Portrait of Franz Koch; Employee of Mendelssohn Bank, Berlin Portraits Men

"15.8.1896 Franz Koch geb. 14.9.1860 gest. 21.10.1927"

Action of ecdysterone on the moulting of amphipod females: Gammarus pulex (L.) and G.fossarum Koch. Early results. [Translation from: Crustaceana 28, 86-88, 1975.]

In studying sexual attraction in gammarids of the group pulex, it has seemed necessary to dissociate the processes of moulting and ovogenesis in order to recognize their respective effects on this phenomenon. For this purpose a synthetic hormone, ecdysterone, was utilized. In the first instance the author followed the action of the hormone on isolated females in vitellogenesis. It was proved that the behaviour of Gammarus pulex and Gammarus fossarum vis-a-vis the ecdysterone used proves to be very close to that of isopods that was observed in Orchestia gammarellus in earlier research. Although they were in vitellogenesis, the females saw their intermoult cycle shortened.

Contribución al estudio anatómico de los géneros Elaeoselinum Koch ex DC., Margotia Boiss. y Distichoselinum García Martín & Silvestre (Umbelliferae), en la Península Ibérica

Se realiza el estudio anatómico de los tallos, hojas y frutos de los taxones ibéricos del género Elaeoselinum s.l. y se discute el valor de los caracteres anatómicos, en orden a considerar como géneros independientes Elaeoselinum Koch ex DC., Margotia Boiss. y Distichoselinum García Martín & Silvestre.

Plants Fagonia cretica L. and Hedera nepalensis K. Koch contain natural compounds with potent dipeptidyl peptidase-4 (DPP-4) inhibitory activity

Ethnopharmacological relevance
The two plants investigated here (Fagonia cretica L. and Hedera nepalensis K. Koch) have been previously reported as natural folk medicines for the treatment of diabetes but until now no scientific investigation of potential anti-diabetic effects has been reported. 

Materials and methods
In vitro inhibitory effect of the two tested plants and their five isolated compounds on the dipeptidyl peptidase 4 (DPP-4) was studied for the assessment of anti-diabetic activity. 

Results
A crude extract of Fagonia cretica possessed good inhibitory activity (IC₅₀value: 38.1 μg/ml) which was also present in its n-hexane (FCN), ethyl acetate (FCE) or aqueous (FCA) fractions. A crude extract of Hedera nepalensis (HNC) possessed even higher inhibitory activity (IC₅₀value: 17.2 μg/ml) and this activity was largely retained when further fractionated in either ethyl acetate (HNE; IC₅₀: 34.4 μg/ml) or n-hexane (HNN; 34.2 μg/ml). Bioactivity guided isolation led to the identification of four known compounds (isolated for the first time) from Fagonia cretica: quinovic acid (1), quinovic acid-3β-O-β-d-glycopyranoside (2), quinovic acid-3β-O-β-d-glucopyranosyl-(28→1)-β-d-glucopyranosyl ester (3), and stigmasterol (4) all of which inhibited DPP-4 activity (IC₅₀: 30.7, 57.9, 23.5 and >100 μM, respectively). The fifth DPP-4 inhibitor, the triterpenoid lupeol (5) was identified in Hedera nepalensis (IC₅₀: 31.6 μM). 

Conclusion
The experimental study revealed that Fagonia cretica and Hedera nepalensis contain compounds with significant DPP-4 inhibitory activity which should be further investigated for their anti-diabetic potential.

Evolution of Koch's postulates: towards a twenty-first century understanding of microbial infection

This editorial discusses strengths and limitations of Koch's postulates reviews modifications that have been used over time, and provides a brief introductory comment to the four papers that comprise the themed section herein.

Michel Kohlhaas / Kleist ; [traduit par L. Koch]

Collection : Les auteurs allemands expliqués d'après une méthode nouvelle par deux traductions françaises, l'une littérale et juxtalinéaire, l'autre correcte et précédée du texte allemand