Angiosarcoma which developed on the abdominal wall: report of a case

We report a 68-year-old Japanese woman with angiosarcoma (AS) on the abdominal wall. To the best of our knowledge, she is the third such patient reported from Japan.

Purification and subunit structure of extracellular superoxide dismutase from mouse lung tissue

The first purification of mouse extracellular superoxide dismutase (EC-SOD) and the analysis of the native enzyme are described. Mouse EC-SOD was purified from lung tissues with a high recovery (41%) and a specific polyclonal antibody against the purified enzyme was obtained. The purified enzyme had a strong affinity for, heparin and a molecular mass of 150 kDa (estimated by a gel filtration chromatography). The native mouse EC-SOD was composed of two different sizes of subunits, a M(r) of 33 and 35 kDa (determined by SDS-PAGE). The 35-kDa subunit had an interchain disulfide bond at the C-terminus and existed as a covalent dimer in the molecule, whereas the 33-kDa subunit resulted from the 35-kDa subunit by truncating its C-terminus as a posttranslational modification, with resultant loss of the interchain disulfide bond. These results suggest that the native mouse EC-SOD is a heterotetramer composed of two different dimers, with or without a covalent bond.

Rearrangement of the BCL6 gene in B-cell lymphoid neoplasms

We report here a large series of B-cell neoplasms with regard to rearrangement of the BCL6 gene on chromosome band 3q27. Southern blot analysis using probes from the major translocation cluster (MTC) region of the BCL6 revealed rearrangement in 32 of a total of 222 patients with various subtypes of B-cell neoplasm. In non-Hodgkin's lymphoma (NHL), rearrangements of the BCL6 gene were not closely associated with a specific histopathologic subtype but distributed in subcategories in the Working Formulation. A comparative study between NHL associated either with BCL2 or BCL6 rearrangement showed that advanced disease and bone marrow involvement were more frequent in BCL2(+) NHL. In contrast, extranodal involvement was more frequently observed in the BCL6(+) NHL. The survival curve of BCL6(+) NHL was characterized by a rapid decline followed by a plateau. Of the total of 32 BCL6(+) patients, 6 carried both BCL2 and BCL6 rearrangements, and showed clinicopathological properties of follicular lymphoma. This study suggests that BCL6 rearrangement is primarily associated with large cell lymphoma, and that BCL2(-)BCL6(+) NHL could potentially be curable with modern combination chemotherapy.

Long distance polymerase chain reaction for detection of chromosome translocations in B-cell lymphoma/leukemia

To establish a rapid and sensitive method to detect neoplastic cells carrying a specific chromosomal translocation in B-cell lymphoma/leukemia, we have developed a novel strategy based on long distance polymerase chain reaction (LD-PCR) amplification. Genomic DNA were extracted from tumor cells carrying a t(14;19)(q32;q13), a t(8;14)(q24;q32), a t(3;22)(q27;q11), a t(2;3)(p12;q27), and a t(3;14)(q27;q32). Oligonucleotide primer pairs were designed to be complementary to exons or flanking sequences of the BCL3, c-MYC and BCL6 oncogenes, and to constant region genes of the IG genes. LD-PCR with a newly available Taq polymerase for longer product synthesis successfully amplified fragments representing BCL3/C alpha junctional sequences for t(14;19); c-MYC/C mu, c-MYC/C gamma and c-MYC/C alpha for t(8;14); BCL6/C lambda for t(3;22); BCL6/C kappa for t(2;3); 5'-BCL6/C mu and 5'-BCL6/C gamma for t(3;14), respectively. The sizes of the amplified fragments were varied from 1.8 kb to 12 kb, which were specific to each material. Present study provides a useful tool for diagnosis and subsequent management of B-cell lymphoma/leukemia characterized with specific chromosomal translocation.

[Genetic evaluation for rifampicin-susceptibility of Mycobacterium tuberculosis]

We evaluated the relationship between rifampicin (RFP)-susceptibility and genetic alterations in rpoB gene of clinically isolated Mycobacterium tuberculosis strains, collected from different geographic locations within Japan. Alterations in rpoB gene were detected by PCR-direct sequencing analysis, and the minimum inhibitory concentrations (MICs) of RFP were determined by broth microdilution method using Middlebrook 7H9 broth. One hundred and sixty six epidemiologically unrelated M. tuberculosis strains were examined. A total of 99 genetic alterations in the 69 bp core region of rpoB gene were detected in 95 out of 166 strains. Among them, 96 out of 166 strains showed RFP-resistant phenotypes with MICs > or = 2 micrograms/ml. Examination of the correlation between the MICs of RFP and amino acid substitutions in 69 bp core region of rpoB gene revealed that 58 out of 59 strains containing amino acid substitution in codon 531 showed highly RFP-resistant phenotypes with MICs > or = 64 micrograms/ml. In contrast, a variable level of RFP-susceptibility was observed among strains containing amino acid substitutions in either codon 516 or 526. On the other hand, the MICs of three strains with a point mutation in either codon 515 or 533 were all < or = 1 microgram/ml. Our results suggest that rpoB gene sequencing is useful for not only the detection of RFP-resistant M. tuberculosis strains, but also the prediction of RFP-susceptibility of the strains.

[Efficacy of erythromycin inhalation in chronic respiratory infection caused by Pseudomonas aeruginosa]

The prognosis of chronic respiratory tract infection with Pseudomonas aeruginosad considered to be poor. However, low-dose and long-term 14 membered macrolide, such as erythromycin or clarithromycin, treatment has been reported as effective clinically in chronic lower respiratory tract disease. There was no report to investigate the effect of macrolide on chronic biofilm related Pseudomonas aeruginosa respiratory tract infection in vivo. In a newly established murine model of chronic Pseudomonas aeruginosa respiratory infection mimicking diffuse panbronchiolitis (DPB), we investigated the effect of erythromcin inhalation on viable bacteria in the lungs. Infection was produced by placement of a plastic tube in the bronchus with inoculating. Pseudomonas aeruginosa suspended in saline was also inoculated in bronchus after intubation of the tube. Viable bacteria were constantly isolated at 10(4) 10(6) cfu-specimen from the lungs for more than 30 days. Treatment with erythromycin inhalation for four days reduced the number of viable bacteria in the lungs with statistically significant. Our result indicated that our new model of chronic respiratory tract infection is simple and provides a useful tool to study the pathogenic process and treatment of such infection. Our results also suggest that the erythromycin inhalation is effective on chronic Pseudomons aeruginosa respiratory infection.

AP-3: an adaptor-like protein complex with ubiquitous expression

We have identified two closely related human proteins (sigma3A and sigma3B) that are homologous to the small chains, sigma1 and sigma2, of clathrin-associated adaptor complexes. Northern and Western blot analyses demonstrate that the products of both the sigma3A and sigma3B genes are expressed in a wide variety of tissues and cell lines. sigma3A and sigma3B are components of a large complex, named AP-3, that also contains proteins of apparent molecular masses of 47, 140 and 160 kDa. In non-neuronal cells, the 47 kDa protein most likely corresponds to the medium chain homolog p47A, and the 140 kDa protein is a homolog of the neuron-specific protein beta-NAP. Like other members of the medium-chain family, the p47A chain is capable of interacting with the tyrosine-based sorting signal YQRL from TGN38. Immunofluorescence microscopy analyses show that the sigma3-containing complex is present both in the area of the TGN and in peripheral structures, some of which contain the transferrin receptor. These results suggest that the sigma3 chains are components of a novel, ubiquitous adaptor-like complex involved in the recognition of tyrosine-based sorting signals.

Neural reflex-mediated tracheal response during bronchoconstriction induced by ovalbumin antigen in guinea pigs

1. The biphasic reflex tracheal response (constriction followed by dilatation) occurred during bronchoconstriction induced by inhalation of ovalbumin antigen (OA) in sensitized guinea pigs. 2. The reflex tracheal constriction was largely reduced by atropine, and the dilatation was inhibited by propranolol and N omega-nitro-L-arginine methyl ester (L-NAME). The noradrenaline, adrenaline, cyclic AMP, and cyclic GMP contents in the tracheal segment were significantly higher during reflex tracheal dilatation. 3. These findings suggest that cholinergic nerves may mediate reflex tracheal constriction and that adrenergic and NOergic nerves may mediate the ensuing reflex tracheal dilatation.

Three approaches for laparoscopic unroofing of simple and complicated renal cysts

We report 2 cases of simple renal cysts which were marsupialized with 2 laparoscopic approaches involving either transperitoneal, with reflection of the colon medially or dissection through the mesocolon, and a case of a multilocular renal cyst which was treated by the retroperitoneal approach. Although laparoscopic unroofing of a renal cyst is a safe and effective alternative to open surgical techniques, the transperitoneal approach should only be used for simple renal cysts. The retroperitoneal approach for complicated renal cysts may be indicated if preoperative examinations exclude the possibility of malignancy.

Effect of swimming training on antioxidant enzymes in kidney of young and old mice

The current study was undertaken to investigate the effect of swimming training on the antioxidant enzyme system in kidney of young and old mice. Both young and old mice, aged 2 and 26 months old, respectively, were divided into the sedentary and swimming-trained groups. The trained mice underwent a 6-week swimming program (1 h/day, 5 days/week) in water at 35-36 degrees C. Cu,Zn-superoxide dismutase (Cu,Zn-SOD) activity was significantly decreased with aging but was not influenced by swimming training, such changes being similar to those noted for catalase activity rather than for glutathione peroxidase activity. After swimming training Mn-SOD activity increased significantly only in old mice but was unaffected by aging. Although neither aging nor swimming training had overt effect on the expression of Cu,Zn-SOD mRNA, the immunoreactive Cu,Zn-SOD content in young mice decreased significantly after the training. Meanwhile, Mn-SOD mRNA expression in old mice was reduced by half after swimming training, accompanied by a significant decrease in its immunoreactive content; unexpectedly, however, Mn-SOD content in young mice did not parallel its mRNA expression. These findings suggest that the antioxidant enzyme system in mouse kidney trends to be down-regulated with aging, and that swimming training fails to attenuate such reduced levels of the antioxidant enzymes.

Effect of cast solvent on the electron transfer reaction for poly(ethylene oxide)-modified myoglobin on the electrode in poly(ethylene oxide) oligomers

Myoglobin from horse skeletal muscle was modified with poly(ethylene oxide) (PEO) with an average molecular weight of 2000 or 5000. Myoglobin was soluble after this modification in several organic solvents and PEO oligomers. The electron transfer reactions of PEO-modified myoglobin cast on the indium tin oxide (ITO) glass electrode were investigated by cyclic voltammetry. The PEO-modified myoglobin, cast on the electrode from water or a methanol solution, showed quasi-reversible redox reactions in PEO (average MW of 400). On the other hand, no redox response was seen in PEO-modified myoglobin cast on it using chloroform or benzene as a casting solvent. A clear redox response of the PEO-modified myoglobin was observed after methanol treatment of these layers cast from chloroform or a benzene solution. This suggests that the conformational change of the adsorbed PEO-modified myoglobin layer on the ITO electrode cast from chloroform or a benzene solution was not irreversible. The cast condition of PEO-modified myoglobin on the ITO glass electrode was revealed to affect the electron transfer reaction for protein considerably in PEO oligomers.

A shift from negative to positive selection of autoreactive T cells by the reduced level of TCR signal in TCR-transgenic CD3 zeta-deficient mice

T cell selection is thought to be determined through the interaction between TCR and Ag/MHC. However, the contribution of the level of TCR signal to thymic selection remains unclear. To address this issue, we analyzed T cell selection of male Ag (HY)-specific TCR transgenic (HYTg) mice crossed with CD3 zeta-deficient (zeta KO) mice (HYTg/zeta KO), which have impaired signaling through TCR. In male HYTg/zeta KO mice, the number of thymocytes was comparable to that in normal mice, and almost all the peripheral T cells were HY specific, although these positively selected cells were anergic to male Ag. From these observations, the decrease in TCR signaling by CD3 zeta deficiency resulted in both the avoidance of negative selection and the acquisition of positive selection of autoreactive T cells in male HYTg/zeta KO mice. There was a shift of T cell selection from positive to no selection of HY-specific T cells in female HYTg/zeta KO mice also. Collectively, these findings suggest that the level of TCR signal directly regulates T cell selection; furthermore, the findings have integrated the models of T cell selection into a concept based on the quantity of TCR signal.

A shift from negative to positive selection of autoreactive T cells by the reduced level of TCR signal in TCR-transgenic CD3 zeta-deficient mice

T cell selection is thought to be determined through the interaction between TCR and Ag/MHC. However, the contribution of the level of TCR signal to thymic selection remains unclear. To address this issue, we analyzed T cell selection of male Ag (HY)-specific TCR transgenic (HYTg) mice crossed with CD3 zeta-deficient (zeta KO) mice (HYTg/zeta KO), which have impaired signaling through TCR. In male HYTg/zeta KO mice, the number of thymocytes was comparable to that in normal mice, and almost all the peripheral T cells were HY specific, although these positively selected cells were anergic to male Ag. From these observations, the decrease in TCR signaling by CD3 zeta deficiency resulted in both the avoidance of negative selection and the acquisition of positive selection of autoreactive T cells in male HYTg/zeta KO mice. There was a shift of T cell selection from positive to no selection of HY-specific T cells in female HYTg/zeta KO mice also. Collectively, these findings suggest that the level of TCR signal directly regulates T cell selection; furthermore, the findings have integrated the models of T cell selection into a concept based on the quantity of TCR signal.

[Localization of 8q24 break-point of Burkitt lymphoma in Japan : relationship to EBV status]

It has been reported that the break point of 8q24 in t (8; 14) (q24; q32) is located far up-stream from c-myc gene locus in endemic EBV (Epstein-Barr virus)-positive BL, while the break-point is located close to the 1st intron of c-myc gene in sporadic EBV-negative BL. Considering that no statistical analysis is available regarding BL in Japan, the break-point of chromosome No.8 was investigated in 13 BL/L3 cell lines (having t(8; 14)) and 4 fresh samples derived from Japanese patients, including 3 EBV-positive BL cell lines, by using long-distance PCR. In this PCR, one primer was set in the 2nd intron of the c-myc gene, and the other primer in Ig constant region gene, mu, gamma, alpha and epsilon. This long distance PCR can cover up to 30 kb. Thus, this PCR does'nt generate product, if the 8q24 break-point is located far up-stream (more than 50 kb) fom c-myc gene. In 2 of the 3 t (8; 14) EBV-positive BL lines, no product was generated in two lines(N831 and Middle 91), while a product was synthesized in one line(Akata), indicating that the 8q24 break-point is near the c-myc gene in Akata. In all the other BL/L3 lines, a product was synthesized. A larger number of BL cases are necessary to investigate in order to know which 8q24 break-point pattern is exhibited by EBV-positive BL in Japan, while this method is suitable for testing a large number of case materials.

High altitude training increases reactive carbonyl derivatives but not lipid peroxidation in skeletal muscle of rats

The oxidative stress related consequences of physical training at high altitude are not known. The hypothesis was tested that physical training and exposure to high altitude have adverse effects on free radical generation and activities of antioxidant enzymes. The present results showed that 4 weeks of exercise at an altitude of 4000 m increased the activity of Mn-SOD in both white and red types of skeletal muscle. The activities of Cu,Zn-SOD, catalase, and glutathione peroxidase, as well as the level of lipid peroxidation measured by TBARS and lipid hydroperoxides, did not change significantly. In contrast, the level of reactive carbonyl derivatives measured by anti-2,4-dinitrophenylhydrazone antibodies and spectrophotometry showed an increase in both types of muscle of altitude trained rats compared with sea level trained and control groups. It was suggested that the oxidative modification of certain amino acids is due to the increasing gap between activity of SOD and peroxide scavenging enzymes, which results in increases in the number of hydrogen peroxide molecules. Thus, since the mechanism of generation and/or the mode of action of radicals resulting in lipid peroxidation and protein oxidation appears to be different in vivo, both processes should be studied during oxidative stress.

A recurring translocation, t(3;6)(q27;p21), in non-Hodgkin's lymphoma results in replacement of the 5' regulatory region of BCL6 with a novel H4 histone gene

3q27 translocations affecting the BCL6 gene can involve not only immunoglobulin genes (IG) but also other as yet uncharacterized chromosomal loci as partners. Here, we describe cloning of the junctional area of a recurring translocation, t(3;6)(q27;p21), in non-Hodgkin's lymphoma of B-cell type and isolation of clones from 6p21; high resolution fluorescence in situ hybridization mapped the clones to sub-band 6p21.3. Nucleotide sequence analysis of a fragment from the junctional area of 6p21 revealed the presence of a novel H4 histone gene that was included in the histone gene cluster on this particular region, and the same fragment detected approximately 380-bp transcripts in hematological tumor cells. Breakpoints on 3q27 of two cases carrying t(3;6) were immediately 3' of the BCL6 exon 1, and the H4 histone gene was substituted for the 5' regulatory elements of BCL6. Because H4 gene expression is tightly coupled to DNA replication, this study suggested an immediate mechanism for deregulated expression of BCL6, leading to the development of non-Hodgkin's lymphoma.

Effects of swimming training on brown-adipose-tissue activity in obese ob/ob mice: GDP binding and UCP m-RNA expression

Brown adipose tissue (BAT) of obese animals is generally in a relatively atrophied and thermogenically quiescent state. The aim of the current study was to investigate the effect of swimming training on BAT activity in lean and obese (ob/ob) mice. The trained mice underwent a 6-week endurance swimming training (1 h/day, 5 days/week) in water at 35-36 degrees C. The swimming training significantly increased BAT mass and its protein content in both the lean and obese mice, suggesting hypertrophy. After swimming training, the amounts of protein and guanosine 5'-diphosphate binding in the mitochondria recovered from BAT of both mice increased significantly as compared with the respective sedentary groups, whereas the uncoupling protein (UCP) content increased significantly only in lean mice. After swimming training, the level of UCP mRNA expression did not change substantially in lean mice but appeared to increase in obese mice. The results obtained here suggest that swimming training leads to an increase in the nonshivering thermogenesis of obese mice in addition to lean mice.

The t(9;14)(p13;q32) chromosomal translocation associated with lymphoplasmacytoid lymphoma involves the PAX-5 gene

The t(9;14)(p13;q32) translocation is associated with approximately 50% of lymphoplasmacytoid lymphoma (LPL), a subtype of B-cell non-Hodgkin's lymphoma (NHL). We cloned the chromosomal breakpoint of der (14) from an LPL case (1052) and showed that it involved a junction between 9p13 and the switch micro region of the Ig heavy chain locus (IgH) on 14q32. Using a YAC contig spanning 1.5 megabase (Mb), we determined that the 9p13 breakpoint in one case (1052) mapped within a 270-kb restriction fragment containing two previously reported 9p breakpoints associated with a alpha-heavy chain disease case (MAL) and KI-1 positive diffuse large cell lymphoma (DLCL) cell line (KIS-1). The same fragment also contained the PAX-5 gene which encodes a B-cell specific transcription factor involved in the control of B-cell proliferation and differentiation. The breakpoints of KIS-1 and 1052 were mapped within the 5' noncoding region of PAX-5, while the 9p13 breakpoint of MAL mapped 230 to 270 kb upstream to PAX-5. In all three cases, the translocation caused the juxtaposition of the PAX-5 gene to the IgH locus in the opposite direction of transcription. When compared with six other DLCL cell lines lacking t(9;14)(p13;q32), the KIS-1 cell line showed an 11-fold overexpression of PAX-5 mRNA and a significantly reduced expression of the p53 gene, which is normally regulated by PAX-5. Moreover, metaphase and interphase fluorescence in situ hybridization (FISH) analysis using a YAC clone spanning 1 Mb including the PAX-5 as a probe identified chromosomal translocations in 5 of 7 cases carrying 9p13 translocations. These findings suggest that the PAX-5 gene is the target of the t(9;14) in LPL whereby its expression may be deregulated by juxtaposition to IgH regulatory elements, thus contributing to lymphomagenesis.

Pyruvate dehydrogenase complex-catalyzed formation of N-arylacetohydroxamic acids from nitroso aromatic compounds in rat isolated cells and perfused organs

The formation of N-arylacetohydroxamic acid derivatives from m-nitrosobenzyl alcohol (MBNO) and a nitroso derivative of chloramphenicol, 2,2-dichloro-N-[2-hydroxy-1-(hydroxymethyl)-2-(4-nitrosophenyl) ethyl]acetamide, in the presence of pyruvate was investigated with rat isolated cells (heart, kidney, liver, small intestine, lung, bone marrow and spermatozoa) and perfused organs (liver and heart). The activity in N-(m-hydroxymethylphenyl) acetohydroxamic acid (MBHA) formation was found in all the cells tested. Measurement of the kinetic parameters revealed that K(m) values of MBNO were ca. 0.3 mM and that the order of Vmax per cell was heart > kidney > liver > small intestine. In the hepatocytes, MBHA was metabolized further and the in vitro intrinsic clearance of MBHA was 1.91 +/- 0.24 ml/min/10(8) cells. In a single-pass perfusion of rat liver with MBNO, the corresponding amino, acetylamino and azoxy derivatives and unknown materials were formed in addition to MBHA. The activity in MBHA formation was increased by the addition of both diethyl maleate and paraoxon. In a recirculating perfusion of rat liver with MBNO, however, the net MBHA formation was hardly detected, because of the disposition of MBHA formed. The hepatic clearance of MBHA was 1.15 +/- 0.06 ml/min/g of liver. In a recirculating perfusion of isolated rat heart with MBNO, MBHA was formed as a major metabolite and further biotransformation was not found. The N-arylacetohydroxamic acid derivative of 2,2-dichloro-N-[2-hydroxy-1-(hydroxymethyl)-2-(4-nitrosophenyl) ethyl]acetamide was also formed in rat bone marrow cells and the isolated perfused heart. These results indicate that the formation of N-arylacetohydroxamic acids from nitroso aromatic compounds and pyruvate catalyzed by pyruvate dehydrogenase complex proceeds in virtually all mammalian tissues.

[Differential diagnosis of tuberculous pleurisy by the measurement of cytokine concentration in pleural effusion]

Pleural fluids obtained from 26 patients with tuberculous pleurisy (T-group), 11 with parapneumonic pleurisy (B-group) and 21 with malignant pleurisy (M-group) were tested for their biologic parameters and cytokine concentrations. 1) The average age of T-group was over 10 years lower than that of M-group with a statistically significant difference. 2) The average CRP value of B-group and the positivity on PPD skin test of T-group were higher than those of the other groups, respectively. 3) Yellowish pleural fluids were mainly observed in T- and B-group, while bloody pleural fluids were mostly seen in M-group with a statistically significant difference. The average total protein amount and adenosine deaminase value in pleural fluid significantly increased in T-group. The percentage of polymorphonuclear leukocytes showed a significant increase in B-group, while lymphocytes significantly increased in T-group with a statistically significant difference. 4) Although no significant difference in concentrations of IL-1 beta, IL-2, IFN-gamma and TNF-alpha in serum was noticed among the three groups, the average concentrations of IFN-gamma and TNF-alpha in pleural fluid in T-group were significantly higher than those in the other groups. 5) TNF-alpha-mRNA of mononuclear cells in pleural fluid was strongly expressed in 3 out of 11 patients of T-group, while no expression was observed in 6 patients of M-group. In conclusion, the measurement of concentrations of two kinds of cytokines in pleural fluid, IFN-gamma and TNF-alpha, may be clinically useful for the differential diagnosis of tuberculous pleurisy from parapneumonic pleurisy and malignant pleurisy.

Carotid artery disease in patients with retinal artery occlusion

Embolization from the carotid bifurcation has been proposed as the most common cause of central retinal artery occlusion (CRAO) and branch retinal artery occlusion (BRAO). The purpose of this study was to evaluate carotid artery disease in patients with CRAO and BRAO. Using carotid ultrasonography, 17 patients (13 males, 4 females, mean age 68.7 +/- 7.1 years) with CRAO and BRAO were examined for stenotic findings and plaque morphology (homogeneous or heterogeneous) within 7 days after onset. The internal carotid artery (ICA) ipsilateral to the affected side showed a significantly higher incidence of severe carotid stenosis as compared to the non-affected side. The occurrence of heterogeneous plaques in the ICA did not differ between the affected and the non-important affected side. We suspect that severe carotid stenosis in addition to heterogeneous plaques plays an important role in retinal artery occlusion.

Evaluation of water durability at adhesion interfaces by peeling test of resin film

The water durability at adhesion interfaces was investigated by measurement of the peeled area of thin resin films bonded with 4-META resin on metal surfaces after imposing thermal stress using liquid nitrogen. Thermal stress at the adhesion interface was calculated by a computer-aided finite element method. On 18-8 stainless-steel specimens which bond strongly with 4-META resin, total interface failure occurs on specimens with resin thicker than 0.55 mm in dry condition. A resin layer of 0.25 mm was chosen to study degradation of the adhesion interface by water. The shearing stress was calculated as 16 MPa for a 0.25 mm thick resin layer. On mild-steel adherent interface with 4-META resin which degrades rapidly by water molecule, the relationship between water immersion time and degradation at the adhesion interface was discussed together with the amount of water penetrated at the interface. The method proposed in the present study is effective as a quick evaluation method for water durability at the adhesion interface.

Structural determinants of interaction of tyrosine-based sorting signals with the adaptor medium chains

Many integral membrane proteins contain tyrosine-based signals within their cytoplasmic domains that mediate internalization from the cell surface and targeting to lysosomal compartments. Internalization depends on an interaction of the tyrosine-based signals with the clathrin-associated adaptor complex AP-2 at the plasma membrane, whereas lysosomal targeting involves interaction of the signals with an analogous complex, AP-1, at the trans-Golgi network. Recent studies have identified the medium chains mu2 of AP-2 and mu1 of AP-1 as the recognition molecules for tyrosine-based signals. We have now investigated the structural determinants for interaction of the signals with mu2 and mu1. The position of the signals was found to be an important determinant of interactions with mu2 and mu1; signals were most effective when present at the carboxyl terminus of a polypeptide sequence. Another important determinant of interactions was the identity of residues surrounding the critical tyrosine residue. Mutation of some residues affected interactions with mu2 and mu1 similarly, whereas other mutations had differential effects. These observations suggest that both the position and the exact sequence of tyrosine-based sorting signals are major determinants of selectivity in their interaction with clathrin-associated adaptor complexes.

Sequence requirements for the recognition of tyrosine-based endocytic signals by clathrin AP-2 complexes

We recently determined that fusion proteins containing tyrosine-based endocytic signals bind to the mu 2 subunit of AP-2, the complex that drives clathrin coat formation and mediates endocytosis from the plasma membrane. Here we analyze the selectivity of peptide recognition by mu 2 and by AP-2 using combinatorial selection methods and surface plasmon resonance. Both mu 2 and AP-2 are shown to interact with various sequences of the form tyrosine-polar-polar-hydrophobic (Yppø) found on receptors that follow the clathrin pathway. The optimal sequence for interaction with mu 2 and with AP-2 has tyrosine as an anchor and prefers arginine at position Y + 2 and leucine at position Y + 3. In contrast, no preferred sequence is detected surrounding the Yppø signal, indicating that recognition of the Yppø endocytic signal does not require a prefolded structure. We conclude that sorting into the endocytic pathway is governed by a surprisingly simple interaction between the mu 2 chain and a tyrosine-containing tetrapeptide sequence.