Mitochondrial aldehyde dehydrogenase 2 (ALDH2) plays a major role in acetaldehyde detoxification. The alcohol sensitivity is associated with a genetic deficiency of ALDH2. We have previously reported that this deficiency influences the risk for late-onset Alzheimer's disease. However, the biological effects of the deficiency on neuronal cells are poorly understood. Thus, we obtained ALDH2-deficient cell lines by introducing mouse mutant Aldh2 cDNA into PC12 cells. The mutant ALDH2 repressed mitochondrial ALDH activity in a dominant negative fashion, but not cytosolic activity. The resultant ALDH2-deficient transfectants were highly vulnerable to exogenous 4-hydroxy-2-nonenal, an aldehyde derivative generated by the reaction of superoxide with unsaturated fatty acid. In addition, the ALDH2-deficient transfectants were sensitive to oxidative insult induced by antimycin A, accompanied by an accumulation of proteins modified with 4-hydroxy-2-nonenal. Thus, these findings suggest that mitochondrial ALDH2 functions as a protector against oxidative stress.

Various laminin isoforms have specific biological functions depending on their structures. Laminin 5A, which consists of the three truncated chains ␣3A, ␤3, and ␥2, is known to have strong activity to promote cell adhesion and migration, whereas a laminin 5 variant consisting of a full-sized ␣3 chain (␣3〉) and the ␤3 and ␥2 chains, laminin 5B, has not been characterized yet. In the present study, we for the first time cloned a fulllength human laminin ␣3B cDNA and isolated the human laminin 5B protein. The molecular size of the mature ␣3B chain (335 kDa) was approximately twice as large as the mature ␣3A chain in laminin 5A. Laminin 5B had significantly higher cell adhesion and cell migration activities than laminin 5A. In addition, laminin 5B potently stimulated cell proliferation when added into the culture medium directly. Furthermore, we found that the ␣3B chain undergoes proteolytic cleavage releasing a 190-kDa NH 2 -terminal fragment. The 190-kDa fragment had activities to promote cellular adhesion, migration, and proliferation through its interaction with integrin ␣ 3 ␤ 1 . These activities of the NH 2 -terminal structure of the ␣3B chain seem to contribute to the prominent biological activities and the physiological functions of laminin 5B.Laminins are an important family of extracellular matrix proteins, which are mainly localized in the basement membranes of various tissues and regulate various cellular functions including cell adhesion and migration (1, 2). The different combinations of five ␣, three ␤, and three ␥ chains give rise to at least 15 laminin heterotrimers with the well known crossshaped structure (1). Of the three laminin subunits, the ␣ chain is most important in determining the tissue-specific distribution and specific biological activity of the laminin isoforms (3). The laminin ␣ chains are classified into two groups, "full-sized" (␣1, ␣2, ␣3〉, and ␣5) and "truncated" (␣3A and ␣4) (1). The amino-terminal region of the full-sized ␣ chains contains three globular domains (VI, IVb, and IVa) and three rodlike domains (V, IIIb, and IIIa) consisting of laminin type epidermal growth factor repeats. The laminin NH 2 -terminal domain VI, which is completely absent in the truncated ␣ chains (␣3A and ␣4), is thought to be essential for the self-assembly and co-polymerization of laminins into large noncovalent networks in the basement membranes and have several cell-binding sites (1). On the other hand, all ␣ chains contain a globular (G) domain consisting of five laminin G modules (G1 to G5) at the COOH terminus. The COOH-terminal G domain of the ␣ chains plays major roles in the interaction with cell surface receptors such as integrins, syndecans, and dystroglycan (4 -6).Typical laminins are produced by the assembly of different ␣ chains with the laminin ␤1 or ␤2 and ␥1 chains, whereas laminin 5 (LN5) 1 is produced by the combination of ␣3A, ␤3, and ␥2 chains. The ␤3 and ␥2 chains are found only in LN5, and all the three LN5 subunits are truncated in the short arms (NH 2 -terminal regions). Cons...

Background: Atopic dermatitis (AD) has a complicated pathogenesis and its clinical features vary greatly among patients. Although many clinical parameters have been reported, it remains difficult to evaluate AD skin conditions adequately. Objective: To support better evaluation of AD patients, we attempted to develop a new, objective and noninvasive method that assesses skin condition in AD using biochemical markers in the skin’s horny layer (HL). Methods: Thirty-six patients with AD, 8 with psoriasis and 16 healthy volunteers were recruited. HL samples were obtained by tape stripping from involved and uninvolved skin of the forearms. Expression levels of 6 proteins in the HL [fatty acid-binding protein-5 (FABP-5), squamous cell carcinoma antigens 2 (SCCA2), α-enolase, annexin II, apolipoprotein A-I and albumin] were analyzed by immunoblotting and compared with clinical data. Results: The 6 proteins were detected at a high level in AD skin lesions, but scarcely in the normal controls. FABP-5 showed correlation with the local severity of the involved skin. Annexin II, apoprotein A-I and albumin showed correlation with the severity of specific eruptions. SCCA2 correlated significantly with total serum IgE level. Albumin levels in the uninvolved skin of AD patients showed significant correlation with the local severity in the involved skin of the same patient and with the trans-epidermal water loss. Albumin levels in psoriatic skin were very low, even with scratch marks, compared to those in AD skin. Conclusion: FABP-5, albumin and some other proteins in HL seem to be useful as biomarkers to evaluate inflammation and skin barrier conditions in AD patients.

The NHAP group was clinically different from the O-HCAP group, based on bacteriological examination and mortality rates. In order to accurately diagnose, and formulate optimum treatment strategies for Japanese patients, the categories of HCAP, as specified in the ATS/IDSA guidelines, should not be applied directly either to patients with NHAP or those with O-HCAP.