Chondrocytes, the cellular component of the articular cartilage, have long been recognized as strainsensitive cells, and have the ability to sense mechanical stimulation through surface receptors and intracellular signaling pathways. This strain-induced biological response of chondrocytes has been exploited to acilitate chondrocyte culture in in vitro systems; examples include the application of hydrostatic pressure, dynamic compression, hydrodynamic shear (i.e., rotating bioreactors), and low-intensity pulsed ultrasound (US). While the ability of US to influence chondrogenesis has been documented, the precise mechanisms of US-induced stimulation continue to be investigated.

The hair follicle has the unique capacity to undergo periods of growth, regression, and rest before regenerating itself to restart the cycle. This dynamic cycling capacity enables mammals to change their coats, and for hair length to be controlled on different body sites. More recently, the process of club fiber shedding has been described as a distinct cycle phase known as exogen, and proposed to be an active phase of the hair cycle. This review focuses on the importance of the shedding phase of the hair cycle and, in the context of current literature, analyzes the processes of club fiber formation, retention, and release, which may influence progression through exogen, particularly in relation to human hair.

Bereits 1713 beobachtete Ramazzini, dass Kornhändler und Bauern im Tal des Pos in Italien häufig an Lungenkrankheiten litten. Campbell beschrieb 1932 in England zum ersten Mal das klinische Bild der Farmerlunge. Williams zeigte 1960, dass die klinische Symptomatik einige Stunden nach Inhalation von schimmeligem Heu auftrat. Pepys konnte eine Assoziation zwischen präzipitierenden Antikörpern und dem Krankheitsbild nachweisen.

Bei der exogen-allergischen Alveolitis wird der Pneumologe mit sehr speziellen Problemen konfrontiert, insbesondere dann, wenn die Krankheit durch die berufliche Tätigkeit hervorgerufen wird. Manche Antigene kommen extrem selten vor; sie werden hier beschrieben. Eine Herausforderung für den Pneumologen ist die Begutachtung seltener allergischer Alveolitiden.

Exogen is a distinct phase of the hair cycle describing the process by which the hair club fibre is shed from the follicle. This process is difficult to study in human skin and little is known about the mechanisms involved in the release of club fibres. We sought an alternative model system to study exogen in more detail, and therefore utilised the vibrissa system on the rodent mystacial pad. The time at which a vibrissa club hair will be lost can be predicted, based on the relative lengths of the new growing fibre and old club fibre.