Comment on "Heterogeneous Hadean hafnium: evidence of continental crust at 4.4 to 4.5 Ga"

Harrison et al. (Reports, 23 December 2005, p. 1947) proposed that plate tectonics and granites existed 4.5 billion years ago (Ga), within 70 million years of Earth's formation, based on geochemistry of >4.0 Ga detrital zircons from Australia. We highlight the large uncertainties of this claim and make the more moderate proposal that some crust formed by 4.4 Ga and oceans formed by 4.2 Ga.     

Comparative pharmacokinetics of meloxicam in clinically normal horses and donkeys

OBJECTIVE: To determine the disposition of a bolus of meloxicam (administered IV) in horses and donkeys (Equus asinus) and compare the relative pharmacokinetic variables between the species. ANIMALS: 5 clinically normal horses and 5 clinically normal donkeys. PROCEDURES: Blood samples were collected before and after IV administration of a bolus of meloxicam (0.6 mg/kg). Serum meloxicam concentrations were determined in triplicate via high-performance liquid chromatography. The serum concentration-time curve for each horse and donkey was analyzed separately to estimate standard noncompartmental pharmacokinetic variables. RESULTS: In horses and donkeys, mean +/- SD area under the curve was 18.8 +/- 7.31 microg/mL/h and 4.6 +/- 2.55 microg/mL/h, respectively; mean residence time (MRT) was 9.6 +/- 9.24 hours and 0.6 +/- 0.36 hours, respectively. Total body clearance (CL(T)) was 34.7 +/- 9.21 mL/kg/h in horses and 187.9 +/- 147.26 mL/kg/h in donkeys. Volume of distribution at steady state (VD(SS)) was 270 +/- 160.5 mL/kg in horses and 93.2 +/- 33.74 mL/kg in donkeys. All values, except VD(SS), were significantly different between donkeys and horses. CONCLUSIONS AND CLINICAL RELEVANCE: The small VD(SS) of meloxicam in horses and donkeys (attributed to high protein binding) was similar to values determined for other nonsteroidal anti-inflammatory drugs. Compared with other species, horses had a much shorter MRT and greater CL(T) for meloxicam, indicating a rapid elimination of the drug from plasma; the even shorter MRT and greater CL(T) of meloxicam in donkeys, compared with horses, may make the use of the drug in this species impractical.     

Values of urine specific gravity for thoroughbred horses treated with furosemide prior to racing compared with untreated horses.

The distribution of specific gravity values for 2,599 urine samples collected from racing Thoroughbred horses that were known to have received furosemide prior to racing was compared with that for 1,669 urine samples from racing Thoroughbred horses that reportedly had not received furosemide. Values of specific gravity for furosemide-treated horses were significantly lower (P < 0.001) than those for horses that had not received furosemide, and the proportion of horses with urine specific gravity either <1.010 or <1.012 was significantly greater (P < 0.001) among the furosemide-treated horses. These data indicate that evaluation of urine specific gravity would be a useful component of drug testing programs for regulation of furosemide use.     

RADIOGRAPHIC, COMPUTED TOMOGRAPHIC AND HISTOPATHOLOGIC APPEARANCE OF A PRESUMED SPINAL CHORDOMA IN A DOG

A 4-year-old Labrador Retriever presented for urinary incontinence and constipation of 2 weeks duration. There was a tender abdomen, lumbar pain and conscious proprioceptive deficits in both pelvic limbs. Depressed pelvic limb reflexes were present consistent with a lower motor neuron lesion. In radiographs of the lumbar spine there was narrowing of the intervertebral disc space at L5-L6 with irregular, multifocal areas of mineralized opacities dorsal to the intervertebral disc space, presumably within the vertebral canal. On computed tomography, an intramedullary, partially mineralized mass was identified in the spinal cord at the level of caudal L5 through cranial L6. At necropsy there was a four-centimeter enlarged, irregular segment of spinal cord at the level of L5-L6. When sectioned, the spinal cord bad a mineralized texture. Histologically there were variable sized cells that were stellate in appearance with vacuolated cytoplasm (physaliferous cells) and mucinous background consistent with a chordoma. Chordoma is a rare, skeletal neoplasm that originates from mesoderm-derived notochord and has been reported in humans and animals. Extraskeletal development of a chordoma within the spinal cord is a rare manifestation of this neoplasm. However, based on other reports in dogs, solitary extraskeletal locations of chordomas may be the typical expression of this neoplasm in the dog. Differentiation of similar histologically appearing tumors, such as a parachordoma or myxoid chondrosarcoma, will require immunohistochemical characterization of these tumors in veterinary patients.     

Submillimeter heterodyne detection of interstellar carbon monoxide at 434 micrometers

A submillimeter heterodyne radiometer, developed for astronomical applications, uses an optically pumped laser local oscillator and a quasi-optical Schottky diode mixer. The resultant telescope-mounted system, which has a noise temperature less than 4000 K (double sideband) and high frequency and spatial resolution, has been used to detect the J = 6 --> 5 rotational transition of carbon monoxide at 434 micrometers in the Orion molecular cloud. The measurements, when compared with previous millimeter-wave data, indicate that the broad carbon monoxide emission feature is produced by an optically thin gas whose temperature exceeds 180 K.     

Inorganic pyrophosphate: energy source for sulfate-reducing bacteria of the genus desulfotomaculum

Sulfate-reducing bacteria belonging to the genus Desulfotomaculum utilized inorganic pyrophosphate as a source of energy for growth in the presence of fixed carbon (acetate and yeast extract) and sulfate. Pyrophosphate does not support the growth of Desulfovibrio under the same growth conditions. Over a limited range of concentrations, growth is proportional to pyrophosphate, and extracts of bacteria grown on pyrophosphate medium have enzymatic activities similar to extracts prepared from bacteria grown on medium containing lactate plus sulfate. The variety of cell types observed in crude anaerobic pyrophosphate-enrichment cultures from a marine environment suggests that this unique type of energy metabolism is not restricted to the sulfate-reducing bacteria of the genus Desulfotomaculum.     

Inhalant anesthetic requirement in cats is animal-dependent

Minimum alveolar concentration (MAC) of an inhalant is an indicator of its anesthetic potency. Individuals vary in their sensitivity to anesthetic agents as demonstrated by different individual MAC values. We hypothesized that individual animal sensitivity would be maintained with different inhalant anesthetics. As part of separate studies, six female DSH cats, aged 24 ± 2.5 (mean ± SD) months and weighing 3.5 ± 0.3 kg, were studied similarly on three separate occasions over a 12‐month period to determine the MAC of isoflurane (ISO), sevoflurane (SEVO), and desflurane (DES), respectively. In each study, chamber induction was followed by orotracheal intubation, and anesthesia was maintained via a nonrebreathing circuit. ECG, pulse oximetry, Doppler systolic blood pressure, end‐tidal gases, and esophageal temperature were monitored. End‐tidal gases were hand‐sampled from a catheter whose tip lay level with the distal end of the ET tube. Gases were analyzed by Raman spectrometry and, for each agent, the analyzer was calibrated with at least three gas standards. MAC was determined in triplicate using standard tail‐clamp technique. Data were analyzed by two‐way anova followed by Tukey's test and significant differences were found. Average MACs (%) for ISO, SEVO, and DES were 1.90 ± 0.18, 3.41 ± 0.65, and 10.27 ± 1.06, respectively. Body temperatures, Doppler systolic blood pressure, and SpO₂ were recorded at the time of MAC determinations for ISO, SEVO, and DES were 38.3 ± 0.3, 38.6 ± 0.1, 38.3 ± 0.35 °C; 71 ± 8, 75 ± 16, 88 ± 12 mm Hg; 99 ± 1, 99 ± 1, 99 ± 1%, respectively. Both the anesthetic agent and the individual cat had significant effects on MAC (p = 0.0001 and 0.0185, respectively). MAC varied between individuals and cats were consistent in their order of sensitivity to inhalant anesthetics across the three agents. Within this group of cats, the relationship of individual MAC to the group MAC for each of the three inhalant agents was maintained. This suggests that any individual may be consistently more or less sensitive to a variety of inhalant agents.     

Calibration of two techniques for estimating herbage mass

Two non-destructive techniques for estimating herbage mass (dry matter yield) were evaluated during the growing season of 1988, from April to September. Samples were collected from four sites, with ten observations made on twenty-five days at each site, giving a total of 612 sample units. Observations were obtained from each unit, either with a plastic rising-plate meter (335) or with a metal rising-plate meter (227). In addition, measurements with a single-probe capacitance meter (Pasture Probe) were also made on all units. The usefulness of the non-destructive methods for predicting the actual yield was evaluated by calibrating them by means of regression on the yield determined by mowing 1·5-m² quadrats, weighing, subsampling and drying the grass. The yield measurements were logarithmically transformed to correct for the proportionality of the residual variance with the mowed dry matter yield. Logarithmic transformation of the sensor measurements improved the linearity of the calibration relationships. The combination of one rising-plate meter and the Pasture Probe resulted in a linear and additive model with a larger adjusted R² than models with just one of these two sensors. The addition of the predictors ‘external moisture’ (e.g. dew), ‘day number after mowing’ and ‘site number’ significantly increased the goodness of fit of many models. In some models addition of the logarithm of the ‘dry matter percentage’ was significant. Other predictors in these models such as “Julian day number” and “grazing” proved not to be significant. The adjusted R²s in the best models for the metal and the plastic discs were 89·7% and 87·3% respectively. The corresponding coefficients of variation were 26·2% and 26·1%. The results show that further research is necessary to refine the techniques or to develop new techniques to estimate the dry matter yield, before the sensors can be usefully integrated into a management system.     

Variation in the laboratory susceptibility of turf‐infesting white grubs (Coleoptera: Scarabaeidae) to biological,biorational and chemical control products

BACKGROUND: White grubs are the most widespread and damaging pests in turfgrass habitats of the northeast USA, and their management is highly dependent on chemical pesticides. Because this complex includes at least eight species, opportunities for pest management would be enhanced by understanding how susceptibility to control products varies across taxa. The objective of this laboratory study was to measure variation in the susceptibility of four species to 18 biological, biorational and chemical insecticides used as curative controls. RESULTS: Across species, the most efficacious biological and chemical insecticide alternatives were Steinernema scarabaei and chlorpyrifos respectively. For biorational and chemical insecticides, the European chafer [Amphimallon majale (Razoumowsky)] was the least susceptible species. For biologicals, the Japanese beetle (Popillia japonica Newman) was the least susceptible. Considering all control products, the oriental beetle [Anomala orientalis (Waterhouse)] was the most susceptible. CONCLUSION: The magnitude of variation in susceptibility supports the idea that a single product will not reliably suppress populations of all taxa, and highlights the need for pest management practitioners to identify white grub species before intervention. This differential susceptibility could have broader consequences for grub management if a numerically dominant target species is more completely suppressed than a co‐occurring species. Copyright © 2009 Society of Chemical Industry     

Impacts of climate change on the complex life cycles of fish

To anticipate the response of fish populations to climate change, we developed a framework that integrates requirements in all life stages to assess impacts across the entire life cycle. The framework was applied on plaice (Pleuronectes platessa) and Atlantic herring (Clupea harengus) in the North Sea, Atlantic cod (Gadus morhua) in the Norwegian/Barents Seas and European anchovy (Engraulis encrasicolus) in the Bay of Biscay. In each case study, we reviewed habitats required by each life stage, habitat availability, and connectivity between habitats. We then explored how these could be altered by climate change. We documented environmental processes impacting habitat availability and connectivity, providing an integrated view at the population level and in a spatial context of potential climate impacts. A key result was that climate‐driven changes in larval dispersion seem to be the major unknown. Our summary suggested that species with specific habitat requirements for spawning (herring) or nursery grounds (plaice) display bottlenecks in their life cycle. Among the species examined, anchovy could cope best with environmental variability. Plaice was considered to be least resilient to climate‐driven changes due to its strict connectivity between spawning and nursery grounds. For plaice in the North Sea, habitat availability was expected to reduce with climate change. For North Sea herring, Norwegian cod and Biscay anchovy, climate‐driven changes were expected to have contrasting impacts depending on the life stage. Our review highlights the need to integrate physiological and behavioural processes across the life cycle to project the response of specific populations to climate change.