Showing papers by "University of Utah published in 1969"

Catheter mounted artificial heart valve for implanting in close proximity to a defective natural heart valve

Abstract: An artificial heart valve for implantation in close proximity to a malfunctioning or damaged natural aortic or mitral heart valve by remote means without performing an open chest or other major surgical operation The artificial heart valve comprises a flexible membrane in the form of an umbrella in that the apex of the umbrella resides in the direction that blood flow is to be periodically prevented while the distal end opens sufficiently to contact the inner walls of the vessel to prevent the reverse flow of blood and the membrane collapses about the axis of the umbrella to allow the forward flow of blood

Laboratory Evaluation of Antiepileptic Drugs

Abstract: SUMMARY The historical development of the laboratory evaluation of anticonvulsant drugs was briefly reviewed. Attention was directed to the fact that such evaluation can be approached from several biological levels. The numerous methods which have been employed for the study of antiepileptic drugs were summarized and mention made of their relative value in drug evaluation. The usual method for the determination of minimal neurotoxicity was described and six of the classical assay procedures were reviewed. It was pointed out that no one laboratory test is sufficient to delineate the anticonvulsant potential of a new drug and, therefore, a battery of 4 tests (Maximal Electroshock Seizure test, a.c. Electroshock Seizure Threshold test, Hyponatremic Electroshock Seizure Threshold test, and s.c. Metrazol test) has been employed in our laboratories. It was further emphasized that valuable confirmatory data and preliminary clinical information can be obtained by pre-clinical testing of promising drugs in psychiatric patients undergoing electroshock seizure therapy. Finally, the predictive value of the battery of four tests was considered and the need for more selective assay procedures emphasized. RESUME Ľevolution historique des methodes de laboratoire utilisees pour apprecier la valeur des medicaments anticonvulsifs est brievement passee en revue. Ľattention est attiree sur le fait que cette evaluation peut etre abordee a partir de plusieurs niveaux biologi-ques. Les nombreuses methodes utilisees pour ľ;etude des medicaments antiepilep-tiques sont decrites en resume avec une appreciation de leur valeur relative pour ľ;evaluation des medicaments. La methode habituellement appliquee pour la determination de la neurotoxicite minimum ainsi que six des methodes classiques ďessai sont passees en revue. II est souligne qu'aucun test de laboratoire n'est suffisant a lui seul pour apprecier le pouvoir anticonvulsif ďun medicament; aussi utilisons-nous, dans nos laboratoires, une batterie de quatre tests (test de la convulsion maximum par electrochoc, test du seuil de convulsion par electrochoc en courant alter-natif, test du seuil de convulsion par electrochoc sous hyponatremie et test du metrazol en injection sous-cutanee). Ľ;accent est, en outre, mis sur le fait que des donnees de confirmation importantes et des informations cliniques preliminaires peuvent etre recueillies par ľessai preclinique de medicaments prometteurs chez des patients psychiatriques soumis a un traitement par electrochoc. Enfin, la valeur de prediction de notre batterie de quatre tests est appreciee et la necessite de pouvoir disposer de methodes ďessai plus selectives est soulignee.

The continuum interpretation for fracture and adhesion.

Abstract: Continuum fracture concept indicating essential surface energy interpretation difference in otherwise similar adhesive and cohesive failures

Penetration of 14C-inulin and 14C-sucrose into brain, cerebrospinal fluid, and skeletal muscle of developing rats.

Abstract: 1. We studied the decrease in brain uptake of two substances, inulin and sucrose, during maturation of the brain. Concentration ratios of CSF/plasma and brain/plasma for 14C-labeled inulin and sucrose were calculated and time-uptake curves plotted for prenatal and postnatal rats. Comparisons of these ratios among the various ages showed a progressive decrease in the inulin ratios of both compartments with increasing age. Sucrose “spaces” were always larger than inulin “spaces,” suggesting possible sucrose penetration into cells. The brain/CSF concentration ratio for inulin, however, appears to reflect brain extracellular space in young rats, but not in older animals. Electrolyte concentration ratios of CSF and plasma suggested progressive maturation of transport mechanisms at the choroid plexus and increase of CSF flow. The degree of concentration of inulin in the developing brain and the CSF of the young rat probably reflects cellular maturation of both barrier and secretory mechanisms. 2. We also measured the inulin and sucrose space of skeletal muscle in rats of different age. In contrast to brain, the spaces measured by the two substances were the same and decreased with maturation of the animals.

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.

Enterobius vermicularis: 10,000-year-old human infection.

Abstract: Eggs of Enterobius vermicularis (human pinworm) were found in hum coprolites from Hopug and Danger Caves, western Utah. The Caves were inhabitated by man from 10,000 B.C. to A.D. 1400. The oldest coprolite containing dated at 7837 B.C. This represents the earliest known association between man abd this exclusively human parasite.

Precipitate strengthening mechanisms in magnesium zinc alloy single crystals

Abstract: The mechanical behaviour of Mg-5.1 wt % Zn alloy single crystals was studied in the 4.2 to 300° K temperature range. Quenched crystals have activation energies and volumes best associated with the cutting of small clusters of Zn atoms by dislocations. Fully hardened crystals contain fine β 1′ and occasionalβ 2′ precipitates with an averageβ 1′ interparticle spacing of 330 to 660 A. Strengthening in these crystals is mainly ascribed to the cutting of β 1′ particles by dislocations. In the overaged condition β 1′, β 2′ and equilibrium β particles are present and lead to a considerable temperature-dependence unusual for an overaged condition. Analysis of this temperature-dependence suggests that below 77° K the relatively easy cutting of β 1′ particles by dislocations takes place in addition to the cutting of β 2′ and β particles. Above 77° K the difficult cutting of β 2′ and β particles alone controls the deformation, β 1′ being more easily cut with the aid of thermal fluctuations.

Generation of Variance, “Theoretical Plates,” Resolution, and Peak Capacity in Electrophoresis and Sedimentation

Abstract: The rate of generation of variance, dσ2/dX, is a fundamental parameter which determines peak or boundary width and, thus, resolution in many differential migration systems. This parameter can be identified with the “plate height” of chromatography. By extending this nomenclature and the underlying concepts to electrophoresis and sedimentation, we arrive at parameters, particularly the “number of theoretical plates,” which allow a comparison of the effectiveness of these diverse methods. Equations are derived for the plate number as well as for resolution and peak capacity. Numerical comparisons are shown. Optimization is discussed with reference to maximum resolution, peak capacity, and separation speed.

Atomic Hyperfine Structure. II. First-Order Wave Functions for the Ground States of B,C,N,O, and F

Abstract: Ab initio computations of hyperfine structure have been made for the ground states of B, C, N, O, and F using a first-order wave function designed to include the strongly structure-dependent part of the electron distribution. The magnetic hyperfine constants are in poorer agreement with experiment than for the previously studied and less extensive polarization wave functions, but the discrepancies are more uniform, particularly for the spin density at the nucleus.

SO2 (35S labeled) absorption by the nose and mouth under conditions of varying concentration and flow.

Abstract: Sulfur dioxide35S (35SO2) was administered to the surgically isolated upper airways of anesthetized dogs via a mask with separate connections to the nose and mouth. The 35SO2 that passed through the upper airways was monitored continuously; nearly complete removal could be measured to within several hundredths of a percent. Nasal uptake of the incoming gas (1 to 50 ppm) exceeded 99% at a flow of 3.5 liters/min and fell only several percent when flow was increased tenfold (1, 10 ppm). Uptake by the mouth averaged more than 95% at a flow of 3.5 liters/min (1, 10 ppm) but fell to under 50% when flow was increased tenfold. Following penetration of the mouth or nose by 35SO2, desorption of the gas from the mucosa could be demonstrated more than 25 minutes after the end of exposure.

Electronically generated perspective images

Abstract: A method and system for electronically generating and displaying shaded two-dimensional perspective images of three-dimensional objects in which sharp resolutions of intersections of the objects is maintained, by providing electrical signals representative of surfaces of the objects and determining the spatial relationship between these surfaces and progressively smaller portions of a two-dimensional view plane or the viewing screen of the display These spatial relationships are then utilized to determine the surfaces to be displayed within each of the ultimate portions of the view plane or viewing screen

Detection by immunofluorescenge of antibodies specific for human malignant melanoma cells

Abstract: Cells were separated from tissue specimens of human malignant melanoma and grown in tissue culture on coverslips. After 8 days of growth the explanted cells were fixed and stored until used. Sera from 15 patients with malignant melanoma were reacted with the fixed melanoma cells and a variety of other cells. The indirect immunofluorescence method was used to test for presence of antibodies. Sera from all 15 melanoma patients reacted with fixed melanoma cells giving intense fluorescence of intracytoplasmic granules. The fluorescent material appeared to be independent of melanin granules. Homogenate of fresh melanoma but not of other neoplastic or normal tissue absorbed out the anti-melanoma antibodies. The human antimalignant melanoma antibodies did not react with live malignant melanoma cells or with fixed or live cells from benign nevi or fixed guinea pig kidney, human kidney or HeLa cells. The evidence suggests that these antibodies are unable to penetrate living cell membranes.

The effect of alcohol on sensory phenomena and cognitive and motor tasks.

Abstract: FOUR TESTS CALLING FOR COGNITIVE AND MOTOR SKILLS WERE ADMINISTERED TO EXAMINE PERFORMANCE AFTER SMALL AND MODERATE DOSES OF ALCOHOL. SENSORY PHENOMENA, VISUAL RESPONSES, AND SOMATOSENSORY EVOKED RESPONSES WERE EXAMINED. PERFORMANCE AT VARYING BLOOD ALCOHOL LEVELS IS DESCRIBED. ASPECTS DISCUSSED INCLUDE CRITICAL FLICKER FUSION, PULSE RATE, AND SPIRAL AFTEREFFECT OF ALCOHOL. /HSL/

Thomy-Headed Worm Infection in North American Prehistoric Man

Abstract: Examination of ova and parasites from coprolites of probable human origin revealed eggs of the phylum Acanthocephala. Specimens were gathered from Danger Cave in Utah, an area heavily populatd with definitive rodent hosts for the Acanthocephala species Moniliformis clarki. It is postulated that prehistoric man developed Acanthocephala infection by ingesting the arthropod intermediate host, or that he was a victim of false parasitism by ingesting the whole rodent.

The concurrent reinforcement of two interresponse times: the relative frequency of an interresponse time equals its relative harmonic length.

Abstract: The relative lengths of two concurrently reinforced interresponse times were varied in an experiment in which three pigeons obtained food by pecking on a single key. Visual discriminative stimuli accompanied the two time intervals in which reinforcements were scheduled according to a one-minute variable-interval. The steady-state relative frequency of an interresponse time approximately equalled the complement of its relative length, that is, its relative harmonic length. Thus, lengths of interresponse times and delays of reinforcement have the same effect on the relative frequencies of interresponse times and choices in one-key and two-key concurrent variable-interval schedules, respectively. A second experiment generalized further the functional equivalence between the effects of these one-key and two-key concurrent schedules by revealing that the usual matching-to-relative-immediacy in two-key concurrent schedules is undisturbed if reinforcement depends upon the occurrence of a response at the end of the delay interval, as it does in the one-key schedules. The results of both experiments are consistent with a quantitative theory of concurrent operant behavior.

Influence of steroid distribution between microsomes and soluble fraction on steroid metabolism by microsomal enzymes.

Abstract: When progesterone labeled with one isotope and 17-hydroxyprogesterone labeled with another were incubated together in the presence of an 800 ×g × 10 min supernatant fraction of mouse testis homogenate, the ratio of progesterone label to 17-hydroxyprogesterone label in androstenedione and testosterone was greater than in the original mixture. No evidence of a pathway from progesterone to androstenedione not involving 17-hydroxy progesterone could be found. When the same substrate mixture was incubated with a similar homogenate fraction in the absence of both oxygen and cofactors, very little metabolism occurred. The mitochondrial and microsomal fractions were separated from the incubated mixture and the proportion of the 2 substrates in each was determined. The ratios of the 2 in the particulate fractions resembled those in androstenedione and testosterone under normal incubation conditions rather than the ratio added. Thus, it seems that there is a differential distribution of the 2 steroids into the micr...

On the effect of initial curvature on cracked flat sheets

Abstract: A survey of existing solutions describing the stress distribution around the crack tip of an initially curved sheet is made and a method for estimating approximate stress intensity factors of other more complicated shell geometries is discussed.