Caribbean salinity anomalies contributed to variable North Atlantic circulation and climate during the Common Era.

Paleoceanographic reconstructions show that the strength of North Atlantic currents decreased during the Little Ice Age. In contrast, the role of ocean circulation in climate regulation during earlier historical epochs of the Common Era (C.E.

Response of the North Atlantic surface and intermediate ocean structure to climate warming of MIS 11.

Investigating past interglacial climates not only help to understand how the climate system operates in general, it also forms a vital basis for climate predictions. We reconstructed vertical stratification changes in temperature and salinity in the North Atlantic for a period some 400 ka ago (MIS11), an interglacial time analogue of a future climate. As inferred from a unique set of biogeochemical, geochemical, and faunal data, the internal upper ocean stratification across MIS 11 shows distinct depth-dependent dynamical changes related to vertical as well as lateral shifts in the upper Atlantic meridional circulation system.

PALEOCEANOGRAPHY. A warm and poorly ventilated deep Arctic Mediterranean during the last glacial period.

Changes in the formation of dense water in the Arctic Ocean and Nordic Seas [the "Arctic Mediterranean" (AM)] probably contributed to the altered climate of the last glacial period. We examined past changes in AM circulation by reconstructing radiocarbon ventilation ages of the deep Nordic Seas over the past 30,000 years. Our results show that the glacial deep AM was extremely poorly ventilated (ventilation ages of up to 10,000 years).

Palaeoceanographic implications of genetic variation in living North Atlantic Neogloboquadrina pachyderma.

The shells of the planktonic foraminifer Neogloboquadrina pachyderma have become a classical tool for reconstructing glacial-interglacial climate conditions in the North Atlantic Ocean. Palaeoceanographers utilize its left- and right-coiling variants, which exhibit a distinctive reciprocal temperature and water mass related shift in faunal abundance both at present and in late Quaternary sediments. Recently discovered cryptic genetic diversity in planktonic foraminifers now poses significant questions for these studies.

Digital light microscopy: prerequisite for optimum contrast enhancement and increase of resolution.

Since the reproducible production of microscope objectives was enabled by the lens calculations of Ernst Abbe in 1872, various attempts have been made to further increase the resolution of light microscopes. Apart from the improvements on the optical side, especially the introduction of fluorescence methods, the use of digital cameras connected to computers have brought us close to the theoretical limits of optical resolution. Due to improved speed and memory capacity of modern computers mathematical methods can be applied to stored three-dimensional (3D) sequences of digital images which, in addition to just contrast and edge enhancement, may result in the case of real 3D deconvolution, even in the visualisation of structures beyond the theoretical limitations of light optical resolution.

Tissue-specific neuro-glia interactions determine neurite differentiation in ganglion cells.

Guided formation and extension of axons versus dendrites is considered crucial for structuring the nervous system. In the chick visual system, retinal ganglion cells (RGCs) extend their axons into the tectum opticum, but not into glial somata containing retina layers. We addressed the question whether the different glia of retina and tectum opticum differentially affect axon growth.

Axonal versus dendritic outgrowth is differentially affected by radial glia in discrete layers of the retina.

Formation of neural cell polarity defined by oriented extension of axons and dendrites is a crucial event during the development of the nervous system. Ganglion cells of the chicken retina extend axons exclusively into the inner retina, whereas their dendrites grow into the outer retina. To analyze guidance cues for specific neurite extension, novel in vitro systems were established.

Photoreceptor differentiation analyzed by the novel monoclonal antibody 1G1.

In vertebrates, photoreceptor development has become a key model system to study mechanisms of cell differentiation. A still unresolved question is why photoreceptor maturation is retarded over an extended period of embryogenesis though photoreceptors are among the first cells born in the retina. We have generated the novel monoclonal antibody 1G1 which binds to outer photoreceptor segments of adult retinae of various species including chicken and rat.

Epithelial folding in vitro: studies on the cellular mechanism underlying evagination of thyrocyte monolayers.

Epithelial monolayers in suspension culture fold in a way which closely resembles epithelial evagination. We have used freshly isolated segments of porcine thyroid follicles to study the mechanism underlying this evagination process. Epithelial folding was accompanied by dramatic changes in cell shape: the cells elongated and apical cell surfaces widened, whereas the basal cell portions were narrowed to about 20% of their original width.

Neurothelin: amino acid sequence, cell surface dynamics and actin colocalization.

Neurothelin is a cell surface protein of chicken endothelial cells at the blood-brain barrier and also of pigment epithelial cells forming the blood-eye barrier. Peptide sequencing of affinity-purified neurothelin revealed that it is likely to be identical with the protein called HT7. It belongs to the immunoglobulin superfamily having two extracellular C2-type domains, a membrane spanning region and a cytoplasmic tail.

Norepinephrine and neuropeptide Y increase intracellular Ca2+ in cultured porcine aortic smooth muscle cells.

We used the fluorescent Ca2+ indicator Fura-2 in cultured porcine aortic smooth muscle cells (PASMC) to study effects of the sympathetic neurotransmitters norepinephrine (NE) and neuropeptide Y (NPY) on free intracellular Ca2+ (Cai). Both transmitters transiently increased intracellular Ca2+ in a concentration-dependent manner. Selective agonists and antagonists demonstrated that the NE-stimulated Cai increase is predominantly (if not exclusively) mediated by alpha 2-adrenoceptors, whereas the NPY response appears to be mediated by the peptide YY-insensitive Y3-like receptor subtype.

[N2O-supplemented intravenous anesthesia versus inhalation anesthesia. A comparative study of the sympathoadrenergic reaction and postoperative vigilance].

The aim of the present study was a comparison of the intraoperative sympathoadrenergic response and the postoperative vigilance of a propofol/alfentanil anaesthesia to a conventional isoflurane anaesthesia. 25 patients were admitted to the study undergoing septorhino surgery. Patients with continuous intravenous anaesthesia with propofol/alfentanil combined with nitrous oxide showed better haemodynamic conditions without an increase of blood pressure and catecholamines under laryngoscopy, intubation and surgical stimulation.

Development of hypertension in neuroblastoma during therapy: a case report.

A case of stage 4 neuroblastoma that developed excessive hypertension on day 120 of chemotherapy is presented. The tumor initially had responded well to chemotherapy; however, while the tumor mass decreased, plasma and urine catecholamines and the blood pressure increased. The plasma concentrations of noradrenaline, adrenaline, and dopamine increased to 26.

Terbutaline-induced desensitization of beta 2-adrenoceptor in vivo function in humans: attenuation by ketotifen.

Use of beta-adrenoceptor agonists in long-term treatment of patients with chronic asthma bronchiale or heart failure is of limited value because beta-adrenoceptor desensitization develops. The antiallergic drug ketotifen prevents beta-adrenoceptor agonist-induced desensitization of rat and human pulmonary and lymphocyte beta 2-adrenoceptors. In 10 healthy volunteers in a double-blind, placebo-controlled study, we investigated whether ketotifen also prevents beta-adrenoceptor agonist-induced desensitization of beta 1- and/or beta 2-adrenoceptor-mediated physiologic in vivo effects.

Effects of insulin-induced hypoglycemia on beta 2-adrenoceptor density and proliferative responses of human lymphocytes.

We studied the effects of insulin (0.1 IU/kg BW, iv)-induced hypoglycemia on lymphocyte beta 2-adrenoceptor function, lymphocyte subset distribution, and proliferative response to mitogen stimulation in 10 healthy volunteers. Thirty minutes after insulin injection plasma glucose levels were markedly decreased; concomitantly, plasma epinephrine levels had increased about 10-fold; plasma norepinephrine levels, however, increased only moderately.

Adrenaline and noradrenaline as possible chemical mediators in the pathogenesis of arteriosclerosis.

We studied the relationships between adrenaline and noradrenaline and factors associated with arteriosclerosis to determine whether catecholamines contribute to the atherogenetic process. We investigated the effects of adrenaline and noradrenaline on cultures of vessel wall cells from rats and analyzed plasma catecholamine levels in humans exposed to atherogenic risk factors, undergoing hemodialysis treatment or following myocardial infarction or stroke. I.

[Functional differentiation of the vascular endothelium in high risk pregnancies].

Endothelial cell functions regulating fetal hemodynamics and placental perfusion are modulated by metabolites of arachidonic acid, in particular derivatives of cyclooxygenase such as prostaglandins. We utilized an in vitro system to study the possible role of the vascular endothelium in the pathogenesis of chronic placental insufficiency. Cellular growth and prostaglandin metabolism were investigated in cultured umbilical vein endothelial cells from mothers exposed to risk factors such as smoking and diabetes mellitus during pregnancy.