the United Nations concerning the legal status of any country, territory, city or area, or of its authorities, or concerning the delimitation of its frontiers or boundaries. The country names used in this document are, in most cases, those that were in use at the time the data were collected or the text prepared. In other cases, however, the names have been updated, where this was possible and appropriate, to reflect political changes. Scientific Annexes Annex A. Medical radiation exposures Annex B. Exposures of the public and workers from various sources of radiation INTROdUCTION 1. In the course of the research and development for and the application of atomic energy and nuclear technologies, a number of radiation accidents have occurred. Some of these accidents have resulted in significant health effects and occasionally in fatal outcomes. The application of technologies that make use of radiation is increasingly widespread around the world. Millions of people have occupations related to the use of radiation, and hundreds of millions of individuals benefit from these uses. Facilities using intense radiation sources for energy production and for purposes such as radiotherapy, sterilization of products, preservation of foodstuffs and gamma radiography require special care in the design and operation of equipment to avoid radiation injury to workers or to the public. Experience has shown that such technology is generally used safely, but on occasion controls have been circumvented and serious radiation accidents have ensued. 2. Reviews of radiation exposures from accidents have been presented in previous UNSCEAR reports. The last report containing an exclusive chapter on exposures from accidents was the UNSCEAR 1993 Report [U6]. 3. This annex is aimed at providing a sound basis for conclusions regarding the number of significant radiation accidents that have occurred, the corresponding levels of radiation exposures and numbers of deaths and injuries, and the general trends for various practices. Its conclusions are to be seen in the context of the Committee's overall evaluations of the levels and effects of exposure to ionizing radiation. 4. The Committee's evaluations of public, occupational and medical diagnostic exposures are mostly concerned with chronic exposures of …

sources and effects of ionizing radiation

Pathology and genetics of tumours of the urinary system and male genital organs

Background and Methods On behalf of the Gynecologic Oncology Group, we performed a randomized trial of radiotherapy in combination with three concurrent chemotherapy regimens — cisplatin alone; cisplatin, fluorouracil, and hydroxyurea; and hydroxyurea alone — in patients with locally advanced cervical cancer. Women with primary untreated invasive squamous-cell carcinoma, adenosquamous carcinoma, or adenocarcinoma of the cervix of stage IIB, III, or IVA, without involvement of the para-aortic lymph nodes, were enrolled. The patients had to have a leukocyte count of at least 3000 per cubic millimeter, a platelet count of at least 100,000 per cubic millimeter, a serum creatinine level no higher than 2 mg per deciliter (177 μmol per liter), and adequate hepatic function. All patients received external-beam radiotherapy according to a strict protocol. Patients were randomly assigned to receive one of three chemotherapy regimens: 40 mg of cisplatin per square meter of body-surface area per week for six weeks (g...

Concurrent Cisplatin-Based Radiotherapy and Chemotherapy for Locally Advanced Cervical Cancer

Clinical gains have been reported from the use of nonstandard fractionation schedules planned with a radiobiological basis. Hyperfractionation provides the leading example, as described below, with accelerated fractionation being developed more recently. Although examples of almost every kind of fractionated schedule can be found in the literature over the past 90 years, it is only within the last decade that the biological factors concerning overall time and delayed proliferation after irradiation, and the effect of dose per fraction, have been understood. Both these factors operate differently on late- and early-reacting tissues, because cell proliferation in late-reacting tissues is slow or absent, but early reacting tissues and tumours depend upon cells that proliferate rapidly. This basic knowledge is still diffusing through the radiotherapy community and I hope this review will help the diffusion process. The biological factors concerning fractionation seem to apply to the majority of tissues and tu...

The linear-quadratic formula and progress in fractionated radiotherapy

There are a number of different mechanisms that can lead to an improved therapeutic result by the combination of radiotherapy and chemotherapy. Some require interaction between the effects of the two modalities; others require independence of effect. Enhanced killing of tumor cells is only one possible mechanism. There are serious conceptual problems in demonstrating greater-than-additive cell kill whenever dose-response curves are nonlinear. An approach to this problem is suggested, based on an “envelope of additivity” in an iso-effect plot.

Exploitable mechanisms in combined radiotherapy-chemotherapy: the concept of additivity.

https://www.thegreenjournal.com/pb/assets/raw/Health%20Advance/journals/radion/ecco15.pdf

The radioresponsiveness of human tumours and the initial slope ofthe cell survival curve

Histopathology in the prediction of relapse of patients with stage i testicular teratoma treated by orchidectomy alone

Between July 1979 and December 1981, 43 patients with metastatic germ-cell tumours (36 testicular non-seminomas and 7 testicular seminomas) were treated with 2-6 cycles of bleomycin, etoposide and cis-platin (BEP). Forty (93%) are alive, 37 (86%) with no evidence of disease. Of 36 men with testicular non-seminoma 30 (83.3%) are alive and disease-free at 8-38 months (median 17.0 months). In the latter group 25/28 (89.3%) who had had no prior irradiation are alive and disease-free. Fourteen non-seminoma patients had small volume metastases and 13 are in complete remission, as are 12/14 patients with bulky disease. All 7 patients with advanced seminoma are alive and disease-free. It is concluded that BEP is a well tolerated and effective first line treatment for patients with metastatic germ-cell tumours.

M. J. Peckham

Papers

Exploitable mechanisms in combined radiotherapy-chemotherapy: the concept of additivity.

The radioresponsiveness of human tumours and the initial slope ofthe cell survival curve

Histopathology in the prediction of relapse of patients with stage i testicular teratoma treated by orchidectomy alone

The treatment of metastatic germ-cell testicular tumours with bleomycin, etoposide and cis-platin (BEP)

Combined management of malignant teratoma of the testis