Syringomyelie oder Tumor medullae?

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Anhangbemerkung

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Natriuretic action of central angiotensin II in conscious rats

The effects of intracerebroventricular (i.c.v.) injections of angiotensin II (ANG II, 10 pg, 100 pg and 10 ng) on renal sodium excretion were investigated in conscious rats instrumented with a chronic urethral catheter. ANG II increased renal sodium excretion dose-dependently with a threshold i.c.v. dose of 10 pg. Only after the highest dose was a concomitant increase in arterial blood pressure and urinary flow observed. The ANG II-induced natriuresis began within 5 min of the i.c.v. injection and lasted for more than 1 h. The angiotensin receptor antagonist saralasin (1 ng, i.c.v.) largely prevented the natriuretic effect of i.c.v. injected ANG II (100 pg). Our results lend further support to the hypothesis that brain ANG II by its potent natriuretic actions may be instrumental in central osmotic control.     

Diode laser thermokeratoplasty – first clinical experience Erste klinische Erfahrungen*,**

Purpose: Pulsed holmium lasers are currently used to correct hyperopia by means of laser thermokeratoplasty (LTK). Series of μs laser pulses are applied with a high repetition rate to induce shrinkage of corneal collagen fibers. The pulsed energy application results in intrastromal temperature peaks of up to 200 °C. A continuously emitting laser diode can – as we demonstrated recently in an invivo study on minipigs – be used for LTK and may be of advantage because the temperature rise is more steady. The aim of this study was to examine the safety, amount, and stability of hyperopic correction of diode LTK on blind human eyes.     

Identification of the substrate binding region of vesicular monoamine transporter-2 (VMAT-2) using iodoaminoflisopolol as a novel photoprobe

Monoamines, such as serotonin, dopamine, and norepinephrine, are sequestered into synaptic vesicles by specific transporters (vesicular monoamine transporter-2; VMAT2) using energy from an electrochemical proton gradient across the vesicle membranes. Based on our previous studies using photoaffinity-labeling techniques in characterizing the VMAT2-specific ligands ketanserin and tetrabenazine, this study describes the synthesis and characterization of a fluorenone-based compound, iodoaminoflisopolol (IAmF), as a photoprobe to identify the substrate binding site(s) of VMAT2. Using vesicles prepared from rat VMAT2 containing recombinant baculovirus-infected Sf9 cells, we show the inhibition of [3H]5-hydroxytryptamine (5-HT) uptake and [3H]dihydrotetrabenazine (TBZOH) binding by aminoflisopolol and iodoaminoflisopolol. The interaction of [125I]IAmF with VMAT2 is highly dependent on the presence of ATP and an intact proton gradient. We report a simple and novel method to distinguish between a ligand and substrate using classic compounds such as [3H]5-HT and [3H]TBZOH by incubating the compound with the vesicles followed by washes with isotonic and hypotonic solutions. Using this method, we confirm the characterization of IAmF as a novel VMAT2 substrate. Sf9 vesicles expressing VMAT2 show reserpine- and tetrabenazine-protectable photolabeling by [125I]IAmF. [125I]IAmF photolabeling of recombinant VMAT2, expressed in SH-SY5Y cells with an engineered thrombin site between transmembranes 6 and 7, followed by thrombin digestion, retained photolabel in a 22-kDa fragment, indicating that iodoaminoflisopolol binds to the C-terminal half of the VMAT2 molecule. Thus, IAmF possesses a unique combination of VMAT2 substrate properties and a photoprobe and is, therefore, useful to identify the substrate binding site of the vesicular transporter.     

Acute interstitial pancreatitis in the rat induced by excessive doses of a pancreatic secretagogue

Summary Conscious rats were infused via a jugular vein catheter with 5×10^–6 g/kg/h caerulein for periods up to 24 h. On macroscopic inspection a progressive interstitial oedema is seen to develop in the pancreas, from one hour of infusion on and is most marked at twelve hours. This oedema is largely reabsorbed after 24 h treatment, but the pancreas is considerably indurated by this time. Serum amylase levels increase consistently to reach a tenfold elevation above controls after three, six or twelve hours infusion. Premature fusion of condensing vacuoles and secretory granules leads to formation of large vacuoles in the cytoplasm of exocrine pancreatic cells. These vacuoles fuse with the lateral and basal plasma membrane and realease their content into the extracellular space. Regular discharge of zymogen granules at the cell apex into the duct system does not occur. Vacuole formation is associated with cytoplasmic destruction of the pancreatic cells. The rate of protein synthesis decreases consistently as a result of these structural alterations and this change corresponds largely to a reduction of cellular respiration. Release of amylase from isolated pancreatic lobules of caerulein infused animals shows a progressive increase of unstimulated discharge, while in vitro stimulation with 5×10^–6 M carbamylcholine gives secretion patterns of wash-out kinetics. Stimulated discharge of labeled secretory proteins indicates a progressive reduction in the in vitro sensitivity of the pancreatic cells to secretagogues. After 24 h infusion of 5×10^–6 g/kg/h caerulein the pancreatic lobules are totally insensitive to the in vitro effect of carbamylcholine or caerulein.Supported by a grant from Deutsche Forschungsgemeinschaft, Bonn-Bad Godesberg (Ke 113/10)The expert technical assistance of Miss Hiltraud Hosser and Miss Helga Hollerbach is gratefully acknowledged     

Changes in plasma levels of interleukin-2 receptor in relation to disease exacerbations and levels of anti-dsDNA and complement in systemic lupus erythematosus.

Interleukin-2 receptor (IL-2R) is expressed and released predominantly by activated T cells. In order to investigate whether disease exacerbations of systemic lupus erythematosus (SLE) are preceded by T cell activation, we prospectively measured levels of IL-2R once a month, from 6 months prior to exacerbations until 1 month afterwards. To assess the temporal relation between T cell activation and B cell activation, we measured, in addition, levels of anti-dsDNA, complement C3/C4, and total IgG. During a mean follow-up period of 23 months, 40 exacerbations occurred in 21 out of the 71 participating patients. For the present study one exacerbation per patient was evaluated. During exacerbation levels of IL-2R were increased in 18 out of the 21 cases and correlated with levels of anti-dsDNA (P less than 0.02), C3 (P less than 0.02), and C4 (P less than 0.01), but not with the score of the disease activity index. Levels of IL-2R rose prior to the exacerbation (P less than 0.02) and fell afterwards following treatment (P less than 0.05). Even in the absence of disease activity or during minor disease symptoms IL-2R levels were higher (P less than 0.01) than in healthy controls. Sixteen out of the 21 exacerbations (76%) were preceded by a significant increase in IL-2R. Changes in levels of anti-dsDNA and complement C3/C4 tended to precede changes in levels of IL-2R. We conclude that increased levels of IL-2R, compatible with T cell activation, are present in SLE already during inactive disease. These levels further increased prior to exacerbations of disease. As such, IL-2R is an indicator of disease activity in SLE. Serial measurement of IL-2R is a sensitive test for predicting disease exacerbations of SLE.     

Inositol 1,4,5-trisphosphate formation, cytoplasmic calcium dynamics, and α-amylase secretion of pancreatic acini isolated from aged and chronically alcohol-fed rats

Methods. Three-month-old female Wistar rats were fed with 20% alcohol in their drinking fluid over 6–17 mo using an interrupted feeding regimen. At different times, pancreatic acini were isolated by mild collagenase digestion. The concentrations of inositol-1,4,5-trisphosphate (1,4,5-IP3) were determined by a specific radioreceptor assay, before and at different times after stimulation with varying concentrations of CCK-8. CCK-induced dynamics of cytoplasmic calcium ([Ca²⁺]_c) was investigated in acinar cells by confocal laser raster microscopy. Acinar α-amylase (Aml) secretion was measured as enzyme activity in the medium compared to the total activity in the suspension. Results. In 12–13-mo-old rats, the CCK-stimulated 1,4,5-IP₃ formation in acini was found to be decreased compared to young rats (age 4 mo). In rats of the same age fed with ethanol from the age of 3 mo on, 1,4,5-IP₃ concentrations in acini were higher and reached values comparable to those in young rats. Corre-spondingly, the CCK-induced [Ca²⁺]_c dynamics in acini isolated from 9-mo-old rats was impaired compared to that of young rats but normal in aged, chronically alcohol-fed rats. Aml secretion under CCK stimulation, however, which was decreased in aged rats, was additionally impaired after alcohol feeding.