A novel GalR2-specific peptide agonist

The galanin peptide family and its three receptors have with compelling evidence been implicated in several high-order physiological disorders. The co-localization with other neuromodulators and the distinct up-regulation during and after pathological disturbances has drawn attention to this neuropeptide family. In the current study we present data on receptor binding and functional response for a novel galanin receptor type 2 (GalR2) selective chimeric peptide, M1145 [(RG)₂-N-galanin(2-13)-VL-(P)₃-(AL)₂-A-amide]. The M1145 peptide shows more than 90-fold higher affinity for GalR2 over GalR1 and a 76-fold higher affinity over GalR3. Furthermore, the peptide yields an agonistic effect in vitro, seen as an increase in inositol phosphate (IP) accumulation, both in the absence or the presence of galanin. The peptide design with a N-terminal extension of galanin(2-13), prevails new insights in the assembly of novel subtype specific ligands for the galanin receptor family and opens new possibilities to apply the galanin system as a putative drug target.     

Mechanical energy absorption in human hand-arm exposed to sinusoidal vibration

Summary A possible basis for risk assessment of human exposure to vibration when using hand-held tools may be to determine the amount of mechanical energy that is absorbed by the hand-arm system. The aim of this investigation was to study the absorption of mechanical energy in the human hand-arm system during exposure to sinusoidal vibration within the frequency range of 20 to 1500 Hz. A handle, specially designed for this type of experiments, was used during the measurements. The influence of various experimental conditions, such as three different hand-arm postures, grip force (25–75 N) and vibration levels (27–53 mm/s_rms), were studied on eight subjects. The outcome clearly shows that the energy absorption properties of the human hand-arm system are more or less dependent on all of the experimental conditions studied, but mainly to the frequency of the vibration stimuli. Furthermore, the results indicate a non-linear relationship between the energy absorbed and all other variables studies.     

Vibration exposure and conditioning lesion effect in nerves: an experimental study in rats.

The effects of controlled vibrations of defined frequency (80 Hz), acceleration (32 m/s2 root mean square), and duration (5 hours daily, 2 or 5 days) induced to the hind limb of rats on the regeneration potential in the sciatic nerve after a test crush lesion were determined. Exposure to vibration induced a marked and significant increase in outgrowth length of axons from the crush injury as evaluated after 3 and 6 days with the pinch reflex test. This effect was still observed 1 month but not 3 months after exposure to vibration. Even such a short duration of vibration exposure as 2 days induced an increased length of outgrowth. Such a conditioning effect may be due to local changes in the environment of the axons or to changes in the nerve cell bodies in the dorsal root ganglion. The results indicate that an alarm reaction exists in the nerve at a time point where no structural changes are observed in the nerve. By inducing such a conditioning lesion to nerve tissue, vibration represents a trauma corresponding to a crush lesion or transection of the nerve.     

Mortality and lead exposure: a retrospective cohort study of Swedish smelter workers

The study is based on the work histories and mortality data for 3832 male workers first employed before 1967 at a copper smelter in northern Sweden and followed up from 1950 to 1981. From the 3832 workers a lead cohort consisting of 437 workers employed for at least three years at sites with considerable lead exposure during 1950-74 was selected. These workers had regularly had blood lead measurements performed since 1950. Based on the cumulative blood lead dose 1950-74 and peak blood lead values, the cohort was subdivided into high mean, low mean, high peak, and low peak groups. Standardised mortality ratios (SMR) were calculated for the six groups using general and local reference populations. The original cohort of 3832 workers showed considerable excess of deaths for total mortality, malignant neoplasms especially lung and stomach cancer, ischaemic heart diseases, and cerebrovascular diseases when compared with the general population. In the lead cohort where the workers had been subjected to a considerable lead exposure only the raised SMR for lung cancer was sustained (SMR = 162; not significant). No significant differences were found between high lead and low lead exposed smelter workers.     

Physico-chemical considerations of titanium as a biomaterial

Physico-chemical properties of titanium are discussed. Special attention is paid to those of amorphous TiO 2 that contact tissues in vivo. In aqueous environments TiO 2. (aq) has low ion-formation tendency and low reactivity with macromolecules. This is accompanied by low toxicity. Titanium does not facilitate reactive oxygen radical generation during inflammatory conditions as observed in in-vitro experiments. The outermost layers of the oxide are in the Ti(IV) oxidation state, although using electron spin resonance (ESR) techniques, formation of Ti(III) is observed at atmospheric conditions. The impact of similarities between water and TiO 2 is speculated upon, and the physico-chemical properties of titanium are tentatively linked to some in-vivo consequences.     

An azurocidin-like protein is induced in Trichoplusia ni larval gut cells after bacterial challenge

Trichoplusia ni immune genes up-regulated in response to bacterial infection have been isolated using differential display polymerase chain reaction. Here we report the cloning and characterisation of a gut-specific immune gene encoding an azurocidin-like protein. The deduced protein is 317 amino acid residues long with a hydrophobic C-terminus and a predicted 17-residue signal peptide. The mature T. ni protein shows 30% identity to human azurocidin, an antibacterial protein. Like azurocidin, the T. ni protein contains two amino acid substitutions in the active site triad normally present in serine proteases. The T. ni protein was synthesised with a six-histidine C-terminal extension using the baculovirus expression system. Sequencing of the recombinant azurocidin-like protein confirmed the predicted cleavage of the signal peptide. Northern blots show that T. ni azurocidin-like protein is expressed solely in the larval gut and that expression is up-regulated by injecting or feeding bacteria. Expression reaches its highest level at 10 h after bacteria injection.     

Vilse, a conserved Rac/Cdc42 GAP mediating Robo repulsion in tracheal cells and axons

Slit proteins steer the migration of many cell types through their binding to Robo receptors, but how Robo controls cell motility is not clear. We describe the functional analysis of vilse, a Drosophila gene required for Robo repulsion in epithelial cells and axons. Vilse defines a conserved family of RhoGAPs (Rho GTPase-activating proteins), with representatives in flies and vertebrates. The phenotypes of vilse mutants resemble the tracheal and axonal phenotypes of Slit and Robo mutants at the CNS midline. Dosage-sensitive genetic interactions between vilse, slit, and robo mutants suggest that vilse is a component of robo signaling. Moreover, overexpression of Vilse in the trachea of robo mutants ameliorates the phenotypes of robo, indicating that Vilse acts downstream of Robo to mediate midline repulsion. Vilse and its human homolog bind directly to the intracellular domains of the corresponding Robo receptors and promote the hydrolysis of RacGTP and, less efficiently, of Cdc42GTP. These results together with genetic interaction experiments with robo, vilse, and rac mutants suggest a mechanism whereby Robo repulsion is mediated by the localized inactivation of Rac through Vilse.     

Calcium-independent release of gamma-aminobutyrate from nerve processes in the developing rabbit retina

Retinas from 3- and 10-day-old rabbits, and from young (29 days), or adult animals were used to study in parallel the development of synaptic vesicles in amacrine cells and the Ca2+ dependence of the K+-stimulated [3H]gamma-aminobutyrate release from them. Few synaptic vesicles were observed in the amacrine cell processes in retinas from the 3-day-old rabbits. The number of vesicles significantly increased between 3 and 10 days and increased further between day 10 and the adult animal. The Ca2+ dependence of the K+-stimulated release decreased with increasing age. There is thus a poor correlation between the Ca2+ dependent transmitter release and the number of synaptic vesicles in the nerve terminal, favouring the existence of a Ca2+ dependent nonvesicular process for the [3H]gamma-aminobutyrate release in the rabbit retina.     

Altered impedance during pigment aggregation in<Emphasis Type="Italic">Xenopus laevis</Emphasis> melanophores

Melanophores are dark-brown pigment cells located in the skin of amphibia, fish and many invertebrates. The skin colour of these organisms is regulated by the translocation of pigment organelles, and the pigment distribution can be altered by external stimuli. The ability to change colour in response to stimuli makes these cells of interest for biosensing applications. It was investigated whether pigment aggregation in Xenopus laevis melanophores can be detected by impedance measurements performed in transparent microvials. The results show that cell attachment, cell spreading and pigment aggregation all resulted in impedance changes, seen particularly at the highest frequency tested (10 kHz). The mechanisms behind the impedance changes were investigated by the addition of latrunculin or melatonin, both of which cause pigment aggregation. The latrunculin-induced aggregation was associated with cell area decrease and filamentous actin (F-actin) breakdown, processes that can influence the impedance. Lack of F-actin breakdown and an increase in cell area during melatonin-induced aggregation suggest that some other intracellular process also contributes to the impedance decrease seen for melatonin. It was shown that impedance measurements reflect not only cell attachment and cell spreading, but also intracellular events.     

3-Hydroxyanthranilic acid accumulation following administration of the 3-hydroxyanthranilic acid 3,4-dioxygenase inhibitor NCR-631

In the kynurenine pathway of tryptophan metabolism, 3-hydroxyanthranilic acid is the substrate for formation of the excitotoxin quinolinic acid by 3-hydroxyanthranilic acid 3, 4-dioxygenase. This study was designed to characterize the effects on 3-hydroxyanthranilic acid after treatment with the 3-hydroxyanthranilic acid 3,4-dioxygenase inhibitor 4, 6-di-bromo-3-hydroxyanthranilic acid (NCR-631) in Sprague-Dawley rats. The blood plasma and brain concentrations of 3-hydroxyanthranilic acid were found to increase rapidly in a dose-dependent manner after gavage administration of NCR-631. However, the effect was relatively transient, with a decline in 3-hydroxyanthranilic acid levels already at 1h after NCR-631 treatment. Similar increases in plasma levels of 3-hydroxyanthranilic acid were observed following either gavage or parenteral (i.v. or s.c.) administration of NCR-631 (25 mg/kg). Only a minor enhancement of the NCR-631-induced increase in plasma 3-hydroxyanthranilic acid levels was found after sub-chronic treatment (25 mg/kg by gavage; 7 days, b.i.d.), suggesting a low propensity for altered 3-hydroxyanthranilic acid 3,4-dioxygenase activity following repeated inhibition. Administration of [14C]NCR-631 suggested 20 min initial plasma half life and an oral absorption around 50%. A dose of 250 mg/kg [14C]NCR-631 given by gavage provided plasma levels of almost 2 micromol/ml and a brain concentration of approximately 16 nmol/g, when analyzed 15 min after administration. Neither acute nor sub-chronic administration of NCR-631 caused any substantial effects on quinolinic acid levels in plasma or brain. Also, the plasma levels of kynurenic acid, another neuroactive kynurenine pathway metabolite, were unaffected by acute NCR-631 treatment. Moreover, the brain levels of the major cerebral tryptophan metabolites 5-hydroxytryptamine and 5-hydroxyindoleacetic acid remained unchanged following administration of NCR-631. Although reversible inhibition of 3-hydroxyanthranilic acid 3, 4-dioxygenase with NCR-631 in normal rats is insufficient to cause substantial changes in the levels of quinolinic acid or other important tryptophan metabolites, it causes a major accumulation of the substrate 3-hydroxyanthranilic acid.