Amyloid beta inhibits ectodomain shedding of N-cadherin via down-regulation of cell-surface NMDA receptor.

Dysfunction in the synapse is recognized as an early and the primary pathological process in Alzheimer's disease (AD). N-cadherin, an essential adhesion molecule for excitatory synaptic contact, forms a complex with presenilin 1 (PS1) and beta-catenin in the synaptic membrane. N-cadherin is sequentially cleaved by ADAM10 and PS1/gamma-secretase, producing a cytoplasmic fragment, N-cadherin C-terminal fragment (Ncad/CTF2) after NMDA receptor stimulation [Marambaud P, Wen PH, Dutt A, Shioi J, Takashima A, Siman R, Robakis NK (2003) A CBP binding transcriptional repressor produced by the PS1/epsilon-cleavage of N-cadherin is inhibited by PS1 FAD mutations. Cell 114:635-645; Reiss K, Maretzky T, Ludwig A, Tousseyn T, de Strooper B, Hartmann D, Saftig P (2005) ADAM10 cleavage of N-cadherin and regulation of cell-cell adhesion and beta-catenin nuclear signalling. EMBO J 24:1762]. Ncad/CTF2 translocates to the nucleus together with beta-catenin to enhance beta-catenin nuclear signaling [Uemura K, Kihara T, Kuzuya A, Okawa K, Nishimoto T, Bito H, Ninomiya H, Sugimoto H, Kinoshita A, Shimohama S (2006a) Activity-dependent regulation of beta-catenin via epsilon-cleavage of N-cadherin. Biochem Biophys Res Commun 345:951-958]. To examine whether an impairment of N-cadherin metabolism is involved in AD pathogenesis, we investigated the effect of amyloid beta peptide (Abeta) treatment on sequential N-cadherin cleavage. Here, we demonstrate that both synthetic and cell-derived Abeta species inhibit ectodomain shedding of mouse N-cadherin. Inhibition of N-cadherin cleavage by Abeta treatment was suggested to be mediated by the enhanced endocytosis of NMDA receptor, resulting in reduced turnover of N-cadherin. Since both N-cadherin and beta-catenin are essential for synaptic plasticity, impairment of N-cadherin cleavage caused by Abeta may underlie the synapse toxicity involved in AD pathogenesis.

Reduced amount of secretory component of IgA secretion in tears of patients with atopic dermatitis.

Coupled with the previous finding that sIgA excretion was reduced onto the surface of the skin, we demonstrated that sIgA secretion in the tears of patients with atopic dermatitis (AD) was significantly lower than that of normal subjects, using a small stick made of nitrocellulose membrane. In the bacterial cultures, we have also detected a higher frequency of Staphylococcus aureus in the tears from patients with AD compared to normal subjects. These findings suggested reduced sIgA secretion on the mucous membrane might play a crucial role in the pathomechanisms of the ocular lesions, such as abnormal bacterial flora and ocular complications as well as the establishment of skin lesions in AD.

Presence of elevated carcinoembryonic antigen on absorbent disks applied to nipple area of breast carcinoma patients.

BACKGROUND: Carcinoembryonic antigen (CEA) is used as a serum marker to detect and monitor the status of various kinds of malignant tumors. To determine whether CEA might be detected in secretions collected topically from around the nipple area, and whether its secretion might differ in a cancerous versus a noncancerous breast, we developed a simple method for collecting and measuring CEA, using a small cellulose membrane disk and an enzyme immunoassay. METHODS: We measured the amount of CEA excreted from the nipple area of 22 healthy control women and 32 women with unilateral breast carcinoma confirmed histologically. Secretions were collected from the nipple area by affixing a small (20 mm diameter) absorbent disk made of nitrocellulose membrane backed with filter paper to that area for 24 hours. Substances absorbed by the membrane were then subjected to an immunoassay for CEA using anti-CEA antibodies. RESULTS: In the 22 healthy subjects, a small amount of CEA (0.6 +/- 0.9 units) was secreted from each nipple, which was equally low regardless of the phase of the menstrual cycle. In contrast, 30 of the 32 women with breast carcinoma secreted significantly greater amounts of CEA from the cancerous (16.1 +/- 8.2) than the noncancerous (2.0 +/- 2.2) breast. Such a difference (14.1 +/- 8.0) in CEA excretion was not observed in the healthy controls (0 +/- 0). CONCLUSIONS: These findings suggest that such disks may provide a simple and noninvasive method of collecting trace molecules, including CEA, in skin secretions around the nipple to evaluate functional disorders of the mammary glands, particularly breast carcinoma. Additional studies are indicated in larger groups of women with various stages of breast carcinoma as well as with benign breast diseases.

A simple method for measuring the amount of immunoglobulin A secreted onto the skin surface.

We developed a simple method for measuring the amount of the secretory form of immunoglobulin A (sIgA) present in sweat. A small disk (10 x 10 mm) made of cellulose membrane was attached to the skin surface for periods of 1 to 24 h. SIgA was absorbed to the membrane and accumulated during the period of application. Enzyme immunoassay using anti-sIgA and antisecretory component (SC) antibodies revealed distinct dots on the disk that corresponded to the eccrine excretory ducts. A densitograph was used to determine the number and density of the dots, thus obtaining the amount of sIgA excreted to the surface of the skin (per mm2). The amount of skin sIgA excreted differed inter-individually as well as intra-individually. That is, it varied according to the region of the skin, and its distribution roughly reflected that of the sweat ducts. SIgA excretion was maintained at a certain level, regardless of the increased sweating produced by either heat or exercise, which raised the output of sweat 3- to 15-fold. Immunohistochemical studies revealed that fewer glandular cells expressed SC in their cytoplasm as the amount of sIgA decreased. Such an independence of the excretion of sIgA from that of sweat may be necessary to the local immune defenses of the skin.

Reduced secretion of IgA to skin surface of patients with atopic dermatitis.

To investigate whether the secretory form of immunoglobulin A (sIgA) was reduced on the skin surface in atopic dermatitis, the amount of sIgA present in sweat was measured in 40 patients with atopic dermatitis and in 50 healthy volunteers by attaching a cellulose membrane disk (10 x 10 mm) to the inner aspect of the upper arm skin for 24 hours. The secretory form of IgA, which was absorbed to the membrane and accumulated during the period of application, was revealed as dots by an enzyme immunoassay in which antibodies for IgA and for the secretory component were used. The density and number of dots (per mm2/day), which corresponded to the openings of eccrine excretory ducts, were determined with a densitometer. The mean amount of sIgA secreted by those patients was 3.86 +/- 0.71 pg/mm2/day (range, 0 to 21.17 pg/mm2/day), whereas that of the control subjects was significantly higher (p < 0.001), 16.79 +/- 2.80 pg/mm2/day (range, 0.79 to 133.77 pg/mm2/day). This may be related to the high incidence of bacterial and viral skin infections seen in patients with atopic dermatitis, and in addition, to the development of eczematous lesions through a defect in ridding the skin of allergens and/or microorganisms.

Efficacy of emetic and United State pharmacopoeia ipecac syrup in prevention of drug absorption.

The efficacy of both the emetic syrup prepared in the previous report and the United States Pharmacopoeia (USP) ipecac syrup concerning the prevention of drug absorption was investigated in 4 beagle dogs using a randomized and cross-over design. In order to control the intragastric pH of the beagle dogs, the administration of pentagastrin or hydrochloric acid (HCl)-glycine buffer (pH 1.5) was tested. The intragastric pH changed from 7.2 to 1.8 with the intramuscular administration of pentagastrin, but the primary emesis occurred more slowly. On the other hand, the HCl-glycine buffer (pH 1.5) gave the appropriate emesis. Therefore, the HCl-glycine buffer (pH 1.5) was used to control the intragastric pH of the beagle dogs. Acetaminophen (AcA), salicylic acid (SA) and kanamycin (KM) as markers were administered orally after conditioning the intragastric pH at 1.5. The emetic syrup or the USP ipecac syrup was then administered. The recovery rate of AcA and KM from vomit was 42-65%. The emetic syrup and the USP ipecac syrup significantly reduced the absorption of AcA from the calculation of pharmacokinetic parameters compared to the control syrup. It was observed that the absorption of cephaeline (CP) in the emetic syrup was less than that of CP in the USP ipecac syrup.