Pharmacokinetics and urinary excretion of sulphadimidine in buffalo calves

Pharmacokinetics and urinary excretion of sulphadimidine (SDI) were determined in buffalo calves following single oral administration (150 mg/kg). The plasma levels of free sulphadimidine were above minimum effective therapeutic concentration (> 40 micrograms/ml) between 4 and 12 h and the N4-acetylated form of the drug was in the range of 7.2-19.3%. Kinetic evaluation of plasma levels was performed using a two-compartment open model. The absorption and elimination half-lives of SDI were 3.01 and 11.94 h, respectively. Based on this study, an optimal dosage regimen of sulphadimidine in buffalo calves would be 100 mg/kg, followed by 50 mg/kg at 12 h intervals. Sulphadimidine was mainly excreted in the urine as free amine. The percentage of N4-acetyl sulphadimidine in urine was comparatively higher than in plasma.     

Chromosomal aberrations induced in barley by LSD

Seeds of hulled barley (Hordeum vulgare) were germinated and then treated with LSD. Preparations of squashed root tips stained with Feulgen revealed extensive chromosomal aberrations, most of which were chromosome breaks. Nearly half of the breaks occurred in the region of the primary constriction.     

Advanced technology paths to global climate stability: energy for a greenhouse planet

Stabilizing the carbon dioxide-induced component of climate change is an energy problem. Establishment of a course toward such stabilization will require the development within the coming decades of primary energy sources that do not emit carbon dioxide to the atmosphere, in addition to efforts to reduce end-use energy demand. Mid-century primary power requirements that are free of carbon dioxide emissions could be several times what we now derive from fossil fuels (approximately 10(13) watts), even with improvements in energy efficiency. Here we survey possible future energy sources, evaluated for their capability to supply massive amounts of carbon emission-free energy and for their potential for large-scale commercialization. Possible candidates for primary energy sources include terrestrial solar and wind energy, solar power satellites, biomass, nuclear fission, nuclear fusion, fission-fusion hybrids, and fossil fuels from which carbon has been sequestered. Non-primary power technologies that could contribute to climate stabilization include efficiency improvements, hydrogen production, storage and transport, superconducting global electric grids, and geoengineering. All of these approaches currently have severe deficiencies that limit their ability to stabilize global climate. We conclude that a broad range of intensive research and development is urgently needed to produce technological options that can allow both climate stabilization and economic development.     

Lymphatic metastasis in the absence of functional intratumor lymphatics

Lymphatic metastasis contributes to mortality from solid tumors. Whether metastasizing cancer cells reach lymph nodes via intratumor lymphatic vessels is unknown. Here, we examine functional lymphatics associated with mouse tumors expressing normal or elevated levels of vascular endothelial growth factor-C (VEGF-C), a molecule that stimulates lymphangiogenesis. Although VEGF-C overexpression increased lymphatic surface area in the tumor margin and lymphatic metastasis, these tumors contained no functional lymphatics, as assessed by four independent functional assays and immunohistochemical staining. These findings suggest that the functional lymphatics in the tumor margin alone are sufficient for lymphatic metastasis and should be targeted therapeutically.     

On the origins of morphological complexity in block copolymer surfactants

Amphiphilic compounds such as lipids and surfactants are fundamental building blocks of soft matter. We describe experiments with poly(1,2-butadiene-b-ethylene oxide) (PB-PEO) diblock copolymers, which form Y-junctions and three-dimensional networks in water at weight fractions of PEOintermediate to those associated with vesicle and wormlike micelle morphologies. Fragmentation of the network produces a nonergodic array of complex reticulated particles that have been imaged by cryogenic transmission electron microscopy. Data obtained with two sets of PB-PEOcompounds indicate that this type of self-assembly appears above a critical molecular weight. These block copolymers represent versatile amphiphiles, mimicking certain low molecular weight three-component (surfactant/water/oil) microemulsions, without addition of a separate hydrophobe.     

Mitigation of N2O emission from an alluvial soil by application of karanjin

An incubation experiment was conducted to study N₂O emissions from a Typic Ustochrept, alluvial soil, fertilized with urea and urea combined with different levels of two nitrification inhibitors, viz karanjin and dicyandiamide (DCD). Karanjin [a furano-flavonoid, obtained from karanja (Pongamia glabra Vent.) seeds] and DCD were incorporated at rates of 5, 10, 15, 20 and 25% of applied urea-N (100 mg kg^-1 soil), to the soil adjusted to field capacity moisture content. The highest N₂O flux (366 µg N₂O-N kg^-1 soil day^-1) was obtained on day 1 after incubation from soil fertilized with urea without any inhibitor. The presence of the inhibitors appreciably reduced the mean N₂O flux from the urea-treated soils. The application of karanjin resulted in a higher mitigation of total N₂O-N emission (92-96%) compared to DCD (60-71%). Rates of N₂O flux ranged from 0.9 to 140 µg N₂O-N kg^-1 soil day^-1 from urea combined with different levels of the two inhibitors (coefficient of variation=24-272%). Karanjin (62-75%) was also more effective than DCD (9-42%) in inhibiting nitrification during the 30-day incubation period.     

Seasonal pattern of total soil respiration in undisturbed and disturbed ecosystems of Central Himalaya

Summary The rates of CO₂ efflux were measured by an alkali absorption method (using 20 ml 0.5 N NaOH) from soils in four undisturbed sites [two evergreen oak forests, Quercus floribunda Lindl. (tilonj oak), Quercus leucotrichophora A Camus (banj oak), and two evergreen conifer forests, Cedrus deodara Loud. (deodar forest) and Pinus roxburghii Sarg. (chir pine forest)] and three disturbed sites. The sites were located between elevations of 1850 and 2360 m in the Central Himalaya. The seasonal pattern of soil respiration was similar in all the sites with a maximum during the rainy season, intermediate rates during the summer season and the lowest level of activity in winter. The rate of CO₂ efflux was higher in broadleaf than in conifer forests, and it was lowest in the disturbed sites. Among the edaphic conditions, soil moisture, N, organic C, pH, soil porosity, and root biomass positively affected total soil respiration. The proportion of root respiration to total soil respiration was higher in the disturbed sites than the undisturbed sites in winter. Conditions in the winter season were less favourable for microbial respiration than for root respiration.     

Survival of,and root colonization by,alginate-encapsulated Pseudomonas fluorescens cells following introduction into soil

Summary The survival of Pseudomonas fluorescens cells encapsulated in alginate beads and colonization of wheat roots was studied in soil microcosms inoculated with the cells in alginate beads of varying composition. Cells encapsulated in beads and introduced into a non-sterile loamy sand survived better than cells added directly to the same soil. A recovery/growth step for the bead-encapsulated cells was added before they were introduced into the soil, in an attempt to obtain optimal population levels in the soil. Further, bacterial populations that grew to the highest density in the beads subsequently showed the highest survival levels in soil. The addition of 3% skim milk, or 3% skim milk and 3% bentonite clay to all bead types consistently resulted in the highest survival of the encapsulated cells in soil. Root colonization by P. fluorescens was generally not impaired by the encapsulation in alginate. One week after inoculation into the soil, encapsulated cells in the various bead types were able to colonize the wheat rhizoplane at high population levels, similar to or exceeding those found when free cells were inoculated. In a second root colonization experiment the wheat rhizoplane was also efficiently colonized 7 weeks after the inoculant cells had been introduced into the soil in different bead types. In both assays, the cells encapsulated in beads amended with skim milk plus bentonite clay showed the highest root colonization rates. It is clear, therefore, that alginate-mediated establishment of inoculants can improve inoculant effectiveness.     

A diversity analysis of genetic resources in rice

Summary A total of 1407 japonica and 488 indica accessions representing nine countries were randomly drawn from the International Rice Research Institute catalog of germ plasm resources for an analysis of diversity. The qualitative gene frequencies as well as means and coefficients of variation for quantitative traits for each race and country in general confirmed the widely recognized pattern of indica-japonica differentiation but suggested more overlap than often realized. Use of a diversity index showed indica to be more variable than japonica, but with different countries having similar levels of diversity. A multivariate analysis based on 39 characters showed divergence among countries within each race but with a great amount of overlap in the scatter of individual entries. This study was carried out simply to illustrate some genetic resource analyses and it is therefore discussed in relation to the documentation aspects.