Showing papers by "Saint Louis University published in 1968"

The Relationship between Caffeine Contracture of Intact Muscle and the Effect of Caffeine on Reticulum

Abstract: At concentrations between 1 to 10 mM, caffeine reduced the Ca-accumulating capacity of fragmented reticulum obtained from frog and rabbit muscle. With 8 mM caffeine enough Ca was released from frog reticulum to account for the force of the contracture. Caffeine did not affect all reticulum membranes equally. The fraction which was spun down at 2000 g was more sensitive than the lighter fractions. The percentage of the total accumulated Ca released by caffeine decreased with decreasing Ca content of the reticulum. In parallel with their known effects on the caffeine contracture, a drop in temperature increased the caffeine-induced Ca release while procaine inhibited it. Caffeine also inhibited the rate of Ca uptake, which may in part account for the prolongation of the active state caused by caffeine.

The Mechanism of the Action of Caffeine on Sarcoplasmic Reticulum

Abstract: Evidence is presented that caffeine does not act on the mitochondrial Ca uptake system and that its effect cannot be attributed to the accumulation of adenosine 3',5'-phosphate. Two distinct caffeine effects are described. At high ATP concentrations caffeine decreases the coupling between ATP hydrolysis and Ca inflow. It either inhibits inflow without any inhibition of the rate of ATP hydrolysis, or it stimulates the ATPase activity without stimulating Ca inflow. These high ATP concentrations (much higher than needed for the saturation of the transport ATPase) greatly reduce the control of the turnover rate of the transport system, by accumulated Ca. At low ATP concentrations when the transport system is under maximal control by accumulated Ca, caffeine inhibits the ATPase activity without affecting the rate of Ca inflow.

Bacteriophage-induced inhibition of host functions. I. Degradation of Escherichia coli deoxyribonucleic acid after T4 infection.

Abstract: The kinetics of degradation of bacterial deoxyribonucleic acid (DNA) after infection of Escherichia coli with T4D, ultraviolet-irradiated T4D, and two amber mutants, N122 and N94, was studied by zone sedimentation through linear glycerol gradients. Within 5 min after infection with any of the bacteriophages, breakdown of host genome was evident. The first product was a high-molecular-weight material (50S to 70S) and further degradation appeared to occur in discrete steps. Rapid and extensive breakdown of bacterial DNA was seen after infection with am N122 and T4D. Infection with ultraviolet-irradiated phage or with am N94 resulted in an accumulation of high-molecular-weight material. These results suggest that the observed degradation of host DNA begins early and requires sequential action of several phage-induced endo- as well as exodeoxyribonucleases.

Bioassay of vitamin K by intracardial injection in deficient adult male rats.

Abstract: The biological activity of vitamin K was determined by intracardial injection in partially depleted adult male rats Prothrombin levels rose rapidly after the injection of phylloquinone Response to menadione was delayed for several hours The relative molar activity of several forms of vitamin K was determined Menaquinones with side chains containing more than six isoprene units were up to 25 times as active as phylloquinone Bioassay of vitamin K by intravascular injection in deficient animals is a useful technique for the analysis of purified prep arations of the vitamin without the limita tions and uncertainties imposed by the absorptive process In severely deficient chicks vascular penetration is impractical because of resulting hemorrhage; however, in rats it is possible to obtain a reproduc ible intermediate state of deficiency ( 1) permitting the administration of vitamin K by intracardial injection The bioassay of vitamin K by this technique is the subject of this report MATERIALS AND METHODS The conditions of deficiency were those obtained previously with adult male rats fed for 2 weeks a diet containing 21% soy protein, 43% cornstarch, 22% glucose monohydrate,2 5% corn oil, and an ade quate supplement of minerals and vitamins except for vitamin K (1) Rats were se lected from the St Louis University colony at 13 ±1 weeks of age They were housed individually in suspended stainless wire cages and given fresh food at 2or 3-day intervals to permit ad libitum feeding Af ter one week, samples of blood were taken by cardiac puncture and the plasma was analyzed by the method of Hjort et al (2) using Russell's viper venom as an extrinsic activator At 2 weeks the rats were divided into groups of three in such a manner that the average prothrombin levels of each group closely approximated the overall av erage As observed earlier (1) this value was about 40% of normal rat prothrombin activity For intracardial injection, phyllo quinone 3 and menaquinones were dis solved in 5% or less of polyoxyethylene sorbitan monooleate (Tween 80) in saline; menadione and menadiol disphosphate were dissolved in saline4

A reinterpretation of extinction in discriminated avoidance

Abstract: Accepting escape from the warning signal and/or avoidance of shock as the source of reinforcement for the discriminated avoidance response, extinction is redefined in terms of withholding these effects following the response. The effects of warning intervals of 5, 10, and 20 sec on the redefined extinction procedure were reported, and rapid reliable decreases in responding were found for all Ss, similar to positive reinforcement studies.

Lipids, alpha-tocopherol, and erythrocyte hemolysis.

Abstract: Publisher Summary This chapter discusses the relationships of tocopherol requirements to the level of polyunsaturated lipids in the diet and the tissues. Although more is known about the human requirement for tocopherol than about the requirement for vitamin A, the concept of the varying nature of the requirement for tocopherol as a function of the concentration of polyunsaturated fatty acids in the tissue lipids and of a variety of stresses has influenced writers to state that the human requirement for tocopherol is unknown. Without implying that tocopherol acts only as a lipid antioxidant protecting a large variety of tissue enzyme systems, it is a fact that vertebrates can be raised on diets that apparently supply less tocopherol than can be measured by current techniques if other appropriate lipid antioxidants are supplied. An illustration of how much the fatty acids in the erythrocyte are affected by the fat in the diet in 21 days is given in the chapter, which deals with effects in the growing chick.

Effect of cigarette smoking on the circulation of the oral mucosa.

Abstract: Much research has been done on cigarette smoking and its relation to systemic and local pathologic conditions of the human body.1-13 No one has studied the effect of cigarette smoking on blood circulation of the oral mucosa, however. If significant changes occur in the oral circulatory system, they may have undesirable effects on systemic and local pathologic conditions. The purpose of this project was to determine whether smoking without inhaling has an effect of the blood circulation of the oral mucosa that is not mediated through the sympathetic nervous svstem.

Sarcoplasmic Reticulum. VI. Microsomal Ca2+ Transport in Genetic Muscular Dystrophy of Mice

Abstract: SummaryThe Ca2+ transport capacity of microsomes isolated from skeletal muscles of genetically dystrophic mice was significantly less than that of the control.

Biochemical Studies on Adenovirus Multiplication XIII. Synthesis of Virus-Specific Ribonucleic Acid During Infection with Human Adenovirus Type 12

Abstract: The transcription of virus-specific ribonucleic acid (RNA) was studied in KB cells infected with adenovirus type 12 (strain Huie). Viral deoxyribonucleic acid (DNA) synthesis began at 12 to 15 hr after infection, and virus maturation occurred between 20 and 50 hr after infection. The rate of incorporation of 3H-uridine into RNA per infected cell was stimulated, reaching a maximum of 1.6 times that of uninfected cells at 20 hr after infection. “Early” viral messenger ribonucleic acid (mRNA) constituted 0.1% of RNA synthesized at 11 hr, and “late” viral mRNA constituted 50% of RNA synthesized at 45 hr after infection, as determined by hybridization of viral DNA with labeled RNA from infected cells pulse labeled with 3H-uridine. The species of virus-specific RNA synthesized at 22 hr after infection (when virus maturation has just begun) and at 45 hr (when virus maturation is nearly complete) were studied further: (i) 22- and 45-hr RNA had the same average guanine plus cytosine content, 47%, (ii) 22- and 45-hr RNA contained mostly the same viral nucleotide sequences, (iii) 45-hr RNA had a five times higher concentration of virus-specific RNA molecules than did 22-hr RNA, and (iv) 22- and 45-hr RNA contained virus-specific nucleotide sequences transcribed from all, or nearly all, of the viral genome.

The origin and the course of the communicating branch of the facial nerve to the lesser petrosal nerve in man.

Abstract: In order to clarify the origin and the course of the communicating branch, 25 human nerve complexes (entire intra-osseous part of the facial nerve, greater petrosal nerve, lesser petrosal nerve, communicating branch, auricular branch of the vagus) and stapedius muscles were dissected out and removed as a whole. Each of the 25 complexes was dehydrated, sectioned serially at 10–20 μ, and either stained with Luxol Fast Blue or treated with a silver technique. The communicating branch was observed to originate from the auricular branch of the vagus. It ascended first along the anterior side of the third intra-osseous part of the facial nerve and then penetrated the stapedius. From within the stapedius some of its fibers continued anteriorly as a nerve bundle through the facial sheath of the second intra-osseous part of the nerve. This nerve bundle separated from the seventh nerve upon approaching the geniculate ganglion, and joined the lesser petrosal nerve. The communicating branch consisted mainly of small myelinated fibers in the course of which either isolated ganglion cells or small ganglia were sometimes present.