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Aim-To analyse the human corneal stroma in extreme hydration to discover if its structure is responsible for corneal stability. Methods-Corneas in several hydration states were used: postmortem control corneas (PM; n=3), corneas left for 1 day in phosphate buVered saline (PBS; n=4), and corneas left for 1 day (n=4), 2 days (n=4), 3 days (n=2), and 4 days (n=4) in deionised water. All corneas were fixed under standardised conditions and processed for light and electron microscopy. In addition, two fresh corneas from the operating theatre were studied which were processed 6 months after storage in sodium cacodylate buVer. Results-After 1 day in deionised water maximal stromal swelling was reached which did not change up to 4 days. The stroma of deionised water corneas (1400 µm) was much thicker than that of PBS corneas (650 µm) and PM corneas (450 µm). Deionised water treatment led to disappearance of all keratocytes leaving only remnants of nuclei and large interlamellar spaces. In these specimens the distance between the collagen fibres had increased significantly, but the diameter of the collagen fibres did not seem to be aVected. A remarkable observation was that the most anterior part of the stroma (100-120 µm) in all deionised water specimens and those stored for 6 months in buVer was not swollen, indicating that the tightly interwoven anterior lamellae are resistant to extreme non-physiological hydration states. Conclusions-The rigidity of the most anterior part of the corneal stroma in extreme hydration states points to an important role in maintenance of corneal curvature. Since a large part of this rigid anterior part of the stroma is either removed (PRK) or intersected (LASIK), it is possible that in the long run patients who underwent refractive surgery may be confronted with optical problems. (Br J Ophthalmol 2001;85:437-443)

The endoplasmic reticulum (ER) is involved in a variety of essential and interconnected processes in human cells, including protein biogenesis, signal transduction, and calcium homeostasis. The central player in all these processes is the ER-lumenal polypeptide chain binding protein BiP that acts as a molecular chaperone. BiP belongs to the heat shock protein 70 (Hsp70) family and crucially depends on a number of interaction partners, including co-chaperones, nucleotide exchange factors, and signaling molecules. In the course of the last five years, several diseases have been linked to BiP and its interaction partners, such as a group of infectious diseases that are caused by Shigella toxin producing E. coli. Furthermore, the inherited diseases Marinesco-Sjögren syndrome, autosomal dominant polycystic liver disease, Wolcott-Rallison syndrome, and several cancer types can be considered BiP-related diseases. This review summarizes the physiological and pathophysiological characteristics of BiP and its interaction partners.

We characterized interactions between the human proteins Sec62 and Sec63 as well as the putative interaction of human Sec62 with ribosomes. The data demonstrate evolutionary conservation of Sec62/Sec63 interaction and indicate that in the course of evolution Sec62 of vertebrates has gained the additional function to interact with ribosomes.