Chamber-based system for measuring whole-plant transpiration dynamics

Most of our insights on whole-plant transpiration (E) are based on leaf-chamber measurements using water vapor porometers, IRGAs, or flux measurements. Gravimetric methods are integrative, accurate, and a clear differentiation between evaporation and E can be made. Water vapor pressure deficit (VPD) is the driving force for E but assessing its impact has been evasive, due to confounding effects of other climate drivers. We developed a chamber-based gravimetric method, in which whole plant response of E to VPD could be assessed, while keeping other environmental parameters at predetermined values. Stable VPD values (0.5-3.7 kPa) were attained within 5 min after changing flow settings and maintained for at least 45 min. Species differing in life form and photosynthetic metabolism were used. Typical runs covering the range of VPDs lasted up to 4 h, preventing acclimation responses or soilborne water deficit. Species-specific responses of E to VPD could be identified, as well as differences in leaf conductance. The combined gravimetric-chamber-based system presented overcomes several limitations of previous gravimetric set ups in terms of replicability, time, and elucidation of the impact of specific environmental drivers on E, filling a methodological gap and widening our phenotyping capabilities.

Predicting factors for chronic colonization of Pseudomonas aeruginosa in bronchiectasis

About 25% of the patients with bronchiectasis are likely to develop a chronic colonization with Pseudomonas aeruginosa. A better understanding of predictors of acquiring Pseudomonas within the patient population may facilitate future focused research. The aim of this retrospective observational study was to investigate predicting factors for P. aeruginosa colonization in patients with bronchiectasis. This was a single-center retrospective cohort study using a bronchiectasis database which consisted of 211 patients with bronchiectasis. Data were collected for demographic details, etiology, spirometry, microbiology data, maintenance medication use, exacerbation frequency, hospital admission rate, and FACED and Bronchiectasis Severity Index (BSI) score. Two hundred eleven patients were identified from our bronchiectasis database. Overall, 25% of the patients (n = 53) had a chronic colonization with P. aeruginosa. Seventeen patients (8%) died in a 5-year follow-up period of whom 7 (41%) had a chronic P. aeruginosa colonization (p > 0.05). After multiple regression analysis, P. aeruginosa-positive patients were significantly associated with an older age (> 55 years) (p = 0.004), the use of hypertonic saline (0.042), and inhalation antibiotics (< 0.001). Furthermore, the presence of PCD (p < 0.001) and post-infectious etiology (p < 0.001) as underlying causes were significantly associated with P. aeruginosa colonization. We observed that independent predictors for P. aeruginosa colonization were age > 55 years, hypertonic saline, and PCD, and post-infectious etiology as underlying causes of bronchiectasis. Since prevention of P. aeruginosa colonization is an important aim in the treatment of bronchiectasis, more attention could be directed to these groups at risk for Pseudomonas colonization.

The Role of Stromal Cells in Tumor Metastases

Background: In 1889, Stephen Paget hypothesized that metastatic cells - the “seeds” - only grow in the secondary sites - the “soil” - with a permissive microenvironment. Here, we show that the “seeds” can carry their own “soil” - activated fibroblasts from primary site of metastatic tumors. Moreover, we report that carryover of these non-malignant host-derived cells during metastatic cell colonization in the lungs can increase cancer's metastatic efficiency.Materials and Methods: We use multiple animal models and two metastatic tumor cell lines (LLC1 and LA-P0297) to study the composition, origin and role of fragments shed by tumors in the metastatic process.Results: we have shown that, in addition to single cells (81%), tumors shed fragments consisting of both tumor and host cells. We show that these fragments are more viable in the circulation compared to tumor cells alone (p&lt;0.05). When we selectively deplete the host cells in the tumor microenvironment the spontaneous formation of metastases is significantly reduced three weeks after primary tumor resection compared to control mice (p&lt;0.05). Next, survival was significantly increased in mice with metastases after co-implantation of carcinoma-associated fibroblasts (CAFs) isolated from breast cancer patients together with LLC1 cells, but had no effect in mice implanted with LLC1 cells alone (p&lt;0.01) Lastly, we have assessed the nature of these host stromal cells using immunohistochemistry and RT-PCR and indentified the majority of them as being of mesenchymal/fibroblast lineage.Discussion: We found that tumor-associated stromal cells can escape primary tumors along with cancer cells, survive in blood circulation and in metastatic nodules. Pre-existence of a tissue-like structure in the form of heterotypic cell fragments may increase the viability of cancer cells in blood circulation and modulate metastasis efficiency. How this mechanism contributes to the organo-tropism of certain metastatic tumors is not known. But demonstration of the involvement of some of the same tumor “soil” in both local and distant tumor invasion has important conceptual and clinical implications for colonization during metastasis progression.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 6151.

The role of oral fluoropyrimidines in the treatment of advanced gastric cancer

Although the incidence of gastric cancer is declining during the second half of the 20th century, it remains the second leading cause of cancer death worldwide. The majority of patients with gastric cancer will require palliative treatment at some point in the course of their disease. Approximately 50% of patients already have advanced incurable disease at the time of initial presentation, and even those who undergo potentially curative resection have high rates of distant as well as local recurrence. Chemotherapy in advanced gastric cancer demonstrated a significant survival benefit over best supportive care alone. Median overall survival increased from 3-5 to 8-12 months. Today, a platinum based regimen is considered as first-line treatment in advanced gastric cancer. Different regimens are investigated and used in routine practice. Similarly to fluorouracil, capecitabine is well tolerated in combination with a range of cytotoxic drugs. As a single agent, it has not undergone large scale randomised studies. S-1, another oral fluoropyrimidine, is a potential challenger to the role of capecitabine, but is lacking phase III data in Western population.

Brucellar spondylodiscitis: case report

Brucellosis is a common zoonosis which still remains a major health problem in certain parts of the world. Osteoarticular involvement is the most frequent complication of brucellosis, in which the diagnosis of brucellar spondylodiscitis is often difficult since the clinical presentation may be obscured by many other conditions. Herein, we report an uncommon case of spondylodiscitis due to Brucella in a male who presented with abdominal pain. The diagnosis was established by positron emission tomography combined with computed tomography (PET/CT scan) and magnetic resonance followed by a confirmation on Brucella-agglutination test and positive culture of computed tomography (CT) guided punction fluid. This case report illustrates an atypical presentation of spondylitis and points out the difficulties in diagnosing the aetiological agens Brucella and differentiating its specific features from tuberculosis.

The maize Activator/Dissociation system is functional in hexaploid wheat through successive generations

The aim of the present study was to provide useful background information and evidence of the functionality of the maize Activator/Dissociation (Ac/Ds) system in hexaploid wheat. Two transgenic parental wheat lines, one harbouring the immobilised Ac element (iAc) and the other the Ds element (pUbi[Ds-uidA]bar), were crossed. Transient GUS assays confirmed that the iAc transposase is active in hexaploid wheat. Selected F1 and F2 lines were analysed by PCR using primers specific to Ac, uidA and bar genes. The primer pair Ubi/bar-tag was used to detect excision of the Ds-uidA sequence, which occurred at a frequency of 39% in the F1 generation. Lines free of Ac and showing evidence of Ds excision were subject to Southern analysis, which indicated that at least one transposition event might have occurred in these lines. Although more evidence is required to unequivocally support the reintegration of the Ds element in the wheat genome, the evidence presented here nevertheless demonstrates the effectiveness and potential value of using this system to tag genes in wheat.

Seasonal changes in photosynthesis of trees in the flooded forest of the Mapire River

We studied the flood tolerance of five tree species growing in the flooded forest adjacent to the Mapire river, in SW Venezuela. Mean photosynthetic rate and leaf conductance were 11 &mgr;mol m(-2) s(-1) and 700 mmol m(-2) s(-1), respectively. Xylem water potential ranged from -0.08 to -1.15 MPa. Based on leaf gas exchange as a criterion of tolerance to flooding, two response patterns were identified: (1) decreasing photosynthetic rate with increasing flooding and leaf conductance (Psidium ovatifolium Berg. ex Desc., Campsiandra laurifolia Benth., Symmeria paniculata Benth. and Acosmium nitens (Vog.) Benth); and (2) independence of photosynthesis and leaf conductance from flooding (Eschweilera tenuifolia (Berg.) Miers.). In the first response pattern, declining photosynthetic rate with flooding may be interpreted as a sign of reduced flood tolerance, whereas the second response pattern may indicate increased flood tolerance. An increase in xylem water potential with depth of water column was found for all species (with the possible exception of P. ovatifolium), indicating that flooding does not cause water stress in these trees. Submerged leaves that had been under water for between four days and four months generally had photosynthetic rates and leaf conductances similar to those of aerial leaves, indicating maintenance of photosynthetic capacity under water. Daily positive oscillations in glucan content in submerged leaves of P. ovatifolium and C. laurifolia suggest that submerged leaves do not represent a sink for photosynthates produced by aerial leaves.

A highly conserved region of the Sendai virus nucleocapsid protein contributes to the NP-NP binding domain

The nucleocapsid protein (NP) of Sendai virus is an essential component of both the nucleocapsid template and the NP-NP and NP0-P protein complexes required for viral RNA replication. When expressed alone in mammalian cells NP self-assembles into nucleocapsid-like particles which appear to contain cellular RNA. To identify putative NP-NP binding domains, fusions between the monomeric maltose-binding protein (MBP) and portions of NP were constructed. The fusion proteins which contain the central conserved region (CCR) (amino acids 258-357, MBP-NP1) and the N-terminal 255 amino acids (MBP-NP2) of NP both oligomerized, suggesting that these regions contain sequences important for NP-NP self-assembly. In addition, the MBP-NP1 fusion protein can function as an inhibitor of viral RNA replication. Complementary studies involving site-directed mutagenesis of the full-length NP protein have identified specific residues in the CCR which are essential for viral RNA replication in vitro. Two such replication-negative mutants, F324V and F324I, were defective in self-assembly, suggesting that the Phe residue at amino acid 324 is essential for the NP-NP interaction. A third mutant, NP260-1 (Y260D), self-assembled to form aberrant oligomers which exhibit an unusual helical structure and appear to lack any associated RNA. The mutants NP299-5 (L299I and I300V) and NP313-2 (I313F), in contrast, appear to form all the required protein complexes, but were inactive in viral RNA replication, suggesting that interactions specifically with Sendai RNA were disrupted. These data have thus identified specific residues in the CCR of the native NP protein which appear to be important for NP-NP or NP-RNA interactions and for genome replication.

Influence of explant source on in vitro axillary shoot formation in oak seedlings

In vitro shoot development was slower for apical shoot explants of young oak (Quercus robur L.) seedlings growing on Woody Plant Medium containing activated charcoal than for nodal shoot explants. The rate of in vitro shoot development was slowest in explants taken from seedlings that were undergoing rapid shoot elongation and most rapid in explants taken from seedlings that had stopped elongating and had fully expanded leaves. Maximum rooting was achieved on half-strength Woody Plant Medium containing activated charcoal. Rooting ability was not influenced by explant source.