A role for local calcium signaling in rapid synaptic partner selection by dendritic filopodia

Synapse elimination is an important process underlying the establishment of functional neuronal networks during development. Here, we tested the idea that neurons select among potential synaptic partners already during initial contact formation between dendritic filopodia and axons-well before mature synapses are established. We show that filopodia frequently make contact with axons, and while some contacts are selectively stabilized, many are short-lived. More specifically, we demonstrate that contacts with a certain population of GABAergic axons never get stabilized, indicating that filopodia already early on select between different types of axons. Local dendritic calcium transients that are independent of glutamate occur within seconds after contact formation, and their frequency is high where contacts become stabilized and low at short-lived contacts. Thus, filopodia are capable of choosing between potential synaptic partners well before a mature synapse is established.

[Clinical experience in the treatment of neovascular age-related macular degeneration with pegaptanib]

BACKGROUND

Intravitreal anti-VEGF therapy with Pegaptanib was effective in neovascular AMD in the VISION study. We report our experience with Macugen for the treatment of occult or minimally classic choroidal neovascularisation (CNV) due to age-related macular degeneration (AMD).

PATIENTS AND METHODS

35 eyes of 35 patients with occult CNV or minimally classic CNV due to neovascular AMD not eligible for PDT were treated with intravitreal injection of 0.3 mg Pegaptanib. An average of 2.74 injections per patient was administered. Before, and every 3 months after treatment, visual acuity, intraocular pressure measurement, angiography and OCT examinations were performed. One month after treatment only visual acuity, intraocular pressure measurement, and OCT examinations were performed. Visual acuity measurements and an eye examination were done on the first and second day after injection, after 4-6 weeks and at months 3 and 6.

RESULTS

Intravitreal Pegaptanib was well tolerated and we had no complications. Mean visual acuity was 0.38 +/- 0.23 at baseline, after one month 0.38 +/- 0.26, at 3 months it was 0.39 +/- 0.22 and at 6 months 0.41 +/- 0.26. OCT examinations showed a decrease in central retinal thickness from 277 microm to 254 microm. In 91.4 % of the eyes the visual acuity was stabilised or improved. No patient had an elevated intraocular pressure after 6 months.

CONCLUSIONS

Intravitreal therapy with Pegaptanib was safe and effective. The majority of patients showed a stabilisation in all the assessed parameters. In clinical practice unselective VEGF inhibition should be considered carefully for patients with high cardiovascular risk profile or thromboembolic events in the history.

Simultaneous imaging of morphological plasticity and calcium dynamics in dendrites

The structure and function of the nervous system are intricately connected. To investigate their relationship it is essential to image neuronal structure and function simultaneously with high spatio-temporal resolution. For this purpose, we describe here a two-step strategy. First, to visualize neurons and their entire dendritic arborization in neuronal tissue, we use ballistic delivery or single-cell electroporation of a fluorescent calcium indicator and a red fluorescent dye. Second, dual wavelength wide-field fluorescence microscopy or confocal microscopy enables imaging structural plasticity of dendrites (including filopodia and spines) and calcium dynamics together. We routinely apply this strategy to developing neurons in live tissue, but mature neurons can also be loaded and imaged as described. For labeling cells and setting up imaging equipment, approximately 2 h are required.

Endogenous brain-derived neurotrophic factor triggers fast calcium transients at synapses in developing dendrites

Brain-derived neurotrophic factor (BDNF) is involved in many aspects of the formation of functional neuronal networks. BDNF signaling regulates neuronal development not only globally, at the level of entire neurons or networks, but also at a subcellular level and with high temporal specificity; however, the spatiotemporal characteristics of intrinsic BDNF signaling are essentially unknown. Here, we used calcium imaging to directly observe intrinsic BDNF signaling in developing hippocampal neurons. We found that blocking intrinsic BDNF signaling with function-blocking BDNF antibodies (alphaBDNF) or K252-a reduced the frequency of spontaneously occurring fast and localized calcium rises in dendrites. Conversely, focal application of BDNF evoked fast and local dendritic calcium transients, which required activation of TrkB (tropomyosin-related kinase B) receptors as well as activation of voltage-gated sodium and calcium channels. Virus-mediated expression of PSD-95:CFP (postsynaptic density-95 tagged with cyan fluorescent protein) revealed that spontaneous local calcium transients occurred frequently at postsynaptic sites along the dendrite. The frequency of synaptically localized calcium transients was specifically reduced by blocking intrinsic BDNF signaling, whereas nonsynaptic calcium rises were not affected. Furthermore, focal BDNF delivery evoked localized and fast calcium elevations specifically at postsynaptic sites. Together, our results demonstrate that BDNF-dependent calcium signaling in developing hippocampal neurons is fast and occurs at synapses. These temporal and spatial characteristics of intrinsic BDNF signaling as well as its relative abundance renders BDNF an ideal signaling molecule in the establishment of specific synaptic connectivity and functional neuronal networks.

Kontinuierliche interscalenäre Plexusblockade bei einem dreijährigen Kind nach Armamputation - Ein Fallbericht

Amputations of extremities, especially in the childhood, impose high demands on the perioperative management. Apart from the intraoperative care of these children, the postoperative pain therapy has to do one's utmost in the avoidance of the development of phantom limb pain, which can, especially in the childhood, be associated with far reaching psychological consequences. We report the case of a 3-year old boy who had to undergo exarticualtion of his left arm due to an osteosarcoma of the humerus. The perioperative pain management was performed by a preoperatively placed interscalene catheter and infusion of 0.2 % ropivacaine. Within the first six days postoperatively complete pain relief could be ensured with this analgetic regimen.

Regulation of dendritic growth and plasticity by local and global calcium dynamics

The dendritic arbors of neurons are organized into unique spatial patterns that are well suited for their specific functions. Although the intracellular signaling pathways that determine dendritic arbor size and branching patterns during development are not completely understood, it is evident that neurotransmission-mediated elevation in intracellular calcium levels ([Ca2+]i) plays a major role. Recent advances in calcium imaging and genetic approaches have provided new insight into how calcium acts to regulate dendritic growth and remodeling. Global increases in [Ca2+]i that occur upon neuronal depolarization control dendritic arbor growth by regulating transcription. However, the detailed branching patterns of dendritic arbors are regulated by local calcium signaling. Calcium-induced calcium release (CICR) from intracellular stores acts to locally stabilize dendritic branches, presumably triggered by neurotransmission upon contact with newly established inputs. The effects of global and local increases in [Ca2+]i on dendritic structure are cell type- and age-dependent. Unraveling the signaling pathways evoked by local and global rises in [Ca2+]i that shape the developing dendritic arbor at each developmental stage remains challenging but highly important.

Local calcium transients regulate the spontaneous motility of dendritic filopodia

During development, dendrites, and in particular dendritic filopodia, undergo extensive structural remodeling, presumably to help establish synaptic contacts. Here, we investigated the role of calcium signaling in dendritic plasticity by simultaneously recording calcium dynamics and filopodial growth in rat hippocampal slice cultures. Local calcium transients occurred in dendritic filopodia and shafts, often at putative synaptic sites. These events were highly correlated with filopodial motility: comparatively rare when individual filopodia emerged from the dendrite, they became more frequent after filopodia started growing, finally causing them to halt. Accordingly, an experimental reduction of the frequency of local calcium transients elicited filopodial growth and, conversely, calcium uncaging reduced filopodial motility. Our observations suggest that low levels of local calcium transients facilitate filopodial outgrowth, whereas high levels inhibit the formation of filopodia and stabilize newly formed ones. This process may facilitate synapse formation and may serve as a homeostatic mechanism distributing synapses evenly along developing dendrites.

Two different heat shock transcription factors regulate immediate early expression of stress genes in Arabidopsis

In order to assess the specific functional roles of different plant heat shock transcription factors (HSFs) we have isolated T-DNA insertion mutants in the AtHsf1 and AtHsf3 genes of Arabidopsis thaliana. Complete and selective loss of the promoter binding activities of AtHSF1 or AtHSF3, verified by immunoprecipitation assays, had no obvious effects on the heat shock (HS) response in the individual mutant lines. Only hsf1(-) /hsf3(-)double mutants were significantly impaired in HS gene expression. In these plants the inability to form high-molecular-weight HSE-binding complexes correlates with a dramatic change in the kinetics of mRNA accumulation from all HSF target genes tested, including members of the Hsp100, Hsp90, Hsp70 and small Hsp families, and genes for two heat-inducible class B-HSFs. After prolonged HS, the amounts of most heat shock mRNAs expressed, except transcripts of Hsp18.2, reached approximately the same levels as in wild type plants. Our data indicate that AtHSF1 and AtHSF3 are key regulators of the immediate stress-induced activation of HS gene transcription, and consequently determine the kinetics of the negative feed back loop that is responsible for the transience of HS gene expression in wild type.

Heat stress-dependent DNA binding of Arabidopsis heat shock transcription factor HSF1 to heat shock gene promoters in Arabidopsis suspension culture cells in vivo

Using UV laser cross-linking and immunoprecipitation we measured the in vivo binding of Arabidopsis heat shock transcription factor HSF1 to the promoters of target genes, Hsp18.2 and Hsp70. The amplification of promoter sequences, co-precipitated with HSF1-specific antibodies, indicated that HSF1 is not bound in the absence of heat stress. Binding to promoter sequences of target genes is rapidly induced by heat stress, continues throughout the heat treatment, and declines during subsequent recovery at room temperature. The molecular mechanisms underlying the differences between Hsp18.2 and Hsp70 in the kinetics of HSF1/promoter binding and corresponding mRNA expression profiles are discussed.

Imaging calcium dynamics in the nervous system by means of ballistic delivery of indicators

The use of fluorescence-based calcium indicators has, over the years, unraveled important calcium-dependent mechanisms underlying neuronal function and development. However, difficulties associated with the loading of calcium indicators have limited their widespread use, particularly for the study of neuronal processing in the adult nervous system. Here, we show that in the central and peripheral nervous systems, populations of neurons and their processes, including dendritic spines and filopodia, can be labeled rapidly and efficiently by delivering calcium indicator-coated particles using a 'gene gun'. Importantly, neuronal labeling occurred both in vitro and in vivo, and across a wide range of ages and preparations. The labeled cells demonstrate spontaneous and evoked calcium transients, indicating that particle-mediated delivery is not deleterious to neuronal function. Furthermore, unlike loading with patch pipettes, cytoplasmic content is preserved following ballistic loading. This enables the study of calcium-dependent second messenger pathways without loss of signaling components. The ballistic delivery of calcium indicators thus opens up many new avenues for further exploration of the structure and function of the nervous system from single spines to neuronal networks.

Transmitter-evoked local calcium release stabilizes developing dendrites

In the central nervous system, dendritic arborizations of neurons undergo dynamic structural remodelling during development. Processes are elaborated, maintained or eliminated to attain the adult pattern of synaptic connections. Although neuronal activity influences this remodelling, it is not known how activity exerts its effects. Here we show that neurotransmission-evoked calcium (Ca(2+)) release from intracellular stores stabilizes dendrites during the period of synapse formation. Using a ballistic labelling method to load cells with Ca(2+) indicator dyes, we simultaneously monitored dendritic activity and structure in the intact retina. Two distinct patterns of spontaneous Ca(2+) increases occurred in developing retinal ganglion cells--global increases throughout the arborization, and local 'flashes' of activity restricted to small dendritic segments. Blockade of local, but not global, activity caused rapid retraction of dendrites. This retraction was prevented locally by focal uncaging of caged Ca(2+) that triggered Ca(2+) release from internal stores. Thus, local Ca(2+) release is a mechanism by which afferent activity can selectively and differentially regulate dendritic structure across the developing arborization.

Predicting blood-brain barrier permeability of drugs: evaluation of different in vitro assays

The ability of a drug to penetrate the blood-brain barrier (BBB) is essential for its use in the pharmaceutical treatment of CNS disorders. Five different in vitro methods to predict BBB permeability of drugs were compared and evaluated in the present study. All assays were performed with a consistent set of seven compounds and in the same physiological buffer to provide a basis for direct comparison of the results. Octanol-buffer and liposome-buffer partition coefficients were most conveniently obtained but failed to predict BBB permeability for certain drugs. The incorporation of drugs into lipid monolayers at the air-buffer interface was found to be a poor predictor of BBB permeability and was furthermore not considered suitable for screening due to the demanding experimental requirements. Permeability studies using Caco-2 cell monolayers provided a good correlation to an in vitro model of the BBB, which was based on primary cultured porcine brain capillary endothelial cells (PBCEC). However, differences in drug permeability between the intestine and brain derived cells were detected, limiting the advantages of the easy handling of the Caco-2 cell line compared to the more time-consuming primary culture of the BCEC.

Cell-type specific dendritic contacts between retinal ganglion cells during development

The extent of a neuron's dendritic field defines the region within which information is processed. The dendritic fields of functionally distinct ON and OFF center retinal ganglion cells (RGCs) form separate mosaics across the retina. Within each mosaic, neighboring dendritic fields overlap by a constant amount, sampling the visual field with the appropriate coverage. Contact-mediated lateral inhibition between neighboring RGCs has long been thought to regulate both the extent and overlap of dendritic fields during development. Here we show that dendro-dendritic contact exists between developing RGCs and occurs in a manner that would regulate the formation of ON and OFF mosaics separately. Dye-filled neighboring ON and OFF ferret alpha RGCs were reconstructed using multiphoton microscopy. At all neonatal ages examined, we observed dendro-dendritic contacts between RGCs of the same sign (ON/ON; OFF/OFF), but never between cells of opposite signs (ON/OFF). Terminal dendrites of one cell often touched a dendrite of its neighbor as they intersected. In some instances, the distal dendrite of one cell formed a fascicle with the proximal process of its neighbor. Alpha cells did not form contacts with neighboring beta cells of the same sign. Together, these observations suggest that dendro-dendritic contact between RGCs is cell-type specific. Dendritic contacts were observed even before the alpha cell arbors were completely stratified, suggesting that cell-cell recognition may take place early in their development. For each cell type, the relative overlap of dendritic fields was constant with age, despite a two-fold increase in field area. We suggest that dendro-dendritic contacts may be sites of intercellular signaling that could regulate local extension of dendrites to maintain the relative overlap of RGCs within a mosaic during development.

Progesterone receptor immunohistochemical quantitation compared with cytosolic assay: correlation with prognosis in breast cancer

Quantitation of estrogen and progesterone receptors (PR) represents the standard of care in the treatment of patients with breast cancer. Historically this was performed by cytosolic assay; current methods utilize immunohistochemical staining, which may be quantitated visually or by image cytometry. Formalin-fixed paraffin embedded sections from 95 breast carcinomas were immunostained with an avidin-biotin complex technique. steam antigen retrieval, and a monoclonal PR antibody (1/40 Biogenex). Nuclear immunostain was quantitated visually as the percentage of immunopositive nuclei, scored as 0 to 4. By image cytometry, the percentage of positively staining nuclear area (PPNA) was determined in 15 hpf using the CAS 200 Image Analyzer. Dextran-coated charcoal (DCC) ligand binding assay data were divided into negative (<10 fmol), low positive (10-50), or positive (>50). A statistically significant correlation was found between stage (P = 0.0001), the presence of nodal metastases (P = 0.0001), cytosolic assay (P = 0.036), image cytometry (P = 0.01), and disease-free survival. Only stage (P = 0.0001) and PR quantitation per cytosolic assay (P = 0.0001) correlated with overall survival. The method of choice for the assessment of PR hormone status in breast carcinomas is the DCC ligand binding assay. This method correlates with both survival and disease-free survival. Image cytometric quantitation of PR immunohistochemical staining correlates only with disease-free survival. The commonly used method of visual quantitation of PR immunostaining fails to relate either to survival or disease-free survival.

Human osteoblast-like cells phagocytose metal particles and express the macrophage marker CD68 in vitro

Periprosthetic osteolysis is a major cause of aseptic loosening in artificial joint replacement. It is assumed to occur in conjunction with the activation of macrophages. We have shown in vitro that human osteoblast-like cells, isolated from bone specimens obtained from patients undergoing hip replacement, phagocytose fine particles of titanium alloy (TiAlV). The human osteoblast-like cells were identified immunocytochemically by the presence of bone-specific alkaline phosphatase (BAP). With increasing duration of culture, a variable number of the osteoblastic cells became positive for the macrophage marker CD68, independent of the phagocytosis of particles, with a fine granular cytoplasmic staining which was coexpressed with BAP as revealed by immunodoublestaining. The metal particles were not toxic to the osteoblastic cells since even in culture for up to four weeks massively laden cells were vital and had a characteristic morphology. Cells of the human osteosarcoma cell line (HOS 58) were also able to phagocytose metal particles but had only a low expression of the CD68 antigen. Fluorescence-activated cell scanning confirmed our immunocytochemical results. Additionally, the cells were found to be negative for the major histocompatibility complex-II (MHC-II) which is a marker for macrophages and other antigen-presenting cells. Negative results of histochemical tests for tartrate-resistant acid phosphatase excluded the contamination by osteoclasts or macrophages in culture. Our observations suggest that the osteoblast can either change to a phagocytosing cell or that the phagocytosis is an underestimated property of the osteoblast. The detection of the CD68 antigen is insufficient to prove the monocytic lineage. In order to discriminate between macrophages and osteoblasts additional markers should be used. To our knowledge, this is the first demonstration of cells of an osteoblastic origin which have acquired a mixed phenotype of both osteoblasts and macrophages.

Axon regeneration in organotypic slice cultures from the mammalian auditory system is topographic and functional

In vitro models have frequently been employed to investigate the specificity of the formation of axonal projections during both development and regeneration. Such studies demonstrated pathway, target, and laminar specificity, yet they did not tackle the problem of topography. Here, we addressed the issue of regeneration of spatial specificity at the topographic level by lesioning a precisely organized projection from the auditory system of neonatal rats in organotypic slice culture and by analyzing regeneration capacity. Lesioning had no effect on the survival of axotomized neurons or the structure of the auditory nuclei. Anterograde and retrograde biocytin tracing demonstrated that the projection regenerated topographically at the supracellular level. Whole-cell patch-clamp recordings revealed that the regenerated projection was functional. Topographic regeneration was not impaired by blocking spike activity with tetrodotoxin or glycinergic transmission with strychnine. However, if lesioning was performed after the slices had been incubated for 1 week, regeneration capacity was lost despite good survival of neurons. The loss of the regeneration capacity in vitro occurs at a developmental stage that corresponds to the age when the capacity for axonal reorganization is lost in vivo. We conclude that the developmental processes occurring in vivo and in vitro are comparable in this system, which is why we think that essential aspects of the loss of regeneration capacity may be addressed with our culture model in the future.

Development of auditory brainstem circuitry. Activity-dependent and activity-independent processes

Despite its complexity, the neural circuitry in the auditory brainstem of vertebrates displays a fascinating amount of order. How is this order established in such a precise manner during ontogeny? In this review, we will summarize evidence for both activity-independent and activity-dependent processes involved in the generation of the auditory brainstem circuitry of birds and mammals. An example of activity-independent processes is the emergence of crude topography, which, most probably, is determined by molecular markers whose expression is genetically controlled. On the other hand, neuronal activity supports cell survival, affects dendritic and axonal growth, and influences fine tuning of maps. It appears that various types of neuronal activity, namely spontaneous versus acoustically evoked, bilateral versus unilateral, uncoordinated versus patterned, play a role during different aspects of development and cooperate with the activity-independent processes to ensure the proper formation of neuronal circuitry.

Development of glycinergic transmission in organotypic cultures from auditory brain stem

We investigated whether glycinergic transmission develops organotypically in auditory brain stem cultures. Slices of the medial nucleus of the trapezoid body and the lateral superior olive were incubated in medium with a raised extracellular K+ concentration. As in vivo, glycine receptor alpha1 subunit immunoreactivity increased and became clustered on somata and proximal dendrites. Together with organotypic expression of glycine transporter GLYT2, this indicates that molecular components of glycinergic synapses form properly. In contrast, glycinergic synaptic currents did not develop as in vivo: after 7 days in vitro they were still similar to those at the time of culture preparation. We suggest that for organotypic development of glycine receptors and transporters, Ca2+ influx due to elevated K+ is sufficient. The development of functional synaptic transmission, however, may require patterned electrical activity.

Development of a topographically organized auditory network in slice culture is calcium dependent

Inhibitory and excitatory connections of remarkably precise topographic order are characteristic features of the mammalian auditory system, particularly within the superior olivary complex (SOC). Little is known about the requirements for the correct development of these specific connections. Previous in vivo experiments have demonstrated a high expression of calcium-binding proteins in this system during development, pointing to the need for precise calcium regulation. Here, we have employed an organotypic slice culture from the above neuronal network and analyzed the requirements for the maintenance and development of this system in vitro. When slices from neonatal rats were incubated in standard culture medium for up to 7 days, we found no organotypic features. Only if 25 mM KCl was added to the culture medium, the cytoarchitecture of the nuclei, the neuronal morphology, and the specificity and topography of internuclear connections were indistinguishable from that in vivo. The addition of calcium channel blockers (MgCl2 and nifedipine) to the high-KCl medium reduced organotypicity drastically, indicating that a depolarization-induced increase of intracellular calcium is indispensable. Furthermore, the temporal course of the expression of the calcium-binding protein parvalbumin in culture under high KCl mimics that in vivo, demonstrating developmental processes during incubation. The need for calcium influx into neurons of this auditory network in vitro (which is not seen in other slice culture systems) strengthens the hypothesis that an optimal calcium concentration is exceptionally important in auditory neurons. The effect of KCl in the slice cultures may substitute for input activity regulating intracellular calcium in auditory neurons in vivo.

Distribution of the calcium-binding proteins parvalbumin and calretinin in the auditory brainstem of adult and developing rats

Parvalbumin (PV), calretinin (CR), and calbindin (CB) are calcium-binding proteins which are presumably involved in the regulation of the intracellular calcium concentration. Within the rat auditory system, CB is transiently expressed in several nuclei during the period of synapse refinement, indicating a specific function of CB during development, yet little is known in this regard about PV and CR. In order to gather more information about calcium-binding proteins during development, we analyzed the spatiotemporal distribution of PV and CR in the rat auditory brainstem using immunocytochemistry. In the adult, PV was heavily present in somata and neuropil of all nuclei and in fibers of all tracts. CR was found in somata of the cochlear nucleus and peripheral aspects of the inferior colliculus as well as in fibers extending into the superior olivary complex and the nuclei of the lateral lemniscus. The developmental expression of PV was characterized by a relatively late appearance in somata (at postnatal day 8), followed by a rapid increase to adult levels. In contrast, CR immunoreactivity was already strong two days before birth, yet the number and intensity of labeled neurons subsequently decreased and CR disappeared almost completely in the superior olivary complex, nuclei of the lateral lemniscus, and central aspects of the inferior colliculus. These data, together with those on CB, show that CR, CB, and PV are sequentially expressed during auditory brainstem development. They also suggest that the presence of the three proteins can be correlated with definite developmental stages.

Orientation and open-sea navigation in sea turtles

Loggerhead sea turtle hatchlings (Caretta caretta L.) emerge from underground nests, scramble to the sea and begin a transoceanic migration by swimming away from their natal beach and into the open ocean. Evidence suggests that hatchlings sequentially use three different sets of cues to maintain orientation during their initial migration offshore. While on the beach, hatchlings find the ocean by crawling towards the lower, brighter seaward horizon and away from the dark, elevated silhouettes of vegetation and dunes. Upon entering the ocean, turtles initially orient seawards by swimming into waves, which can be detected as orbital movements from under water. Laboratory experiments have demonstrated that turtles can transfer a course initiated on the basis of waves or visual cues to a course mediated by a magnetic compass. Thus, by setting a magnetic course on the basis of nearshore cues that indicate the seaward direction, hatchlings may continue on offshore headings after entering deep water beyond sight of land. Sea turtles may use the earth's magnetic field not only as a cue for compass orientation but also as a source of world-wide positional information. Recent experiments have demonstrated that loggerheads can detect subtle differences in magnetic field inclination and intensity, two geomagnetic features that vary across the surface of the earth. Because most nesting beaches and oceanic regions are marked by a unique combination of these features, these findings raise the possibility that adult sea turtles navigate using a bicoordinate magnetic map.

Role of echocardiography in the diagnosis of occult penetrating cardiac injury

OBJECTIVE

To determine the usefulness of early echocardiography in stable patients with penetrating wounds in proximity to the heart.

DESIGN

Retrospective chart review over a 1-year period.

SETTING

Urban level I trauma center.

PATIENTS

121 clinically stable patients with penetrating wounds in proximity to the heart underwent immediate echocardiography (ECHO). Those with evidence of pericardial effusion then underwent subxiphoid pericardial window (SPW), followed by a median sternotomy if blood was found.

RESULTS

Thirty patients had an ECHO that was positive and underwent immediate SPW. One patient with an initially negative ECHO deteriorated 5 hours after admission; a repeat ECHO was positive, and he also underwent SPW. In 16 of the 31 SPW performed, blood in the pericardial sac was confirmed. Of these 16, four had pericardial blood that cleared with irrigation and required no further intervention. The remaining 12 patients underwent exploration: 3 had injury to the pericardium only, 4 had injury to the right atrium, 3 had injury to the right ventricle, and 2 had injury to the left ventricle. All nine myocardial injuries required operative repair; all survived.

CONCLUSIONS

Using the protocol of early ECHO and selective pericardial window, no clinically significant injuries were missed. In all, 12 penetrating cardiac injuries were identified and repaired successfully. We have found early and aggressive work-up, as outlined herein, to be helpful in the successful treatment of occult cardiac injuries.

Perception of ocean wave direction by sea turtles

At the beginning of their offshore migration, hatchling sea turtles enter the ocean at night and establish a course away from land by swimming directly into oceanic waves. How turtles can detect wave direction while swimming under water in darkness, however, has not been explained. Objects in a water column beneath the surface of the ocean describe a circular movement as waves pass above. In principle, swimming turtles might, therefore, detect wave direction by monitoring the sequence of accelerations they experience under water. To determine whether loggerhead (Caretta caretta L.) and green turtle (Chelonia mydas L.) hatchlings can detect wave direction in this way, we constructed a wave motion simulator to reproduce in air the circular movements that occur beneath small ocean waves. Hatchlings suspended in air and subjected to movements that simulated waves approaching from their right sides attempted to turn right, whereas movements that simulated waves from the left elicited left-turning behavior. Movements simulating waves from directly in front of the turtles elicited little turning in either direction. The results demonstrate that hatchling sea turtles can determine the propagation direction of ocean waves by monitoring the circular movements that occur as waves pass above. Although sea turtles are the first animals shown to be capable of detecting wave direction in this way, such an orientation mechanism may be widespread among other transoceanic migrants such as fish and cetaceans.

DETECTION OF MAGNETIC INCLINATION ANGLE BY SEA TURTLES: A POSSIBLE MECHANISM FOR DETERMINING LATITUDE

For animals that migrate long distances, the magnetic field of the earth provides not only a possible cue for compass orientation, but a potential source of world-wide positional information. At each location on the globe, the geomagnetic field lines intersect the earth's surface at a specific angle of inclination. Because inclination angles vary with latitude, an animal able to distinguish between different field inclinations might, in principle, determine its approximate latitude. Such an ability, however, has never been demonstrated in any animal. We studied the magnetic orientation behavior of hatchling loggerhead sea turtles (Caretta caretta L.) exposed to earth-strength magnetic fields of different inclinations. Hatchlings exposed to the natural field of their natal beach swam eastward, as they normally do during their offshore migration. In contrast, those subjected to an inclination angle found on the northern boundary of the North Atlantic gyre (their presumed migratory path) swam south-southwest. Hatchlings exposed to an inclination angle found near the southern boundary of the gyre swam in a northeasterly direction, and those exposed to inclination angles they do not normally encounter, or to a field inclination found well within the northern and southern extremes of the gyre, were not significantly oriented. These results demonstrate that sea turtles can distinguish between different magnetic inclination angles and perhaps derive from them an approximation of latitude. Most sea turtles nest on coastlines that are aligned approximately north&shy;south, so that each region of nesting beach has a unique inclination angle associated with it. We therefore hypothesize that the ability to recognize specific inclination angles may largely explain how adult sea turtles can identify their natal beaches after years at sea.

ACQUISITION OF MAGNETIC DIRECTIONAL PREFERENCE IN HATCHLING LOGGERHEAD SEA TURTLES

During their natal migration, hatchling loggerhead sea turtles (Caretta caretta L.) establish courses towards the open ocean and maintain them after swimming beyond sight of land. Laboratory experiments have demonstrated that swimming hatchlings can orient using the earth's magnetic field. For the magnetic compass to function in guiding the offshore migration, however, hatchlings must inherit or acquire a magnetic directional preference that reliably leads them towards the open sea. On land, hatchlings find the ocean using light cues associated with the seaward horizon. To determine whether turtles might acquire a preference for a specific magnetic direction on the basis of such cues, we studied the magnetic orientation of turtles initially exposed to light from either magnetic east or west. Hatchlings that had been exposed to light in the east subsequently oriented eastward when tested in darkness, whereas those that had been exposed to light in the west swam westward. Reversing the magnetic field resulted in a corresponding shift in orientation, indicating that the turtles were orienting to the ambient magnetic field. These results demonstrate that light cues can set the preferred direction of magnetic orientation by loggerhead hatchlings. We therefore hypothesize that hatchlings initially establish a seaward course using visual cues available on or near land, then maintain the course using magnetic cues as they migrate into the open sea.

Gastrin-releasing peptide and cholecystokinin in the regulation of exocrine pancreatic secretion in dogs

Exocrine pancreatic secretion in conscious dogs is significantly stimulated by the intravenous application of small doses of gastrin-releasing peptide (GRP; 30 pmol x kg-1 x h-1). There is no increase of the GRP concentrations in peripheral blood which is also the case under physiological postprandial conditions. There is also no increase in the peripheral cholecystokinin (CCK) concentrations, in contrast to previous reports. Nevertheless other CCK-related mechanisms may play an important role, since the administration of the highly specific CCK receptor antagonist MK-329 causes a marked reduction of the GRP-induced exocrine pancreatic secretion.

Native fluorescence of the cervix uteri as a marker for dysplasia and invasive carcinoma

A non-invasive and non-destructive fluorescence technique developed recently for an in situ detection of melanomas has been applied for determining in vitro dysplasia and invasive carcinomas in the cervix uteri. The cervices uteri exhibit a fluorescence band with a peak at about 475 nm if excited with 365 nm. The fluorescence intensity increases concomitantly with the degree of dysplasia, ranging from 30 counts/100 ms (healthy) to approximately 200 counts per 100 ms (CIN 3). At the rim of a malignancy, the intensity is 250 counts/100 ms and higher and decreases towards the healthy region. In the tumor region, the intensity is about zero or very small, at the most. The naturally occurring chromophore being responsible for the fluorescence observed seems to be NADH.

Lymphocyte response to enterobacterial biostructures in seronegative spondarthritis: specific T-cell mediated immunity or non-specific polyclonal B-cell activation?

The proliferative response, as measured by thymidine uptake and the B-cell differentiation response, as measured by Ig secretion, have been studied in peripheral blood mononuclear cells obtained from patients with ankylosing spondylitis, Yersinia reactive arthritis, Klebsiella infections and healthy controls, following stimulation with enterobacterial biostructures.

Native fluorescence of platelets from patients with occlusive arterial disease

Healthy platelets exhibit a fluorescence band with a peak at 475 nm if excited at 360 nm. This peak increases first with the progression of occlusive arterial disease (OAD) followed by a decrease at an advanced stage. Concomitantly, a new fluorescence band at 445 nm will appear, which increases steadily with the progression of OAD. These findings can be explained by the oxidation of NADH (fluorescence at 475 nm) to NAD (445 nm) and support, thus, the assumption that oxidative processes are involved in the formation of OAD.

["Self-taming": an alternative to the prevention of succinylcholine-induced pain]

Muscle pain associated with single-bolus administration of suxamethonium is reported to be one of the common complications of this technique. Since suxamethonium is the most commonly used relaxant in our department and priming with nondepolarizing muscle relaxants is also reported to be linked with complications, while the literature concerning this problem is very contradictory, we wondered if the so-called "self-taming" method represents an alternative to pretreatment with nondepolarizing muscle relaxants. One hundred thirty-two patients (69 male, 63 female) were randomly allocated to three groups. Anesthesia was induced with thiopentone 7 mg/kg body weight. Group 1 (n = 44) was pretreated with 2 mg pancuronium bromide 3 min prior to full relaxation with suxamethonium 1.5 mg/kg. Group 2 (n = 43) received no pretreatment. Group 3 (n = 45) received 4 mg suxamethonium i.v. after induction. One minute later the remaining dose of suxamethonium was applied ("self-taming"). Muscle fasciculation and postoperative myalgia were verified by means of a score. Neuromuscular transmission was recorded on a monitor after controlled train-of-four stimulus and time of onset of neuromuscular blockade was measured. With regard to muscle fasciculation, postoperative pain, and onset of neuromuscular blockade, "self-taming" with suxamethonium yielded results identical to pretreatment with pancuronium bromide. It may therefore be considered as an alternative to pretreatment with nondepolarizing muscle relaxants.