David Rapport

The regulation of hepatic acetate-1-C14 metabolism by short-chain fatty acids.

Abstract Propionate, isobutyrate, and caproate inhibited all phases of acetate-1-C 14 metabolism studied. Butyrate suppressed acetate utilization and oxidation without affecting the incorporation of acetate-1-C 14 into fatty acids. This evidence suggests that butyrate increases lipogenesis from acetyl groups. It is proposed that fatty acids exert a regulatory action on acetyl metabolism.

Alteration of the pattern of hepatic carbohydrate metabolism by propionate and butyrate

Abstract Butyrate and propionate caused a reduction in C 14 O 2 and lipide-C 14 production from evenly labeled glucose, glucose-1-C 14 , glucose-6-C 14 , and lactate-2-C 14 . Unlike the action of these acids on acetate metabolism, the inhibition of lipogenesis from glucose and lactate was more severe than the reduction in oxidation of these compounds. These striking differences between the inhibitory actions of butyrate and propionate on hepatic acetate metabolism on the one hand and hepatic carbohydrate metabolism on the other seem to suggest that the metabolic path of the C-2 fragment derived from these two sources must differ.

The Market Adaptation of the Firm

Publisher Summary This chapter describes the market adaptation of the firm. A firm emerges as a profit seeker rather than a profit maximizer. It is governed by the rules of thumb in its day to day operations but capable of quite sophisticated considerations in connection with the introduction of new products. This reflects the fact that the top level management is very concerned with the new product decision. Discussion of the model developed in this study with marketing researchers disclosed striking similarities among the concepts presented in the chapter and notions with which they were working. A general view of the adaptation of the firm to its environment is developed. It presents a model of the growth of the output of a monopolistic firm in the absence of extensive information. The chapter discusses how a firm with a definite commodity in mind can decide whether to enter a given established market. It also considers how the firm could determine what sort of product it could create to take advantage of perceived profit opportunities.

Changes Induced in Ascites Tumor Cells by Ultraviolet Irradiation

Suspensions of mouse ascites tumor cells were irradiated in the cold with ultraviolet light. Observations were made on the changes in optical density at 260 mµ, and in the amount of acid-insoluble, acid-soluble and inorganic phosphate, as well as protein, in the suspension, the cell-free medium, and in the supernatant solution after acid precipitation, for the purpose of detecting changes in the nucleic acids and their derivatives. The data show that the irradiation caused a marked increase in the permeability of some or all of the cells. Under the circumstances of the irradiation, there was no evidence of the breakdown of high polymer nucleotides to smaller fragments, contrary to the findings with pure solutions of such compounds. It was incidentally found that the ribonuclease activity of the tumor cells was reduced to an average of one-third its original value by irradiation under the conditions of the experiments.

Effect of Amino Acid Deficiency on Rat Liver Before and After Partial Hepatectomy.

Conclusion 1. The total weight and total solids of regenerated liver 96 hours after partial hepatectomy are unaffected by diets in which gelatin and zein are the sole sources of protein. 2. On a casein diet, the regenerated liver has a higher P.N.A. content than the prehepatectomy liver. This is also true on a gelatin diet and on a purina chow diet, but not on a zein diet, indicating that the apparent stimulus to extra P.N.A. content normally induced in the regenerating liver, is inhibited by the lack of dietary lysine. There is no significant effect on the D.N.A. content either before or after hepatectomy, on any of the diets. 3. On gelatin and zein diets, the tryptophane content of the pre-hepatectomy livers was only slightly less than on adequate diets; the same held true for the regenerating liver, indicating that the liver was capable of obtaining almost its normal content of needed tryptophane from other sources. 4. In contrast to the constancy of the total solids, the total nitrogen of both the pre-hepatectomy and regenerating liver was significantly less on the zein diet than on the Purina chow, casein, and gelatin diets. This implies that on the zein diet, the decreases in nitrogen were associated with an increase in other constituents. On the basis of Koster-litzs (loc. cit.) results, this may have been glycogen.

Effect of growth influencing factors on the in vitro deamination of dl-alanine.

Summary Experiments on the effect of hormonal factors capable of influencing growth have failed to yield evidence of a decreased deamination of dl-alanine by rat liver and kidney.

Galorigenic Action of Methylene Blue During Muscular Exercise.

In previous communications (Rapport, 1 Canzanelli, Segal and Rapport 2 ) we have presented evidence indicating that while the energy of the calorigenic action of certain substances, (such as protein, certain amino acids, thyroxine, etc.) can not be used as a fuel for muscular work, that of carbohydrate and fat could be so used. The present communication deals with similar observations in regard to methylene blue, a substance foreign to the body, which, when administered, has a considerable effect on the total metabolism. The experiments were made on a single well-trained female dog, weighing about 9 kilos, and subsisting on a constant maintenance diet, the methods being the same as those used in the above mentioned researches. The gaseous exchange was obtained in a closed system, into which, for the purpose of exercise, a horizontal treadmill was introduced. Exercise consisted of 15 minutes running at about 2.5 kilometers per hour, and the metabolism of exercise and recovery was calculated by computing the amount of respiratory exchange in excess of that at rest. This was done both on days when the resting metabolism was basal, and on days after the injection of 10 mg. of methylene blue in one percent watery solution per kilo of body weight. Three alcohol checks were performed during the course of the work, the respiratory quotients being 0.660, 0.667 and 0.671 respectively, the maximum error in the R.Q. being 0.007, or about one percent. The results are shown in Table I. In 4 experiments under “basal” conditions, the resting metabolism was 11.9 cal. per hour. When the animal was exercised, there was an “extra” metabolism which averaged 1.81 ± 0.07 gm. cal. per “horizontal” kilogrammeter of work. After giving methylene blue, the resting metabolism averaged 16.9 cal. per hour, an increase over the basal of 42%.