All morphogens of the Hedgehog (Hh) family are synthesized as dual-lipidated proteins, which results in their firm attachment to the surface of the cell in which they were produced. Thus, Hh release into the extracellular space requires accessory protein activities. We suggested previously that the proteolytic removal of N-and Cterminal lipidated peptides (shedding) could be one such activity. More recently, the secreted glycoprotein Scube2 (signal peptide, cubulin domain, epidermal-growth-factor-like protein 2) was also implicated in the release of Shh from the cell membrane. This activity strictly depended on the CUB domains of Scube2, which derive their name from the complement serine proteases and from bone morphogenetic protein-1/tolloid metalloproteinases (C1r/C1s, Uegf and Bmp1). CUB domains function as regulators of proteolytic activity in these proteins. This suggested that sheddases and Scube2 might cooperate in Shh release. Here, we confirm that sheddases and Scube2 act cooperatively to increase the pool of soluble bioactive Shh, and that Scube2-dependent morphogen release is unequivocally linked to the proteolytic processing of lipidated Shh termini, resulting in truncated soluble Shh. Thus, Scube2 proteins act as protease enhancers in this setting, revealing newly identified Scube2 functions in Hh signaling regulation.

The study was undertaken to evaluate the kinetics and distribution patterns of several immunohistochemical markers in ischemically and hypoxically damaged myocardium. The myocardium of 8 cases of acute myocardial infarction (AMI), 8 cases of diagnosed acute cardiac death (ACD) and 12 cases of acute exogenic hypoxia (AEH) due to CO poisoning or hanging were analysed for depletion of the cardiac antigens FABP, troponin C and T, desmin and myoglobin, loss of CD59 and deposition of the plasma antigens fibrinogen, fibronectin and the terminal complement complex C5b-9. The visualisation of the terminal complement complex was positive as early as 30 min after onset of symptoms of AMI. Depletion of cellular antigens started earlier than the deposition of plasma antigens. The deposition of fibronectin and fibrinogen began earlier than the detection of C5b-9 but later than the depletion of the cellular antigens. Our findings indicate that for the immunohistochemical detection of very early myocardial damage, the depletion of myoglobin is at least of the same rank or better than depletion of FABP and troponin.

SUMMARYSince its invasion of Europe in the early 1980s, the Asian clam Corbicula fluminea has become very abundant in nearly all western river systems. Today this species is one of the most important biomass producers in the River Rhine. Monitoring the valve movements of C. fluminea over a period of 2 years revealed a circadian rhythm in summer,with extended periods (10-12 h) of valve closure, predominantly in the morning hours. Altogether valve movements were very scarce, frequently fewer than four movements per individual per day.Simultaneous measurements of heat dissipation and oxygen consumption(calorespirometry) revealed an intermittent metabolism in the clam. With the onset of valve closure, C. fluminea reduced its metabolic rate to 10%of the standard metabolic rate (SMR) measured when the valves were open. Nevertheless, this depressed metabolism remained aerobic for several hours,enabling the clam to save energy and substrates compared to the requirements of the tenfold higher SMR. Only during long-lasting periods of valve closure(more than 5-10 h) did the clams become anaerobic and accumulate succinate within their tissues (2 μmol g-1 fresh mass). Succinate is transported into the mantle cavity fluid, where it reaches concentrations of 4-6 mmol l-1. Because this succinate-enriched fluid must pass the gills when the valves open again, we suggest that this anaerobic end product is at least partly reabsorbed, thus reducing the loss of valuable substrates during anaerobiosis. Propionate was also produced, but only during experimental N2-incubation, under near-anoxic conditions.The intermittent metabolism of C. fluminea is discussed as an adaption to efficiently exploit the rare food supply, saving substrates by the pronounced metabolic depression during valve closure.

Decision making in cellular ensembles requires the dynamic release of signaling molecules from the producing cells into the extracellular compartment. One important example of molecules that require regulated release in order to signal over several cell diameters is the Hedgehog (Hh) family, because all Hhs are synthesized as dual-lipidated proteins that firmly tether to the outer membrane leaflet of the cell that produces them. Factors for the release of the vertebrate Hh family member Sonic Hedgehog (Shh) include cell-surface sheddases that remove the lipidated terminal peptides, as well as the soluble glycoprotein Scube2 that cell-nonautonomously enhances this process. This raises the question of how soluble Scube2 is recruited to cell-bound Shh substrates to regulate their turnover. We hypothesized that heparan sulfate (HS) proteoglycans (HSPGs) on the producing cell surface may play this role. In this work, we confirm that HSPGs enrich Scube2 at the surface of Shh-producing cells and that Scube2-regulated proteolytic Shh processing and release depends on specific HS. This finding indicates that HSPGs act as cell-surface assembly and storage platforms for Shh substrates and for protein factors required for their release, making HSPGs critical decision makers for Scube2-dependent Shh signaling from the surface of producing cells.

The vestibulospinal aspects of vestibular function are commonly neglected in the evaluation of alcohol-induced intoxication. Thus, in the present study the effect of an acute intoxication with a low or moderate quantity of alcohol was examined with respect to the equilibrium in 30 healthy subjects. The blood alcohol concentration (BAC) was measured 30 min after the ingestion of the last alcohol, ranging between 0.22 and 1.59 per thousand. Stability of stance was quantified by static platform posturography in Romberg-test conditions with eyes open and eyes closed. Among other parameters, the average body sway path (SP) and area of body sway (SA) were assessed. Posturography revealed a significant increase in body sway. There was a positive correlation between SA (or SP) and BAC both with eyes open and eyes closed. Multiple group comparisons revealed that the large-alcohol-dose group (BAC > or = 1.0 per thousand) could be clearly differentiated from test cases with BAC lower than 0.8 per thousand. Sway area was the most sensitive parameter for detecting increased body sway after alcohol ingestion. The area increase, present not only with eyes closed but with eyes open, revealed an inadequate compensation of the ethanol-induced ataxia by visual stabilization. The Romberg's quotient, which denotes eyes closed relative to eyes open, remained constant. The increase in sway path with eyes closed showed an omnidirectional sway. A comparison of the sway pattern of subjects after acute ethanol ingestion with the data of patients with permanent cerebellar lesions suggested that the acute effect of alcohol resembles that of a lesion of the spinocerebellum. This finding contrasts with earlier studies, which postulated an acute effect of ethanol resembling that in patients with an atrophy of the anterior lobe of the cerebellum due to chronic alcohol abuse. In seven cases of the lower dose group (BAC < or = 0.8 per thousand), a reduction in body sway after alcohol ingestion was observed. This finding may be consistent with a dose-related biphasic action of alcohol, which - besides its well-known depressant effects with high doses - also shows stimulatory action with small doses.