News Media Use and Adolescents' Attitudes about Nuclear Issues: An American-Soviet Comparison

Both Soviet and American youth show a great concern about the possible effects of nuclear war, with heavy media users in both countries more optimistic, but the relation was stronger among Soviet students.     

High and low density water and resting, active and transformed cells

Melanoma is prone to spread to the brain and is the third most common source of intracranial metastasis. Patients usually present with signs and symptoms of increased intracranial pressure, a new focal neurologic deficit, or seizures. Contrasted magnetic resonance imaging (MRI) is the single most valuable imaging modality. Surgical therapy is the appropriate choice for single lesions that are accessible, especially if they are causing significant mass effect or are located in the posterior fossa. Patients with several intracranial metastases who undergo resection of all lesions may have a similar prognosis to those with single resected lesion. Stereotactic radiosurgery appears to provide good local control of small lesions. External beam radiotherapy may provide some benefit to patients, and is often used in conjunction with surgery or stereotactic radiosurgery. To date, chemotherapy has been limited because of chemo-resistance and drug delivery issues. Future directions for treatment may include local sustained delivery of either chemotherapy or immunoregulatory molecules.     

Inhibition of plasma membrane Ca(2+)-ATPase activity by volatile anesthetics

BACKGROUND: The precise sites and mechanisms of action of volatile anesthetics remain unknown. Recently, several integral membrane proteins have been suggested as potential targets to which anesthetics can bind at hydrophobic regions. Impairment of cell Ca2+ homeostasis has been postulated as one of the possible mechanisms of anesthetic action. To test these hypotheses, the authors selected the human erythrocyte Ca(2+)-ATPase as a model membrane protein. This enzyme is an integral membrane protein that is instrumental in maintaining Ca2+ homeostasis in the cell in which it is the sole Ca(2+)-transporting system. Thus, any functional alteration of the Ca(2+)-ATPase by anesthetics may lead to serious perturbations in Ca(2+)-regulated processes in the cell. METHODS: The Ca(2+)-ATPase activity was measured as a function of increased concentration of four volatile anesthetics: halothane, isoflurane, enflurane, and desflurane. RESULTS: All four anesthetics significantly inhibited the Ca(2+)-ATPase activity in a dose-dependent manner. The half-maximal inhibition occurred at anesthetic concentrations from 0.3 to 0.7 vol% at 37 degrees C, which, except for desflurane, is a clinically relevant concentration range. The greater the clinical potency of the volatile anesthetics studied, the less was the concentration required to inhibit the Ca(2+)-ATPase activity. The inhibition was less at 25 degrees C than at 37 degrees C, which is consistent with direct interactions of the nonpolar interfaces of the enzyme with the nonpolar of the portions of the anesthetics. CONCLUSIONS: The authors' findings indicate that the Ca(2+)-ATPase is a suitable model for investigating the mechanism of action of volatile anesthetics on the integral membrane protein, and that this inhibition may be specific.     

The monoamine regulon including syntheses of arylsulfatase and monoamine oxidase in bacteria

Bacterial cells respond to monoamine compounds, such as tyramine, dopamine, octopamine, or norepinephrine, and induce the syntheses of tyramine oxidase encoded by tynA and monoamine oxidase encoded by maoA. These monoamine compounds also derepress the synthesis of atsA-specified arylsulfatase that is repressed by sulfur compounds. These complex mechanisms of regulons regulated by monoamine and sulfur compounds has been analyzed by cloning and characterization of genes that are involved in the repression and derepression of the synthesis of arylsulfatase. The atsA gene forms an operon with the atsB gene, which encodes an activator of the expression of atsA. The negative regulator gene for arylsulfatase was found to code for dihydrofolate reductase (folA). The maoA gene forms an operon with the maoC gene, which has similarity to a dehydrogenase involved in the tyramine metabolism. The moaF gene encoding a 30-kDa protein, which is induced by tyramine, also forms an operon with the moaE gene. Finally, the moaR gene, which is induced by monoamine, was found to play a central role in the positive regulation of the expression of the monoamine regulon (moa) including the atsBA, maoCA, moaEF, and tyn operons. The moaR expression is subject to autogenous regulation and to cAMP-CRP control. The MoaR protein has a helix-turn-helix motif in its C terminus. Thus, the MoaR protein probably regulates the operons by binding to the regulatory region of the moa regulon.     

Using airborne laser scanning to monitor tree migration in the boreal-alpine transition zone

The boreal tree line is expected to advance upwards into the mountains and northwards into the tundra due to global warming. The major objective of this study was to find out if it is possible to use high-resolution airborne laser scanner data to detect very small trees — the pioneers that are pushing the tree line up into the mountains and out onto the tundra. The study was conducted in a sub-alpine/alpine environment in southeast Norway. A total of 342 small trees of Norway spruce, Scots pine, and downy birch with tree heights ranging from 0.11 to 5.20 m were precisely georeferenced and measured in field. Laser data were collected with a pulse density of 7.7 m^− 2. Three different terrain models were used to process the airborne laser point cloud in order to assess the effects of different pre-processing parameters on small tree detection. Greater than 91% of all trees > 1 m tall registered positive laser height values regardless of terrain model. For smaller trees (< 1 m), positive height values were found in 5-73% of the cases, depending on the terrain model considered. For this group of trees, the highest rate of trees with positive height values was found for spruce. The more smoothed the terrain model was, the larger the portion of the trees that had positive laser height values. The accuracy of tree height derived from the laser data indicated a systematic underestimation of true tree height by 0.40 to 1.01 m. The standard deviation for the differences between laser-derived and field-measured tree heights was 0.11-0.73 m. Commission errors, i.e., the detection of terrain objects — rocks, hummocks — as trees, increased significantly as terrain smoothing increased. Thus, if no classification of objects into classes like small trees and terrain objects is possible, many non-tree objects with a positive height value cannot be separated from those actually being trees. In a monitoring context, i.e., repeated measurements over time, we argue that most other objects like terrain structures, rocks, and hummocks will remain stable over time while the trees will change as they grow and new trees are established. Thus, this study indicates that, given a high laser pulse density and a certain density of newly established trees, it would be possible to detect a sufficient portion of newly established trees over a 10 years period to claim that tree migration is taking place.     

Theoretical and experimental investigation of flow and heat transfer in an internally-heated naturally-ventilated space

This paper presents the findings of a theoretical and experimental investigation of the thermodynamics of an internally heated control volume, ventilated by natural convection. A simple bench-type experiment has been used to determine the temperature history of the air, in support of a global calculation by numerical methods. Good agreement has been achieved between the experimental results and the mathematical prediction, which has wide ranging applications in practical situations.     

Genetic control of differential baseline breathing pattern

The purpose of the present study was to determine the genetic control of baseline breathing pattern by examining the mode of inheritance between two inbred murine strains with differential breathing characteristics. Specifically, the rapid, shallow phenotype of the C57BL/6J (B6) strain is consistently distinct from the slow, deep phenotype of the C3H/HeJ (C3) strain. The response distributions of segregant and nonsegregant progeny were compared with the two progenitor strains to determine the mode of inheritance for each ventilatory characteristic. The BXH recombinant inbred (RI) strains derived from the B6 and C3 progenitors were examined to establish strain distribution patterns for each ventilatory trait. To establish the mode of inheritance, baseline breathing frequency (f), tidal volume, and inspiratory time (TI) were measured five times in each of 178 mature male animals from the two progenitor strains and their progeny by using whole body plethysmography. With respect to f and TI, the two progenitor strains were consistently distinct, and segregation analyses of the inheritance pattern suggest that the most parsimonious genetic model for response distributions of f and TI is a two-loci model. In similar experiments conducted on 82 mature male animals from 12 BXH RI strains, each parental phenotype was represented by one or more of the RI strains. Intermediate phenotypes emerged to confirm the likelihood that parental strain differences in f and TI were determined by more than one locus. Taken together, these studies suggest that the phenotypic difference in baseline respiratory timing between male B6 and C3 mice is best explained by a genetic model that considers at least two loci as major determinants.     

The fibrinolytic system in neoplasia

During activation of the fibrinolytic system plasminogen is converted to plasmin by tissue plasminogen activator (t-PA) or urokinase-type plasminogen activator (u-PA). t-PA is predominantly released from endothelial cells, u-PA primarily by renal parenchymal cells. The activation of plasminogen is regulated by plasminogen activator inhibitor-1 (PAI-1), plasmin is controlled by alpha 2-plasmin inhibitor. The fibrinolytic system is not only involved in the intravascular dissolution of fibrin (thrombi), it also plays a vital role in normal physiologic reproduction, wound repair, angiogenesis, and tissue remodeling. Fibrinolysis is also a vital component in the pathogenesis of neoplastic disease. It is essential in releasing cells from their primary site of origin, providing nutrition for neoplastic cell growth and promoting cell mobility and motility. In neoplastic cells the degradation of the extracellular matrix proteins is facilitated by excessive expression of u-PA, t-PA, and u-PAR. In many forms of carcinoma increased expression of u-PAR and u-PA is associated with significantly shorter survival. Greater expression of u-PA in breast cancer cells, for example, is associated with shorter survival and increased relapse rate. Progressively aggressive neoplastic cells evidence high expression of u-PA and u-PAR activities, variable expression of t-PA, and enhanced PAI-1 and PAI-2 activities. In acute nonlymphocytic leukemias, poor outcome correlates with high t-PA levels. In acute progranulocytic leukemia there is a high incidence of DIC. Neoplastic prostatic tissue also expresses high u-PA activity and the more aggressive the cell line, the greater the number of u-PAR and the higher the u-PA activity. In gynecologic malignancies, a greater expression of u-PA in combination with cathepsin D is associated with widespread disease and poor prognosis. High u-PA values were also seen in patients with brain, gastric, and hepatic malignancies. It is evident that the plasminogen-plasmin system is a vital component in the biology of neoplastic disease and that it is, in theses conditions, in no way beneficial to the host.     

Consumer preference not to choose: Methodological and policy implications

Residential consumers remain reluctant to choose new electricity suppliers. Even the most successful jurisdictions, four US states and other countries, have had to adopt extensive consumer education procedures that serve largely to confirm that choosing electricity suppliers is daunting. Electricity is not unique in this respect; numerous studies find that consumers are generally reluctant to switch brands, even when they are well-informed about product characteristics. If consumers prefer not to choose, opening regulated markets can reduce welfare, even for some consumers who do switch, as the incumbent can exploit this preference by raising price above the formerly regulated level. Policies to open markets might be successful even if limited to industrial and commercial customers, with residential prices based on those in nominally competitive wholesale markets.     

Synaptically evoked glutamate transport currents may be used to detect the expression of long-term potentiation in cerebellar culture

Cerebellar long-term potentiation (LTP) is a use-dependent increase in the strength of the granule cell-Purkinje neuron synapse that occurs after brief stimulation of granule cell axons at 2-8 Hz. Previous work has shown that cerebellar LTP also may be seen when synaptic currents are evoked in granule cell-glial cell pairs in culture. This finding suggests a model in which cerebellar LTP is expressed presynaptically and therefore may be detected by either neuronal or glial postsynaptic cells. However, synaptic currents evoked in both granule cell-glial cell pairs and granule cell-Purkinje neuron pairs in culture are mediated primarily by alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)/kainate receptors, raising the possibility that cerebellar LTP might be expressed postsynaptically in both glial cells and Purkinje neurons in a similar manner. To address this question, glutamate transport currents were recorded in granule cell-glial cell pairs in culture by pharmacological isolation. These currents were increased by substitution of internal Cl with NO3 and were blocked by -pyrrolidine-2,4-dicarboxylate, both characteristics of the major cloned Bergmann glial cell glutamate transporter, EAAT1. After acquisition of baseline responses, LTP of isolated transport current was evoked by stimulation at 4 Hz (100 pulses) and could be blocked by removal of external Ca during this stimulation. The expression of LTP was associated with a decrease in the rate of synaptic failures and a decrease in the degree of paired-pulse facilitation. These findings, when taken together with the previous observation that both Purkinje neuron and glial AMPA/kainate responses can be used to detect cerebellar LTP, strongly suggest that the expression of cerebellar LTP is, at least in part, presynaptic. This strategy should also be useful in illuminating the locus of expression of other model systems of information storage such as hippocampal LTP/long-term depression.