Serum cytokine levels in neonates with congenital diaphragmatic hernia.

Cytokines play an important role in immune regulation and fetal lung development. The systemic inflammatory response in newborns with congenital diaphragmatic hernia (CDH) has not been characterized so far. We compared various concentrations of cytokines in serum from newborns with CDH and in healthy term neonates. We analyzed cytokine patterns of CDH newborns under extracorporeal membrane oxygenation (ECMO) and mechanical ventilation (MV).38 newborns with CDH were included: ECMO group (n=13) and non-ECMO group (n=25). Healthy term neonates served as controls (n=13). Serum samples were obtained prospectively after birth and during therapy.Concentrations of IFN-α, IL-3,-6,-7,-8,-10, MIP-1α,-1ß and TNF-α in serum of newborns with CDH were higher than in umbilical cord blood of term neonates. Infants with severe CDH requiring ECMO therapy had higher postnatal IL-8,-10, and MIP-1α levels than newborns with milder disease in the non-ECMO treated group. IL-10 progressively decreased during the first 3 days following birth under ECMO. In contrast, the chemokine MIP-1α remained elevated during ECMO therapy compared to mechanically ventilated CDH newborns.The pattern of cytokines in the serum of newborns with CDH showed significant elevations compared to term neonates. Our findings indicate that CDH is associated with systemic inflammatory response immediately after birth. ECMO and MV show a similar increase of IL-1α and IP-10 in CDH newborns assuming a persistent pulmonary inflammatory reaction irrespective of the conducted treatment.

Implication of pulse oxymetry screening for detection of congenital heart defects.

BACKGROUND: In newborns congenital heart defects can take an asymptomatic course, causing a diagnostic gap in the routine examination. Therefore pulsoxymetric screening is under discussion, as it could close this diagnostic gap. PATIENTS AND METHODS: Non-invasive postductal peripheral oxygen saturation assessment was carried out in 3 364 term neonates, 6-36 h of age, in 2008. In asymptomatic neonates with values > or = 95%, no further steps were applied. In those with values between 90% and 94% and no clinical abnormalities, a check-up was carried out 4-6 h later. Echocardiography was performed when the initial value was below 90% or persisted < 95 %. RESULTS: A total of 18 (0.5%) abnormal pulse oximetry values requiring echocardiographic investigation were found in the 3 364 neonates examined. 9 congenital heart defects that had not been recognized prenatally were diagnosed. 4 of these children were also found to have anomalies at the clinical examination. Persistent fetal circulation was noted in 2 of the neonates.In addition neonatal infections has been detected in 7 newborns. 1 neonate with stenosis of the aortic isthmus and 1 with pulmonary stenosis were missed in the screening program, with pulse oximetry saturation levels >95%. These data represent a sensitivity of 82% and a specificity of 99.9%, with a positive predictive value of 50% and a negative predictive value of 99.9%. CONCLUSIONS: Together with the clinical examination, pulse oximetry in neonates is a screening method that has high levels of sensitivity and specificity for early diagnosis of congenital heart defects. The risk-benefit profile may favour pulse oximetry to be standardized and universally used.

Use of a sound-based vibratome by leaf-cutting ants.

Leaf-cutting ants harvest fresh vegetation that they then use as food for symbiotic fungi. When cutting leaf fragments, the ants produce high-frequency vibrations with a specialized organ located on the gaster. This stridulation behavior is synchronized with movements of the mandible, generating complex vibrations of the mandibles. The high vibrational acceleration of the mandible (up to three times the gravitational force at peak acceleration at about 1000 hertz) appears to stiffen the material to be cut. An identical effect is achieved when soft material is sectioned with a vibratome. This hypothesis is supported by experiments simulating the cutting process with vibrating isolated mandibles: When tender leaves were cut, the vibration of the mandible reduced force fluctuations and thus permitted a smoother cut to be made.

Fast trap jaws and giant neurons in the ant odontomachus.

Ants of the ponerine genus Odontomachus use a trap jaw mechanism when hunting fast prey. When particular trigger hairs, located on the inner edge of the mandibles, are touched by prey, the jaws close extremely rapidly and trap the target. This trap jaw response lasts only 0.33 to 1 millisecond. Electrophysiological recordings demonstrated that the trigger hairs function as mechanoreceptors. Associated with each trigger hair are large sensory cells, the sensory axons of which measure 15 to 20 micrometers in diameter. These are among the largest sensory neurons, and their size implies that these axons conduct information very rapidly.

Honeybee navigation: nature and calibration of the "odometer".

There are two theories about how honeybees estimate the distance to food sources. One theory proposes that distance flown is estimated in terms of energy consumption. The other suggests that the cue is visual, and is derived from the extent to which the image of the world has moved on the eye during the trip. Here the two theories are tested by observing dances of bees that have flown through a short, narrow tunnel to collect a food reward. The results show that the honeybee's "odometer" is visually driven. They also provide a calibration of the dance and the odometer in visual terms.

Antennal neuropile in the brain of the crayfish: morphology of neurons.

The cellular composition of the antennal neuropile of the crayfish is described. As a context for this work the distribution of neuronal cell bodies throughout the supraoesophageal ganglion (brain) is also described. The neuronal cell bodies in the brain are concentrated in 19 distinct clusters. Three paired clusters are located on the dorsal side of the brain, four paired and one midline cluster bend around the brain laterally and frontally respectively. Fewer than ten somata lie outside of these clusters. The antennal neuropile is composed of primary afferent terminals, efferents, and projecting and local interneurons. The structures of individual neurons of all four types were determined by filling them with Lucifer yellow, and an overview of the neuropile structure was obtained with cobalt backfills of selected nerves. The antennal afferents are concentrated in four main tracts that run medially in the outer layer of the antennal neuropile. Up to 11 orthogonal side branches occur at equal distances (25-35 microns) along the main branches and penetrate the neuropile. The efferents contribute very thin dendrites to the antennal neuropile. The majority of the neuronal mass of the antennal lobe consists of projecting and local interneurons. The branching pattern of the interneurons within the antennal neuropile also shows an orthogonal arrangement of main branches and higher-order branches. Thus the antennal neuropile displays a strong geometrical regularity: Main processes of all four types of neurons run in bundles the length of the long axis of the neuropile (lateral to medial inside the brain) giving rise to orthogonal side branches at regular intervals. This branching pattern leads to a striped appearance of the antennal lobe.

Interneurons in the tritocerebrum of the crayfish.

In isolated head preparations of the freshwater crayfish Orconectes limosus 268 local and projecting interneurons with branches in the tritocerebrum have been penetrated with glass microelectrodes and characterized for their sensory inputs. Using 3 criteria (sensory modality, site of receptors, response type of interneurons), the interneurons found were divided into 16 classes. The interneurons were either unimodal mechanoreceptive (89%) or bimodal (9% responding to mechanical and chemical stimuli, 2% responding to mechanical and visual stimuli). No trimodal interneurons were found. Within each modality the neurons received mostly bilateral input (70% of all interneurons responding to antennal stimulation, 84% of all chemosensitive interneurons). If the input was lateralized it was more often ipsilateral. The types of interneuronal responses evoked by sensory stimulation were: neurons that were exclusively excited (84%), those that were exclusively inhibited (10%), those that were excited or inhibited depending on the modality or laterality of the stimulus (6%), those showing long lasting excitatory aftereffects (3%), and those showing excitation or inhibition upon identical stimulation depending on the state of the neurons while being stimulated (1%). Interneurons that responded to mechanical antennal stimulation responded best either to low (10 Hz) or to high (100 Hz) stimulus frequencies. Six neurons responded best to a certain phase relationship between the movements of both antennal flagellae.

Honeybee waggle dance: recruitment success depends on the dance floor

The waggle dance of the honeybee Apis mellifera, used to recruit nestmates to a food source, takes place on the surface of the combs in the dark hive. The mechanism of information transfer between dancer and follower bees is not entirely understood. The results presented here reveal a novel factor that must be brought into any consideration of this mechanism, namely that the nature of the floor on which the bees dance has a considerable influence on the recruitment of nestmates to a food source. Dancers on combs with open empty cells recruit three times as many nestmates to a food source as dancers on capped brood cells.

Transmission of vibration across honeycombs and its detection by bee leg receptors

Vibration of the rims of open cells in a honeycomb, applied in the plane of the comb face, is transmitted across the comb. Attenuation or amplification of the vibratory signal depends on its frequency and on the type of comb. In general, framed combs, both large and small, strongly attenuate higher frequencies, whereas these are amplified in small open combs. The very poor transmission properties of the large framed combs used in commercial hives may explain the bees' habit of freeing an area of comb from the frame in those areas used for dancing. Extracellular electrical recordings from the leg of a honeybee detect large action potentials from receptors that monitor extension of the tibia on the femur. Measurements of threshold displacement amplitudes show these receptors to be sensitive to low frequencies. The amplification properties of unframed combs extend the range of these receptor systems to include frequencies that are emitted by the bee during its dance, namely the 15 Hz abdomen waggle and 250 Hz thorax vibration.

Functional morphology of the subgenual organ of the carpenter ant.

Using light microscopy, confocal microscopy, electron microscopy and histochemistry, the subgenual organ (SGO) of an ant, Camponutas ligniperda, is investigated. Sensory units and attachment cells together enclose a large extracellular cavity, which is filled by acid mucopolysaccharides, as revealed by staining with ruthenium red. Due to this cavity, the whole SGO has the shape of a deformed sphere and the scolopidia exhibit a distribution of angles between 0 degrees and 60 degrees with the tibial long axis (as is shown by phalloidin-rhodamin staining of the actin filaments of the scolopale, viewed in situ by laser scanning confocal microscopy). The subgenual organ is innervated by a branch of the tibial nerve, which splits within or shortly distal to the femur-tibia joint. The other features of the SGO of Camponotus ligniperda are similar as in other insects: the SGO of Camponotus ligniperda contains about 35 scolopidial sensilla; it is fixed to the subgenual nerve on its proximal end, by its attachment cells to the opposite part of the cuticle; the fixation by the attachment cells is accomplished by a vast quantity of cytoplasmic microtubules; the construction of the sensory units is the same as in other mononematic scolopidial organs. The role of the extracellular lumen inside the organ and the special shape of the SGO of Camponotus ligniperda in mechanical transmission is discussed.

Individual versus social pathway to honeybee worker reproduction (Apis mellifera): pollen or jelly as protein source for oogenesis?

Honeybee workers, Apis mellifera, can reproduce in queenless colonies. The production of queen-like pheromones may be associated with their reproductive activity and induce nestmates to respond by feeding them. Such frequent trophallaxis could supply their protein needs for oogenesis, constituting a social pathway to worker reproduction. However, some individuals can develop ovaries without producing queen pheromones. The consumption of protein-rich pollen could be an alternative solitary pathway for them to satisfy this dietary requirement. In order to investigate the way in which workers obtain proteins for oogenesis, we created orphaned worker groups and determined ovarian and pheromonal development in relation to pollen consumption of selected workers. Individuals that did not consume pollen had significantly more developed ovaries and produced significantly more queen mandibular pheromone than workers that fed directly on pollen. Our results suggest that workers producing queen-like secretions are fed trophallactically. However, reproductive workers that lacked queen pheromones had consumed little or no pollen, suggesting that they also obtained trophallaxis. Although pollen consumption might contribute to sustaining oogenesis, it does not appear to be sufficient. Trophallaxis as a means of obtaining proteins seems to be necessary to attain reproductive status in queenless honeybee colonies.

[New guidelines for the assessment of bioavailability and bioequivalence]. / Neue Richtlinien für die Beurteilung der Bioverfügbarkeit/Bioäquivalenz.

Bioavailability and bioequivalence studies are essential in the clinical development of medicinal products and the optimization of pharmaceutical forms. Bioavailability means the rate and extent to which the active substance or active moiety is absorbed from a pharmaceutical form and becomes available at the site of action. In practice, drug concentration-time courses are measured in the systemic circulation, and the area under the curve (AUC) as well as the observed maximum concentration (C(max)) are determined. Products are considered bioequivalent if their bioavailabilities after administration of the same molar doses are similar to such a degree that their effects, with respect to both efficacy and safety, will be essentially the same and thus, there are no relevant differences in terms of AUC and C(max). In 2002 a revised version of the 'Note for Guidance on the Investigation of Bioavailability and Bioequivalence' came into effect (CPMP/EWP/QWP/1401/98). Relevant changes in comparison to the previous version are: request for GLP-compliant bioanalytical measurements; for long half-life drugs a truncated AUC is acceptable; acceptance criteria for bioequivalence assessment and requirements for a waiver of bioequivalence studies were further specified. In this context the Biopharmaceutics Classification System (BCS) seems appropriate to decide whether in special cases of rapidly dissolving solid oral dosage forms a biowaiver may be granted or not. Products not considered critical in this matter are medicinal products for which the formulation does not affect the rate and extent of absorption, i. e. bioavailability, of the active moiety. Highly soluble (and highly permeable) drugs (BCS class I) are such candidates. Comprehensive state-of-the-art guidance on the design, conduct and analysis of bioavailability and bioequivalence studies is given in the current European guideline.

Ultrastructure and mechanical properties of an insect mechanoreceptor: stimulus-transmitting structures and sensory apparatus of the cercal filiform hairs of Gryllus.

1. The following features of the cercal filiform hairs of the cricket Gryllus were investigated: (a) the ultrastructure and geometrical peculiarities of the various auxiliary structures in the region of the hair base, as well as those of (b) the stimulus-receiving outer segment of the dendrite (including the tubular body), and (c) the mechanical properties (directionality and linearity and frequency dependence of mobility) of the hair. 2. When stimulated by vibrations of the medium, the filiform hairs show regular or irregular oscillations depending on stimulus intensity. At higher stimulus intensities (xi > congruent to 100 microns at 100 Hz) the hairs flutter irregularly in various directions, at somewhat lower intensities preferentially in the plane of best mobility in even lesser intensities in the plane of stimulus vector. In the plane ob best mobility the maximal angle of deflection from the resting position is 5.3 +/- 1.4 degrees. 3. The dependence of hair mobility on stimulus frequency was tested in the range 20-1000 Hz. Best mobility was found in the range 100-200 Hz. 4. The directional characteristic of hair mobility has the form of a figure eight. Hairs can be grouped into three classes on the basis of direction (with respect to the long axis of the cercus) of best mobility: parallel (L-hairs), transverse (T-hairs), and diagonal (D-hairs). 5. The plane of best mobility corresponds with the plane symmetry of the hair base. The hair can be deflected furthest from the resting position in the direction of a cuticular peg at the hair base, which projects toward the lumen of the hair and marks the flat side of the tubular body within the terminal dendrite segment. Deflection of the hair shaft in the opposite direction is limited by a fibrous cushion, which exerts a counter-pressure. When the hair is deflected, the cuticular peg causes deformation of the tubular body. 6. The direction of best mobility of the hair is the direction in which the sensory cell is depolarized; the direction of depolarization can thus be determined entirely by morphological criteria.

Recruitment of honeybees to non-scented food sources.

Small groups of honeybees (five to nine individuals) were trained to forage at feeders 150 m, 300 m and 800 m from an observation hive. Their behaviour in the hive and at the feeder was recorded by observers that maintained continuous radio contact with one another. At low concentrations of sugar in the feeder (0.5 mol x l(-1)) foragers do not dance in the hives, their flights to the feeder are often undertaken alone, they land immediately after arrival at the site and no recruits from the hive landed on the feeder during 30 h of observation. Raising the concentration of sugar in the feeder to 2 mol x l(-1) leads to vigorous dancing by the foragers and the gradual (over 10-15 min) synchronisation of their flights so that they arrive in groups of up to five bees at the feeder and undertake circular "buzzing" flights before landing. Such behaviour of the foragers is associated with the appearance of recruits which were never seen to fly around the feeder and land alone or before the foragers. Recruits typically circle the feeder together with foragers and land with them or continue their circling flights to land about 10 s later. While circling the feeder recruits, but not foragers, will fly after a moving lure if the presentation of the lure is accompanied by the release of geraniol scent. We propose that recruits that have witnessed a waggle dance are unlikely to find a non-scented feeder unless the foragers continue their flights to that feeder and provide supplementary visual and/or olfactory cues, at least in the vicinity of the feeder. We propose that the synchronisation of the flights of foragers and their behaviour at the feeding site is a strategy designed to overcome a navigational gap in the recruiting process in which the dance can indicate the general area of a food source but not the precise position of a highly localised site.

Hydrodynamic orientation of crayfish (Procambarus clarkii) to swimming fish prey.

Reversibly blindfolded crayfish (Procambarus clarkii) react to small swimming fish (Astyanax fasciatus mexicanus) approaching or passing nearby with antennal and cheliped movements and body turns (Fig. 3). We studied the accuracy and dynamics of crayfish orientation responses to the previously analyzed hydrodynamic disturbances caused by the fish, mostly produced by tail flicks. Antennal and cheliped movements started slightly before the onset of turning responses (Fig. 4). Antennal sweeps were performed most rapidly. 50% of the appendage sweeps resulted in contacts with the fish (Fig. 5). Most turns were directed toward the stimulus (Fig. 6). Response amplitudes increased with increasing stimulus angle. Turns were accurate for small stimulus angles, but smaller than expected for larger ones. Sweeps of ipsilateral antennae and chelipeds were generally directed backwards, while those of contralateral appendages were smaller and directed forwards. The amplitudes of appendage sweeps first increased with increasing stimulus angle and then decreased again for more caudal stimulus directions. Lateral stimuli (60 degrees-120 degrees) from opposite sides were usually significantly distinguished. The amplitudes of the different elements of orientation behaviour were highly correlated with each other, indicating that they were directed by the same sensory input.

Comb-wax discrimination by honeybees tested with the proboscis extension reflex.

We used the proboscis extension reflex of honeybees to test their ability to discriminate between comb waxes of different ages (wax scales, 1-week-old wax, 2- to 3-year-old wax, 8- to 10-year-old wax). Such waxes differ in their chemical composition, and an ability to discriminate between them may aid the orientation of the bees in the nest. To train the bees, we used whole extracts of waxes and four different fractions of the whole extract based on different elutions of solid-phase extractions (extract I, fraction A eluted with hexane and fraction B with diethylether; extract II, fraction B further subdivided into fraction C by elution with isopropylchloride and fraction D by elution with diethylether). In a differential training regime (six learning and six test trials) with whole extracts or with the different fractions, we paired one type of wax with a reward and another with no reward. The bees learned to discriminate between all tested pairs of whole extracts. The two subfractions (fractions A and B) gave different results: the bees could discriminate between waxes of different ages when fraction B was used but not when fraction A was used. A further subdivision of fraction B into fractions C and D showed that only fraction D contained the elements that enabled bees to discriminate between old and new wax. Fraction D makes up only 5?8 % of the total wax mass and contains hydroxy alkyl esters (5?6 % of the total wax mass), primary alcohols (0.3?0.5 % of the total wax mass) and acids (0.06?1. 0 % of the total wax mass). Fractions A and C (together forming 62?64 % of the total wax mass), which consist of unbranched and branched aliphatic hydrocarbons and alkyl esters, could not be discriminated by the bees. The remaining wax mass (25?29 %) was eluted with a mixture of chloroform, methanol and water (13:5:1) as fraction E.

Behaviour-locked signal analysis reveals weak 200-300 Hz comb vibrations during the honeybee waggle dance.

Waggle-dancing honeybees produce vibratory movements that may facilitate communication by indicating the location of the waggle dancer. However, an important component of these vibrations has never been previously detected in the comb. We developed a method of fine-scale behavioural analysis that allowed us to analyze separately comb vibrations near a honeybee waggle dancer during the waggle and return phases of her dance. We simultaneously recorded honeybee waggle dances using digital video and laser-Doppler vibrometry, and performed a behaviour-locked Fast Fourier Transform analysis on the substratum vibrations. This analysis revealed significantly higher-amplitude 200-300 Hz vibrations during the waggle phase than during the return phase (P=0.012). We found no significant differences in the flanking frequency regions between 100-200 Hz (P=0.227) and 300-400 Hz (P=0.065). We recorded peak waggle phase vibrations from 206 to 292 Hz (244+/-28 Hz; mean +/- s. d., N=11). The maximum measured signal - noise level was +12.4 dB during the waggle phase (mean +5.8+/-2.7 dB). The maximum vibrational velocity, calculated from a filtered signal, was 128 microm s(-)(1) peak-to-peak, corresponding to a displacement of 0.09 microm peak-to-peak at 223 Hz. On average, we measured a vibrational velocity of 79+/-28 microm s(-)(1) peak-to-peak from filtered signals. These signal amplitudes overlap with the detection threshold of the honeybee subgenual organ.

Comparison of directional selectivity in identified spiking and nonspiking mechanosensory neurons in the crayfish Orconectes limosus.

We have recorded electrical activity from two identified synaptically coupled mechanosensory interneurons in the abdominal nervous system of the crayfish Orconectes limosus and have studied their responses to constant-velocity water-jet stimuli presented from different directions. The two neurons, the ascending caudal photoreceptor (CPR) and the local directionally selective neuron, responded preferentially to stimuli delivered ipsilaterally to their dendritic input regions. Both neurons featured responses consisting of a phasic excitatory "on" response and a tonic depolarizing plateau. The different response components showed various degrees of directional selectivity: The initial "on" peak of the response was the least sensitive and the plateau was the most sensitive to stimulus direction. The CPR showed a sharp cut-off in responsiveness to contralateral stimuli, whereas the local directionally selective neuron showed a more gradual decrease in its directional responsiveness. This difference is a consequence of the feed-forward lateral inhibition that the local directionally selective neuron exerts on the CPR and of the threshold for initiation of action potentials in the CPR. A comparison of the spiking response of the CPR with its generator potential shows that the number and frequency of action potentials are a more sensitive indicator of directional preference than the generator potential response. The directional characteristic of the CPR is discussed as a filter matched to a specific spatial aspect of biologically relevant water movements.

Visual constraints in foraging bumblebees: flower size and color affect search time and flight behavior.

In optimal foraging theory, search time is a key variable defining the value of a prey type. But the sensory-perceptual processes that constrain the search for food have rarely been considered. Here we evaluate the flight behavior of bumblebees (Bombus terrestris) searching for artificial flowers of various sizes and colors. When flowers were large, search times correlated well with the color contrast of the targets with their green foliage-type background, as predicted by a model of color opponent coding using inputs from the bees' UV, blue, and green receptors. Targets that made poor color contrast with their backdrop, such as white, UV-reflecting ones, or red flowers, took longest to detect, even though brightness contrast with the background was pronounced. When searching for small targets, bees changed their strategy in several ways. They flew significantly slower and closer to the ground, so increasing the minimum detectable area subtended by an object on the ground. In addition, they used a different neuronal channel for flower detection. Instead of color contrast, they used only the green receptor signal for detection. We relate these findings to temporal and spatial limitations of different neuronal channels involved in stimulus detection and recognition. Thus, foraging speed may not be limited only by factors such as prey density, flight energetics, and scramble competition. Our results show that understanding the behavioral ecology of foraging can substantially gain from knowledge about mechanisms of visual information processing.

Phase reversal of vibratory signals in honeycomb may assist dancing honeybees to attract their audience.

Forager honeybees dancing on the comb are able to attract dance-followers from distances across the comb that are too remote for tactile or visual signals to play a role. An alternative signal could be the vibrations of the comb at 200-300 Hz generated by dancing bees but which, without amplification, may not be large enough to alert remote dance-followers. We describe here, however, an unexpected property of honeycomb when it is subjected to vibration at around 200 Hz that would represent an effective amplification of the vibratory signals for remote dance-followers. We find that, at a specific distance from the origin of an imposed vibration, the walls across a single comb cell abruptly reverse the phase of their displacement and move in opposite directions to one another. Behavioural measurements show that the distance from which the majority of remote dance-followers are recruited coincides with the location of this phase-reversal phenomenon relative to the signal source. We propose that effective signal amplification by the phase-reversal phenomenon occurs when bees straddle a cell across which the phase reversal is expressed. Such a bee would be subjected to a situation in which the legs were moving towards and away from one another instead of in the same direction. In this manner, remote dance-followers could be alerted to a dancer performing in their vicinity.