Showing papers by "University of Colorado Boulder published in 1969"

The Meaning and Use of the Arrhenius Activation Energy

Abstract: The nature of the Arrhenius activation energy and frequency factor is reexamined in terms of information now becoming available on the microscopic aspects of collisional reactions. It is pointed out that the activation energy is not generally equal to the threshold for reaction, and its correct conceptual meaning is discussed. The temperature dependence of this quantity and its relation to the threshold energy is developed for a number of representative forms of the energy dependence of the reaction cross-section (excitation function). The uses and limitations of the activation energy as a means of evaluating thresholds, excitation functions, and the presence of tunneling processes are discussed.

An instrument for producing deep muscle relaxation by means of analog information feedback.

Abstract: An instrument that assists subjects in attaining deep muscle relaxation by means of analog information feedback is described. Subjects hear a tone with a pitch proportional to the electromyographic activity in a given muscle group. Results showed that subjects receiving this type of analog feedback reached deeper levels of muscle relaxation than those receiving either no feedback or irrelevant feedback. The basic method employed-electronic detection, immediate information feedback, and systematic shaping of responses-would seem potentially applicable to a variety of physiological events, and might be useful both in behavior therapy and in certain psychosomatic disorders.

Genetics of somatic mammalian cells. IX. Quantitation of mutagenesis by physical and chemical agents

Abstract: The system previously described for inducing single gene mutations in Chinese hamster cells has been extended to produce additional auxotrophic mutants. An improved method for quantitating the efficiency of single gene mutation to specific auxotrophies has been developed. Mutagenesis in the forward direction has been measured after treatment of these cells with ethyl methanesulfonate, N-methyl-N1-nitro-N-nitrosoguanidine, hydroxylamine, an acridine mustard (ICR-191), caffeine and ultraviolet- and X-irradiation. For each agent, the single cell survival curve and the efficiency of chromatid breakage and rearrangement were measured. Similar measurements were also carried out with a water-soluble carcinogen N-nitrosomethylurea, which was shown to be effective in producing auxotrophic, somatic mutations. These results offer promise of illuminating the relationships between cell killing, chromosomal aberration, single gene mutations and carcinogenesis produced by various agents. The methods described can be used in routine testing of drugs, food additives, and environmental pollutants for mutagenic action in mammalian cells in vitro.

Eeg, psychological, and neurological alterations in humans with organophosphorus exposure*

Abstract: In the early 195O’s, the University of Colorado Medical Center conducted a multidisciplinary investigation of industrial and agricultural workers acutely exposed to a variety of pesticides. The focus of this program was a special project involving the intensive study of workers engaged in the manufacture of several organophosphorus (OP) anticholinesterase compoh,. ’.,. Because of the acute confusional states induced by O P exposure and because of the need for more information regarding the central effects of OP exposure in humans, an effort was made to examine certain psychological, neurological, and clinical-neurophysiological variables; additionally, a number of biochemical parameters were investigated. Since January, 1965, a group of men from this same industrial population has been studied; many of the current subjects have been continuously employed in the same capacity since 1950. This report is concerned primarily with some of the psychological, neurological, and clinical-neurophysiological results of these studies. In the 1952 program, psychological testing involved a large battery of measures designed to search for classic evidences of brain damage. Data analysis revealed no formal evidences of organic brain damage in psychological test terms. Testing done within 72 hours of exposure almost always showed erratic and slowed functioning, interpreted as indicating the presence of clinical delirium for many individuals within three days of a symptomatic exposure. The one differentiating test in the original study was the Rotary-Pursuit task, a test of hand-eye coordination. Recently exposed men had worse performance than controls, but we have since found that this type of test is unreliable because of technical limitations. Neurological examinations revealed multiple minor signs such as generalized weakness and confusion shortly after exposure; hard neurological signs were absent after treatment and clinical recovery. In the 1952 study, electroencephalograms were done as close to time of exposure as possible and, in many cases, repeated after treatment and recovery. Typical slow-wave bursts after activation by overbreathing were observed if EEGs were done soon after untreated exposure (FIGURE 1 ). These findings were similar to those reported by Grob (1953). A t this time, it was believed that adequate treatment normalized the EEG. These old EEGs have been reevaluated in light of findings from our current investigations and modern knowledge of the neurophysiology of drowsiness and sleep. Upon reevaluation, we find an increase in medium-voltage, irregular theta activity, OCcurring in bursts of one to five seconds’ duration, most often seen during light drowsiness. Special characteristics of the drowsy EEG-there is a normal increase in slow activity-made it easy to overlook this change. In the 1952 study, psychiatric interviews were done o n 78 men: 56 with histories

Inhibition of the hammerhead ribozyme by neomycin.

Abstract: A series of antibiotics was tested for stimulation or inhibition of the hammerhead ribozyme cleavage reaction. Neomycin was found to be a potent inhibitor of the reaction with a Kl of 13.5 microM. Two hammerheads with well-characterized kinetics were used to determine which steps in the reaction mechanism were inhibited by neomycin. The data suggest that neomycin interacts preferentially with the enzyme-substrate complex and that this interaction leads to a reduction in the cleavage rate by stabilizing the ground state of the complex and destabilizing the transition state of the cleavage step. A comparison of neomycin with other aminoglycosides and inhibitors of hammerhead cleavage implies that the ammonium ions of neomycin are important for the antibiotic-hammerhead interaction.

Effects of Propranolol and Isosorbide Dinitrate on Exercise Performance and Adrenergic Activity in Patients with Angina Pectoris

Abstract: Twelve patients with angina pectoris were evaluated in a single blind crossover study with respect to objective changes in exercise performance on the treadmill and subjective, clinical improvement on oral administration of propranolol, isosorbide dinitrate (ISD), and a combination of propranolol and ISD. Combined objective and subjective evaluations showed that nine of 12 patients improved on propranolol, seven of 10 on ISD, and all 10 on the combination of drugs. The differences in objective improvement between the various drug regimens were not significant. However, subjectively all patients on the combination of drugs improved markedly. The patients on propranolol or the combination had a decrease in pressure-rate index of about 30% both at rest and during exercise, while these values did not change on ISD. A significant reduction in exercise-induced S-T depression was observed with propranolol alone and in combination with ISD at grade 3+ pain. Adrenergic activity, estimated from plasma and urinary catecholamines, appeared to be increased in these patients before drug treatment and was not altered during treatment. It is concluded that propranolol, ISD, and the combination of these drugs all improve exercise performance in patients with angina. Although the combination of drugs could not be shown to produce a greater increase in exercise performance than either drug alone, the combination effected a greater overall clinical improvement.

Convection Heat Transfer in Rotating Systems

Abstract: Publisher Summary Because the convective heat transfer phenomena in rotating systems are intimately related to the flow characteristics, they too are quite complex and offer challenges to theoreticians as well as experimenters. Heat transfer by convection to or from bodies of revolution spinning about their axes of symmetry in an otherwise undisturbed fluid has been studied analytically and experimentally by numerous authors. This chapter summarizes results of more recent investigations. The flow and heat transfer characteristics of spinning bodies of revolution in a forced flow field are important for projectiles or re-entry missiles with spin as well as for certain other engineering problems. The fluid-mechanical phenomena of enclosed rotating disks and of parallel corotating disks are distinctly different from those of disks rotating in an infinite environment. In general, the results for convection heat transfer of a disk rotating in an infinite environment can, therefore, not be applied to shrouded or corotating disks. When a quiescent horizontal layer of fluid is heated from below, the fluid at the bottom becomes lighter than the fluid at the top and convection currents are set into motion. The chapter deals with convection in fluids that are set in motion principally by rotating bounding surfaces, but that do not have an independent axial flow. It also deals with heat transfer by convection in systems in which the fluids also have an independent axial motion superimposed on the rotating motion.

Undernutrition and cerebellar development.

Abstract: UNDERNUTRITION in laboratory animals has been shown to result in a permanent impairment of brain and body growth1, in decreased brain cholesterol2 and synthesis of cerebroside sulphate3,4 and in decreased brain cellularity5,6. The number of cells in the brain was determined by measuring the amount of DNA present, assuming this to be constant in each nucleus. In these studies, however, whole brain was used for DNA analyses, and possible alterations in DNA in parts of the brain were not allowed for. The purpose of the study described here was to ascertain whether malnutrition has any regionally specific effect on cell growth.

Mariner 6: ultraviolet spectrum of Mars upper atmosphere.

Abstract: Emission features from ionized carbon dioxide and carbon monoxide were measured in the 1900- to 4300-angstrom spectral region. The Lyman alpha 1216-angstrom line of atomic hydrogen and the 1304-, 1356-, and 2972-angstrom lines of atomic oxygen were observed.

The developing animal as a model.

Abstract: SUMMARY Evidence is presented that some excitatory systems are mature at birth and that inhibitory systems develop rapidly during the first 3 weeks after birth. During early postnatal development, the anticonvulsant drug, diphenylhydantoin, exerts excitatory effects by blocking both presynaptic and postsynaptic inhibitory systems. At later stages of development and adulthood this excitatory effect is counteracted by the slight activation of postsynaptic inhibitory systems and the marked depression of the spread of seizure discharge by diphenylhydantoin. Hence, the net anticonvulsant effect of this drug becomes predominant in rats after 3 weeks of age. In view of the fact that during early postnatal development the spinal cord is more mature than the brain, the excitatory effects of diphenylhydantoin may be attributed primarily to the blocking effects of the drug on spinal cord inhibition. After 21 days, when the cerebral cortex is functionally more mature, the blocking effects of diphenylhydantoin on some inhibitory systems are overpowered by its marked depressant effects on higher CNS excitatory systems. The predominance of excitatory effects of diphenylhydantoin observed in the offspring of rats treated with the drug during gestation emphasizes the vulnerability of the fetal CNS to exogenous agents and suggests the great need to evaluate drug effects on the fetus. RESUME Les auteurs presentent des elements qui tendent a demontrer que certains systemes excitateurs ont atteint leur maturityea la naissance et que des systemes inhibiteurs se developpent rapidement au cours des trois premieres semaines qui suivent la naissance. Au cours de la periode du debut du developpement postnatal, ľanticonvulsif qu'est la diphenylhydantoine exerce des effets excitateurs en bloquant les systemes inhibiteurs tant presynaptiques que postsynaptiques. Aux stades ulterieurs du developpement et aľâge adulte, cet effect excitateur est contrecarre par la legere activation des systemes inhibiteurs postsynaptiques et par la diminution marquee de ľextension de la decharge convulsive par la diphenylhydantoine. C'est ainsi que ľeffet net anti-convulsif de ce medicament devient predominant chez les rats âges de plus de trois semaines. Etant donne que pendant la periode du debut du developpement postnatal, la moelle epiniere a atteint un stade de maturitye plus avance que celui du cerveau, les effets excitateurs de la diphenylhydantoine peuvent etre attribues en premier lieu aux effets de blocage de ce medicament sur ľinhibition de la moelle epiniere. Au bout de 21 jours, lorsque ľecorce cerebrale a atteint un stade de maturitye fonctionnelle plus avance, les effets de blocage de la diphenylhydantoine sur certains systemes inhibiteurs sont surpasses par ses effets deprimants marques sur les systemes excitateurs superieurs du systeme nerveux central. La predominance des effets excitateurs de la diphenylhydantoine qui a ete observee chez les descendants de rats traites avec ce medicament pendant la gestation fait ressortir la vulnerabilite du systeme nerveux central du foetus aľegard des agents exogenes et montre combien il est necessaire ďevaluer les effets des medicaments sur le foetus.

Locus of control and self-reported depression among college students.

Abstract: The Internal-External Control, Guilford Depression, and Marlowe-Crowne Social Desirability Scales were administered to 69 university undergraduates to test the hypothesis that depression is associa...

Influence of thyroid on formation of myelin lipids.

Abstract: —The formation of lipids found primarily in the myelin sheath was investigated in rats made hypothyroid, at birth. A marked reduction in cerebroside, sulphatide, and cholesterol of brains was found in 18-day-old hypothyroid animals. These lipids were also reduced, although to a lesser degree, in 30-day-old ex-hypothyroid animals allowed to return to the euthyroid state at age 18 days. The onset of formation of sulphatide in vivo was delayed in the hypothyroid animals. Sulphatide formation reached a peak at a later time and was greatly reduced in comparison to control animals. The activity in vitro of galactolipid sulphotransferase, which forms sulphatide from cerebroside and PAPS, was reduced only when exogenous PAPS was not added to the assay medium. This finding suggests a defect in the formation of PAPS from ATP and sulphate in the hypothyroid brain. In addition, T3 (tri-iodothyronine) had a stimulatory effect in vivo of formation brain sulphatide when administered to rats during the first 5 days of life.

Electron scattering by atomic hydrogen using a pseudo-state expansion. i. elastic scattering.

Abstract: A modified close-coupling expansion has been developed and applied to calculate elastic electron-hydrogen-atom scattering phase shifts. This expansion into a complete discrete orthonormal basis set is a variant of the more usual close-coupling expansion into eigenstates of the target Hamiltonian. We retain the first few hydrogen-atom eigenstates and augment these terms with pseudo-states chosen, in our particular case, to incorporate fully the ground-state polarizability of the hydrogen atom. The resulting phase shifts are compared, where possible, with those obtained in the most accurate variational calculations available, and they indicate a distinctly improved convergence over those obtained in the close-coupling expansion.

Complementation Analysis on Virus-Fused Chinese Hamster Cells with Nutritional Markers

Abstract: Cell fusion experiments have been carried out with Chinese hamster cell mutants with different nutritional growth requirements. Conditions have been devised in which approximately 1 to 2 percent of the cell population remaining after fusion are fused, hybrid cells. The all-or-none nature of the genetic markers employed and the extremely low reversion rates insure that no contamination of the hybrid population with parental forms occurs. Hybrids between glycine- and hypoxanthine-requiring mutants are prototrophic, which indicates that both mutations are recessive. Hybrids between a glycine-deficient mutant and a singlestep mutant which requires glycine, hypoxanthine, and thymidine are relieved of the glycine dependency, an indication that the two loci associated with glycine dependence are different. This mutation to the triple-supplement requirement as well as a proline deficiency were also shown to be recessive mutations. The system appears applicable to a variety of genetic problems.

Rocket measurement of nitric oxide between 60 and 96 kilometers

Abstract: The height profile of the nitric oxide airglow in the gamma bands (A²Σ+ — X²Π) is presented from measurements by a sounding rocket at evening twilight. The nitric oxide density profile is deduced from these measurements. The density profile is used to deduce the dominant processes controlling nitric oxide in the 60- to 96-kilometer range. Above 75 kilometers the dominant process is found to be atmospheric mixing. The chemical reaction of nitric oxide with ozone is suggested as the dominant process below 70 kilometers.

Phenylalanine hydroxylase activity in mammalian cells.

Abstract: Survey of twelve mouse tissues revealed the presence of appreciable phenylalanine hydroxylase activity in the pancreas and kidney as well as the liver but in no other of the tissues tested. Single cell suspensions of mouse liver were prepared by use of tetraphenylboron. The enzyme activity of such suspensions was much more stable than that of liver extracts, and permitted determination of the Michaelis-Menten constant, the pseudo-first order reaction velocity constant on a cell-number basis, and the temperature coefficient and apparent activation energy of the enzyme activity. Possible applications of these methods to problems in cellular biology have been indicated.

Phosphotransferase System of Staphylococcus aureus: Its Requirement for the Accumulation and Metabolism of Galactosides

Abstract: The phosphotransferase system of Staphylococcus aureus was characterized. Mutants defective in enzyme I and heat-stable (HPr) protein as well as in the two components specific to lactose accumulation, factor III and enzyme II, were isolated. Colorimetric assays for each of the components are presented based on the formation of o-nitrophenyl-β-d-galactoside-6-phosphate by the system and its hydrolysis by the staphylococcal 6-phospho-β-galactosidase. The components were partially purified and their molecular weights were estimated: enzyme I, 100,000 ± 15%; HPr, 10,000 ± 15%; factor III, 30,000 ± 15%; 6-phospho-β-galactosidase, 45,000. Enzyme II is a membrane-bound protein.

Disseminated intravascular coagulation in the newborn.

Abstract: Eleven of 19 sick newborn infants were shown to have either laboratory and/or pathologic evidence of disseminated intravascular coagulation (DIC) during an observation period of 8 months. Three of the affected infants had severe viral diseases (rubella, cytomegalic inclusion virus, and herpes simplex). Seven of the infants had severe idiopathic respiratory distress syndrome (IRDS), and one infant (the product of a severely toxemic mother) had transient respiratory distress. The remainder of the sick infants had mild IRDS without evidence of DIC. Diagnosis of DIC in the newborn is best made by reliance upon specific clotting factor assays (platelets, fibrinogen, and factors V and VIII) rather than nonspecific screening tests or presence of fibrin degradation products. DIC may be a more common complication of severely ill newborn infants than is generally realized.