Possible methane-induced polar warming in the early Eocene

Reconstructions of early Eocene climate depict a world in which the polar environments support mammals and reptiles, deciduous forests, warm oceans and rare frost conditions. At the same time, tropical sea surface temperatures are interpreted to have been the same as or slightly cooler than present values. The question of how to warm polar regions of Earth without noticeably warming the tropics remains unresolved; increased amounts of greenhouse gases would be expected to warm all latitudes equally. Oceanic heat transport has been postulated as a mechanism for heating high latitudes, but it is difficult to explain the dynamics that would achieve this. Here we consider estimates of Eocene wetland areas and suggest that the flux of methane, an important greenhouse gas, may have been substantially greater during the Eocene than at present. Elevated methane concentrations would have enhanced early Eocene global warming, and also might specifically have prevented severe winter cooling of polar regions because of the potential of atmospheric methane to promote the formation of optically thick, polar stratospheric ice clouds.

Identification of a maize nucleic acid-binding protein (NBP) belonging to a family of nuclear-encoded chloroplast proteins

A cDNA encoding a nuclear-encoded chloroplast nucleic acid-binding protein (NBP) has been isolated from maize. Identified as an in vitro DNA-binding activity, NBP belongs to a family of nuclear-encoded chloroplast proteins which share a common domain structure and are thought to be involved in posttranscriptional regulation of chloroplast gene expression. NBP contains an N-terminal chloroplast transit peptide, a highly acidic domain and a pair of ribonucleoprotein consensus sequence domains. NBP is expressed in a light-dependent, organ-specific manner which is consistent with its involvement in chloroplast biogenesis. The relationship of NBP to the other members of this protein family and their possible regulatory functions are discussed.

Human ectopic fascioliasis in Australia: first case reports

OBJECTIVE

To describe the manifestations of two cases of migratory ectopic fascioliasis diagnosed in Australia, including the first report of lymphatic infection.

PRESENTATION

Both patients presented with acute, superficial swellings. In the first, a 46-year-old woman, the lump was found to be a cervical lymph node containing a mature Fasciola hepatica which had released eggs into surrounding tissues. The second patient was a 34-year-old male abattoir worker, in whom the subcutaneous lesion resembled an infected sebaceous cyst and contained an immature fluke.

FINDINGS

Both lesions were resected and diagnosed histologically. Fasciola eggs were not found in the faeces of either patient. Blood eosinophilia was not detected in either case. A serological test for fascioliasis was carried out in the second case and the result was positive. In both cases, infection was probably acquired in Australia, although neither patient had eaten watercress.

OUTCOME

Neither patient was specifically treated with anthelminthic agents, and neither suffered further complications.

CONCLUSION

Migratory fascioliasis occurs in Australia. It can present as superficial or deep focal lesions, not necessarily in association with peripheral blood eosinophilia or Fasciola eggs in faeces. Serological tests may be helpful in diagnosing such cases.

Pleuropulmonary paragonimiasis in a Laotian immigrant to Australia

A case of pleuropulmonary paragonimiasis that mimicked reactivation of pulmonary tuberculosis, pneumonia, and neoplasm occurred in a Laotian immigrant to Australia. The key to the diagnosis of this condition is awareness of the disease in persons from this region. The diagnosis was supported by enzyme-linked immunosorbent assay testing. The patient was successfully treated with praziquantel.

Modelling the Phanerozoic carbon cycle and climate: constraints from the 87Sr/86Sr isotopic ratio of seawater

A numerical model describing the coupled evolution of the biogeochemical cycles of carbon, sulfur, calcium, magnesium, phosphorus, and strontium has been developed to describe the long-term changes of atmospheric carbon dioxide and climate during the Phanerozoic. The emphasis is on the effects of coupling the cycles of carbon and strontium. Various interpretations of the observed Phanerozoic history of the seawater 87Sr/86Sr ratio are investigated with the model. More specifically, the abilities of continental weathering, volcanism, and surface lithology in generating that signal are tested and compared. It is suggested that the observed fluctuations are mostly due to a changing weatherability over time. It is shown that such a conclusion is very important for the modelling of the carbon cycle. Indeed, it implies that the conventional belief that the evolution of atmospheric carbon dioxide and climate on a long time scale is governed by the balance between the volcanic input of CO2 and the rate of silicate weathering is not true. Rather carbon exchanges between the mantle and the exogenic system are likely to have played a key role too. Further, the increase of the global weathering rates with increasing surface temperature and/or atmospheric CO2 pressure usually postulated in long-term carbon cycle and climate modelling is also inconsistent with the new model. Other factors appear to have modulated the weatherability of the continents through time, such as mountain building and the existence of glaciers and ice sheets. Based on these observations, a history of atmospheric carbon dioxide and climate during Phanerozoic time, consistent with the strontium isotopic data, is reconstructed with the model and is shown to be compatible with paleoclimatic indicators, such as the timing of glaciation and the estimates of Cretaceous paleotemperatures.

Assessing the effects of odorants on nasal airway size and breathing

A technique was developed to obtain continuous measurements of both respiratory behavior and nasal patency in response to well-controlled odorant stimulation. An automated apparatus similar to that described by Walker et al. (27) was used to present precise concentrations of an odorant. The pressure-flow technique (28) was used to continuously measure nasal airway cross-sectional area, nasal airflow rate, air volume and time characteristics associated with breathing before and during odorant stimulation. Immediately following each odorant presentation, subjects entered their psychophysical responses into a microcomputer via an electronic mouse. Respiratory and psychophysical responses of ten normal subjects to four concentrations of acetic acid during eight odorant trials were recorded; eight clean-air trials were also conducted. At the highest concentration, changes in respiratory behavior were observed as early as 200 ms after stimulus onset in some subjects. Inspiratory volumes during odorant presentation were lower than those seen just before stimulation. The magnitude of this decrease was directly related to the concentration of acetic acid and to the perceived intensity of the odor and degree of nasal irritation.

Environmental tobacco smoke: current assessment and future directions

Scientific information on environmental tobacco smoke (ETS) is critically reviewed. Key areas addressed are: differences in chemical composition between mainstream smoke, sidestream smoke, and ETS; techniques for measurement of ETS; epidemiology; in vitro and in vivo toxicology; and chamber and field studies of perceptual or physiological effects. Questions concerning estimation of ETS exposure, suitability of various biomarkers, calculation of lifetime dose, control of confounding variables, use of meta-analysis, and the relationship between ETS concentrations and human responses all emphasize the need for additional research in order to assess potential effects of ETS on health or comfort.

Effects of fuel and forest conservation on future levels of atmospheric carbon dioxide

We develop a numerical simulation of the global biogeochemical cycles of carbon that works over time scales extending from years to millions of years. The ocean is represented by warm and cold shallow water reservoirs, a thermocline reservoir, and deep Atlantic, Indian, and Pacific reservoirs. The atmosphere is characterized by a single carbon reservoir and the global biota by a single biomass reservoir. The simulation includes the rock cycle, distinguishing between shelf carbonate and pelagic carbonate precipitation, with distinct lysocline depths in the three deep ocean reservoirs. Dissolution of pelagic carbonates in response to decrease in lysocline depth is included. The simulation is tuned to reproduce the observed radiocarbon record resulting from atomic weapon testing. It is tuned also to reproduce the distribution of dissolved phosphate and total dissolved carbon between the ocean reservoirs as well as the carbon isotope ratios for both 13C and 14C in ocean and atmosphere. The simulation reproduces reasonably well the historical record of carbon dioxide partial pressure as well as the atmospheric isotope ratios for 13C and 14C over the last 200 yr as these have changed in response to fossil fuel burning and land use changes, principally forest clearance. The agreements between observation and calculation involves the assumption of a carbon dioxide fertilization effect in which the rate of production of biomass increases with increasing carbon dioxide partial pressure. At present the fertilization effect of increased carbon dioxide outweighs the effects of forest clearance, so the biota comprises an overall sink of atmospheric carbon dioxide sufficiently large to bring the budget approximately into balance. This simulation is used to examine the future evolution of carbon dioxide and its sensitivity to assumptions about the rate of fossil fuel burning and of forest clearance. Over times extending up to thousands of years, the results are insensitive to the formulation of the rock cycle and to the dissolution of deep sea carbonate sediments. Atmospheric carbon dioxide continues to increase as long fossil fuel is burned at a significant rate, because the rate of fossil fuel production of carbon dioxide far exceeds the rates at which geochemical processes can remove carbon dioxide from the atmosphere. The maximum concentration of carbon dioxide achieved in the atmosphere depends on the total amount of fossil fuel burned, but only weakly on the rate of burning. The future course of atmospheric carbon dioxide is, however, very sensitive to the fate of the forests in this simulation because of the important role assigned to carbon dioxide fertilization of plant growth rate. Forest clearance drives up atmospheric carbon dioxide not only by converting biomass into atmospheric carbon dioxide but more importantly by reducing the capacity of the biota to sequester fossil fuel carbon dioxide. In this simulation, atmospheric carbon dioxide levels could be sustained indefinitely below 500 parts per million (ppm) if fossil fuel combustion rates were immediately cut from their present value of 5 x 10(14) m/y to 0.2 x 10(14) m/y (a factor of 25 reduction) and if further forest clearance were halted. If neither of these conditions is met and if we consume most of the world's fossil fuel reserves, peak carbon dioxide concentrations of 1000-2000 ppm are probable within the next few centuries.

Isolation and expression of a maize type 1 protein phosphatase

The dephosphorylation of phosphoproteins by protein phosphatases represents an important mechanism for regulating specific cellular processes in eukaryotic cells. The aim of the present study was to examine the structural and biochemical characteristics of a specific class of protein Ser/Thr phosphatases (type 1 protein phosphatases) which have received very little attention in higher plants. A cDNA clone (ZmPP1) was isolated from a maize (Zea mays L.) cDNA library. The deduced amino acid sequence is 80% identical with a 292-amino acid core region of rabbit and yeast type 1 protein phosphatase catalytic subunit. Southern blot analysis indicates that ZmPP1 may belong to a family of related genes in maize. ZmPP1 RNA was present in all maize tissues examined, indicating that it may play a fundamental role in cellular homeostasis. To demonstrate that ZmPP1 encodes an active protein phosphatase and, in an effort to characterize this gene product biochemically, high levels of ZmPP1 were expressed in Escherichia coli. Active ZmPP1 enzyme dephosphorylates rabbit phosphorylase a and is strongly inhibited by okadaic acid and by the mammalian inhibitor-2. These data show that ZmPP1 is structurally and biochemically very similar to the corresponding enzyme in animal cells. These results also suggest that the function and regulation of the higher plant type 1 protein phosphatases may be similar to the mammalian protein phosphatases.

Functional properties of the anaerobic responsive element of the maize Adh1 gene

The functional properties of the anaerobic responsive element (ARE) of the maize Adh1 gene have been analysed using a transient expression assay in electroporated maize protoplasts. The ARE functions in both orientations although inversion of the ARE sequence relative to the TATA box element produces slightly weaker promoter activity under anaerobic conditions and elevated expression under aerobic conditions. Promoter activity under anaerobic conditions is proportional to the number of complete ARE sequences in the Adh1 promoter. The ARE contains two sub-regions and dimers of sub-region II are as efficient as the wild-type sequence in activating gene expression under anaerobic conditions. However, sub-region I dimers do not appear capable of inducing gene expression in response to anaerobic stress. We conclude that sub-region II is essential for anaerobic induction of gene expression. Reporter gene expression remains constant when the spacing between sub-regions of the ARE is increased up to at least 64 bp, but increased spacing of 136 bp or greater abolishes expression in both aerobic and anaerobic conditions, indicating that a close association of the two sub-regions is required both for anaerobic responsiveness and for maximal levels of aerobic gene expression. When the ARE is placed upstream of position -90 of the CaMV 35S promoter, the ARE produces a high level of expression in both aerobic and anaerobic conditions. The general enhancement of gene expression driven by the hybrid ARE/35S promoter in aerobic conditions requires an intact sub-region II motif since mutation or deletion of sub-region II from the hybrid promoter reduces the level of expression to that observed for the truncated 35S promoter alone. In addition, mutation of the sub-region I sequences in the ARE/35S hybrid promoter does not significantly reduce expression in aerobic conditions, relative to pARE/delta 35S(-90), suggesting that sub-region I does not contribute to this general enhancer function.

A numerical simulation of climate changes during the obliquity cycle on Mars

A one-dimensional seasonal energy balance climate model has been developed for the Martian surface and coupled to a model of CO2 distribution between atmosphere, regolith, and polar caps. This model takes into account the greenhouse warming of carbon dioxide, the meridional transport of heat, the CO2 condensation and sublimation cycle, and its adsorption in the regolith. The model takes into consideration the diurnal variation of solar irradiation, since it is shown that disregard of this effect yields temperatures too high by several degrees. The yearly-averaged temperatures calculated from this climate model at different obliquities are used to estimate the importance of CO2 exchanges between the regolith and atmosphere-cap systems during the obliquity cycle. For this purpose, the equation of thermal diffusion into the ground is solved for each latitude belt. The results differ substantially from those of previous studies, due in part to the consideration of the diurnal and seasonal variations of the solar irradiance. The model shows the importance of taking these short-period variations into account instead of using yearly-averaged quantities, due to the strong nonlinearity of the climate system on Mars. The roles of meridional heat transport and greenhouse warming are analyzed and shown to be important. For example, a permanent polar cap of carbon dioxide is destroyed by heat transport when the obliquity is high, while at low obliquity, high-pressure systems without permanent cap can exist if enough exchangeable carbon dioxide is available. Further, the results show the possible existence of hysteresis cycles in the formation and sublimation of permanent deposits during the course of the obliquity cycle.

Relationship of a putative receptor protein kinase from maize to the S-locus glycoproteins of Brassica

The protein kinase family of enzymes mediates the responses of eukaryotic cells to both inter- and intracellular signals. These enzymes are either serine/threonine-specific or tyrosine-specific. Many of the latter are transmembrane receptors and are important in transduction of extracellular signals across the plasma membrane, whereas few examples of receptor serine kinases have been reported. We have now identified a complementary DNA clone from Zea mays (L.) encoding a putative serine/threonine-specific protein kinase structurally related to the receptor tyrosine kinases. This structural similarity is evidence for a previously undescribed class of transmembrane receptor in higher plants likely to be involved in signal reception and transduction. Furthermore, the catalytic domain of this protein kinase is linked through a transmembrane domain to an extracellular domain similar to that of glycoproteins encoded in the self-incompatibility locus of Brassica which are involved in the self-recognition system between pollen and stigma.

Precambrian evolution of the climate system

Climate is an important environmental parameter of the early Earth, likely to have affected the origin and evolution of life, the composition and mineralogy of sedimentary rocks, and stable isotope ratios in sedimentary minerals. There is little observational evidence constraining Precambrian climates. Most of our knowledge is at present theoretical. Factors that must have affected the climate include reduced solar luminosity, enhanced rotation rate of the Earth, an area of land that probably increased with time, and biological evolution, particularly as it affected the composition of the atmosphere and the greenhouse effect. Cloud cover is a major uncertainty about the early Earth. Carbon dioxide and its greenhouse effect are the factors that have been most extensively studied. This paper presents a new examination of the biogeochemical cycles of carbon as they may have changed between an Archean Earth deficient in land, sedimentary rocks, and biological activity, and a Proterozoic Earth much like the modern Earth, but lacking terrestrial life and carbonate-secreting plankton. Results of a numerical simulation of this transition show how increasing biological activity could have drawn down atmospheric carbon dioxide by extracting sedimentary organic carbon from the system. Increasing area of continents could further have drawn down carbon dioxide by encouraging the accumulation of carbonate sediments. An attempt to develop a numerical simulation of the carbon cycles of the Precambrian raises questions about sources and sinks of marine carbon and alkalinity on a world without continents. More information is needed about sea-floor weathering processes.

IQ levels following trauma

One hundred fifteen consecutive trauma patients who experienced a head injury and were administered a Wechsler Intelligence Scale as outpatients were selected for study from the Neuropsychology Registry. These patients ranged in age from 4 to 61 years. At the time of examination, all were living at home with their families. Dividing this group of patients on the basis of a Glasgow Coma Score (GCS) of 10 revealed significant differences in group mean post-traumatic IQs. The more severely injured group of patients had a mean post-traumatic IQ of 93.6; the less severely injured patients had a mean IQ of 103.5. The difference between these two groups is significant (p less than 0.005). When divided on the basis of a GCS of 13, the more severely injured group of patients had a mean post-traumatic IQ of 94.2 and the less severely injured group of patients had a mean post-traumatic IQ of 104.2. The difference between these two groups is also statistically significant (p less than 0.0005). There was no statistically significant (p greater than 0.05) difference in the mean post-traumatic IQs of these patients divided on the basis of an Injury Severity Score (ISS) of 15. However, there was a significant difference (p less than 0.05) when the patients were divided at ISS of 17. The less severely injured patients had a mean post-traumatic IQ of 101.2 and the more severely injured patients had a mean post-traumatic IQ of 95.8. The difference between these two groups is statistically significant (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

The effect on Earth's surface temperature from variations in rotation rate, continent formation, solar luminosity, and carbon dioxide

Proposed evolutionary histories of solar luminosity, atmospheric carbon dioxide amounts, Earth rotation rate, and continent formation have been used to generate a time evolution of Earth's surface temperature. While speculative because of uncertainties in the input parameters, such a study does help to prioritize the areas of most concern to paleoclimatic research while illustrating the relationships and mutual dependencies. The mean temperature averages about 5 K higher than today over most of geologic time; the overall variation is less than 15 K. The evolution of Earth's rotation rate makes a significant contribution to the surface temperature distribution as late as 0.5 b.y. ago. While there is little change in equatorial temperatures, polar temperatures decrease, being some 15 K lower 3.5 b.y. ago than with present day rotation. The effect of continent growth on albedo is of secondary importance.

Proteus syndrome

The term Proteus syndrome was coined in 1983 to describe a disorder of skeletal, hamartomatous, and other mesodermal malformations. The syndrome was named after the Greek god Proteus, whose name means "the Polymorphous." Clinical features of this new syndrome are currently being defined. Including the case reported herein, we have found 34 patients with Proteus syndrome described in the English literature. Major clinical findings, defined as those findings seen in more than half of the cases, include hemihypertrophy, macrodactyly, exostoses, epidermal nevi, characteristic cerebriform masses involving the plantar or palmar surfaces, a variety of subcutaneous masses, and scoliosis. Histologic examination of subcutaneous masses has identified a variety of lipomatous, hamartomatous, and angiomatous tumors.

Mössbauer, EPR and NMR studies of the acid-induced reduction and changes in spin state of ferric bleomycin

Iron-57 Mössbauer, electron paramagnetic resonance (EPR) and H-1 nuclear magnetic resonance (NMR) studies of iron-bleomycin complexes in the pH range from 1.0 to 6.0 are reported. Sequential protonation of the ligands produces a variety of high-spin and low-spin complexes of the metal. Of particular interest is the reversible equilibrium between Fe(III)- and oxygen-stable Fe(II)-bleomycin. Below pH 3.5 Fe(II) complexes form, with maximal reduction occurring at approximately pH 2. At still lower pH, Fe(III) complexes unassociated with bleomycin become dominant. The observed reduction in the absence of exogenous reducing agents suggests the possible involvement of intramolecular autoreduction in bleomycin-mediated DNA degradation.

Psychological consequences of blunt head trauma and relation to other indices of severity of injury

To investigate the relationship between APACHE II, Injury Severity Score (ISS), Glasgow Coma Score (GCS), and behavioral outcome, a group of 39 patients who had been admitted on an emergency basis with a traumatic head injury were selected from the Neuropsychology Registry for study. Except for subtle personality and cognitive changes, all of the patients were making good neurological recoveries. The Halstead-Reitan Neuropsychological Test Battery, which has been shown to be accurate in identifying brain-damaged patients, was used as the measure of outcome. The age of the patients ranged from 16 to 49 years (mean, 25.6; SD, 9.3). The patients' educational levels ranged from elementary school to college (mean, 11.6 years of education; SD, 1.5). Halstead Impairment Indexes (HII) ranged from 0.0 to 1.0 (mean, 0.6; SD, 0.26). APACHE II scores were calculated using the worst values, obtained during the first 24 hours. These scores ranged from 5 to 35 (mean, 16; SD, 7). APACHE II was found to not significantly correlate with HII (r = 0.21, P greater than .05). ISS was calculated for each patient and ranged from 5 to 70 (mean, 27; SD, 13). ISS was found to significantly correlate with HII (r = 0.38, P less than .01). GCS ranged from 3 to 15 (mean, 9.3; SD, 3.4). Of all the correlations, GCS was the most strongly correlated with outcome as measured by the HII (r = -0.44, P less than .01). Our data emphasize that head-injured patients have subtle cognitive dysfunction even when apparently recovering well and demonstrate the need for formal psychological evaluation in all patients with injury significant enough to warrant hospitalization.