We studied the effects of human recombinant interleukin-1 beta on proteoglycan metabolism of bovine articular cartilage in organ culture. IL-1 was more potent in inhibiting synthesis (IC50 4 ng/mL) than in stimulating breakdown of proteoglycans (EC50 200 ng/mL). Inhibition of proteoglycan synthesis began to plateau earlier (2 days) than stimulation of proteoglycan release (4 days). Both effects could be neutralized with a polyclonal anti-IL-1 beta antibody; however, higher antibody titers were required to block IL-1 effects on proteoglycan synthesis than to neutralize those on proteoglycan release. Chloroquine, but not hydrocortisone, blocked IL-1-mediated proteoglycan breakdown. Both drugs, however, augmented IL-1-induced inhibition of proteoglycan synthesis. Our data suggest that the effects of IL-1 on articular cartilage proteoglycan synthesis and proteoglycan breakdown can be regulated independently.

Ion channels formed by the peptide gramicidin A in planar lipid membranes have been reported to react very sensitively upon irradiation of the membrane by ionizing radiation (radiolysis), by UV light (photolysis), or by visible light in the presence of appropriate photosensitizers (photodynamic inactivation). In all three cases the effect is due to the presence of the four tryptophan residues of the pentadecapeptide. Modifications of these amino acids--due to an interaction with free radicals formed upon water radiolysis or due to light absorption--have been found to reduce the membrane conductance by many orders of magnitude. The present study was intended to correlate functional changes, observed at the level of single ion channels, with changes of the molecular structure identified by mass spectrometry. About 98% of the inactivated channels showed a single-channel conductance of virtually zero, while about 2% of the channels present before irradiation are converted to a state of reduced conductance (and reduced lifetime). On the structural level, irradiation in the presence of the photosensitizer Rose Bengal was found to produce oxidation and fragmentation of the peptide at the positions of the tryptophan residues. Our results provide evidence that the main effect of radiolysis, or of photodynamic treatment, is the cleavage of the peptide backbone leading to immediate closure of an open ion channel.

The xanthone dienone 3b was obtained by synthesis and oxidative condensation of the tetrahydroxybenzophenone 2b. 3 b could be transformed into 10-methyl-10-desmethoxycarbonyl-hemisecalonic acid A (4) by stereoselective reduction. 4 corresponds to one half of the ergochrome secalonic acid A (1) molecule with respect to its configuration at the three ccntcrs of chirality and differs from it only by exchange of the CO2CH3 group with methyl.In connection with this total synthesis an investigation was carried out on the formation and stereochemistry of transformation products of the xanthone dienones 3a and b, as for instance also the seco-xanthone 24, which is structurally related to the ergot pigment ergoxanthin (30).

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Die spontane Ausbreitung flüssiger Lipide auf der menschlichen Haut stellt eine wichtige Eigenschaft für den Gebrauchswert solcher Produkte in kosmetischen und pharmazeutischen Zubereitungen dar. Es wird ein vergleichendes Auswertungsverfahren auf Basis einer Abdruckmethode vorgestellt, welches die Spreitgeschwindigkeit reproduzierbar zu bestimmen erlaubt. Die standardisierten Spreitwerte einer Reihe von Lipiden werden im Vergleich mit deren Strukturmerkmalen und physikalisch‐chemischen Kenndaten wie Viskosität und Grenzflächenspannung diskutiert. Keine dieser Datenreihen korreliert vollständig mit der Spreitung aller untersuchten Lipide, jedoch ist eine Abschätzung der relativen Spreitraten aus diesen Vergleichsdaten innerhalb strukturähnlicher Verbindungsgruppen möglich.