Mostly separate distributions of CLAC- versus Abeta40- or thioflavin S-reactivities in senile plaques reveal two distinct subpopulations of beta-amyloid deposits

Collagenous Alzheimer amyloid plaque component (CLAC) is a unique non-Abeta amyloid component of senile plaques (SP) derived from a transmembrane collagen termed CLAC-precursor. Here we characterize the chronological and spatial relationship of CLAC with other features of SP amyloid in the brains of patients with Alzheimer's disease (AD), Down syndrome (DS), and of PSAPP transgenic mice. In AD and DS cerebral cortex, CLAC invariably colocalized with Abeta42 but often lacked Abeta40- or thioflavin S (thioS)-reactivities. Immunoelectron microscopy of CLAC-positive SP showed labeling of fibrils that are more loosely dispersed compared to typical amyloid fibrils in CLAC-negative SP. In DS cerebral cortex, diffuse plaques in young patients were negative for CLAC, whereas a subset of SP became CLAC-positive in patients aged 35 to 50 years, before the appearance of Abeta40. In DS cases over 50 years of age, Abeta40-positive SP dramatically increased, whereas CLAC burden remained at a constant level. In PSAPP transgenic mice, CLAC was positive in the diffuse Abeta deposits surrounding huge-cored plaques. Thus, CLAC and Abeta40 or thioS exhibit mostly separate distribution patterns in SP, suggesting that CLAC is a relatively early component of SP in human brains that may have inhibitory effects against the maturation of SP into beta-sheet-rich amyloid deposits.     

Advance in animal experiments with the undulation pump total artificial heart: 50 and 54 day survival periods with 1/R control

The undulation pump total artificial heart (UPTAH) is a unique, implantable, total artificial heart (TAH) that uses undulation pumps. To achieve long-term survival in animals with physiologic hemodynamic conditions, a control method based on conductance and arterial pressure was applied to UPTAH. With this control method, called 1/R control, survival periods of 50 days (No. 0016, 49.6 kg) and 54 days (No. 0030, 42.5 kg) were obtained in adult female goats. In No. 0016, 1/R control was applied to the left pump, whereas in No. 0030, it was applied to the right pump. Another pump was used for left-right balance control. The control stability was better in No. 0030 than in No. 0016. The sucking effect of the left atrium was remarkable in No. 0016, possibly because of a time delay when left-right balance control was performed with the right pump. In No. 0016, the cause of death was probably a thrombus flown from a panus in the left atrium. It is possible that the left atrial suction effect influenced the thrombus and panus formation in the left atrium. In No. 0030, the cause of death was a small rupture of the membrane in the right pump. The rupture may have been caused by excessive negative pressure inside the pump. This pressure resulted from suction of the right atrium because of an unexpected control excursion, which was probably caused by a software bug. It will be necessary to redesign the undulation pump and improve the software to achieve longer survival periods for animals with physiologic hemodynamic conditions.     

A Gln/Arg polymorphism at codon 349 of the hBUBR1 gene

We found a glutamine/arginine polymorphism at codon 349 of the hBUBR1 gene, encoding a protein kinase required for spindle assembly checkpoint function. The observed heterozygosity was estimated to be 45% in the Japanese population. This polymorphism may be helpful for genetic studies of many cancer types in which chromosomal instability is observed. Received: October 19, 1998 / Accepted: October 24, 1998     

Delta-like 1 is necessary for the generation of marginal zone B cells but not T cells in vivo

Notch receptors and their ligands contribute to many developmental systems, but it is not apparent how they function after birth, as their null mutants develop severe defects during embryogenesis. Here we used the Cre-loxP system to delete the Delta-like 1 gene (Dll1) after birth and demonstrated the complete disappearance of splenic marginal zone B cells in Dll1-null mice. In contrast, T cell development was unaffected. These results demonstrated that Dll1 was dispensable as a ligand for Notch1 at the branch point of T cell-B cell development but was essential for the generation of marginal zone B cells. Thus, Notch signaling is essential for lymphocyte development in vivo, but there is a redundancy of Notch-Notch ligand signaling that can drive T cell development within the thymus.     

Mutations in the gene encoding KIAA1199 protein,an inner-ear protein expressed in Deiters’ cells and the fibrocytes,as the cause of nonsyndromic hearing loss

We report three possibly disease-causing point mutations in one of the inner-ear-specific genes, KIAA1199. We identified an R187C mutation in one family, an R187H mutation in two unrelated families, and an H783Y mutation in one sporadic case of nonsyndromic hearing loss. In situ hybridization indicated that the murine homolog of KIAA1199 mRNA is expressed specifically in Deiters cells in the organ of Corti at postnatal day zero (Pn) P0 before the onset of hearing, but expression in those cells disappears by day P7. The signal of KIAA1199 was also observed in fibrocytes of the spiral ligament and the spiral limbus through to P21, when the murine cochlea matures. Thus, the gene product may be involved in uptake of potassium ions or trophic factors with a particular role in auditory development. Although the R187C and R187H mutations did not appear to affect subcellular localization of the gene product in vitro, the H783Y mutation did present an unusual cytoplasmic distribution pattern that could underlie the molecular mechanism of hearing impairment. Our data bring attention to a novel candidate for hearing loss and indicate that screening of mutations in inner-ear-specific genes is likely to be an efficient approach to finding genetic elements responsible for deafness.Nucleotide sequence data reported herein are available in the DDBJ/EMBL/GenBank databases; for details, see the electronic eatabase section of this article.     

Mutation (D472Y) in the type 3 repeat domain of cartilage oligomeric matrix protein affects its early vesicle trafficking in endoplasmic reticulum and induces apoptosis

Cartilage oligomeric matrix protein (COMP) is a large pentameric extracellular glycoprotein found in cartilage, tendon, and synovium, and plays structural roles in cartilage as the fifth member of the thrombospondin family. Familial mutations in type 3 repeats of COMP are known to cause pseudoachondroplasia (PSACH) and multiple epiphyseal dysplasia (EDM1). Although such mutations induce enlarged rough endoplasmic reticulum (rER) as a morphological change, the metabolic trafficking of mutated COMP remains unclear. In transfected COS7 cells, wild-type COMP was rapidly secreted into culture medium, while the great majority of COMP with the type 3 repeats mutation (D472Y) remained in the cells and a small portion of mutated COMP was secreted. This finding was followed up with a confocal study with an antibody specific to COMP, which demonstrated mutated COMP tightly associated with abnormally enlarged rER. Phosphorylated eIF2alpha, an ER stress protein, was expressed as a pathological reaction in virtually all COS7 cells expressing mutated but not wild-type COMP. Moreover, COS7 cells expressing mutated COMP exhibited significantly more apoptotic reaction than those expressing wild-type COMP. Pathological accumulation of COMP in rER and apoptosis in COS7 cells that were induced by the mutation (D472Y) in COMP imply that COMP mutations play a role in the pathogenesis of PSACH.     

Wear properties of alumina/zirconia composite ceramics for joint prostheses measured with an end-face apparatus

While only alumina is applied to all-ceramic joint prostheses at present, a stronger ceramic is required to prevent fracture and chipping due to impingement and stress concentration. Zirconia could be a potential substitute for alumina because it has high strength and fracture toughness. However, the wear of zirconia/zirconia combination is too high for clinical use. Although some investigations on composite ceramics revealed that mixing of different ceramics was able to improve the mechanical properties of ceramics, there are few reports about wear properties of composite ceramics for joint prosthesis. Since acetabular cup and femoral head of artificial hip joint are finished precisely, they indicate high geometric conformity. Therefore, wear test under flat contact was carried out with an end-face wear testing apparatus for four kinds of ceramics: alumina monolith, zirconia monolith, alumina-based composite ceramic, and zirconia based composite ceramic. Mean contact pressure was 10 MPa and sliding velocity was 40 mm/s. The wear test continued for 72 hours and total sliding distance was 10 km. After the test, the wear factor was calculated. Worn surfaces were observed with a scanning electron micrograph (SEM). The results of this wear test show that the wear factors of the both composite ceramics are similarly low and their mechanical properties are much better than those of the alumina monolith and the zirconia monolith. According to these results, it is predicted that joint prostheses of the composite ceramics are safer against break down and have longer lifetime compared with alumina/alumina joint prostheses.     

Inhibition of experimental metastasis and cell adhesion of murine melanoma cells by chondroitin sulfate-derivatized lipid, a neoproteoglycan with anti-cell adhesion activity

Chondroitin sulfate dipalmitoylphosphatidylethanolamine (CS-PE), when immobilized onto substratum, inhibited the adhesion of B16F10 mouse melanoma cells to fibronectin-coated dishes (anti-adhesion activity). CS-PE showed the most potent anti-adhesion activity for the melanoma cells among various GAG-PEs. CS-PE also inhibited the adhesion of B16F10 cells to Matrigel and the invasion of the cells into Matrigel. In the in vivo system of experimental metastasis, administration of B16F10 cells with CS-PE into C57BL/6 mice significantly inhibited lung metastasis. The inhibition degree of CS or hyaluronic acid-PE was lower than CS-PE. CS-PE administered intravenously into mice before the injection of B16F10 cells also inhibited metastasis. Pretreatment of B16F10 cells with CS-PE caused some but a lower degree of inhibition. When CS-PE was injected intravenously into mice, more binding in the lung was found than when CS was injected. CS-PE but not CS inhibited the retention in the lung of fluorochrome-labeled B16F10 cells when injected intravenously into mice. Since there was no significant effect of CS-PE on the viability and growth of B16F10 cells, the results suggest that CS-PE immobilized onto the subendothelial matrix may prevent melanoma cells from adhering to the subendothelial substrata of lung capillaries and inhibit subsequent invasion processes of metastasis.     

Morphogenesis of nonpolypoid colorectal adenomas and early carcinomas assessed by cell proliferation and apoptosis

Nonpolypoid neoplasms, as well as ordinary polypoid tumours, are occasionally found in the colorectum. To clarify whether cell kinetic status affects the macroscopic morphology of colorectal neoplasms, we investigated proliferative indices (PI), apoptotic indices (AI), and the expression of apoptosis-related gene products. We examined 110 colorectal neoplasms comprised of 36 polypoid, 38 flat elevated and 36 depressed tumours. According to WHO’s criteria these tumours consisted of 61 adenomas with low grade dysplasia (LGD), 30 adenomas with high grade dysplasia (HGD) and 19 carcinomas with submucosal invasion. Apoptotic cells were detected by TUNEL staining. Proliferating cells and apoptosis-related gene products were assessed by immunohistochemistry for Ki-67, p53, Bcl-2, and Bax antigens. AI were closely associated with macroscopic morphology in adenomas but not in carcinomas. PI were relatively constant among the three macroscopic types in adenomas and carcinomas. Median AI values of polypoid, flat elevated and depressed tumours were 1.8%, 2.1% and 4.6% for adenomas with LGD, 0.8%, 2.4% and 6.2% for adenomas with HGD and 2.9%, 4.0% and 3.6% for carcinomas, respectively. Overall PI were significantly higher in carcinomas than in adenomas with LGD, whereas AI were not different. Although the incidence of expression was significantly higher in carcinomas for p53 and in adenomas for Bcl-2 than the others, the expression of apoptosis-related gene products (p53, Bcl-2 and Bax) was similar among polypoid, flat elevated and depressed tumours. Macroscopic morphology of colorectal adenomas is determined by the apoptosis not by proliferation, and high apoptosis found in depressed adenomas implies their low net growth. Received: 1 July 1999 / Accepted: 17 January 2000