Development of eddy current testing system for inspection of combustion chambers of liquid rocket engines

An eddy current testing (ECT) system using a high sensitive anisotropic magnetoresistive (AMR) sensor was developed. In this system, a 20 turn circular coil with a diameter of 3 mm was used to produce the excitation field. A high sensitivity AMR sensor was used to measure the magnetic field produced by the induced eddy currents. A specimen made of copper alloy was prepared to simulate the combustion chamber of liquid rocket. Scanning was realized by rotating the chamber with a motor. To reduce the influence of liftoff variance during scanning, a dual frequency excitation method was used. The experimental results proved that ECT system with an AMR sensor could be used to check liquid rocket combustion chamber.

An anisotropic magneto resistive sensor with set/reset field

Using a set/reset magnetic field, an anisotropic magneto resistive (AMR) magnetic field sensing system was developed to reduce the low frequency noise of an AMR sensor. The magnetic field resolution of the AMR sensor was improved by about three times at the frequencies below 30 Hz and a magnetic field resolution of about 150 pT/√Hz was obtained at 1 Hz. For magnetic particle detection using an AMR sensor with set/reset method, the thermal disturbance effect was canceled well and the signal-to-noise ratio was improved by about three times.

Intramolecular epitope spreading among anti-caspase-8 autoantibodies in patients with silicosis, systemic sclerosis and systemic lupus erythematosus, as well as in healthy individuals

Dysregulation of apoptosis through the Fas-Fas ligand pathway is relevant in autoimmune disease onset. We recently reported elevated serum levels of sFas in patients with silicosis, systemic sclerosis (SSC) and systemic lupus erythematosus (SLE), and proposed a block of apoptosis in the pathogenesis. The disturbance of apoptosis in lymphocytes including autoreactive clones could induce autoantibody production. Since autoantibodies directed against unknown antigens are present in the sera of these patients, the sera samples were examined for the presence of autoantibodies directed to caspase-8. Using Western blotting, autoantibodies against caspase-8 were detected in healthy individuals and in over 60% of patients. Using epitope mapping employing 12 amino acid polypeptides with SPOTs system, a minimum of 4 epitopes and a maximum of 13 were found, which implied that epitope spreading was in progress. It is noteworthy that two important catalytic cystein residues were included within the epitopes; firstly the active site cystein Cys287, and secondly Cys360 located in the unique pentapeptide motif QACQG. Using recombinant human caspase-8 linked protein chip array, autoantibodies were identified and molecular weight determined. The antibodies were mainly IgG; 80% were subclass IgG1(lambda); 20% were IgG4(kappa). Despite the ratio of human light chain kappa:lambda = 2:1, the predominance of IgG1(lambda) is noticeable. Anti-caspase-8 autoantibodies are detectable in healthy individuals and in patients suffering silicosis, SSc or SLE. A few epitopes were detected in healthy individuals compared to those suffering autoimmune diseases, indicating the intramolecular epitope spreading. Relationship of autoantibodies and the clinical background of the patients requires clarification.

Molecular Biological Diagnosis of Congenital and Acquired Cholesteatoma on the Basis of Differences in Telomere Length

OBJECTIVE

To establish a molecular biological basis for differentiation of congenital and acquired cholesteatoma.

STUDY DESIGN

The time of onset was estimated for congenital cholesteatoma and for acquired cholesteatoma by comparing the telomere length and the telomerase activity in the tissues of both diseases with the values of those parameters in normal external ear canal skin.

METHODS

The telomere length was determined by extracting DNA from each tissue and then applying the Southern blot technique to hybridize it with a 32P-labeled telomeric oligonucleotide (TAAGGG)8 probe. The telomerase activity was analyzed by a modification of the polymerase chain reaction-based telomeric repeat amplification protocol.

RESULTS

The telomere length in congenital cholesteatoma tissue was shorter than the length in normal external ear canal skin from the same patient, whereas in acquired cholesteatoma tissue the telomere length was almost the same as in the normal external ear canal skin. Some of the acquired cholesteatoma tissue specimens and normal external ear canal skin specimens were positive for telomerase activity, but all of the specimens of congenital cholesteatoma tissue were negative for telomerase activity. No correlation was found between the presence of telomerase activity and the telomere length.

CONCLUSIONS

The present results indicate that congenital cholesteatoma manifests at an earlier time compared with acquired cholesteatoma, and the results can be thought to support the theory that congenital cholesteatoma originates from vestigial fetal tissue or aberrant tissue. In addition, the finding that telomerase activity was weak in the congenital cholesteatoma tissue suggests the possibility that vestigial fetal tissues and aberrant tissues are naturally eliminated in normal subjects as a result of apoptosis.

Terminal differentiation of epithelial cells in middle ear cholesteatoma: investigation of patterns of expression of protein kinase C-delta and protein kinase C-eta

OBJECTIVES

The objective of this study was to elucidate the differentiation mechanism of keratinocytes in cholesteatoma.

STUDY DESIGN

To achieve the objective, we analyzed the expressions of various cellular proteins: the delta and eta isoforms of protein kinase C (PKCdelta and PKCeta), which are thought to play key roles in signal transduction in differentiation; cytokeratin 1 (CK1) and cytokeratin 10 (CK10) (cytoskeletal constitutive proteins); and involucrin (a marker of differentiation).

METHODS

The materials used in this study were tissue specimens obtained from cholesteatoma epidermis, normal external ear canal skin, normal inguinal skin, and psoriatic skin. Immunohistochemical staining techniques were applied to compare the expressions of the above proteins (i.e., PKCdelta, PKCeta, CK1, CK10 and involucrin) in those various tissues.

RESULTS

No clear differences in the patterns of expression of PKCdelta and PKCeta were found between the cholesteatoma epidermis and the normal external ear canal skin. These proteins were expressed mainly in the stratum spinosum and stratum granulosum, and their patterns of expression were almost the same as those of the CK1, CK10, and involucrin proteins.

CONCLUSION

The findings of this study indicate that the terminal differentiation of keratinocytes in the cholesteatoma epidermis is the same as in normal skin tissues. It was concluded that the growth of epidermis which has undergone hyperproliferation of keratinocytes because of increased levels of various cytokines is being regulated by means of normal terminal differentiation.

Role of Bcl-xL protein in differentiation and apoptosis of human middle ear cholesteatoma epithelium

OBJECTIVE

To compare the mechanisms of proliferation, differentiation, and apoptosis in middle ear cholesteatoma epithelium with those of normal external ear canal epithelium.

DESIGN

The localizations of the expression of Bcl-xL protein and involucrin and the presence of apoptotic cells were determined for tissue slices of middle ear cholesteatoma epithelium and compared with the findings for normal external ear canal epithelium. In addition, SCC-25/bcl-xL transfectants showing the overexpression of Bcl-xL were used to investigate the effect of this protein on the expression of involucrin, which is a marker of epithelial cell differentiation.

MATERIALS

Cholesteatoma tissue specimens were surgically excised from 10 patients. Normal skin specimens collected from the external ear canal of the 10 patients were used as control specimens.

RESULTS

The expression of Bcl-xL was detected in the vicinity of the basal cell layer of both the cholesteatoma epithelium and the normal external ear canal epithelium. Conversely, the expression of involucrin (ie, a marker of epithelial cell differentiation) increased in proportion to the shallowness of the epithelial layer. In situ labeling detected apoptotic cells in the spinous and granular cell layers of cholesteatoma tissue sections and similar findings in the normal external skin specimens. Western blot analysis confirmed that the expression of involucrin protein was the same in both wild-type SCC-25 cells and the SCC-25/bcl-xL transfectants.

CONCLUSIONS

In both the cholesteatoma epithelium and the normal external ear canal epithelium, differentiation and apoptosis begin when the epithelial cells separate from the basal cells. The mechanisms behind these changes, at least in apoptosis, appear to be controlled by the expression of the Bcl-xL protein.

Expression of transforming growth factor-alpha (TGF-alpha) in cholesteatoma

This study aims at elucidating the role of cytokines in the mechanism of proliferation of cholesteatoma epithelium by investigating the mode of expression of epidermal growth factors, such as TGF-alpha. The subjects of this study were patients who had undergone operation for middle ear cholesteatoma. Skins of the bone region of the external ear canal (normal skin) of the same patients were used as the negative control. The mode of expression of TGF-alpha was studied by immunohistochemistry and in situ hybridization. In the immunohistochemical study, there were no conspicuous differences observed between cholesteatoma tissues and normal skin. After in situ hybridization, expression of TGF-alpha mRNA was mainly observed in the epidermal basal cell layer in the normal skin, while in the cholesteatoma epidermis with severe inflammatory cell infiltration, expression of TGF-alpha mRNA was observed up to layers superior to the basal cell layer. The expression of TGF-alpha mRNA is greatly affected by subepithelial connective tissue, strongly suggesting involvement of paracrine regulation in proliferation of cholesteatoma epithelium.

Severe growth defect in mouse cells lacking the telomerase RNA component

The ribonucleoprotein enzyme telomerase synthesizes telomeric DNA onto chromosome ends. Telomere length is maintained, by the presence of telomerase activity, in the vast majority of primary tumours and stem cells, suggesting that telomere maintenance is essential for cellular immortalization. Recently, the telomerase RNA component in human and mouse (TERC and Terc, respectively), a telomerase-associated protein TEP1/TLP1 (refs 6,7) and the human catalytic subunit protein TERT (refs 8,9) have been identified. To examine the role of telomerase in telomere maintenance and cellular viability, we established Terc-deficient embryonic stem (ES) cells. It is known that telomerase activity is absent in cells from Terc-knockout mice. Although the study showed that telomere shortening was observed in the Terc-deficient cells from first to six generation animals, whether telomerase-dependent telomere maintenance was essential for cellular viability remained to be elucidated. To address this issue, we examined Terc-deficient ES cells under long-term culture conditions. Accompanying the continual telomere shortening, the growth rate of Terc-deficient ES cells was gradually reduced after more than 300 divisions. An impaired growth rate was maintained to approximately 450 divisions, and then cell growth virtually stopped. These data clearly show that telomerase-dependent telomere maintenance is critical for the growth of mammalian cells.

A study on epidermal proliferation ability in cholesteatoma

With the objective of estimating proliferation ability of epidermis of middle ear cholesteatoma, the difference in proliferating cell nuclear antigen (PCNA) staining between the skin of the bone region of the external ear canal (control skin) and cholesteatoma epidermis and the effects on PCNA staining of subepidermal inflammatory cell infiltration of cholesteatoma were immunohistochemically studied using an antibody against PCNA. Transforming growth factor-alpha (TGF-alpha) is known to promote epidermal proliferation based on autocrine mechanism. But it is not clear that cholesteatoma epidermis is actually in the state of hyperproliferation under the effect of this growth factor. To estimate the effect of TGF-alpha on epidermal proliferation ability, the authors compared the location of PCNA and TGF-alpha in the same specimen. Unlike the control skin, not only epidermal basal cell layer and suprabasal cell layer, but also more superior layers were found to have high levels of PCNA staining in the epidermis of cholesteatoma. However, in the same cholesteatoma epidermal tissue, the PCNA staining was varied and the difference was ascribable to subepidermal cell inflammation. It appeared that the proliferation ability was high in regions where subepidermal inflammatory cell infiltration was severe. These differences in microenvironment are inferred to greatly affect proliferation ability of cholesteatoma epidermis.

Cell proliferation and apoptosis in human middle ear cholesteatoma

OBJECTIVE

To compare the pattern of proliferation and apoptotic cell death in cholesteatoma tissues with that in normal skin.

PARTICIPANTS

The cholesteatoma tissue samples were excised from 10 patients during surgery. Normal skin specimens collected from the external ear canal of 6 of the 10 patients were used as controls.

RESULTS

In all cholesteatoma tissue samples, apoptotic cells were not seen in the basal cell layer, but they were observed in the suprabasal, prickle, and granular cell layers. In skin specimens obtained from normal external ear canal skin, in which the suprabasal cell layer was comparatively small, similar kinetics of apoptotic cell death were observed. Immunohistochemical analysis using a monoclonal antibody to proliferation cell nuclear antigen demonstrated the presence of proliferating cells in the basal and suprabasal cell layers of the normal external ear canal skin, whereas in the cholesteatoma tissue samples, large numbers of proliferation cell nuclear antigen-positive cells were also observed in the prickle and granular cell layers.

CONCLUSIONS

Proliferation in cholesteatoma epidermal cells is not uncontrolled, as it is in malignant tumors. Our results demonstrate an increase in the rate of proliferation and apoptotic cell death in cholesteatoma epidermis.

Expression of messenger RNA for keratinocyte growth factor in human cholesteatoma

OBJECTIVE

To understand the interaction between cholesteatoma epithelium and subepithelial connective tissue as a paracrine regulation by keratinocyte growth factor.

DESIGN

Preparation of a specific DNA probe from human fetal fibroblast and detection of localization of keratinocyte growth factor messenger RNA in subepithelial granulation tissue of middle-ear cholesteatoma by a nonradioactive in situ hybridization method.

PARTICIPANTS

The cholesteatoma specimens were excised from 12 patients during surgery. Normal skin specimens collected from the external ear canal of six patients were used as controls.

RESULTS

Signals specific for keratinocyte growth factor messenger RNA were not expressed in the normal skin of the external ear canal, but were observed in fibroblasts of subepithelial connective tissue of cholesteatoma specimens. Signals were observed only in specimens collected from patients whose subepithelial connective tissue was thick and proliferated and whose inflammation was strong.

CONCLUSIONS

A paracrine regulation mechanism involving keratinocyte growth factor may exist for proliferation of epithelium of cholesteatoma. The subepithelial connective tissue of cholesteatoma may play an important role in the proliferation and development of the cholesteatoma, especially under inflammatory conditions.

Involvement of interleukin-1 in middle ear cholesteatoma

PURPOSE

The histopathological characteristics of middle ear cholesteatoma are hyperproliferation and differentiation of the epithelium and accompanying destruction of the bones. We directed our attention to interleukin 1 alpha (IL-1 alpha) and demonstrated localization of IL-1 alpha in the epidermis of cholesteatoma. In addition, a comparative study was made of the relationship of IL-1 alpha with the developmental stage of cholesteatoma, the degree of destruction of the auditory ossicles, presence/absence of otorrhea, and the state of subepithelium.

MATERIALS AND METHODS

Middle ear cholesteatoma tissues collected during operations were used as the experimental material, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis, Western blot, and immunohistological techniques were used as methods.

RESULTS

An anti-IL-1 alpha antibody-positive 17-kd band was observed in 2 of the 17 cases, whereas a 31-kd band was observed in 10 of the 17 cases. Neither the 17-kd band nor the 31-kd band was detected in normal skin tissues. The immunohistological staining showed the presence of IL-1 alpha in a region near the basal membrane of cholesteatoma epithelium.

CONCLUSION

A correlation was observed between IL-1 alpha and patients with vigorous proliferation of granulation in the subepithelium. The presence of granulation in the reverse side of the eardrum plays an important role in the proliferation of cholesteatoma epithelium.

Effects of hypergravity on the elongation growth in radish and cucumber hypocotyls

The elongation growth of the hypocotyls of radish and cucumber seedlings was examined under hypergravity in a newly developed centrifuge (Kasahara et al. 1995). The effects of hypergravity on elongation growth differed between the two species. The rate of elongation of radish hypocotyls was reduced under basipetal hypergravity (H+2O g) but not under acropetal hypergravity (H-13 g), as compared to growth under the control conditions (C+1 g and C-1 g). In cucumber hypocotyls, elongation growth was inhibited not only by basipetal but also by acropetal hypergravity. Under these conditions, the reduction in the elongation growth of both radish and cucumber hypocotyls was accompanied by an increase in their thickness. Although no distinct differences in relative composition of neutral sugars were found, the amounts of cell-wall components (pectic substances, hemicelluloses and cellulose) per unit length of hypocotyls were increased by exposure to hypergravity.

Expression and localization of mRNA for epidermal growth factor and epidermal growth factor receptor in human cholesteatoma

The roles of epidermal growth factor (EGF) and epidermal growth factor receptor (EGF-R) in the proliferation and progression of the epithelium of middle ear cholesteatoma were studied. An attempt was made to elucidate the site and degree of localization of the EGF mRNA and EGF-R mRNA in the epithelium of the cholesteatoma by means of the non-radioactive in situ hybridization method. Ten cholesteatoma specimens excised during operations and six normal skin specimens (control) collected from the external ear canal were used in this study. The signal of the EGF mRNA was slightly expressed in part of the basal cells in only one of the six control specimens, while the signal was strongly expressed along the basal cells of the cholesteatoma epithelium in five of the ten specimens. The signal of the EGF-R mRNA was observed along the basal cell layer in five of the six control specimens, while the signal was strongly expressed in all layers of the cholesteatoma epithelium in all ten specimens. The expression was especially marked in the basal cell layer. These findings suggest the possibilities that abnormal expression of the EGF-R mRNA in nearly entire epithelial layers of cholesteatoma is due to overexpression of EGF-R gene, and that there is a mechanism of epithelial basal cell proliferation through an autocrine regulatory system via EGF and EGF-R.