Irving L. Schwartz

The caloric value of labile body tissue in obese subjects.

The caloric balance normally varies from moment to moment. Food is taken intermittently, absorbed, stored, and used as needed for the continuous requirements of metabolism. Variations of diet and of physical activity on successive days cause temporary inequalities of energy intake and output. Long-term balance requires some system to smooth these fluctuations. In the present work we have endeavored to define one aspect of the system by correlating small changes in body weight with known variations of caloric intake. The ratio of these two quantities -the caloric equivalent of labile body weightsets an upper limit to the energy value of primary storage tissue. The caloric equivalent would be easy to measure if all changes in weight were due to caloric imbalance. In reality, however, various other processes-menstrual changes or venous congestion, for instance-cause body fluid to vary without relation to the caloric status of the individual. Any single measurement of energy balance and weight change fails to define the caloric equivalent because it provides no means to distinguish a specific change of weight from an accidental fluctuation of water balance. Measurement of the total fluid balance cannot resolve the difficulty, however, because a considerable amount of water is held intracellularly with glycogen and protein. If these substances are used for temporary storage of energy their accumulation and discharge will cause an obligate variation of fluid balance, quantitatively related to each caloric change, and thus part of the caloric equivalent. Possibly the volume of extracellular fluid also varies with the caloric response. In any case, the distinction between caloric and noncaloric changes of hydration can be made only by repetition of the measurement, since a specific response to caloric variation is defined solely by the fact of its consistent occurrence. Standard methods for measurement of heat production-a calorimeter room (1) or an exact determination of water loss (2)-would be inconvenient for use in prolonged experiments such as are required by repeated changes of dietary intake. Fortunately, the average energy balance and the caloric equivalent can be measured more easily, and with greater accuracy, by an analysis of the weight response alone. Two known levels of dietary intake are equivalent in this case to the usual pair of data: one known level of intake and the measured rate of heat production. An additional advantage of the method is that it measures the caloric equivalent and the average daily requirement for maintenance under conditions that simulate normal variations of diet.

LINKED-FUNCTION ANALYSIS OF FLUORESCENCE DECAY KINETICS: RESOLUTION OF SIDE-CHAIN ROTAMER POPULATIONS OF A SINGLE AROMATIC AMINO ACID IN SMALL POLYPEPTIDES

A linked‐function approach to fluorescence decay data analysis is presented that permits complex systems to be resolved from a single decay curve. The method involves linking fluorescence decay parameters based on a relationship established by independent physical measurements. As an example, by correlating the fluorescence data with 1H‐NMR results, the complex fluorescence decay kinetics of tyrosine analogs and single tyrosyl residues in simple polypeptides can be explained by ground‐state rotameric populations of the phenol ring about the Cα‐Cβ bond.

THE USE OF A FORMULA DIET FOR WEIGHT REDUCTION OF OBESE OUT-PATIENTS

Excerpt Total replacement of natural food by a nutrient mixture was used for weight reduction of obese patients almost a century ago. In 1866 Karell1described a liquid diet providing only three or ...

Methods for Local Induction and Quantitative Analysis of Human Sweat

Summary Procedures are described for the stimulation of sweat by local injection of a cholinergic drug, the quantitative collection of the output from a definite area during consecutive periods, the determination of the volume and of either the sodium or the urea concentration in each sample. In their present form, these procedures are applicable to quantities of sweat between 10 and 200 mg; with slight modifications of the methods, these limits could be extended.

Comparison of the Pharmacological Properties of Two Highly Potent, Crystalline Neurohypophyseal Hormone Analogs: Deamino-1-Seleno-Oxytocin and Deamino-Oxytocin

Investigations over many years have repeatedly drawn attention to the question of what — if anything — is the biological significance of the disulfide grouping in neurohypophyseal hormones. Two groups of analogs appear to be of special interest in this connection: [1] derivatives lacking both the disulfide grouping and the cyclic component of the molecule (1–8) and [2] derivatives lacking the disulfide grouping but retaining the cyclic component of the molecule (9–11). To gain deeper insight into the function of the disulfide bridge as a unit and to explore the function of each sulfur center individually, one or both of the sulfur atoms was replaced in oxytocin and deamino-oxytocin by selenium atoms (12–14) and the resultant selenium-containing analogs are being studied by chemical, physical and pharmacological methods.

Mechanism of Hormone Action

In presenting this brief historical account for our concepts of hormone action, we have adopted the convention of R. Levine, who distinguished between the functions, the effects, and the actions of hormones. Function is defined as the role that the hormone plays in the economy of the organism. Effect is any observed cellular or subcellular activity that is altered by the hormone. Action is the cellular or molecular event, or the sequence of such events, by which a hormone produces its various effects. The focus of this article is on the latter, namely, on the models of hormone action that have been proposed to account for hormone effects. However, we expand this concept to encompass a description, where possible, of the complete sequence of hormonal effects that account for the specific cellular responses induced by a hormone acting on a target tissue.

Cellular and Molecular Aspects of the Action of Neurohypophyseal Peptides.

Excerpt During the past decade, more than 100 analogs of the natural neurohypophyseal hormones have been synthesized and tested for antidiuretic, pressor, uterotonic, galactobolic, and other biolog...