Elemental and configural olfactory coding by antennal lobe neurons of the honeybee (<Emphasis Type="Italic">Apis mellifera</Emphasis>)

When smelling an odorant mixture, olfactory systems can be analytical (i.e. extract information about the mixture elements) or synthetic (i.e. creating a configural percept of the mixture). Here, we studied elemental and configural mixture coding in olfactory neurons of the honeybee antennal lobe, local neurons in particular. We conducted intracellular recordings and stimulated with monomolecular odorants and their coherent or incoherent binary mixtures to reproduce a temporally dynamic environment. We found that about half of the neurons responded as ‘elemental neurons’, i.e. responses evoked by mixtures reflected the underlying feature information from one of the components. The other half responded as ‘configural neurons’, i.e. responses to mixtures were clearly different from responses to their single components. Elemental neurons divided in late responders (above 60 ms) and early responder neurons (below 60 ms), whereas responses of configural coding neurons concentrated in-between these divisions. Latencies of neurons with configural responses express a tendency to be faster for coherent stimuli which implies employment in different processing circuits.     

Regulation of thermogenesis in flowering Araceae: the role of the alternative oxidase

The inflorescences of several members of the Arum lily family warm up during flowering and are able to maintain their temperature at a constant level, relatively independent of the ambient temperature. The heat is generated via a mitochondrial respiratory pathway that is distinct from the cytochrome chain and involves a cyanide-resistant alternative oxidase (AOX). In this paper we have used flux control analysis to investigate the influence of temperature on the rate of respiration through both cytochrome and alternative oxidases in mitochondria isolated from the appendices of intact thermogenic Arum maculatum inflorescences. Results are presented which indicate that at low temperatures, the dehydrogenases are almost in full control of respiration but as the temperature increases flux control shifts to the AOX. On the basis of these results a simple model of thermoregulation is presented that is applicable to all species of thermogenic plants. The model takes into account the temperature characteristics of the separate components of the plant mitochondrial respiratory chain and the control of each process. We propose that 1) in all aroid flowers AOX assumes almost complete control over respiration, 2) the temperature profile of AOX explains the reversed relationship between ambient temperature and respiration in thermoregulating Arum flowers, 3) the thermoregulation process is the same in all species and 4) variations in inflorescence temperatures can easily be explained by variations in AOX protein concentrations.     

How Could Hospitalisations at the End of Life Have Been Avoided? A Qualitative Retrospective Study of the Perspectives of General Practitioners,Nurses and Family Carers

Background

Although many patients prefer to stay and die at home at the end of life, many are hospitalised. Little is known about how to avoid hospitalisations for patients living at home.

Aim

To describe how hospitalisation at the end of life can be avoided, from the perspective of the GPs, nurses and family carers.

Method

A qualitative design with face-to-face interviews was used. Taking 30 cases of patients who died non-suddenly, 26 GPs, 15 nurses and 18 family carers were interviewed in depth. Of the 30 patients, 20 were hospitalised and 10 were not hospitalised in the last three months of life.

Results

Five key themes that could help avoid hospitalisation at the end of life emerged from the interviews. The key themes were: 1) marking the approach of death, and shifting the mindset; 2) being able to provide acute treatment and care at home; 3) anticipatory discussions and interventions to deal with expected severe problems; 4) guiding and monitoring the patient and family in a holistic way through the illness trajectory; 5) continuity of treatment and care at home. If these five key themes are adopted in an interrelated way, this could help avoid hospitalisations, according to GPs, nurses and family carers.

Conclusions

The five key themes described in this study can be seen as strategies that could help in avoiding hospitalisation at the end of life. It is recommended that for all patients residing at home, GPs and community nurses work together as a team from the moment that it is marked that death is approaching up to the end of life.     

Production of dehydroamino acid-containing peptides by Lactococcus lactis

Nisin is a pentacyclic peptide antibiotic produced by some Lactococcus lactis strains. Nisin contains dehydroresidues and thioether rings that are posttranslationally introduced by a membrane-associated enzyme complex, composed of a serine and threonine dehydratase NisB and the cyclase NisC. In addition, the transporter NisT is necessary for export of the modified peptide. We studied the potential of L. lactis expressing NisB and NisT to produce peptides whose serines and threonines are dehydrated. L. lactis containing the nisBT genes and a plasmid coding for a specific leader peptide fusion construct efficiently produced peptides with a series of non-naturally occurring multiple flanking dehydrobutyrines. We demonstrated NisB-mediated dehydration of serines and threonines in a C-terminal nisin(1-14) extension of nisin, which implies that also residues more distant from the leader peptide than those occurring in prenisin or any other lantibiotic can be modified. Furthermore, the feasibility and efficiency of generating a library of peptides containing dehydroresidues were demonstrated. In view of the particular shape and reactivity of dehydroamino acids, such a library provides a novel source for screening for peptides with desired biological and physicochemical properties.     

Leptospira interrogans is recognized through DC-SIGN and induces maturation and cytokine production by human dendritic cells

Leptospirosis is a global zoonotic disease, caused by pathogenic Leptospira species including Leptospira interrogans, that causes public health and livestock problems. Pathogenesis, immune response and cellular receptors for Leptospira are not well understood. Interaction of dendritic cells (DCs) with L. interrogans serovar Autumnalis L-643 and BL-6 isolated from leptospirosis patients, and both virulent and avirulent serovar Pyrogenes 2317 strains isolated from animal were investigated. Carbohydrate analysis using lectins showed that all of these leptospires contained high mannose components as a common backbone and DC-SIGN was involved in leptospires' attachment. Interaction of the L. interrogans strains with DCs induced maturation, but had different effects on IL-10, IL-12p70 and tumor necrosis factor (TNF)-alpha production. Both virulent and avirulent Pyrogenes 2317 and Autumnalis BL-6 but not L-643 strains induced IL-12p70 and TNF-alpha production, but minimal IL-10 secretion. These data demonstrated that L. interrogans binds DC-SIGN and induces DCs maturation and cytokine production, which should provide new insights into cellular immune processes during leptospirosis.     

A Mycobacterium leprae-specific gene encoding an immunologically recognized 45 kDa protein

By screening a Mycobacterium leprae lambda gt11 expression library with a serum from an Ethiopian lepromatous leprosy (LL) patient a clone was isolated (LL4) belonging to hybridization group III of a panel of previously isolated M. leprae clones. Members of this hybridization group encode a serologically recognized 45 kDa protein. The complete DNA sequences of the partially overlapping clones LL4 and L1 (hybridization group III) are presented and these revealed the presence of an open reading frame (ORF) predicting a protein with a molecular size of 42 448 Da. Southern hybridizations on total genomic DNA of M. Ieprae, Mycobacterium tuberculosis and eight atypical mycobacteria showed that the LL4 DNA fragment is specific for M. Ieprae DNA even under low-stringency conditions. The M. Ieprae specificity of LL4 DNA was further confirmed by the polymerase chain reaction using four different sets of primers. Western blotting analyses showed that the M. Ieprae 45 kDa protein is frequently recognized by antibodies from leprosy patients and that this recognition is specific since no antibodies could be detected in sera of tuberculosis patients. T-cell proliferation assays also demonstrated T-cell recognition by leprosy patients and healthy contacts of the M. Ieprae 45 kDa protein. The specificity of the LL4 DNA region and the 45 kDa antigen that is encoded by hybridization group III could provide unique tools for the development of M. Ieprae-specific immunological and DNA reagents.