Imaging cytoplasmic cAMP in mouse brainstem neurons

Background  

cAMP is an ubiquitous second messenger mediating various neuronal functions, often as a consequence of increased intracellular Ca²⁺ levels. While imaging of calcium is commonly used in neuroscience applications, probing for cAMP levels has not yet been performed in living vertebrate neuronal tissue before.     

Stable isotopic studies of earthworm feeding ecology in tropical ecosystems of Puerto Rico

Feeding strategies of earthworms and their influence on soil processes are often inferred from morphological, behavioral and physiological traits. We used (13)C and (15)N natural abundance in earthworms, soils and plants to explore patterns of resource utilization by different species of earthworms in three tropical ecosystems in Puerto Rico. In a high altitude dwarf forest, native earthworms Trigaster longissimus and Estherella sp. showed less (15)N enrichment ((15)N = 3-6 per thousand) than exotic Pontoscolex corethrurus ((15)N =7-9 per thousand) indicating different food sources or stronger isotopic discrimination by the latter. Conversely, in a lower altitude tabonuco forest, Estherella sp. and P. corethrurus overlapped completely in (15)N enrichment ((15)N = 6-9 per thousand), suggesting the potential for interspecific competition for N resources. A tabonuco forest converted to pasture contained only P. corethrurus which were less enriched in (15)N than those in the forest sites, but more highly enriched in (13)C suggesting assimilation of C from the predominant C(4) grass. These results support the utility of stable isotopes to delineate resource partitioning and potential competitive interactions among earthworm species. Copyright 1999 John Wiley & Sons, Ltd.     

A model for quantitative changes in the magnetic resonance parameters of muscle in children after therapeutic irradiation

Purpose/ObjectiveThis study aimed to develop objective models of radiation effects on musculature in children with soft tissue sarcoma using treatment dosimetry and clinical and quantitative magnetic resonance imaging (MRI) parameters that may be used to guide treatment planning or predict side effects.MethodsIn the initial 13 patients undergoing external beam radiation therapy (RT) on a Phase II study of conformal or intensity-modulated RT for the treatment of soft tissue sarcoma approved by an Institutional Review Board, we evaluated quantitative MRI changes in the musculature to assess radiation-related treatment effects. Patients with soft tissue sarcoma, including Ewing's sarcoma, had quantitative T₁, T₂ and dynamic enhanced MRI (DEMRI) performed before, during (Week 4) and after RT (Week 12). Regions of interest were selected in consistent locations within and outside the high-dose regions (on ipsilateral and contralateral sides when available). Mean RT dose, T₁, T₂ and DEMRI parameters were calculated and modeled using a mixed random coefficient dose model.ResultsThe mean doses to the high- and low-dose regions were 56.4 Gy (41.8–75.3 Gy) and 13.0 Gy (0.1–37.5 Gy), respectively. Compared with tissues distant from the tumor bed, maximal enhancement was significantly increased in tissues adjacent to the tumor/tumor bed prior to RT (60.6 vs. 44.2, P=.045) and remained elevated after 12 weeks. T₁ was significantly elevated in tissues adjacent to the tumor bed prior to RT (942.4 vs. 759.0, P=.0078). The slope of longitudinal change in T₁ was greater for tissues that received low-dose irradiation than those that received high-dose irradiation (P=.0488). The effect of dose on the slope of T₂ was different (P=.0333) when younger and older patients are compared.ConclusionsAcute affects of irradiation in muscle are quantifiable via MRI. These models provide evidence that quantifiable MRI parameters may be correlated with patient parameters of radiation dose and clinical factors including patient age. Long-term follow-up will be required to determine if acute changes correlate with clinically significant late effects.