MAGNETIC RESONANCE IMAGING FEATURES OF CERVICAL SPINAL CORD MENINGIOMAS

The records of four dogs with cervical spinal cord meningiomas were retrospectively reviewed. Signalment, history, laboratory findings, neurological examination, and histopathological findings were evaluated. Magnetic resonance imaging (MRI) was performed using a 1.0-T superconducting magnet and T2-weighted (W) and noncontrast and postcontrast T1-W spin echo pulse sequences. Meningiomas were located at the level of the second, third, and fifth cervical vertebrae and the C2-3 intervertebral space. All meningiomas appeared as focal masses that were hyperintense to the spinal cord on T2-W images and iso- to hypointense on the T1-W images. They could be identified as intradural and extramedullary in origin based on a broad-based dural margin seen on at least one of the imaging planes and a gradual expansion of the subarachnoid space cranial and caudal to the mass, best noted on the transverse and dorsal plane images. On dorsal plane T2-W images in three dogs, expansion of the subarachnoid space adjacent to the mass appeared similar to the myelographic "golf tee" sign. All meningiomas exhibited moderate, well-defined contrast enhancement with dural tails seen in three of the four dogs. One dog had extension into the intervertebral foramen along the nerve and ipsilateral atrophy of the muscles of the neck. By differentiating the meningiomas from intramedullary tumors and by clearly depicting the extent of the masses, MRI provided valuable information about treatment options and prognosis.     

BKCa-Cav channel complexes mediate rapid and localized Ca2+-activated K+ signaling

Large-conductance calcium- and voltage-activated potassium channels (BKCa) are dually activated by membrane depolarization and elevation of cytosolic calcium ions (Ca2+). Under normal cellular conditions, BKCa channel activation requires Ca2+ concentrations that typically occur in close proximity to Ca2+ sources. We show that BKCa channels affinity-purified from rat brain are assembled into macromolecular complexes with the voltage-gated calcium channels Cav1.2 (L-type), Cav2.1 (P/Q-type), and Cav2.2 (N-type). Heterologously expressed BKCa-Cav complexes reconstitute a functional "Ca2+ nanodomain" where Ca2+ influx through the Cav channel activates BKCa in the physiological voltage range with submillisecond kinetics. Complex formation with distinct Cav channels enables BKCa-mediated membrane hyperpolarization that controls neuronal firing pattern and release of hormones and transmitters in the central nervous system.     

Dissolved and colloidal phosphorus fluxes in forest ecosystems—an almost blind spot in ecosystem research

Understanding and quantification of phosphorus (P) fluxes are key requirements for predictions of future forest ecosystems changes as well as for transferring lessons learned from natural ecosystems to croplands and plantations. This review summarizes and evaluates the recent knowledge on mechanisms, magnitude, and relevance by which dissolved and colloidal inorganic and organic P forms can be translocated within or exported from forest ecosystems. Attention is paid to hydrological pathways of P losses at the soil profile and landscape scales, and the subsequent influence of P on aquatic ecosystems. New (unpublished) data from the German Priority Program 1685 “Ecosystem Nutrition: Forest Strategies for limited Phosphorus Resources” were added to provide up‐to‐date flux‐based information. Nitrogen (N) additions increase the release of water‐transportable P forms. Most P found in percolates and pore waters belongs to the so‐called dissolved organic P (DOP) fractions, rich in orthophosphate‐monoesters and also containing some orthophosphate‐diesters. Total solution P concentrations range from ca. 1 to 400 µg P L^?1, with large variations among forest stands. Recent sophisticated analyses revealed that large portions of the DOP in forest stream water can comprise natural nanoparticles and fine colloids which under extreme conditions may account for 40–100% of the P losses. Their translocation within preferential flow passes may be rapid, mediated by storm events. The potential total P loss through leaching into subsoils and with streams was found to be less than 50 mg P m^?2 a^?1, suggesting effects on ecosystems at centennial to millennium scale. All current data are based on selected snapshots only. Quantitative measurements of P fluxes in temperate forest systems are nearly absent in the literature, probably due to main research focus on the C and N cycles. Therefore, we lack complete ecosystem‐based assessments of dissolved and colloidal P fluxes within and from temperate forest systems.     

Surgical management of a canine intracranial abscess due to a bite wound

Objective – To describe the successful surgical management of a brain abscess in a dog secondary to bite wound. Case Summary – A 10‐year‐old neutered female Welsh Corgi/Chihuahua, weighing 5.3 kg, was presented for evaluation of seizures, ataxia, and falling to the left 8 days after a presumptive fight with another dog. On examination at presentation, the dog was alert, responsive, and ambulatory with tetra‐ataxia, falling to the left, left‐sided postural deficits, and absent left menace response. Within 24 hours, the dog progressed to nonambulatory tetraparesis with minimal motor, absent postural reactions of all limbs, left nasal hypalgesia, reduced gag reflex, and depressed mentation. Computed tomographic images of the brain were suggestive of a bite wound fracture of the right parietal bone with secondary meningoencephalitis, right parietal lobe abscessation, and white matter edema adjacent to the bone fracture. A modified right rostrotentorial craniectomy was performed, the abscess was identified, contents of the abscess were removed, and the surgical site was flushed extensively before closing. Corynebacterium spp. was cultured from within the abscess. Within hours of surgery, the dog was quiet but alert, responsive, and sitting up in her cage. In addition to surgical intervention, intensive care, broad‐spectrum IV antimicrobials, and supportive therapy led to significant neurologic improvement with only occasional seizures and mild postural reaction deficits of the left hindlimb remaining. New or Unique Information Provided – Abscess formation within the CNS is uncommon in dogs and cats and is associated with a high mortality rate. In veterinary medicine the management of brain abscesses is controversial with limited information available regarding treatment. This is the first case report that demonstrates surgical intervention in combination with antimicrobial therapy can be used successfully in the treatment of a canine brain abscess.     

Apparent electrical conductivity integrated from layered soil profiles

Time domain reflectometry (TDR) trace analysis aims at extracting the water content profile along TDR probes. This can be done by applying a TDR forward solver inversely. Thus, TDR‐trace inversion is basically an optimization problem. As in any optimization procedure, it is worthwhile to include as much a priori information as possible about the problem to be solved. In this study, we discuss the feasibility to use the apparent electrical conductivity as constraint for the TDR inversion. The resistors‐in‐parallel circuit can be used to integrate a multislice soil model to obtain the apparent electrical conductivity. We apply additionally Archie's law to link the water content of a particular slice with its electrical conductivity. We compare the results from this approach with measured TDR traces and show that the problem is solved exactly. Finally, we address the thin‐layer issue because thin layers with a high permittivity contrast result in a delay of the run time of an electromagnetic pulse. We test numerically whether a similar behavior can be observed for a thin layered electrical conductivity profile. Our results show that the thickness of the soil layer with respect to electrical conductivity has no effect on the apparent electrical conductivity. We conclude that the apparent electrical conductivity is appropriate as boundary condition in TDR inversion as long as a procedure is known to convert the water content of a slice to its electrical conductivity     

Equivalence or complementarity of soil‐solution extraction methods

Several methods are used for the extraction of soil solution. The objective of this study was to find out to what extent the different extraction methods yield complementary or equivalent information. Soil solutions were sampled once at 10 different forest sites in Germany, with 4 sampling points per site, using 5 different extraction methods. Concentrations of the major ions in the 1:2 extracts and the equilibrium soil‐pore solutions (obtained from percolation of field‐fresh soil cores) were generally lower than in desorption solutions, suction‐cup solutions, and saturation extracts. Surprisingly, the latter three methods generally yielded equivalent results. However, possible systematic differences between these methods could have been masked by the high small‐scale spatial variability within the sites.     

Influence of nitrogen on leaf chlorophyll content and photosynthesis of ‘Golden Delicious’ apple

Abstract

The aim of the present study was to estimate the influence of different rates of soil-applied nitrogen on leaf N and chlorophyll content and photosynthesis in ‘Golden Delicious’ apple trees. Three different treatments were included: the trees were either fertilized with 80 kg N ha^?1 (N-80), 250 kg N ha^?1 (N-250) or left unfertilized (CON). Fertilization increased leaf nitrogen content, with a more prominent effect in high N application level treatment. In all treatments, a slight seasonal decrease in leaf nitrogen content was observed. N-250 treatment resulted in higher chlorophyll content; a similar effect was found late in the season for N-80 treatment. Measurements of A-C _i curves, performed on spur leaves, revealed a higher CO₂ saturated photosynthetic rate in N-250 trees compared with low application level fertilized or unfertilized trees. No effect of N fertilization on carboxylation efficiency was found, as revealed by comparisons of the initial slopes of A-C _i curves. The lack of positive effect is rather surprising, since the leaf N content was efficiently increased with application of fertilizer. Obviously, the existing pool of leaf nitrogen in non-fertilized trees does not limit Rubisco activity and efficiency.     

The Potential Effects of Social Interactions on Reproductive Efficiency of Stallions

The reproductive efficiency of stabled domestic stallions is often lower than what could be expected from observations in feral herds. In the wild, stallions typically live with mares in harem bands, with other stallions in bachelor bands, or occasionally in mixed-sex transitional bands. We, therefore, argue that permanent contact with mares may increase reproductive efficiency of stallions suffering from low libido and/or fertility. We also provide a summary of our present knowledge of natural conditions, management, and husbandry of domestic stallions, and of intra- and intersexual behavioral interactions in horses.     

Local macrophage proliferation, rather than recruitment from the blood, is a signature of TH2 inflammation

A defining feature of inflammation is the accumulation of innate immune cells in the tissue that are thought to be recruited from the blood. We reveal that a distinct process exists in which tissue macrophages undergo rapid in situ proliferation in order to increase population density. This inflammatory mechanism occurred during T helper 2 (T(H)2)-related pathologies under the control of the archetypal T(H)2 cytokine interleukin-4 (IL-4) and was a fundamental component of T(H)2 inflammation because exogenous IL-4 was sufficient to drive accumulation of tissue macrophages through self-renewal. Thus, expansion of innate cells necessary for pathogen control or wound repair can occur without recruitment of potentially tissue-destructive inflammatory cells.