Fluorescence methods are being used increasingly in biochemical, medical, and chemical research. This is because of the inherent sensitivity of this technique. and the favorable time scale of the phenomenon of fluorescence. 8 Fluorescence emission occurs about 10- sec (10 nsec) after light absorp tion. During this period of time a wide range of molecular processes can occur, and these can effect the spectral characteristics of the fluorescent compound. This combination of sensitivity and a favorable time scale allows fluorescence methods to be generally useful for studies of proteins and membranes and their interactions with other macromolecules. This book describes the fundamental aspects of fluorescence. and the biochemical applications of this methodology. Each chapter starts with the -theoreticalbasis of each phenomenon of fluorescence, followed by examples which illustrate the use of the phenomenon in the study of biochemical problems. The book contains numerous figures. It is felt that such graphical presentations contribute to pleasurable reading and increased understand ing. Separate chapters are devoted to fluorescence polarization, lifetimes, quenching, energy transfer, solvent effects, and excited state reactions. To enhance the usefulness of this work as a textbook, problems are included which illustrate the concepts described in each chapter. Furthermore, a separate chapter is devoted to the instrumentation used in fluorescence spectroscopy. This chapter will be especially valuable for those perform ing or contemplating fluorescence measurements. Such measurements are easily compromised by failure to consider a number of simple principles."

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Principles of fluorescence spectroscopy

Resistance to insulin-stimulated glucose uptake is present in the majority of patients with impaired glucose tolerance (IGT) or non-insulin-dependent diabetes mellitus (NIDDM) and in ∼25% of nonobese individuals with normal oral glucose tolerance. In these conditions, deterioration of glucose tolerance can only be prevented if the β-cell is able to increase its insulin secretory response and maintain a state of chronic hyperinsulinemia. When this goal cannot be achieved, gross decompensation of glucose homeostasis occurs. The relationship between insulin resistance, plasma insulin level, and glucose intolerance is mediated to a significant degree by changes in ambient plasma free-fatty acid (FFA) concentration. Patients with NIDDM are also resistant to insulin suppression of plasma FFA concentration, but plasma FFA concentrations can be reduced by relatively small increments in insulin concentration.Consequently, elevations of circulating plasma FFA concentration can be prevented if large amounts of insulin can be secreted. If hyperinsulinemia cannot be maintained, plasma FFA concentration will not be suppressed normally, and the resulting increase in plasma FFA concentration will lead to increased hepatic glucose production. Because these events take place in individuals who are quite resistant to insulinstimulated glucose uptake, it is apparent that even small increases in hepatic glucose production are likely to lead to significant fasting hyperglycemia under these conditions. Although hyperinsulinemia may prevent frank decompensation of glucose homeostasis in insulin-resistant individuals, this compensatory response of the endocrine pancreas is not without its price. Patients with hypertension, treated or untreated, are insulin resistant, hyperglycemic, and hyperinsulinemic. In addition, a direct relationship between plasma insulin concentration and blood pressure has been noted. Hypertension can also be produced in normal rats when they are fed a fructose-enriched diet, an intervention that also leads to the development of insulin resistance and hyperinsulinemia. The development of hypertension in normal rats by an experimental manipulation known to induce insulin resistance and hyperinsulinemia provides further support for the view that the relationship between the three variables may be a causal one. However, even if insulin resistance and hyperinsulinemia are not involved in the etiology of hypertension, it is likely that the increased risk of coronary artery disease (CAD) in patients with hypertension and the fact that this risk if not reduced with antihypertensive treatment are due to the clustering of risk factors for CAD, in addition to high blood pressure, associated with insulin resistance. These include hyperinsulinemia, IGT, increased plasma triglyceride concentration, and decreased high-density lipoprotein cholesterol concentration, all of which are associated with increased risk for CAD. It is likely that the same risk factors play a significant role in the genesis of CAD in the population as a whole. Based on these considerations the possibility is raised that resistance to insulin-stimulated glucose uptake and hyperinsulinemia are involved in the etiology and clinical course of three major related diseases— NIDDM, hypertension, and CAD.

Role of Insulin Resistance in Human Disease

A simple and rapid method is presented for the preparation of I/sup 131/- labeled human growth hormone of high specific radioactivity (240-300 mu C/ mu g). Low amounts of carrierfree I/sup 131/ iodide (2 mC) are allowed to react, without prior treatment, with small quantities of protein (5 mu g) in a highyield reaction (approx. 70% transfer of I/sup 131/ to protein). The degree of chemical substitution is minimized (0.5- 1.0 atom of iodine/molecule of protein) by the use of carrier-free I/sup 131/ iodide. The I/sup 131/-labeled hormone (up to 300 mu C/ mu g) contains no detectable degradation products and is immunologically identical with the unlabeled hormone. The loss of immunological reactivity at high specific radioactivities or at high levels of chemical substitution with STAI/sup 127/!iodine is demonstrated. (auth)

The preparation of 131i-labelled human growth hormone of high specific radioactivity

RECENT procedures for the immunological assay of protein hormones in human plasma1–3 require the routine preparation of hormones labelled with iodine-131 of high specific activity.

Preparation of Iodine-131 Labelled Human Growth Hormone of High Specific Activity

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

The three preceding papers we have just been privileged to hear have covered, so thoroughly and elegantly, the past history and present status of the sulfonylureas that there would seem to be little room left for further contributions by the discussants. However, there is always some room for a difference of opinion. Therefore let us take stock of some of the proposed mechanisms of action of these agents for which experimental evidence of one sort or another has been presented. In the simplest terms, as Claude Bernard first pointed out, the level of blood sugar in a fasting animal is determined by the balance between the rate of glucose supply from the liver and the rate of glucose removal into the tissues (figure i ) . The effect of any hypoglycemic agent, therefore, must be due, directly or indirectly, to an acceleration of the rate of removal into the tissues, a diminution in the rate of supply from the liver, or both. The rate of removal is known to be under the influence of insulin, which aids in the penetration of glucose into tissue cells, and it has been suggested that the sulfonylureas exert their hypoglycemic effect through stimulation of insulin secretion, inhibition of insulin degradation or enhancement of the action of insulin peripherally. The other main possible sphere of activity is the inhibition of glucose release from the liver. Thus, it has been suggested that the sulfonylureas act by diminishing the response to epinephrine or glucagon (perhaps through an effect on the phosphokinase system), or by inhibition of glucose-6-phosphatase or phosphoglucomutase activity. Other possible actions of hypoglycemic agents might involve the acceleration of glucagon degradation or the inhibition of glucagon secretion. In fact, it has been claimed that the sulfonylureas induce atrophy of the islet alpha cells. However, these observations have not

Some Remarks on the Mechanism of Action of the Sulfonylureas

The predominant component of immunoreactive ACTH in the plasma of adrenalectomized normal mice and of mice bearing the adrenotropic mouse pituitary tumor, AtT-20, and in extracts of the normal mouse pituitary and pituitary tumor, has an elution volume on Sephadex G-50 gel filtration approximately midway between the void volume and the elution volume of human ACTH (1-39 peptide). The tumor extracts are shown to contain, in addition to this intermediate ACTH, 2 other components of immunoreactive ACTH, one which coelutes with 131I-labeled albumin (big ACTH) and the other with [125I]hACTH (little ACTH). Big and intermediate ACTH are urea-stable. Controlled tryptic digestion of mouse-tumor big ACTH results within 10 seconds in conversion to an intermediate component followed by continued loss of immunoreactivity. Under the same conditions of tryptic digestion of intermediate ACTH, there is only continuous loss of immuno-reactivity with no change of hormonal form. These findings strengthen the hypothesis that mouse intermediate ACTH is not a precursor for little ACTH.

Characterization of mouse ACTH in plasma and in extracts of pituitary and of adrenotropic pituitary tumor.

Radioimmunoassay of Australia Antigen

The presence of a new form of immunoreactive insulin, “big, big insulin”, was first detected in the plasma of an insuloma suspect. On Sephadex gel filtration the elution volume of this insulin is approximately that of 125I-γ-globulin. Its sedimentation velocity on ultracentrifugation is between that of labeled albumin and labeled γ-globulin. Thus, it appears to have a molecular weight of about 100,000. Studies with starch gel and starch block electrophoresis reveal that it is a more basic protein than porcine or crystalline human insulin. It is immunochemically identical with crystalline human insulin, maintains its identity on refractionation on Sephadex gel filtration and is rapidly transformed by trypsin to an insulin-like component. “Big, big insulin” is a minor component (

Rosalyn S. Yalow

Papers

Some Remarks on the Mechanism of Action of the Sulfonylureas

Characterization of mouse ACTH in plasma and in extracts of pituitary and of adrenotropic pituitary tumor.

Radioimmunoassay of Australia Antigen

“Big, big insulin”

State of Human Growth Hormone in Plasma and Changes in Stored Solutions of Pituitary Growth Hormone