The whole and its parts : why and how to disentangle plant communities and synusiae in vegetation classification

Most plant communities consist of different structural and ecological subsets, ranging from cryptogams to different tree layers. The completeness and approach with which these subsets are sampled have implications for vegetation classification. Non‐vascular plants are often omitted or sometimes treated separately, referring to their assemblages as “synusiae” (e.g. epiphytes on bark, saxicolous species on rocks). The distinction of complete plant communities (phytocoenoses or holocoenoses) from their parts (synusiae or merocoenoses) is crucial to avoid logical problems and inconsistencies of the resulting classification systems. We here describe theoretical differences between the phytocoenosis as a whole and its parts, and outline consequences of this distinction for practise and terminology in vegetation classification. To implement a clearer separation, we call for modifications of the International Code of Phytosociological Nomenclature and the EuroVegChecklist. We believe that these steps will make vegetation classification systems better applicable and raise the recognition of the importance of non‐vascular plants in the vegetation as well as their interplay with vascular plants

Discusión taxonómica de algunas especies interesantes de los géneros Biddulphia Gray y Triceratium Ehrenberg (Bacillariophyceae)

A taxonomic revision of some diatom species of the genera Biddulphia Gray and Triceratium Ehrenberg is made. The species are: B. azorica Pavillard, B. schroederiana Schussnig, B. membranacea Cleve. T. formosum Brightwell f.formosum, T. formosum f. quadrangularis (Hustedt), T. formosum f. quinquelobulata (Hustedt), T. shadboltianum Greville, T. shadbottianum f. elongata (Grunow) Hustedt and T. pelagicum (Schroder) Sournia. These species have poor siliciflcation of the frustules, reduced valvar apendixes and spines or none; these features could be regarded as adaptations to pelagic life. Descriptions and microphotographies of the species were made. These Biddulphia spp were found to be very close and some morphometric differences in the relation apical axe/pervalvar axe were taken in order to identify them quickly. All forms were found to be more frequent in no rain season and in high salinity waters (36 ‰). For T. formosum f. quadrangularis (Hustedt) and T. formosum f. quinquelobulata (Hustedt) some explanations were made about its real infrasnecific position, so that T. quadrangulare Greville and T. quinquelobutarum Greville should be regarded as different species of that forms of T.formosum Brightwell. B. azorica Pavillard and B. schroederiana Schussnig are first reported for the Caribbean Sea area

Salvage chemotherapy of biweekly irinotecan plus S-1 (biweekly IRIS) in previously treated patients with advanced gastric cancer

PURPOSE: This phase II trial first describes the combination chemotherapy of biweekly irinotecan plus S-1 (biweekly IRIS) for pretreated advanced gastric cancer (AGC) patients. METHODS: Patients who had previously been treated with greater than or equal to one regimen were enrolled. They received S-1 35 mg/m(2) twice daily on days 1-14 and irinotecan 150 mg/m(2) on days 1 and 15, every 4 weeks. The primary endpoint was overall survival (OS). RESULTS: Among the 38 patients enrolled, 18 patients were treated as second line, and the remaining 20 patients were enrolled as third- or fourth line. A total of 208 cycles were administered with the median being four cycles (range 1-16). The median OS was 8.7 months [95% confidence interval (CI) 7.5-10.3], and the median progression-free survival was 6.3 months (95% CI 5.3-7.3). Low serum albumin (<3.5 mg/dL) was an independent adverse prognosticator for survival. Overall response rate was 17% (95% CI 4-30%). The major grade 3/4 toxicities were neutropenia (26%) and diarrhea (18%). CONCLUSIONS: Biweekly IRIS showed the moderate activity as salvage treatment in AGC. Considering high neutropenia and gastrointestinal toxicity, patient selection should be warranted; serum albumin may be a predictive factor for treatment decisionope

Effects of the combination of camptothecin and doxorubicin or etoposide on rat glioma cells and camptothecin-resistant variants

From the rat C6 glioma cell line in culture, we selected camptothecin-resistant variants by growth in the presence of increasing amounts of this drug (C6CPT10, C6CPT50 and C6CPT100, growing respectively with 10, 50 and 100 ng ml–1camptothecin). The degree of resistance to camptothecin ranged between 15-fold (C6CPT10) and 30-fold (C6CPT50and C6CPT100). The C6CPT10cell line presented a collateral sensitivity to etoposide (3.6-fold), while the C6CPT50 and C6CPT100 cell lines were cross-resistant to etoposide (1.8-fold) The resistant lines were characterised by a two-fold reduced content and catalytic activity of topoisomerase I, and C6CPT50 and C6CPT100 presented a significant increase in topoisomerase IIα content and catalytic activity and a marked overexpression of P-glycoprotein. We explored the cytotoxicity of combinations of a topoisomerase I inhibitor (camptothecin) and a topoisomerase II inhibitor (doxorubicin or etoposide) at several molar ratios, allowing the evaluation of their synergistic or antagonistic effects on cell survival using the median effect principle. The simultaneous combination of camptothecin and doxorubicin or etoposide was additive or antagonistic in C6 cells, slightly synergistic in the C6CPT10 line and never more than additive in the C6CPT50 and C6CPT100 cell lines. The sequential combination of doxorubicin and camptothecin gave additivity in the order camptothecin → doxorubicin and antagonism in the order doxorubicin → camptothecin. Clinical protocols combining a topoisomerase I and a topoisomerase II inhibitor should be considered with caution because antagonistic effects have been observed with combinations of camptothecin and doxorubicin.© 2001 Cancer Research Campaign http://www.bjcancer.co

A preclinical evaluation of pemetrexed and irinotecan combination as second-line chemotherapy in pancreatic cancer

Gemcitabine (GEM)-based chemotherapy is regarded as the standard treatment of pancreatic adenocarcinoma, but yields a very limited disease control. Very few studies have investigated salvage chemotherapy after failure of GEM or GEM-containing chemotherapy and preclinical studies attempting to widen the therapeutic armamentarium, not including GEM, are warranted. MIA PaCa2, CFPAC-1 and Capan-1 pancreatic cancer cell lines were treated with GEM, fluouracil (5-FU), docetaxel (DCT), oxaliplatin (OXP), irinotecan (CPT-11), pemetrexed (PMX) and raltitrexed (RTX) as single agent. Pemetrexed, inducing apoptosis with IC50s under the Cmax in the three lines tested, appeared the most effective drug as single agent. Based on these results, schedule- and concentration-dependent drug interactions (assessed using the combination index) of PMX/GEM, PMX/DCT and PMX–CPT-11 were evaluated. The combinatory study clearly indicated the PMX and CPT-11 combination as the most active against pancreatic cancer. To confirm the efficacy of PMX–CPT-11 combination, we extended the study to a panel of 10 pancreatic cancer cell lines using clinically relevant concentrations (PMX 10 μM; CPT-11 1 μm). In eight of 10 lines, the PMX–CPT-11 treatment significantly reduced cell recovery and increased both the subG1 and caspase 3/7 fraction. After a 5-day wash out period, an increased fraction of subG1 and caspase3/7 persisted in PMX–CPT-11-pretreated cell lines and a significant reduction in the clonogenicity capacity was evident. Finally, in vivo, the PMX/CPT-11 combination showed the ability to inhibit xenograft tumours growth as second-line therapy after GEM treatment. The PMX and CPT-11 combination displays a strong schedule-independent synergistic cytotoxic activity against pancreatic cancer, providing experimental basis for its clinical testing as salvage chemotherapy in pancreatic cancer patients

Prospective Study of Infection, Colonization and Carriage of Methicillin-Resistant Staphylococcus Aureus in an Outbreak Affecting 990 Patients

In the three years between November 1989 and October 1992, an outbreak of methicillin-resistantStaphylococcus aureus (MRSA) affected 990 patients at a university hospital. The distribution of patients with carriage, colonization or infection was investigated prospectively. Nosocomial acquisition was confirmed in at least 928 patients, 525 of whom were identified from clinical specimens as being infected (n=418) or colonized (n=107) by MRSA. An additional 403 patients were identified from screening specimens, of whom 58 subsequently became infected and 18 colonized. Screening of the nose, throat and perineum detected 98 % of all carriers. Of the 580 infections in 476 patients, surgical wound, urinary tract and skin infections accounted for 58 % of the infections. Of the 476 infected patients, death was attributable to MRSA infection in 13 %. Colonization with MRSA was found in 127 patients and 42 % of 165 colonized sites were the skin. Auto-infection from nasal carriage or cross-infection, probably via staff hands, seemed to be the most common mode of acquisition of MRSA infections

Population Structure of a Hybrid Clonal Group of Methicillin-Resistant Staphylococcus aureus, ST239-MRSA-III

The methicillin-resistant Staphylococcus aureus (MRSA) clonal group known as ST239-MRSA-III is notable for its hybrid origin and for causing sustained hospital epidemics worldwide since the late 1970s. We studied the population structure of this MRSA clonal group using a sample of 111 isolates that were collected over 34 years from 29 countries. Genetic variation was assessed using typing methods and novel ascertainment methods, resulting in approximately 15 kb of sequence from 32 loci for all isolates. A single most parsimonious tree, free of homoplasy, partitioned 28 haplotypes into geographically-associated clades, including prominent European, Asian, and South American clades. The rate of evolution was estimated to be approximately 100× faster than standard estimates for bacteria, and dated the most recent common ancestor of these isolates to the mid-20th century. Associations were discovered between the ST239 phylogeny and the ccrB and dru loci of the methicillin resistance genetic element, SCCmec type III, but not with the accessory components of the element that are targeted by multiplex PCR subtyping tools. In summary, the evolutionary history of ST239 can be characterized by rapid clonal diversification that has left strong evidence of geographic and temporal population structure. SCCmec type III has remained linked to the ST239 chromosome during clonal diversification, but it has undergone homoplasious losses of accessory components. These results provide a population genetics framework for the precise identification of emerging ST239 variants, and invite a re-evaluation of the markers used for subtyping SCCmec