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Myocardial ischemia-reperfusion (IR) injury represents a constellation of pathological processes that occur when ischemic myocardium experiences a restoration of perfusion. Reentrant arrhythmias, which represent a particularly lethal manifestation of IR injury, can result when ischemic tissue exhibits decreased excitability and/or changes of action potential duration (APD), conditions that precipitate unidirectional conduction block. Many of the cellular components that are involved with IR injury are modulated by pH and/or phosphometabolites such as ATP and phosphocreatine (PCr), all of which can be manipulated in vivo and potentially in the clinical setting. Using a mathematical model of the cardiomyocyte that we previously developed to study ischemia and reperfusion, we performed a series of simulations with the aim of determining whether pH- or phosphometabolite-related processes play a more significant role in generating changes in excitability and action potential morphology that are associated with the development of reentry. In our simulations, persistent shortening of APD, action potential amplitude (APA), and depolarization of the resting membrane potential were more severe when ATP and PCr availability were suppressed during reperfusion than when extracellular pH recovery was inhibited. Reduced phosphometabolite availability and pH recovery affected multiple ion channels and exchangers. Some of these effects were the result of direct modulation by phosphometabolites and/or acidosis, while others resulted from elevated sodium and calcium loads during reperfusion. In addition, increasing ATP and PCr availability during reperfusion was more beneficial in terms of increasing APD and APA than was increasing the amount of pH recovery. Together, these results suggest that therapies directed at increasing ATP and/or PCr availability during reperfusion may be more beneficial than perturbing pH recovery with regard to mitigating action potential changes that increase the likelihood of reentrant arrhythmias.

Reperfusion injury results from pathologies of cardiac myocyte physiology that develop when previously ischemic myocardium experiences a restoration of normal perfusion. Events in the development of reperfusion injury begin with the restoration of a proton gradient upon reperfusion, which then allows the sodium-proton exchanger (NHE) to increase flux, removing protons from the intracellular space while importing sodium. The resulting sodium overload drives increased reverse-mode sodium-calcium exchanger (NCX) activity, creating a secondary calcium overload that has pathologic consequences. One of the attempts to reduce reperfusion-related damage, NHE inhibition, has shown little clinical benefit, and only when NHE inhibitors are given prior to reperfusion. In an effort to further understand why NHE inhibitors have been largely unsuccessful, we employed a new mathematical cardiomyocyte model that we developed for the study of ischemia and reperfusion. Using this model, we simulated 20 minutes of ischemia and 10 minutes of reperfusion, while also simulating NHE inhibition by reducing NHE flux in our model by varying amounts and at different time points. In our simulations, when NHE inhibition is applied at the onset of reperfusion, increasing the degree of inhibition increases the peak sodium and calcium concentrations, as well as reducing intracellular pH recovery. When inhibition was instituted at earlier time points, some modest improvements were seen, largely due to reduced sodium concentrations prior to reperfusion. Analysis of all sodium flux pathways suggests that the sodium-potassium pump (NaK) plays the largest role in exacerbated sodium overload during reperfusion, and that reduced NaK flux is largely the result of impaired pH recovery. While NHE inhibition does indeed reduce sodium influx through that exchanger, the resulting prolongation of intracellular acidosis paradoxically increases sodium overload, largely mediated by impaired NaK function., Author Summary Myocardial ischemia, commonly observed when arteries supplying the heart become occluded, results when cardiac tissue receives inadequate blood perfusion. In order to minimize the amount of cardiac damage, ischemic tissue must be reperfused. However, reperfusion can result in deleterious effects that leave the heart muscle sicker than if the ischemia had been allowed to continue. Examples of these reperfusion injuries include lethal arrhythmias and an increased region of cell death. Some of the early events that result in reperfusion injury include changes in pH and an overload of sodium inside the cell. During reperfusion, the sodium-proton exchanger (NHE) removes protons from the cell in an effort to restore normal pH, in turn importing sodium ions. Many strategies have been attempted to prevent reperfusion injury, including inhibition of the NHE, with little clinical effect. Using a mathematical model that we developed to study ischemia and reperfusion in cardiac cells, we found that NHE inhibition produces more severe sodium overload, largely due to adverse consequences of the delayed pH recovery produced by NHE inhibition. These results suggest that NHE inhibition alone may not be a viable strategy, and that therapies which prolong intracellular acidosis may be problematic.

The ongoing Federal Highway Administration (FHWA) research program “Nonpoint Source Pollution from Highway Stormwater Runoff” is a four-phase research effort: (1) identification and quantification of the constituents of highway runoff, (2) identification of the sources and migration paths of the constituents, (3) analysis of the effects of pollutants on receiving waters, and (4) development of management practices. Phases 1 through 3 have been completed; interim results of Phase 4 are available. Phase 1 identified runoff constituents and developed a data base of runoff quantity and quality. Phase 2 identified the sources and migration patterns of highway runoff constituents and further developed the Phase 1 data base. Phase 3 results indicated that highway facilities with low to medium ADT (less that 30,000) exhibited minimal impact on receiving water ecology. Interim results of Phase 4 have identified practical, effective, and implementable mitigation measures to reduce or eliminate the impacts from highway stormwater runoff. The final efforts of Phase 4 are ongoing and scheduled for completion in 1988. They include (1) further development of a tool to estimate pollutant loading from highway stormwater runoff and (2) evaluation and development of final design guidelines for retention, detention, and overland flow systems for pollutant removal from highway stormwater runoff.

Protein concentration increases in cerebrum and spinal cord during maturation of the rat were rather similar, but at all ages the spinal cord contained a higher protein concentration than cerebrum. Co

When Lawrence Livermore Laboratory started detonating explosives at its Site 300 test location in the sparsely populated hills east of the Laboratory, residents in neighboring areas complained of sudden loud noises. A combined literature and research study, coupled with an experimental test program, indicated the combination of air temperatures and winds at various elevations was primarily responsible for blast or sound waves being returned to the surface. To solve the noise problem, the Laboratory devised a method for determining the maximum amount of explosives that could be detonated aboveground under various atmospheric conditions without creating excessive noise in populated areas. This method for predicting explosives weight limits using pressure-distance-weight nomograms and the slope of a sound-velocity curve is described in this paper. The sound-velocity curve is computed with temperature information from the U.S. Weather Bureau and wind data from a target-acquisition radar system. By following this method, the Laboratory has been able to detonate thousands of shots without creating excessive noise in nearby communities.

A pilot study was conducted to determine the feasibility of chemical control of phlebotomine sand flies in a highly complex Neotropical rain forest in Panama. The aim was to reduce the risk of contracting leishmaniasis within prescribed areas of the forest utilized by military troops for training or other special activities. The results indicate that an average 30% reduction of anthropophilic sand flies was achieved in 9 months by utilizing malathion as 2% EC spray or 95% ULV fogging applied bimonthly.

A new technique for rearing the Panamanian phlebotomine sand fly Lutzomyia trapidoi (Fairchild & Hertig) described. Experimental data are provided on sugar- and blood-feeding, mating, oviposition and culture of immature stages. As many as 70% of females survived oviposition when maintained in styrofoam chambers and fed concentrated sucrose solutions.

A study of horizontal and vertical movements of phlebotomine sandflies in tropical forest was conducted by means of the mark-release-recapture method utilizing fluorescent pigments. Approximately 20,000 flies were marked and released at ground level and on a canopy platform (30 m high). The median recapture rate of marked flies was 8.6% in the ground release and 1.8% in the canopy release. Analysis of data demonstrated the tendency of flies to remain localized; approximately 90% of marked specimens were captured within a radius of 57 m. The maximum radius of the experimental area was 200 m and 4 marked flies flew to this distance, 1 of them within 1 day after release. The canopy fly population was dominated by Lutzomyia trapidoi (Fairchild & Hertig). This species moved upward at dusk from a number of diurnal resting sites, mainly the forest leaf-litter and the lower parts of tree trunks.

Male and female encoding-decoding of spontaneous and enacted nonverbal affective behavior was evaluated using the Buck (1977) slide-viewing paradigm. The eliciting stimuli were carefully selected and evaluated to insure a comparable emotional impact on both sexes, and all subjects received the same decoding task. Consistent with previous research, females were superior decoders overall. Also as predicted, females were superior encoders, principally when reacting spontaneously to the slides. Given no evidence of differential affective arousal, this sex difference for spontaneous encoding is interpreted to reflect differences in male-female display rules. Contrary to several previous findings spontaneous and enacted encoding measures were not strongly related, especially for males, where display rules may modify their spontaneous and enacted expressive behavior in comparison to females. There was no consistent positive or negative relationship between dimensional or category measures of encoding-decoding for either sex. Future investigations should separately evaluate encoding-decoding phenomena for each sex, employing more precise methods to evaluate the specific nonverbal behaviors actually important to the encoding-decoding communication process.

How can one expect a consultant to accomplish something a president is unwilling or unable to do? The president should be the leader in organization development.

(1971). The effects of an interview on attitudes and behavior. The Journal of Sex Research: Vol. 7, No. 2, pp. 138-152.

The 3 known species of sandflies in California use burrows of a large ground squirrel, Citellus beecheyi , as breeding and diurnal resting sites. In 1965 there were 3 annual field generations with adults being active from May-November. Their annual population peaked near the middle of this period and coincided with emergence of the second adult generation. Adults were primarily crepuscular and nocturnal in their above-ground activities. Although such adult activities were associated with dispersal, feeding and probably mating, the results suggest that feeding and mating of flies also may occur within burrows during the day. Field capture of parous ♀♀ showed that some flies survived long enough to take a second blood meal, but the small percentages of such ♀♀ captured also indicated die short duration of each generation's blood-sucking activities. Flagellate infections in only parous or gravid ♀♀ of P. v. occidentis strongly implies that this species serves as an intermediate host of a protozoan infecting 1 of its natural hosts. The presence of crithidial forms in the midgut indicates a trypanosome infection in the vertebrate host. Trypanosomes were not isolated from a number of reptiles examined, but all studies indicate that the most probable vertebrate host is a species of reptile or anuran on which these flies feed. As fly infections were confined to the posterior station, and because the ♀♀ excrete small droplets from the anus while feeding, the vertebrate host must acquire its infection either by contamination of a wound or by ingesting infected flies.

Some geology teachers spend practically all their time and professional energies being teachers; others are so engrossed in geological research that they are incapable of communicating with students at any level of training. Most teachers of geology would be classed between these extremes, and many possess a reasonably good balance between research activity and teaching. Although obviously valuable to the teacher of geology, research activity possesses only relative values. It is difficult to determine when a teacher does too much or too little research or whether the research is bad or mediocre or good. Despite its equivocal nature, research activity is the soundest criterion for determining that a geologist is professionally alive. It indicates some degree of scientific motivation and competence. Research work provides a fountainhead of enthusiasm every teacher must have to be truly effective. Particularly on the graduate level of instruction, a teacher's reputation in geological research tends to draw ...

The Price formation, the oldest Mississippian formation in the Draper Mountain area, is approximately 1,250 feet thick and consists of sandstone, shale, and conglomerate. Three distinct beds of semi-anthracite coal occur about the middle of the formation. In this general region the Price has been considered by most geologists as continental, but new evidence suggests that in the Draper Mountain area, at least, all except the coal-bearing portion is marine. Fossils indicate that most, if not all, of the Price is of New Providence (Osage) age. The possible Kinderhook age of the lower part of the Price is discussed.