Levels and activity of cyclic guanosine monophosphate-dependent protein kinase in nurse and forager honeybees

Age-dependent division of labour in honeybees was shown to be connected to sensory response thresholds. Foragers show a higher gustatory responsiveness than nurse bees. It is generally assumed that nutrition-related signalling pathways underlie this behavioural plasticity. Here, one important candidate gene is the foraging gene, which encodes a cyclic guanosine monophosphate-dependent protein kinase (PKG). Several roles of members of this enzyme family were analysed in vertebrates. They own functions in important processes such as growth, secretion and neuronal adaptation. Honeybee foraging messenger RNA expression is upregulated in the brain of foragers. In vivo activation of PKG can modulate gustatory responsiveness. We present for the first time PKG protein level and activity data in the context of social behaviour and feeding. Protein level was significantly higher in brains of foragers than in those of nurse bees, substantiating the role of PKG in behavioural plasticity. However, enzyme activity did not differ between behavioural roles. The mediation of feeding status appears independent of PKG signalling. Neither PKG content nor enzyme activity differed between starved and satiated individuals. We suggest that even though nutrition-related pathways are surely involved in controlling behavioural plasticity, which involves changes in PKG signalling, mediation of satiety itself is independent of PKG.

Systematic evaluation of the highest current threshold for regional anaesthesia in a porcine model

BACKGROUND

The purpose of this study was to determine systematically the highest minimal stimulation current threshold for regional anaesthesia in pigs.

METHODS

In an established pig model for regional anaesthesia, needle placements applying electric nerve stimulation were performed. The primary outcome was the frequency of close needle to nerve placements as assessed by resin injects and subsequent anatomical evaluation. Following a statistical model (continual reassessment method), the applied output currents were selected to limit the necessary number of punctures, while providing guidance towards the highest output current range.

RESULTS

Altogether 186 punctures were performed in 11 pigs. Within the range of 0.3-1.4 mA, no distant needle to nerve placement was found. In the range of 1.5-4.1 mA, 43 distant needle to nerve placements occurred. The range of 1.2-1.4 mA was the highest interval that resulted in a close needle to nerve placement rate of > or =95%.

CONCLUSIONS

In the range of 0.3-1.4 mA, all resin deposition was found to be adjacent to nerve epineurium. The application of minimal current intensities up to 1.4 mA does not obviously lead to a reduction of epineural injectate contacts in pigs. These findings suggest that stimulation current thresholds up to 1.4 mA result in equivalent needle tip localisation in pigs.

[Intramuscular lipoma. A differential diagnosis of great prognostic relevance]

Lipomata of the head and neck mostly present as cosmetically disturbing, superficial lesions lying within the subcutaneous tissue such that they can be easily removed by minor surgical interventions. In cases of deeply extended, lipomatous tumors, as reported here regarding two exemplary cases, physicians should always take into account that they might have to deal with infiltrative, intramuscular lipomata or even malignant neoplasms, especially if concomitant functional disorders are observed. Even though such tumors are rare in the head and the neck, preoperative planning must anticipate these possible pathological entities. At any stage, modification of the surgical procedure should be possible according to the intraoperative findings, as these tumors are prone to recurrence after incomplete resection. The actual diagnosis with infiltration of the surrounding tissue cannot be sufficiently made either by adequate imaging techniques or by preoperative fine-needle cytology but only by histological workup of the resected, tumorous tissue.

Correlation-induced double-plasmon excitation in simple metals studied by inelastic x-ray scattering

We report a new type of peaklike structure observed in the tail of the dynamic structure factor of simple metals, measured by inelastic x-ray scattering. Based on the momentum-transfer dependence of the energy position and the intensity of this structure, it has been unambiguously attributed to intrinsic plasmon-plasmon excitations, an electronic correlation effect that was theoretically predicted by many-body perturbation theory of the homogeneous-electron-gas model beyond the random-phase approximation. This signature appears to be largely unaffected by electron-ion interaction effects. Thus a structure that is primarily caused by correlation effects in the electron gas has been found experimentally in the dynamic structure factor of simple metals.

Relation between food intake and visual analogue scale ratings of appetite and other sensations in healthy older and young subjects

OBJECTIVE

Visual analogue scales are widely used in appetite research, yet the validity of these scales to evaluate appetite and mood has not been assessed in older subjects. The aim of this study was to determine the relations between food intake and visual analogue scale (VAS) ratings of appetite and nonappetite sensations in healthy older and young subjects.

DESIGN

Retrospective combined analysis of four single-blind, randomised, controlled appetite studies.

SETTING

All studies were conducted in the University of Adelaide, Department of Medicine, Adelaide, Australia.

SUBJECTS

A total of 45 healthy young men (n=24) and women (n=21) aged 18-35 y and 45 healthy older men (n=24) and women (n=21) aged 65-85 y were recruited by advertisement.

INTERVENTIONS

Oral, intraduodenal or intravenous administration of treatments which suppressed food intake were compared to control. Up to 90 min after treatment, a test meal was offered and subjects ate freely for between 30 and 60 min. Perceptions were assessed by 100-mm visual analogue scales administered at regular intervals.

RESULTS

Food intake at the test meal was positively related to perceptions of hunger, drowsiness, and calmness at both baseline and premeal (r>0.16, P<0.05), and inversely related to premeal ratings of fullness (r> 0.2, P<0.05) in both older and young subjects. Food intake was related to VAS ratings at least as strongly, if not more so, in older as in young subjects.

CONCLUSIONS

These observations (i) confirm that food intake is related to perceptions of hunger and fullness as assessed by VAS in healthy older and young subjects, and (ii) suggest that sensations, not obviously associated with appetite, including 'drowsiness' and 'calmness', are also associated with food intake.

Intravenous drug injection habits: drug users' self-reports versus researchers' perception

The present study was designed to obtain human data on the speed of intravenous (i.v.) injection of cocaine, heroin, and morphine as well as on the rate of onset of their subjective effects and their duration in order to improve the accuracy of animal and human experimental models of i.v. drug abuse. To that end, a questionnaire was submitted both to clients of a substitution therapy outpatient clinic and to members of the drug abuse research community. It was found that i.v. drug abusers injected cocaine, heroin, or morphine much faster and also experienced the drug effects much faster than assumed by the drug abuse researchers. The time course of the reemergence of craving was also greatly misjudged by the researchers. On the other hand, the i.v. drug users' self-reports were internally consistent and corresponded well to data obtained in several different human behavioral laboratories. Interestingly, more than half of the i.v. drug users reported that injection speed was not important when injecting cocaine (57%), heroin (72%) or morphine (73%) under conditions that guarantee a maximum effect, suggesting that the rate of the rise in the brain concentration of a drug of abuse is less important for its reinforcing effect and, thus, for its abuse liability, than previously assumed, at least within the time frame of an i.v. drug injection.

Involvement of CCK in the paraventricular nucleus of the hypothalamus in the CNS regulation of colonic motility

The effects of cholecystokinin octapeptide (CCK(8)), the CCK-A receptor antagonist, MK-329, and the CCK-B receptor antagonist, L-365, 260, microinfused into the paraventricular nucleus of hypothalamus (PVN) on colonic motor function was investigated in awake rats, chronically implanted with a microinjection cannula into the PVN and a catheter into the proximal colon. In fasted rats, bilateral microinfusion of CCK(8) at doses of 1.5 and 3.0 microg/rat into the PVN stimulated colonic transit, as shown by a significant increase in the geometric center by 47 and 54%, respectively. This effect of CCK(8) was site-specific to the PVN, since microinjection of the peptide into sites outside of but adjacent to PVN had no effect. In non-fasted rats, L-365,260 bilaterally microinjected into the PVN at a dose of 1.5 microg/rat inhibited propulsive colonic motor function; colonic transit time significantly increased by 73% in comparison to the control condition. Microinfusion of the CCK-A antagonist into in the PVN did not affect colonic transit. These results show that the PVN is a responsive site for the central CCK(8)-induced modulation of colonic motility. The data suggest, that endogenous CCK in the paraventricular nucleus of the hypothalamus unfolds a stimulatory effect on colonic transit through action on CCK-B receptors.

Autonomic seizures versus syncope in 18q- deletion syndrome: a case report

PURPOSE

The 18q- deletion syndrome (18qDS) is frequently associated with cardiac anomalies. Patients with this syndrome may also have epilepsy, which presents certain diagnostic difficulties. This case report aims to illustrate these diagnostic problems, document the usefulness of heart rate-based seizure detection algorithms in this setting, and define the epilepsy syndrome associated with 18qDS.

METHODS

Closed-circuit video electroencephalogram (EEG) monitoring using a heart rate-based seizure detection software was used to identify the event in question and to establish the diagnosis of epilepsy. Chromosomal analysis and magnetic resonance imaging (MRI) were used to further define the epilepsy syndrome.

RESULTS

We report on a patient with an atrial septal defect, enlargement of the right heart, and incomplete right bundle branch block, who developed episodes of tachycardia, loss of consciousness, and pallor, for which he was amnesic. Chromosomal analysis demonstrated karyotype 46,XY,del(18)(q21.3). ish del(18)(wcp18+,D18Z1+) with a loss of the gene for myelin basic protein. MRI revealed multifocal dysmyelination. Video-EEG monitoring using an electrocardiogram (ECG)-triggered seizure detection software proved to be indispensable in detecting an autonomic seizure and establishing the correct diagnosis; the procedure also allowed for the definition of the epilepsy syndrome. The patient was treated with carbamazepine and remained seizure-free.

CONCLUSIONS

Video-EEG monitoring using a heart rate-based seizure detection software can be helpful in diagnostically differentiating autonomic seizures from syncope. Dysmyelination due to loss of the myelin basic protein gene on 18q and cortical dysgenesis may be of pathogenic relevance.

Pgk1 and Hprt gene activity in the peri-implantation mouse embryo is influenced by the parental origin of the X-chromosome

The activity of two X-linked genes, Pgk1 and Hprt, that are localized on X-chromosomes of different parental origins in the XX mouse embryo was analyzed by the quantification of allele-specific transcripts. For the Pgk1 gene, the maternal allele-specific transcripts were consistently more abundant than the paternal transcripts in the blastocyst and the late gastrula. For the Hprt gene, the Hprt(b) allele was preferentially expressed in the blastocysts when it is present on the maternal X-chromosome. However, this skewed expression of the maternal allele was not observed in the reciprocal situation when the Hprt(a) allele was on the maternal X-chromosome. Like the Pgk1 locus, significantly more maternal Hprt transcripts were found in the gastrula-stage embryos irrespective of their genotypes. One possible interpretation of these results is that, in the XX mouse embryos, the genetic loci on maternal X-chromosome may be transcriptionally more active than their paternal counterparts during peri-implantation development.

Separate progenitors for radial and tangential cell dispersion during development of the cerebral neocortex

Cell lineage analyses suggest that cortical neuroblasts are capable of undertaking both radial and tangential modes of cell movement. However, it is unclear whether distinct progenitors are committed to generating neuroblasts that disperse exclusively in either radial or tangential directions. Using highly unbalanced mouse stem cell chimeras, we have identified certain progenitors that are committed to one mode of cell dispersion only. Radially dispersed neurons expressed glutamate, the neurochemical signature of excitatory pyramidal cells. In contrast, tangential progenitors gave rise to widely scattered neurons that are predominantly GABAergic. These results suggest lineage-based mechanisms for early specification of certain progenitors to distinct dispersion pathways and neuronal phenotypes.

Exendin(9-39)amide is an antagonist of glucagon-like peptide-1(7-36)amide in humans

The gastrointestinal hormone, glucagon-like peptide-1(7-36)amide (GLP-1) is released after a meal. The potency of synthetic GLP-1 in stimulating insulin secretion and in inhibiting glucagon secretion indicates the putative physiological function of GLP-1. In vitro, the nonmammalian peptide, exendin(9-39)amide [ex(9-39)NH2], is a specific and competitive antagonist of GLP-1. This in vivo study examined the efficacy of ex(9-39)NH2 as an antagonist of exogenous GLP-1 and the physiological role of endogenous GLP-1. Six healthy volunteers underwent 10 experiments in random order. In each experiment, a 30-min period of euglycemia was followed by an intravenous infusion of glucose for 150 min that established a stable hyperglycemia of 8 mmol/liter. There was a concomitant intravenous infusion of one of the following: (1) saline, (2) GLP-1 (for 60 min at 0.3 pmol . kg-1 . min-1 that established physiological postprandial plasma levels, and for another 60 min at 0.9 pmol . kg-1 . min-1 to induce supraphysiological plasma levels), (3-5) ex(9-39)NH2 at 30, 60, or 300 pmol . kg-1 . min-1 + GLP-1, (6-8) ex(9-39)NH2 at 30, 60, or 300 pmol . kg-1 . min-1 + saline, (9 and 10) GIP (glucose-dependent insulinotropic peptide; for 60 min at 0.8 pmol . kg-1 . min-1, with saline or ex(9-39)NH2 at 300 pmol . kg-1 . min-1). Each volunteer received each of these concomitant infusions on separate days. ex(9-39)NH2 dose-dependently reduced the insulinotropic action of GLP-1 with the inhibitory effect declining with increasing doses of GLP-1. ex(9-39)NH2 at 300 pmol . kg-1 . min-1 blocked the insulinotropic effect of physiological doses of GLP-1 and completely antagonized the glucagonostatic effect at both doses of GLP-1. Given alone, this load of ex(9-39)NH2 increased plasma glucagon levels during euglycemia and hyperglycemia. It had no effect on plasma levels of insulin during euglycemia but decreased plasma insulin during hyperglycemia. ex(9-39)NH2 did not alter GIP-stimulated insulin secretion. These data indicate that in humans, ex(9-39)NH2 is a potent GLP-1 antagonist without any agonistic properties. The pancreatic A cell is under a tonic inhibitory control of GLP-1. At hyperglycemia, the B cell is under a tonic stimulatory control of GLP-1.

Dynamic Structure Factor: An Introduction

The doubly differential cross-section for weak inelastic scattering of waves or particles by manybody systems is derived in Born approximation and expressed in terms of the dynamic structure factor according to van Hove. The application of this very general scheme to scattering of neutrons, x-rays and high-energy electrons is discussed briefly. The dynamic structure factor, which is the space and time Fourier transform of the density-density correlation function, is a property of the many-body system independent of the external probe and carries information on the excitation spectrum of the system.

The relation of the electronic structure factor to the density-density response function defined in linear-response theory is shown using the fluctuation-dissipation theorem. This is important for calculations, since the response function can be calculated approximately from the independent-particle response function in self-consistent field approximations, such as the random-phase approximation or the local-density approximation of the density functional theory. Since the density-density response function also determines the dielectric function, the dynamic structure can be expressed by the dielectric function.

5-sulfamoylorthanilic acids, a sulfonamide series with salidiuretic activity

A series of 4,N-disubstituted 5-sulfamoylorthanilic acids was synthesized by nucleophilic substitution reactions starting either from 2,4-dihalogeno-5-sulfamoylbenzenesulfonic acids or, in most cases, from phenyl 2,4-dihalogeno-5-sulfamoylbenzenesulfonates. The latter method is based on the relative stability of the phenoxysulfonyl group to nucleophiles, e.g., amines, phenols, and thiols, and the possibility of smooth hydrolytic or hydrogenolytic cleavage as a final step, with formation of the SO3H group. On evaluation of these compounds for salidiuretic activity in rats orally (po), and in dogs orally and intravenously (iv), a number of highly active substances was found; the best had a threshold dose of 0.02 mg/kg po in dogs. The results are given in tables, and the structure-activity relationships within the series are discussed. Besides the known effect of the phenoxy radical, an outstanding activating effect was shown by the butylsulfonyl and cycloalkylsulfonyl radicals and by the N-methylanilino radical in particular when they were located in the 4-position of the orthanilic acid molecule. The sulfanilic acid isomers corresponding to three of the most active compounds were synthesized and proved to be completely inactive in rats.

The contribution of the parallel and series elastic components to the dynamic properties of the rat tail artery under two different smooth muscle tones

The dynamic elastic modulus (Ed) and the coefficient of wall viscosity (eta w) of the tail artery of normotensive rats were determined as functions of the circumferential wall stress under quasistatic and dynamic conditions. The experiments were performed under strong smooth muscle activation induced by norepinephrine, and during relaxation induced by papaverine. The following results were obtained. 1. Ed and eta w increase with increasing wall stress. At a given wall stress, Ed is virtually independent of frequency while eta w decreases markedly with increasing frequency. This behaviour of eta w is called thixotropy or pseudoplasticity. 2. In the wall stress range from 5--60 kPa the values of Ed, and in the wall stress range from 60--140 kPa those of eta w obtained under smooth muscle activation and during relaxation are virtually identical. 3. In the relaxed smooth muscle, the phase angles between sinusoidal pressure and radius changes area virtually independent of the mean wall stress at all frequencies. In the low stress range, the phase angles are greater at low frequencies in the activated state than in the relaxed state, decrease with increasing wall stress, and are virtually identical to the values under papaverine at high wall stresses. At high frequencies no dependence of the phase angles on the mean wall stress can be seen.