Harry Sobotka

A new assay method for biotin in blood, serum, urine, and tissues

Abstract A new microbiological assay of biotin in blood, serum, urine, liver and brain tissue, using the protozoan Ochromonas danica , is described. Results are given for 12 normal subjects and 10 histological normal liver and brain specimens obtained at post mortem.

Choline-Esterase Activity of Human Sera, with Special Reference to Hyperthyroidism.

Summary The acetylcholine esterase activity of the blood serum was determined in 500 individuals including normal and pathological cases. A modification of the Ammon gasometric method was utilized. The acetylcholine esterase was relatively high in cases of untreated hyperthyroidism. The acetylcholine esterase activity may be one of the elements related to the so-called sympathicotonicity or vagotonicity of an individual.

The gelation of bile salt solutions

Abstract The gelation of aqueous bile salt solutions, accidentally observed in bacteriological media, has been studied. This property was observed with deoxycholic acid and lithocholic acid. It precedes or competes with crystalline precipitation. No gelation is observed with cholic acid, nor with conjugated bile acids. The maximum effect is found at pH 7, but at higher concentrations of bile acids gelation may be observed between pH 6.4 and 7.8. Under certain conditions spherical gel particles occur and may eventually form a gel within a gel. The phenomenon and its specificity are explained on the basis of the specific molecular architecture of the bile acids. The analogy to the gelation of bromophenol blue solutions is pointed out.

SOME PHARMACOLOGIC PROPERTIES OF HOLOTHURIN A, A GLYCOSIDIC MIXTURE FROM THE SEA CUCURMBER

Interest in the toxic principle holothurin, derived from the sea cucumber dctinopyga agassizi Selenka, stems largely from recent observations (Nigrelli, 1952; Nigrelli and Zahl, 1952; Nigrelli et al., 1955; Chanley et al., 1955) employing partially purified preparations that pointed to an antitumorous activity as well as a spectrum of other pharmacological actions. Among the latter, sufficient evidence of action against nerves was found to warrant the present study of the crystalline material on the propagated action potential in desheathed bullfrog sciatic nerve, on single nerve-fiber preparations from the frog, and on the rat nerve-diaphragm preparation.

Microbiological Assay Methods for Vitamins

Publisher Summary Vitamins are organic substances of natural origin, required in minute quantities, and their effects are not based on their caloric value, but exclusively on their catalytic nature. Vitamins, especially the water-soluble ones, provide the coenzymes for the most fundamental cellular reactions. Microchemical methods are used for the determination of thiamine, riboflavin, and some fat-soluble vitamins, based on most sensitive colorimetric and fluorometric techniques. Microbiological assays are applicable when a microorganism responds to a metabolite for which physical and chemical determinations are neither sensitive nor specific enough. One must select a microorganism sensitive to the substance under assay—it should be cultivable with ease; the growth response should be easily measurable and the response should be specific; and it should be non-pathogenic. The chapter accounts for the microbiological assay techniques for the determination of vitamins like thiamine, pantothenic acid, nicotinic acid and amide, biotin, inositol, vitamin B 6 , folic acid, folinic acid, and vitamin B 12 in body fluids. The establishment of quantitative methods for the determination of vitamins in body fluids and tissues by microbiological assay techniques should stimulate the search for the significance of vitamins in disease, not only in nutritional deficiency, but also in much wider field of all metabolic disturbances. Functional vitamin deficiencies are produced by malabsorption, by inhibitors of the vitamin function through products of the body, and particularly through drugs and other toxic substances.

NUTRITIONAL FACTORS IN THERMOPHILY: A COMPARATIVE STUDY OF BACILLI AND EUGLENA

The biochemical prerequisites for thermophily (here defined as growth above 55O C.) have attracted intense interest because of the insights offered into the determinants of the stability of protoplasm, particularly of proteins and enzymes. Furthermore, a s the nutrition of thermophilic bacilli (henceforth denoted simply a s “thermophiles”) is becoming known in some detail, thermophiles are emerging a s tools for uncovering many metabolic pathways hitherto almost completely inaccessible to analysis by the microbial tools which have been so successful with other systems; e.g., B vitamins, nucleic acid components, and amino acids. This paper describes the development of chemically defined culture media for representatives of several species of thermophiles including many strains of Bacillus stearothermophitus. Several of these strains have been grown here in chemically-defined media at 80’ C. Since permeability emerged a s one of the important-perhaps a decisive-factor in thermophily , the investigation was broadened to include a study of Euglena gradis, strains of which fell into two sharply distinct groups in respect t o temperature optima and the correlated use of organic nutrients. Strains of E. gracilis that live a t the higher temperatures utilize a much wider array of substrates than do the “low temperature” forms. A s media were improved, the rapidity of growth and the freedom from contamination revealed possibilities for assays for B vitamins and for B vitamins and for thermolabile materials. The increased solubility of lipids at these high incubation temperatures likewise opened avenues of attack on the nutritional biochemistry and histological distribution of lipids. W e thought i t worthwhile, therefore, to describe in some detail the experiments that were designed t o evolve techniques for making lipids nutritionally effective to bacteria. This is a matter of some moment, because, for lack of microbiological assay methods, knowledge of the mode of action of such lipids a s the fat-soluble vitamins has lagged far behind corresponding knowledge of the B vitamins. In this respect, the presed investigation broadened beyond the original a i m of understanding the metabolic basis of thennophily.

Radioactive tracer studies of monolayers: II. Comparison of floating and built-up monolayers☆

Abstract The composition of built-up calcium stearate stearic acid layers has been studied with Ca45. The results diverge from those obtained by conventional chemical analysis of the floating layers (“H-layers”), from which the built-up layers were formed. Similar discrepancies have been observed when building layers of fatty acids on a hypophase containing bivalent organic cations. In all these instances the cations seem to form an integral part of the H-film, but are eliminated, probably by exchange against protons, during the building-up operation.

A comparison of maternal and foetal folic acid and vitamin B12 at parturition.

It had been hoped that the E.EG. record would give objective evidence of. the onset of the transitional phase between sleep and wakefulness; that the rhythm would revert to normal before the patient awoke. This did not occur. Clinical observation gave as early information as did the E.E.G. Two patients admitted to hospital in barbiturate coma were given bemegride, and their course was followed by intermittent E.E.G. recordings. Each patient returned to consciousness while on treatment with bemegride, but the E.E.G. records gave no indication of the depth of coma, and indeed evidence of barbiturate activity on the E.E.G. persisted for many hours after the patient wakened. This confirms the findings of Peacock (1956). The E.E.G. evidence might suggest that bemegride is not a specific barbiturate antagonist, but the site of action of sodium amylobarbitone may be principally in the hypo-

ULTRAFILTRABLE MAGNESIUM IN HYPERTHYROIDISM

The following report is concerned with the study of magnesium metabolism in clinical and experimental hyperthyroidism. This first communication deals primarily with the ratio of diffusible magnesium to total serum magnesium in the hyperthyroid state. The general question of relationship of total serum magnesium to its ultrafiltrable fraction in 8 normal individuals has been discussed by Watchorn and McCance (1). They found that normally approximately 25 per cent of the total serum magnesium is non-diffusible. These authors suggest that there are probably 2 factors which play a part in determining the amount of ionizable magnesium. The bound magnesium may be in combination either with the protein in the serum or with the serum phosphatides. These acids, which behave similarly to protein, are present in adequate quantities to bind considerable amounts of magnesium. Brull (2) and Scholtz (3) also believe that both calcium and magnesium form colloidal phosphate complexes.

Study of Folic Acid and Vit. B12 in Blood and Urine During Normal Pregnancy.

Summary A comparison of PGA and vit. B12 levels in blood and urine during pregnancy shows that levels of PGA are high, and those of B12 are low. Possible explanations for these findings are discussed.