Observations of a probable change in the solar radius between 1715 and 1979.

Solar eclipses were observed from locations near both edges of the paths of totality in England in 1715, in Australia in 1976, and in North America in 1979. Analysis of these observations shows that the solar radius has contracted by 0.34 +/- 0.2 arc second in 264 years.

Imaging of small-scale features on 433 Eros from NEAR: evidence for a complex regolith.

On 25 October 2000, the Near Earth Asteroid Rendevous (NEAR)-Shoemaker spacecraft executed a low-altitude flyover of asteroid 433 Eros, making it possible to image the surface at a resolution of about 1 meter per pixel. The images reveal an evolved surface distinguished by an abundance of ejecta blocks, a dearth of small craters, and smooth material infilling some topographic lows. The subdued appearance of craters of different diameters and the variety of blocks and different degrees of their burial suggest that ejecta from several impact events blanketed the region imaged at closest approach and led to the building up of a substantial and complex regolith consisting of fine materials and abundant meter-sized blocks.

Novel burn device for rapid, reproducible burn wound generation.

INTRODUCTION: Scarring following full thickness burns leads to significant reductions in range of motion and quality of life for burn patients. To effectively study scar development and the efficacy of anti-scarring treatments in a large animal model (female red Duroc pigs), reproducible, uniform, full-thickness, burn wounds are needed to reduce variability in observed results that occur with burn depth. Prior studies have proposed that initial temperature of the burner, contact time with skin, thermal capacity of burner material, and the amount of pressure applied to the skin need to be strictly controlled to ensure reproducibility. The purpose of this study was to develop a new burner that enables temperature and pressure to be digitally controlled and monitored in real-time throughout burn wound creation and compare it to a standard burn device. METHODS: A custom burn device was manufactured with an electrically heated burn stylus and a temperature control feedback loop via an electronic microstat. Pressure monitoring was controlled by incorporation of a digital scale into the device, which measured downward force. The standard device was comprised of a heat resistant handle with a long rod connected to the burn stylus, which was heated using a hot plate. To quantify skin surface temperature and internal stylus temperature as a function of contact time, the burners were heated to the target temperature (200±5°C) and pressed into the skin for 40s to create the thermal injuries. Time to reach target temperature and elapsed time between burns were recorded. In addition, each unit was evaluated for reproducibility within and across three independent users by generating burn wounds at contact times spanning from 5 to 40s at a constant pressure and at pressures of 1 or 3lbs with a constant contact time of 40s. Biopsies were collected for histological analysis and burn depth quantification using digital image analysis (ImageJ). RESULTS: The custom burn device maintained both its internal temperature and the skin surface temperature near target temperature throughout contact time. In contrast, the standard burner required more than 20s of contact time to raise the skin surface temperature to target due to its quickly decreasing internal temperature. The custom burner was able to create four consecutive burns in less than half the time of the standard burner. Average burn depth scaled positively with time and pressure in both burn units. However, the distribution of burn depth within each time-pressure combination in the custom device was significantly smaller than with the standard device and independent of user. CONCLUSIONS: The custom burn device's ability to continually heat the burn stylus and actively control pressure and temperature allowed for more rapid and reproducible burn wounds. Burns of tailored and repeatable depths, independent of user, provide a platform for the study of anti-scar and other wound healing therapies without the added variable of non-uniform starting injury.

Role of interferon-gamma in counteracting the suppressive effects of transforming growth factor-beta 2 and glucocorticoids on the production of tumor necrosis factor-alpha.

The multipotential cytokine, transforming growth factor-beta 2 (TGF-beta 2), is as effective as glucocorticoids in suppressing the production of tumor necrosis factor-alpha (TNF-alpha) by lipopolysaccharide (LPS)-stimulated macrophages, and this inhibition can be abrogated by exogenous interferon-gamma (IFN-gamma). Porcine alveolar macrophages triggered with LPS produce TNF-alpha as identified by complete blocking of cytotoxicity on WEHI 164 clone 13 cells in macrophage supernatants by a monoclonal antibody to human TNF-alpha. Platelet-derived porcine TGF-beta 2, at a concentration of 4 nM, inhibited LPS-induced production of TNF-alpha by 93%. Dexamethasone was as effective as TGF-beta 2, suppressing TNF-alpha production by 86% at a concentration of 4 nM. The natural but less potent glucocorticoid cortisol inhibited TNF-alpha production by 100% at a 100-fold higher concentration (400 nM). Recombinant PoIFN-gamma consistently primed LPS-triggered macrophages for increased production of TNF-alpha by 50-100%, and this priming was totally blocked by a polyclonal antibody to rPoIFN-gamma. Furthermore, the suppression in LPS-induced production of TNF-alpha caused by TGF-beta 2, dexamethasone, and cortisol could be reversed by addition of rPoIFN-gamma. These data show that alveolar macrophages can be effectively primed by rPoIFN-gamma even in the presence of moderately suppressive doses of TGF-beta 2 and antiinflammatory steroids.

Hypophysectomy inhibits the synthesis of tumor necrosis factor alpha by rat macrophages: partial restoration by exogenous growth hormone or interferon gamma.

We recently demonstrated that GH and interferon-gamma (IFN gamma) act in a similar manner to prime macrophages in vitro and in vivo for enhanced superoxide anion release. In this report we investigated the physiological role of the pituitary gland and GH in in vivo priming of resident peritoneal macrophages for the synthesis of tumor necrosis factor-alpha (TNF alpha) in vitro. Compared to normal rats, hypophysectomized animals had an 83% reduction in macrophage production of TNF alpha after in vitro stimulation with lipopolysaccharide. Sham operation had no significant effect on the ability of macrophages to secrete TNF alpha in response to lipopolysaccharide. Both native pituitary-derived porcine GH (48 micrograms/rat.9 days) and native pituitary-derived rat GH (96 micrograms/rat.9 days) more than tripled the in vitro production of TNF alpha by macrophages from hypophysectomized rats (342 and 358 vs. 112 U/mg protein for placebo-treated rats, respectively). Each of these preparations of GH also increased growth more than 6-fold in hypophysectomized rats (32 and 30 g vs. 5 g in placebo controls). Heat inactivation of native pituitary-derived porcine GH significantly reduced its in vivo ability to augment both TNF alpha synthesis by macrophages and body growth. Recombinant rat IFN gamma (2000 U/rat.9 days) more than tripled the production of TNF alpha by macrophages from hypophysectomized rats (343 vs. 112 U/mg protein). In contrast to its in vivo effects, addition of GH in vitro to macrophages from hypophysectomized rats did not prime these cells for the synthesis of TNF alpha, indicating an indirect mechanism of action for GH. To further test the biological relevancy of GH with respect to synthesis of TNF alpha, hemorrhagic necrosis of TNF alpha-sensitive murine methyl-cholanthrene-induced tumors was assessed in pituitary-intact mice. Native porcine GH (133 micrograms/mouse.7 days) significantly augmented both the necrosis to tumor ratio and the hemorrhage to tumor ratio. These findings establish the physiological relevance of the pituitary gland and GH in the priming of macrophages for TNF alpha synthesis.

The adaptive role of maladaptive neurosis.

A hypothesis is proposed which postulates that repeated failure in social competition may lead to a "neurotic" maladaptive vicious cycle. It is proposed that by magnifying genetically transmitted differences in fitness, this mechanism emphasizes the superiority of the better endowed, both in mate choice and in fitness of offspring. Species displaying high plasticity and flexibility, the concomitants of high intellectual ability, may be more susceptible to neurosis, hence may be more likely to be influenced by the vicious cycle mechanism operating at the ontogenetic level. Such species would display an accelerated rate of adaptation and intelligence. Some of the implications of the hypothesis for sexual selection, change in status, and preventive mental health are discussed.

Fortuitous esophageal intubation.

Esophageal malposition is a potentially disastrous complication of attempted airway intubation. We report an unusual case in which a promptly recognized esophageal intubation aided detection of a perforated gastric ulcer. After the endotracheal tube was repositioned and the ulcer was surgically repaired, our patient had an excellent outcome.

Aluminium in rat cerebellar primary cultures: glial cells and GABAergic neurones.

Experimental evidence of the preferential uptake of aluminium by GABAergic neurones and glial cells was provided by synchrotron spectromicroscopy studies. We observed rat cerebellar cultures enriched for GABAergic neurones or glial cells exposed to aluminium ions, detecting the presence and identifying the chemical status of aluminium on cell structures.

Aluminium in rat cerebellar neural cultures.

A systematic microchemical analysis of unstained and uncoated neurone cultures was performed with synchrotron radiation photoemission spectromicroscopy after exposure to an aluminium solution. Clear evidence was found for localized aluminium uptake in a few cells. Their possible identification based on morphology is discussed.

Characterization of porcine xenoreactive cytotoxic T lymphocytes.

Cytotoxic T lymphocytes (CTL) against mouse P815 cells were detected after stimulation of porcine peripheral blood mononuclear cells (PBMC) with irradiated Balb/c splenocytes. In vivo priming prior to in vitro stimulation slightly enhanced CTL activity, but lysis of targets was undetectable from lymphocytes from non-immune or immune animals that were not cultured with mouse splenocytes. After primary culture with Balb/c (H-2d) splenocytes, specific killing of P815 (H-2d) targets and not L929 (H-2k) targets indicated that recognition was specific for the H-2 locus. Similarly, CTL primed by mouse cells from either of two congenic strains recognized targets with alleles homologous to the stimulating cells. The anti-murine CTL was confirmed to be a CD8+ T cell based on studies using specific monoclonal antibodies to the porcine CD4 or CD8 cells. The cells responsible for the cytotoxicity of P815 targets lacked the characteristics of non-specific NK cells because (1) naive PBMC were unable to lyse NK targets (K562 cells) during the 4 h cytotoxic assay and (2) CTL killing of P815 targets increased with time after primary stimulation, whereas killing of K562 cells remained low at all times. These results suggest that porcine CTL can be readily generated against the xenogeneic mouse major histocompatibility complex.

Cognitive difficulty of a peripherally presented visual task affects head movements during gaze displacement.

The maintenance and adjustment of visual gaze are functions both of eye and of head movement. Compared to the factors that affect eye movement during gaze displacement, the factors that affect head movement have received relatively little attention. Most experimenters have restricted head movements to determine how the eye acquires information. Information is commonly acquired without head movements (e.g., it is likely you are moving your eyes without moving your head as you read the words on this page). However, when visual information beyond the written page is acquired head movements in addition to eye movements are likely to occur. The purpose of this experiment was to study gaze displacement under more natural conditions in which the eyes and head were both free to move. Specifically, the purpose of this experiment was to identify the pattern of gaze displacement as a function of cognitive task difficulty. Visual information was presented at an eccentricity of 40 degrees of visual angle either to the left or to the right of a center fixation point (0 degree eccentricity) to 24 undergraduate subjects (12 male). On each trial, five integers were presented in rapid succession; subjects were asked to count the number of odd integers or to arithmetically manipulate the integers. When subjects expected to perform the more difficult task of arithmetic manipulation, they were more likely to make head movements in the direction of the stimuli, F1,16 = 9.34, P < 0.05. Those subjects who made head movements to acquire the peripherally presented visual information made significantly more errors than the 'non-movers', F1,24 = 6.03, P < 0.05. These results suggest subjects who moved their head to acquire peripheral information may have found the task to be more difficult than subjects who did not make head movements. The results confirm that head movements play a critical role in the intake of information even in structured laboratory tasks and suggest the common method of restricting head movements to study eye movements may not be a natural method of information intake.

Slow brain potentials in a visual-spatial memory task: topographic distribution and inter-laboratory consistency.

Slow brain electrical potentials (SPs) were investigated in a visual-spatialmemory task. Two issues were addressed: (1) the nature and topographic distribution of the potentials obtained under such conditions; and (2) the consistency of the SPs when recorded in six identically configured laboratories. Fifteen young male subjects were studied at each laboratory (total n = 90). The paradigm entailed presentations of paired-visual patterns (S1 and S2), to which subjects responded with a choice reaction time response indicating whether or not the two patterns matched. A biphasic contingent negative variation (CNV) was produced which consisted of an early symmetric component with bilateral foci at posterior temporal sites and a subsequent mid-parietal dominant wave later in the retention interval. Although the CNVs from all laboratories were similar in waveform and in topographic distribution, there were significant inter-laboratory differences in amplitude of the slow potential components. The topographic distributions of the components and the possible role of sampling effects are discussed.

Increased aggressiveness after brief social isolation of adult fish: a connectionist model which organizes this literature.

We examine the literature on fishes' aggressive behaviour after social isolation, in the light of a connectionist adaptive control system model for robot motivation and learning. If animals used the model's motivation modules, then social isolation would cause two simultaneous processes to occur-one progressively increasing motivation, the other decreasing display readiness. The readiness decrement would have the temporal flexibility typical of motivation changes, and would disappear soon after social stimuli reappeared. The incremental effect would be synaptic, and would be temporally more stable. Due to this stability difference, brief post-isolation aggression tests would tend to show that social isolates have depressed attack readiness, but longer tests would uncover the underlying increase in aggressiveness. In reviewing the literature, we find that this has been overwhelmingly the case. A new hypothesis about the adaptive value of the increase of aggression during isolation is outlined, which may help make the phenomenon more understandable.

Different aggressive behaviours are exaggerated by facing vs. broadside subliminal stimuli shown to socially isolated Siamese fighting fish, Betta splendens.

We report and analyse some features of a new phenomenon: socially isolated Betta splendens become extremely hyper-aggressive after seeing brief glimpses of fish models or mirrors. These brief glimpses are below the threshold for releasing aggressive display, so they are considered subliminal aggressive stimuli. The hyper-aggressiveness was observed to last for weeks. To confirm that hyper-aggressiveness was dependent upon the aggressive significance of the subliminal stimuli, we presented socially isolated Betta splendens with subliminal models in either a `facing' posture (used mainly in aggressive contexts), or a `broadside' posture (used in many social contexts). The fish shown the aggressive `facing' subliminal stimuli became more aggressive, while those shown `broadside' stimuli performed more generalized advertisement behaviours. The display posture of the model, which may incorporate specific features relevant to aggression, therefore determined how the subliminal aggressive stimuli altered subsequent aggressiveness. This difference was also persistent. Subliminal stimuli may thus be implicated in the hyper-aggressiveness so often reported after social isolation.

Social isolation increases social display after priming in Betta splendens but decreases aggressive readiness.

We socially isolated adult, male Siamese fighting fish for 0 to 7 weeks but avoided sensory deprivation, and then measured aggressive display as the fish responded to a series of novel models. Isolates displayed much more strongly than non-isolates to the last model of the series, and display intensity became monotonically stronger with longer social isolation. By contrast, display to the first model seen after isolation was weaker the longer the social isolation. A second experiment compared responses of fish after three weeks during which controls displayed to a conspecific for two minutes every two days, while isolates saw a complex visual stimulus which did not release display. Again, isolates had depressed display readiness, but higher display rates once they were primed. This result supports the hypothesis that social isolation has two effects on aggressive display in Betta, causing decreasing readiness to display, but leading to greater display rates once fish are 'primed'. We discuss two models which predict these phenomena, and show that one of them suggests a new understanding of the function of motivational increases when aggression is 'dammed up'. Methodological issues relevant for examining the rodent behavior literature in the light of the new model are discussed.