71 Matching Results

Search Results

Advanced search parameters have been applied.

in subjects: "551000 -- Physiological Systems"

open access

Microwaves affect thermoregulatory behavior in rats

Rats, with their fur clipped, pressed a lever to turn on an infrared lamp while in a cold chamber. When 2450 Megahertz continuous wave microwaves were presented for 15 minutes, the rate of turning on the infrared lamp decreased as a function of the microwave power density, which ranged between 5 MW/cm/sup 2/ and 20 MW/cm/sup 2/. This result indicates that behaviorally significant levels of heating occur at exposure durations and intensities that do not produce reliable changes in either colonic… more

Date: January 1, 1979

Creator: Stern, S.; Margolin, L.; Weiss, B.; Lu, S.T. & Michaelson, S.M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Effects of chemical carcinogens on hemopoiesis, immunopoiesis and viral oncogenesis. Three year technical progress report, February 1, 1977-September 30, 1979. [MMS; BP; DMBA; propane sultone; MCA; mice]

Studies were initiated to evaluate in an in vitro system selected chemical carcinogens derived from energy producing hydrocarbons for their effect on the hematopoietic and immune systems. Studies were also conducted to determine whether the selected carcinogens could interact with leukemogenic virus to produce leukemia in mice. Five compounds have been investigated thus far: (1) methylmethane sulfonate (MMS); (2) benzo(a)pyrene (BP); (3) 7,12 dimethylbenz(a)anthracene (DMBA); (4) propane sulton… more

Date: September 1, 1979

Creator: OKunewick, J.P.; Raikow, R.B. & Meredith, R.F.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Biological response modifiers

Much of what used to be called immunotherapy is now included in the term biological response modifiers. Biological response modifiers (BRMs) are defined as those agents or approaches that modify the relationship between the tumor and host by modifying the host's biological response to tumor cells with resultant therapeutic effects.'' Most of the early work with BRMs centered around observations of spontaneous tumor regression and the association of tumor regression with concurrent bacterial inf… more

Date: October 1, 1991

Creator: Weller, R. E.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Superimposition of carbon dioxide on acute isobaric hypoxia: plasma erythropoietin, acid-base status, and P/sub 50/ in the unanesthetized rabbit

Major factors affecting changes of the arterial Hb--O/sub 2/ affinity (P/sub 50/) were examined in relation to the initiation of erythropoietin (ESF) production in unanesthetized New Zealand white male rabbits. They were exposed to an isobaric hypoxic environment (8.8 percent O/sub 2/) with and without CO/sub 2/ (5.6 percent or 10 percent). During 5 hrs exposure, samples of arterial blood were collected for measurements of plasma ESF titers; whole-blood pH, P/sub CO2/, S/sub O2/, lactate, pyruv… more

Date: June 1, 1978

Creator: Wolf-Priessnitz, J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

A model for the immune system response to HIV: AZT treatment studies

We use mathematical models to describe the interaction of the immune system with the human immunodeficiency virus (HIV). Our model includes T-lymphocytes and macrophages, cells which can be infected with the virus. Using our model we compare the efficacy of AZT treatments given at different stages of disease progression in order to predict when treatment should be initiated.

Date: January 1, 1993

Creator: Kirschner, D.E. (Vanderbilt Univ., Nashville, TN (United States). Dept. of Mathematics) & Perelson, A.S. (Los Alamos National Lab., NM (United States))

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Sensitive, coupled assay for plasminogen activator using a thiol ester substrate for plasmin

Several assays for plasminogen activator employ a direct assay method. These are remarkably sensitive methods, yet they suffer in comparison to the sensitivity of coupled methods. Coupling the assay with plasminogen not only amplifies the sensitivity by the multiplicative effect of plasmin, but insures that only those proteases specific for plasminogen are assayed. The choice of substrate for plasmin is critical. A thiol ester substrate, thiobenzyl benzyloxy-carbonyl-L-lysinate (Z-Lys-SBzl), ha… more

Date: January 1, 1980

Creator: Coleman, P L & Green, G D.J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Root adaptations at stress levels of nitrate, phosphate, or both simultaneously

Sunflowers in flowing hydroponic culture show reduced growth rates at nitrate levels below 10 ..mu..M nitrate or phosphate levels below 0.3 ..mu..F. At least for phosphate, this level is a very small fraction (0.003) of the K/sub m/ for the uptake systems. We have quantified four major adaptations that enable high growth rates under incipient stress: increased root:shoot ratio; increased uptake capacity (V/sub max/) per unit root mass; nocturnal uptake of nutrients; and (only partially adaptive… more

Date: August 1, 1984

Creator: Gutschick, V.P. & Kay, L.E.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Mechanism of histamine release from human basophils

The theory of histamine release of Dembo, Goldstein, Sobotka, and Lichtenstein is able to explain a variety of kinetic experiments in a self consistent and quantitative way. The principal elements of the theory are: the histamine content of basophils is divided into a large number of discrete and independent quanta; release of the contents of a quanta is a stochastic event; a certain fraction of the quanta in a population of basophils is nonreleasable; the probability per unit time, P/sub R/, o… more

Date: January 1, 1978

Creator: Dembo, M. & Goldstein, B.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Energy budgets of animals: behavioral and ecological implications

This year's progress has been: (1) to extend the general microclimate model two ways: (a) to incorporate wet ground surfaces (bogs), and (b) to incorporate slope effects. Tests of the model in a Michigan bog and the Galapagos Islands show temperature accuracies to within 4/sup 0/C at worst at any soil or air location, which is about a 2% error in estimation of metabolism. (2) The addition to ectotherm modeling an analysis of: (a) reproduction in heterogeneous and uncertain environments; (b) pre… more

Date: January 1, 1979

Creator: Porter, W P

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

A quantum theory of the mind-brain interface

The Heisenberg quantum mechanical conception of nature is extended and applied to the brain. Strict adherence to the principle of parsimony, and to quantum thinking, produces naturally, on the basis of an overview of brain operation compatible with the information provided by the brain sciences, a unified description of the physical and mental aspects of nature that can account in principle for the full content of felt human experience. 33 refs.

Date: July 30, 1990

Creator: Stapp, Henry P.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Energy metabolism and thermoregulation in old age

Over their life spans, mice and men alike show a 15 to 30% decrease in their minimum, or resting, levels of energy metabolism, and a 50 to 70% decrease in the metabolism of activity. This, together with age-decrements in the capacity to regulate heat loss, makes the old person more susceptible to hypothermia that the young. Two independent relations of length of life to metabolic rate have been found in mice. First, as average metabolic rate increases, survival time decreases, and second, as th… more

Date: January 1, 1979

Creator: Sacher, G.A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Effect of light on respiration and development of photosynthetic cells. Progress report, September 1, 1977--August 31, 1978

The biophotolysis of water by photosynthetic cells resulting in the formation of hydrogen gas is of prime concern. That algal cells require both photosystems to complete this process is established. That a reduced carbon source can be photoxidized to release hydrogen and carbon dioxide has been proven. On the other hand, whether water is split to hydrogen and oxygen by the intact cell adapted to a hydrogen metabolism is an open question. A reconstituted preparation of higher plants can split wa… more

Date: August 31, 1977

Creator: Gibbs, M

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Photochemistry and enzymology of photosynthesis. Progress report, November 1, 1978--March 31, 1979

The authors continued seeking the source of electrons for the Calvin cycle in bundle sheath chloroplasts of C/sub 4/ plants using corn or spinach leaves that are free from mesophyll but still retain their photochemical activity. Results indicate that cross transfer of electrons between photosynthetic chains occurs both upstream with plastoquinone and downstream with cytochrome f. (PCS)

Date: April 1, 1979

Creator: Kok, B. & Golbeck, J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Dual photon absorptiometer utilizing a HpGe detector and microprocessor controller. [Application to bone mineral content determinations]

The analysis of bone mineral content (BMC) using a single energy-photon beam assumes that there are only two materials present, bone mineral and a uniform soft tissue component. Uncertainty in the value of BMC increases with different adipose tissue components in the transmitted beam. These errors, however, are reduced by the dual energy technique. Also, extension to additional energies further identifies the separate constituents of the soft tissue component. A multi-energy bone scanning appar… more

Date: 1978~

Creator: Ellis, K. J.; Vartsky, D.; Pearlstein, T. B.; Alberi, J. L. & Cohn, S. H.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Behavior as a sentry of metal toxicity

Many of the toxic properties of metals are expressed as behavioral aberrations. Some of these arise from direct actions on the central nervous system. Others arise from primary events elsewhere, but still influence behavior. Toxicity may be expressed either as objectively measurable phenomena, such as ataxia, or as subjective complaints, such as depression. In neither instance is clinical medicine equipped to provide assessments of subtle, early indices of toxicity. Reviewers of visual disturba… more

Date: January 1, 1978

Creator: Weiss, B.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Brain plasticity, memory, and aging: a discussion

It is generally assumed that memory faculties decline with age. A discussion of the relationship of memory and aging and the possibility of retarding the potential decline is hampered by the fact that no satisfactory explanation of memory is available in either molecular or anatomical terms. However, this lack of description of memory does not mean that there is a lack of suggested mechanisms for long-term memory storage. Present theories of memory usually include first, neurophysiological or e… more

Date: December 1, 1977

Creator: Bennett, E. L. & Rosenzweig, M. R.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

[Characterization of a putative S locus encoded receptor protein kinase and its role in self-incompatibility]

The serine/threonine protein kinase (SRK) protein was predicted to be similar to the growth factor receptor tyrosine kinases in animals but its amino acid sequence of the catalytic domain is more similar to that of the catalytic domains of protein serine/threonine kinases than to protein tyrosine kinases. We have shown that the SRK protein has intrinsic scrine/threonine kinase activity. We subcloned the protein kinase-homologous domain of the SRK[sub 6] cDNA into the bacterial expression vector… more

Date: January 1, 1993

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Amphetamine margin in sports. [Effects on performance of highly trained athletes]

The amphetamines can enhance athletic performance. That much seems clear from the literature, some of which is reviewed here. Increases in endurance have been demonstrated in both man and rat. Smith and Beecher, 20 years ago, showed improvement of running, swimming, and weight throwing in highly trained athletes. Laboratory analogues of such performance have also been used and similar enhancement demonstrated. The amount of change induced by the amphetamines is usually small, of the order of a … more

Date: January 1, 1980

Creator: Laties, V. G. & Weiss, B.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Dosimetry, instrumentation and exposure chambers for dc magnetic field studies

The principal objective of this report is to describe in detail an exposure chamber that was developed at the Lawrence Berkeley Laboratory for automated, noninvasive studies of rodent physiology during exposure to high DC magnetic fields. A second objective is to discuss some of the unique instrumentation problems that must be overcome in order to record bioelectric signals from laboratory animals in the presence of a magnetic field. Finally, a description will be given of the various dosimetry… more

Date: March 1, 1979

Creator: Tenforde, T. S.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Kidney compartment model. [Mathematical model for iodohippurate distribution as a function of time]

A multiparameter kidney compartment model which quantitates the amount of iodohippurate concentration as a function of time in the blood, tissue, kidneys and bladder is developed from a system of differential equations which represent first order kinetics. The kinetic data are obtained using a gamma camera and an HP5407 computer system which allows one to delineate areas of interest for the blood and tissue, kidneys, and bladder thus separating the data into four data sets. The estimated tubula… more

Date: 1976

Creator: Gullberg, G. T.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Thermoregulation and temperature relations of alligators and other large ectotherms inhabiting thermally stressed habitats. Annual progress report, July 1, 1975--June 30, 1976

The effects of radiation and convection on the equilibrium body temperatures of alligators have been determined. Gaping has been shown to be an effective thermoregulatory device for retarding heat gain in the heads of these animals. Initial time dependent experiments have been completed and ketamine hydrochloride has been shown to be an effective anesthetic for alligators. Evaporative water loss rates have been measured as a function of size, temperature and wind speed for the turtle Chrysemys … more

Date: March 1, 1976

Creator: Spotila, J. R.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Physiopathology of blood platelets and development of platelet substitutes. Progress report, August 1, 1975--July 31, 1976

Progress is reported on studies on the physiology of blood platelets in thrombocytopenic patients and rabbits. Methods for the detection of platelet antibodies and the preservation of platelets in vitro were investigated. Studies on the effect of low doses of x irradiation (up to 1000 R) on platelet function indicate that platelets exposed to ionizing radiation have increased functional activity. A list is included of publications that report the results of the studies in detail.

Date: April 28, 1976

Creator: Baldini, M G

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Analysis of the human electroencephalogram with methods from nonlinear dynamics

We apply several different methods from nonlinear dynamical systems to the analysis of the degree of temporal disorder in data from human EEG. Among these are methods of geometrical reconstruction, dimensional complexity, mutual information content, and two different approaches for estimating Lyapunov characteristic exponents. We show how the naive interpretation of numerical results can lead to a considerable underestimation of the dimensional complexity. This is true even when the errors from… more

Date: September 8, 1986

Creator: Mayer-Kress, G. & Holzfuss, J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Thermoregulation and temperature relations of alligators and other large ectotherms inhabiting thermally stressed habitats. Progress report, 1 October 1974--30 September 1977

Significant progress has been made in determining the mechanisms by which large ectotherms adjust to thermal stress in their natural environment. The effect of mouth gaping on head temperatures and the role of radiation, conduction and convection on body temperatures of alligators have been determined. The utility of energy budget modeling as a method for studying the thermoregulatory mechanisms of animals has been demonstrated. Steady state and time dependent models of body temperature have be… more

Date: June 1, 1977

Creator: Spotila, J. R.

Item Type: Report

Partner: UNT Libraries Government Documents Department