[Growth factor-induced stimulation of proteoglycan synthesis in corneal endothelium cells]. / Wachstumsfaktor-induzierte Stimulation der Proteoglykansynthese in Kornea-Endothelzellen.

BACKGROUND: Cultured bovine corneal endothelial cells (CEC) synthesize heparan sulfate and dermatan sulfate containing proteoglycans and distribute them between different compartments. METHODS AND RESULTS: [35S]sulfate labelled proteoglycans are found associated with the cell layer, secreted into the culture medium and deposited into the underlaying extracellular matrix. In the presence of basic fibroblast growth factor (bFGF)-a strong mitogen for CEC-subconfluent cells incorporate [35S]sulfate into the sulfated proteoglycans at a rate three times higher as compared with the proteoglycans of CEC in the absence of bFGF. The enhanced proteoglycan synthesis is accompanied with a shift in the proteoglycan distribution pattern. While in control cells the cell-associated heparan sulfate accounts for about 30% of the total glycosaminoglycans under the influence of bFGF the HS percentage increases to approximately 60%. CONCLUSIONS: CEC synthesize and deposit endogenous bFGF into the extracellular matrix. Heparitinase treatment of the extracellular matrix releases bFGF activity which is able to stimulate the 35S incorporation into proteoglycans in a comparable manner as exogenous bFGF but does not influence the proteoglycan distribution pattern. Pretreatment of the matrix-bound bFGF activity with polyclonal antibodies against bFGF abolishes its stimulating activity.

Ammonia formation in the medicinal leech, Hirudo medicinalis--in vivo and in vitro investigations.

1. The excretion of N compounds was investigated in leeches fed various test solutions. 2. Ingestion was followed by a striking increase of NH3 release exhibiting a characteristic time-course. 3. The NH3 excreted resulted from the degradation of N compounds present in the test solutions. 4. Formation of NH3 from proteins was inhibited by kanamycin, but was unaffected in the case of amino acids. 5. Symbiotic microorganisms do not significantly contribute to NH3 formation. 6. Glutamate dehydrogenase and AMP deaminase are the enzymes most likely to be responsible for NH3 formation in Hirudo.