Foliar water supply of tall trees: evidence for mucilage-facilitated moisture uptake from the atmosphere and the impact on pressure bomb measurements.

The water supply to leaves of 25 to 60 m tall trees (including high-salinity-tolerant ones) was studied. The filling status of the xylem vessels was determined by xylem sap extraction (using jet-discharge, gravity-discharge, and centrifugation) and by (1)H nuclear magnetic resonance imaging of wood pieces. Simultaneously, pressure bomb experiments were performed along the entire trunk of the trees up to a height of 57 m. Clear-cut evidence was found that the balancing pressure (P(b)) values of leafy twigs were dictated by the ambient relative humidity rather than by height. Refilling of xylem vessels of apical leaves (branches) obviously mainly occurred via moisture uptake from the atmosphere. These findings could be traced back to the hydration and rehydration of mucilage layers on the leaf surfaces and/or of epistomatal mucilage plugs. Xylem vessels also contained mucilage. Mucilage formation was apparently enforced by water stress. The observed mucilage-based foliar water uptake and humidity dependency of the P(b) values are at variance with the cohesion-tension theory and with the hypothesis that P(b) measurements yield information about the relationships between xylem pressure gradients and height.

High-grade lymphoma mimicking bone crisis in Gaucher's disease.

A 33-year-old woman with type 1 Gaucher's disease developed painful swelling of her right tibia. Initial diagnostics suggested a typical bone crisis. However, clinical course and subsequent imaging pointed to malignant disease, which was specified as high-grade lymphoma. Chemotherapy was applied together with enzyme replacement and resulted in complete remission of the lymphoma. We conclude that osseous lesions, although suggestive of common manifestations of Gaucher's disease, should be discriminated very carefully from neoplastic infiltration to maintain curative treatment options.

[MR tomographic characterization of suspicious breast lesions with dynamic susceptibility-weighted T2* sequences]. / MR-tomographische Charakterisierung suspekter Mammabefunde mittels suszeptibilitätsgewichteter T2*-Sequenzen.

PURPOSE: To increase specificity of MR-mammography by using dynamic T2* sequences. METHODS: 23 patients with suspicious lesions of the breast underwent conventional dynamic T1-weighted (T1-dynamic) breast MRI and, subsequently, dynamic T2*-weighted (T2*-dynamic) perfusion studies. To assess the T1-dynamic, signal enhancement during the first minute (E1) was calculated. To evaluate the T2*-dynamic, relative signal intensity loss after administration of contrast medium was determined. RESULTS: After administration of contrast medium, 6 of 13 malignant lesions did not show a signal decrease during the T2*-dynamic. Two of them exhibited an atypical signal enhancement in the T1-dynamic, with E1 < 100%. On the other hand, in 5 of 10 benign tumors a relative signal decrease of between 5-17% occurred during the T2*-dynamic. Four benign lesions showed a strong early signal enhancement during the T1-dynamic (E1 > 100%), which is more typical for malignant lesions. DISCUSSION: The use of dynamic T2* sequences, following dynamic T1-weighted breast MRI and administration of contrast medium, does not sufficiently increase diagnostic sensitivity. Thus, this study does not support the potential advantage of susceptibility MR imaging for a further characterization of breast lesions.