Body masses,functional responses and predator–prey stability

The stability of ecological communities depends strongly on quantitative characteristics of population interactions (type‐II vs. type‐III functional responses) and the distribution of body masses across species. Until now, these two aspects have almost exclusively been treated separately leaving a substantial gap in our general understanding of food webs. We analysed a large data set of arthropod feeding rates and found that all functional‐response parameters depend on the body masses of predator and prey. Thus, we propose generalised functional responses which predict gradual shifts from type‐II predation of small predators on equally sized prey to type‐III functional‐responses of large predators on small prey. Models including these generalised functional responses predict population dynamics and persistence only depending on predator and prey body masses, and we show that these predictions are strongly supported by empirical data on forest soil food webs. These results help unravelling systematic relationships between quantitative population interactions and large‐scale community patterns.     

Diagnostic value of JC/BK virus antibody immunohistochemistry staining in urine samples from posttransplant immunosuppressed patients in relation to polyomavirus reactivation

OBJECTIVE: To compare the diagnostic value of cytology and immunohistochemistry staining (IHS) of urine samples for polyomavirus reactivation diagnosis. STUDY DESIGN: Sixty-eight urine samples collected from 18 immunosuppressed patients were analyzed by Papanicolaou and IHS with a JC/BK virus-specific monoclonal antibody. RESULTS: Overall, polyomavirus BK (BKV) was positive in 11 of 18 patients (61.1%) (3 of whom developed hemorrhagic cystitis) and in 23 of 68 urine samples (28%). Of 23 samples, 4 (17%) were positive by 1 of the 2 techniques, only. Of 23 samples, 19 (83%) were positive by both methods. In matching urine samples from the same patient, the number of BKV-infected positive cells detected by IHS in urine slides was higher than those detected by Papanicolaou staining (71.3%). CONCLUSION: The main advantage of LHS is that it allowed confirmation of BKV infection diagnosis in urine samples. IHS detected more BKV-infected cells in samples with few positive urothelial cells, which would have gone undetected if only Papanicolaou staining had been used as the BKV screening method. Urine samples testing for BKV by both techniques will improve diagnosis in asymptomatic patients, allowing early therapeutic intervention and a better clinical outcome.     

Characterization and expression in Streptomyces lividans of cefD and cefE genes from Nocardia lactamdurans: the organization of the cephamycin gene cluster differs from that in Streptomyces clavuligerus

Summary The cefD and cefE genes of Nocardia lactamdurans, which encode isopenicillin N epimerase and deacetoxycephalosporin C synthase respectively, have been located 0.63 kb upstream from the lysine-6-amino-transferase (lat) gene. cefD contains an open reading frame (ORF) of 1197 nucleotides (nt) encoding a protein of 398 amino acids with a M_r of 43 622. The deduced amino acid sequence exhibits 62.2% identity to the cefD gene product of Streptomyces clavuligerus. The sequence SXHKXL in isopenicillin N epimerase resembles the consensus sequence for pyridoxal phosphate binding found in several amino acid decarboxylases from Enterobacteria. cefE contains an ORF of 945 nt encoding a protein of 314 amino acids with a M_r of 34532, which is similar to the deacetoxycephalosporin C synthase of S. clavuligerus. Expression of both genes, cefD and cefE, in S. lividans transformants, results in deacetoxycephalosporin C synthase and isopenicillin N epimerase activities that are 10–12 times higher than those in N. lactamdurans. The cefD and cefE genes of N. lactamdurans are closely linked but the overall organization of the cephamycin gene cluster differs in N. lactamdurans and S. clavuligerus.     

Synthesis and Cytostatic Activity of Halomethylthiazole C-Nucleosides and Analogues1

Abstract

The synthesis of 2-(β-D-ribofuranosyl)-and 2-(tetrahydropyran-2-yl)-4-halomethylthiazoles from 2, 5-anhydro-D-allonthioamide and tetrahydropyran-2-thiocarboxamide is described. Bromination of 2-(β-D-ribofuranosyl)- and 2-tetrahydropyran-2-yl)-4-methylthiazole with NBS is studied. Cytostatic activity against HeLa cells of all the compounds is reported.     

Antigenic Proteins Involved in Occupational Rhinitis and Asthma Caused by Obeche Wood (Triplochiton Scleroxylon)

Background

Obeche wood dust is a known cause of occupational asthma where an IgE-mediated mechanism has been demonstrated.

Objective

To characterize the allergenic profile of obeche wood dust and evaluate the reactivity of the proteins by in vitro, ex vivo and in vivo assays in carpenters with confirmed rhinitis and/or asthma

Materials and methods

An in-house obeche extract was obtained, and two IgE binding bands were purified (24 and 12 kDa) and sequenced by N-terminal identity. Specific IgE and IgG, basophil activation tests and skin prick tests (SPTs) were performed with whole extract and purified proteins. CCD binding was analyzed by ELISA inhibition studies.

Results

Sixty-two subjects participated: 12 with confirmed occupational asthma/rhinitis (ORA+), 40 asymptomatic exposed (ORA−), and 10 controls. Of the confirmed subjects, 83% had a positive SPT to obeche. There was a 100% recognition by ELISA in symptomatic subjects vs. 30% and 10% in asymptomatic exposed subjects and controls respectively (p<0.05). Two new proteins were purified, a 24 kDa protein identified as a putative thaumatin-like protein and a 12 kDa gamma-expansin. Both showed allergenic activity in vitro, with the putative thaumatin being the most active, with 92% recognition by ELISA and 100% by basophil activation test in ORA+ subjects. Cross-reactivity due to CCD was ruled out in 82% of cases.

Conclusions

Two proteins of obeche wood were identified and were recognized by a high percentage of symptomatic subjects and by a small proportion of asymptomatic exposed subjects. Further studies are required to evaluate cross reactivity with other plant allergens.     

First proposal of quality indicators and standards and recommendations to improve the healthcare in the Spanish National Registry of Hip Fracture

BackgroundThe Spanish National Hip Fracture Registry (or Registro Nacional de Fractura de Cadera, RNFC) is a database of hip fracture patients admitted to Spanish hospitals. Its goals include assessment and continuous improvement of the care process.ObjectivesTo (1) establish a series of indicators, (2) evaluate their initial fulfillment, (3) propose quality standards, (4) suggest recommendations to facilitate standards compliance, and (5) monitor the indicators.MethodThe indicators fulfilled the criteria of (1) evaluating the process or outcome, (2) being clinically relevant for patients, (3) being modifiable through changes in healthcare practice, and (4) being considered important by the RNFC participants. The first quartile obtained by the group of hospitals in each of the respective variables was proposed as the standard. The Indicators Advisory Committee (IAC) elaborated a list of recommendations for each indicator, based on the available evidence.ResultsSeven indicators were chosen. These indicators (its baseline compliance vs. the standard to be reached, respectively) were: the proportion of patients receiving surgery within 48 h (44% vs. 63%), mobilized the first postoperative day (56% vs. 86%), with antiosteoporotic medication at discharge (32% vs. 61%), with calcium supplements at discharge (46% vs. 77%), with vitamin D supplements at discharge (67% vs. 92%), who developed pressure ulcers during hospitalization (7.2% vs. 2.1%) and with independent mobility at 30 days (58% vs. 70%). The IAC has established 25 recommendations for improving care.ConclusionThe indicators and standards chosen are presented, as well as the list of recommendations. This process completes the first step to improve quality of care. The results will be evaluated 6 months after implementing the recommendations.     

The Old World sparrows (genus Passer) phylogeography and their relative abundance of nuclear mtDNA pseudogenes

The phylogenetic relationships of genus Passer (Old World sparrows) have been studied with species covering their complete world living range. Mitochondrial (mt) cyt b genes and pseudogenes have been analyzed, the latter being strikingly abundant in genus Passer compared with other studied songbirds. The significance of these Passer pseudogenes is presently unclear. The mechanisms by which mt cyt b genes become pseudogenes after nuclear translocation are discussed together with their mode of evolution, i.e., transition/transversion mitochondrial ratio is decreased in the nucleus, as is the constraint for variability at the three codon positions. However, the skewed base composition according to codon position (in 1^st position the percentage is very similar for the four bases, in 2^nd position there are fewer percentage of A and G and more percentage of T, and in 3^rd codon position fewer percentage of G and T and is very rich in A and C) is maintained in the translocated nuclear pseudogenes. Different nuclear internal mechanisms and/or selective pressures must exist for explaining this nuclear/mitochondrial differential DNA base evolutive variability. Also, the phylogenetic usefulness of pseudogenes for defining relationships between closely related lineages is stressed. The analyses suggest that the primitive genus Passer species comes from Africa, the Cape sparrow being the oldest: P. hispaniolensis italiae is more likely conspecific to P. domesticus than to P. hispaniolensis. Also, Passer species are not included within weavers or Estrildinae or Emberizinae, as previously suggested. European and American Emberizinae sparrows are closely related to each other and seem to be the earliest species that radiated among the studied songbirds (all in the Miocene Epoch). Received: 29 November 2000 / Accepted: 22 March 2001