Vasoconstrictor effects in vivo and plasma disappearance rate of neuropeptide Y in man

Vascular effects of neuropeptide Y (NPY) and noradrenaline (NA) were studied in six human volunteers. Systemic infusion of human NPY for 40 min (5 pmol X kg-1 X min-1) increased arterial plasma NPY-like immunoreactivity (NPY-LI) from 12 +/- 2 to 356 +/- 30 pM. This concentration caused no systemic cardiovascular effects. The disappearance curve for NPY-LI was biphasic; the slopes of the two phases corresponding to half lives of 4.1 +/- 0.4 and 20 +/- 2 min respectively. Close i.a. infusion of human NPY in the forearm caused a slowly developing and dose dependent decrease in forearm blood flow (FBF) and increase in venous tone with maximal values of 44 +/- 6 and 235 +/- 81% of control respectively at 5 nmol X min-1. The corresponding values for NA (5 nmol X min-1) were 21 +/- 9 and 489 +/- 78% of control. A threshold concentration for a decrease in FBF was obtained at a plasma NPY-LI of 3.7 +/- 0.6 nM. The decrease in FBF caused by NPY was maintained for a much longer period compared to that of NA.     

Occurrence of VIP and peptide HM in human pancreas and their influence on pancreatic endocrine secretion in man

By immunohistochemistry it was found that VIP- and peptide HI/peptide HM (PHI/PHM)-like immunoreactivity occurred in autonomic neurons in the human pancreas. Antisera against both VIP and PHI/PHM reacted with neuronal cells in local ganglia and these ganglia also contained PHI/PHM- and VIP-immunoreactive fibre plexuses. VIP- and PHI/PHM-positive fibres were also seen close to the Langerhans' islets. In addition, PHI/PHM- but not VIP-like immunoreactivity was observed in the endocrine cells often located in the periphery of the islets. The nature of these PHI/PHM-positive cells remains to be established. I.v. infusion of VIP at constant rates of 300 and 900 pmol/kg X h for 30 min in 6 healthy volunteers resulted in plateau values of 102 +/- 26 and 291 +/- 25 pM, respectively. These levels of VIP which are above those found in the circulation under physiological conditions stimulated secretion of insulin, C-peptide and pancreatic glucagon dose-dependently. On the contrary prolonged (60 min) infusion of PHM in doses resulting in plasma levels up to 1340 +/- 405 pM had no effect on pancreatic hormone secretion. These findings suggest that VIP is a likely neurotransmitter in the control of endocrine pancreatic secretion while PHM has a less prominent role, if any.     

Species richness in mammalian herbivores: patterns in the boreal zone

Latitudinal gradients in species diversity are well established for a number of plant and animal taxa. Both historical and present-day environmental factors have been suggested to be responsible for observed patterns. We tested the hypothesis that current environmental features of the environment (primary productivity and regional landscape structure) may explain the longitudinal variation in species richness of mammalian herbivores in the Holarctic boreal zone. Mammalian herbivore species diversity was strongly correlated with a number of environmental variables measured. We reduced the data set by a principal components analysis (PCA), and found that in the Palearctic, species richness is positively related to warm climate (high temperature sum), the number of hardwood species, and the area of boreal forest. In the Nearctic, species richness increases as the length of the growing season and the number of coniferous tree species increase. Thus indirect measures of primary productivity as well as tree species number may accurately predict species richness in mammalian herbivores. In addition, there seems to be a strong species-area effect at the regional level. The larger and more homogeneous in terms of forest coverage a boreal section is, the more species coexist there.     

Studying the uptake of cell-penetrating peptides

More than a decade ago, it was discovered that cationic peptides could traverse the cellular plasma membrane without specific transporter proteins or membrane damage. Subsequently, it was found that these peptides, known as cell-penetrating peptides (CPPs), were also capable of delivering cargos into cells, hence the great potential of these vectors was acknowledged. Today, many different research groups are working with CPPs, which necessitates efforts to develop unified assays enabling the comparison of data. Here we contribute three protocols for evaluation of CPPs which, if used in conjunction, provide complementary data about the amount and mechanism of uptake (fluorometric analysis and confocal microscopy, respectively), as well as the extent of degradation (HPLC analysis of cell lysates). All three protocols are based on the use of fluorescently labeled peptides and can be performed on the same workday.     

A single fixation protocol for proteome-wide immunofluorescence localization studies

Immunofluorescence microscopy is a valuable tool for analyzing protein expression and localization at a subcellular level thus providing information regarding protein function, interaction partners and its role in cellular processes. When performing sample fixation, parameters such as difference in accessibility of proteins present in various cellular compartments as well as the chemical composition of the protein to be studied, needs to be taken into account. However, in systematic and proteome-wide efforts, a need exists for standard fixation protocol(s) that works well for the majority of all proteins independent of subcellular localization. Here, we report on a study with the goal to find a standardized protocol based on the analysis of 18 human proteins localized in 11 different organelles and subcellular structures. Six fixation protocols were tested based on either dehydration by alcohols (methanol, ethanol or iso-propanol) or cross-linking by paraformaldehyde followed by detergent permeabilization (Triton X-100 or saponin) in three human cell lines. Our results show that cross-linking is essential for proteome-wide localization studies and that cross-linking using paraformaldehyde followed by Triton X-100 permeabilization successfully can be used as a single fixation protocol for systematic studies.     

Inhibition of low pH evoked activation of airway sensory nerves by capsazepine, a novel capsaicin-receptor antagonist.

Low pH is a well known sensory irritant in pathological conditions such as inflammation. The mechanisms underlying this low pH effect were therefore studied in the guinea pig. Acid exposure caused marked nasal irritation via a specific subset of sensory nerves sensitive to capsaicin. Furthermore, acid caused bronchoconstriction via release of neuropeptides from capsaicin sensitive afferents. Interestingly, capsazepine, a recently developed competitive capsaicin receptor antagonist, selectively inhibited these responses to low pH. Ruthenium red, which blocks the cation channel associated with the capsaicin receptor, had effects similar to those of capsazepine. Therefore, acid irritation of the airway mucosa may involve capsaicin-receptor mechanisms and capsazepine represents a novel protective agent.     

Balancing selection in Pattern Recognition Receptor signalling pathways is associated with gene function and pleiotropy in a wild rodent

Pathogen‐mediated balancing selection is commonly considered to play an important role in the maintenance of genetic diversity, in particular in immune genes. However, the factors that may influence which immune genes are the targets of such selection are largely unknown. To address this, here we focus on Pattern Recognition Receptor (PRR) signalling pathways, which play a key role in innate immunity. We used whole‐genome resequencing data from a population of bank voles (Myodes glareolus) to test for associations between balancing selection, pleiotropy and gene function in a set of 123 PRR signalling pathway genes. To investigate the effect of gene function, we compared genes encoding (a) receptors for microbial ligands versus downstream signalling proteins, and (b) receptors recognizing components of microbial cell walls, flagella and capsids versus receptors recognizing features of microbial nucleic acids. Analyses based on the nucleotide diversity of full coding sequences showed that balancing selection primarily targeted receptor genes with a low degree of pleiotropy. Moreover, genes encoding receptors recognizing components of microbial cell walls etc. were more important targets of balancing selection than receptors recognizing nucleic acids. Tests for localized signatures of balancing selection in coding and noncoding sequences showed that such signatures were mostly located in introns, and more evenly distributed among different functional categories of PRR pathway genes. The finding that signatures of balancing selection in full coding sequences primarily occur in receptor genes, in particular those encoding receptors for components of microbial cell walls etc., is consistent with the idea that coevolution between hosts and pathogens is an important cause of balancing selection on immune genes.