Structured chaos in a devil's staircase of the Josephson junction

The phase dynamics of Josephson junctions (JJs) under external electromagnetic radiation is studied through numerical simulations. Current-voltage characteristics, Lyapunov exponents, and Poincaré sections are analyzed in detail. It is found that the subharmonic Shapiro steps at certain parameters are separated by structured chaotic windows. By performing a linear regression on the linear part of the data, a fractal dimension of D = 0.868 is obtained, with an uncertainty of ±0.012. The chaotic regions exhibit scaling similarity, and it is shown that the devil's staircase of the system can form a backbone that unifies and explains the highly correlated and structured chaotic behavior. These features suggest a system possessing multiple complete devil's staircases. The onset of chaos for subharmonic steps occurs through the Feigenbaum period doubling scenario. Universality in the sequence of periodic windows is also demonstrated. Finally, the influence of the radiation and JJ parameters on the structured chaos is investigated, and it is concluded that the structured chaos is a stable formation over a wide range of parameter values.

Generation of dendritic cells and macrophages from human induced pluripotent stem cells aiming at cell therapy

This report describes generation of dendritic cells (DCs) and macrophages from human induced pluripotent stem (iPS) cells. iPS cell-derived DC (iPS-DC) exhibited the morphology of typical DC and function of T-cell stimulation and antigen presentation. iPS-DC loaded with cytomegalovirus (CMV) peptide induced vigorous expansion of CMV-specific autologous CD8+ T cells. Macrophages (iPS-MP) with activity of zymosan phagocytosis and C5a-induced chemotaxis were also generated from iPS cells. Genetically modified iPS-MPs were generated by the introduction of expression vectors into undifferentiated iPS cells, isolation of transfectant iPS cell clone and subsequent differentiation. By this procedure, we generated iPS-MP expressing a membrane-bound form of single chain antibody (scFv) specific to amyloid β (Aβ), the causal protein of Alzheimer's disease. The scFv-transfectant iPS-MP exhibited efficient Aβ-specific phagocytosis activity. iPS-MP expressing CD20-specific scFv engulfed and killed BALL-1 B-cell leukemia cells. Anti-BALL-1 effect of iPS-MP in vivo was demonstrated in a xeno-transplantation model using severe combined immunodeficient mice. In addition, we established a xeno-free culture protocol to generate iPS-DC and iPS-MP. Collectively, we demonstrated the possibility of application of iPS-DC and macrophages to cell therapy.

Identification of SARS-COV spike protein-derived and HLA-A2-restricted human CTL epitopes by using a new muramyl dipeptidederivative adjuvant

Severe acute respiratory syndrome (SARS) spread during the winter of 2003, and attempts have been made to develop vaccines against SARS corona virus (SARS-CoV). The present study provides a strategy to rapidly identify SARS-CoV-derived antigenic peptides recognized by HLA-A2-restricted cytotoxic T lymphocytes (CTLs). Forty-three candidate peptides having HLA-A2-binding motifs were selected in silico and HLA-A2/Db chimeric MHC class I-transgenic mice were immunized with these peptides and a new derivative of muramyl dipeptide that can induce upregulation of HLA-DR, CD80, CD86, and CD40 in human CD14+ antigen presenting cells, was administered as an adjuvant. Six HLAA2-restricted mouse CTL epitopes were identified, including two new epitopes which have never been reported before. One of the novel peptides was naturally processed and successfully induced HLAA2-restricted specific CTLs in both HLA transgenic mice and healthy donors. The method was useful, convenient and efficient for rapid identification of CTL epitopes derived from SARS-CoV proteins and will be possibly applicable for other pathogens to develop a peptide-based vaccine.

Growth inhibition efficacy of an adenovirus expressing dual therapeutic genes, wild-type p53, and anti-erbB2 ribozyme, against human bladder cancer cells

The altered expression of both p53 and erbB2 is strongly related to the disease status and the outcome of bladder cancers. We examined the antitumor efficacy by the modulation of these genetic alterations with a newly designed dual-gene-expressing adenovirus (Ad-p53/erbB2Rz), which expresses p53 and anti-erbB2 ribozyme simultaneously in human bladder cancer cells. Cell growth inhibition efficacy along with biological responses of this virus was compared with other viral vectors (Ad-p53, which expresses wild-type p53 cDNA, and Ad-erbB2Rz, which expresses anti-erbB2 ribozyme, solely or in combination). Sufficient transgene expression in targeted cells and the altered expression of the targeted genes and their encoded proteins were obtained by each therapeutic vector. Each of the three therapeutic viral vectors inhibited bladder cancer cell growth, and the putative additive antitumor effect was shown by the combination of two of the therapeutic vectors. Furthermore, Ad-p53/erbB2Rz had superior therapeutic efficacy when the same titers of viruses were infected. Nonspecific vector-related toxicity was minimized by reducing the total amount of viral titers by using the dual-gene-expressing adenovirus. Modulation of multiple genetic abnormalities might enhance the therapeutic efficacy, and vector-related toxicity could be minimized when the total amount of viral titers are reduced.

Hammerhead ribozymes as therapeutic agents for bladder cancer

Hammerhead ribozymes have been investigated extensively as therapeutic agents against cancer. Aberrant or overexpression of genes related to tumorigenicity or cancer growth might be the appropriate targets for ribozyme strategies. Ribozyme-mediated gene therapy should be applied to those diseases that have no successful conventional therapy such as advanced or treatment-resistant bladder cancer. Many genetic alterations have been identified in bladder cancer related to both tumorigenesis and disease progression. Mutated H-ras, fos, and erb-B2 genes have been chosen as targets for ribozymes in previous studies, and antitumor efficacy has been demonstrated by reversion of the malignant phenotypes and by inhibition of tumor growth both in vitro and in vivo. The efficiency of various delivery systems has also been evaluated. An overview of ribozyme strategies, especially for therapeutic applications against bladder cancer, is described here.

Feasibility and assessment of non-invasive in vivo redox status using electron paramagnetic resonance imaging

PURPOSE

To test the feasibility of electron paramagnetic resonance imaging (EPRI) to provide non-invasive images of tissue redox status using redox-sensitive paramagnetic contrast agents.

MATERIAL AND METHODS

Nitroxide free radicals were used as paramagnetic agents and a custom-built 300 MHz EPR spectrometer/imager was used for all studies. A phantom was constructed consisting of four tubes containing equal concentrations of a nitroxide. Varying concentrations of hypoxanthine/xanthine oxidase were added to each tube and reduction of the nitroxide was monitored by EPR as a function of time. Tumor-bearing mice were intravenously infused with a nitroxide and the corresponding reduction rate was monitored on a pixel-by-pixel basis using 2D EPR of the tumor-bearing leg and normal leg serving as control. For animal studies, nitroxides were injected intravenously (1.25 mmol/kg) and EPR projections were collected every 3 min after injection using a magnetic field gradient of 2.5 G/cm. The reduction rates of signal intensity on a pixel-by-pixel basis were calculated and plotted as a redox map. Redox maps were also collected from the mice treated with diethylmaleate (DEM), which depletes tissue thiols and alters the global redox status.

RESULTS

Redox maps obtained from the phantoms were in agreement with the intensity change in each of the tubes where the signals were decreasing as a function of the enzymatic activity, validating the ability of EPRI to accurately access changes in nitroxide reduction. Redox imaging capability of EPR was next evaluated in vivo. EPR images of the nitroxide distribution and reduction rates in tumor-bearing leg of mice exhibited more heterogeneity than in the normal tissue. Reduction rates were found to be significantly decreased in tumors of mice treated with DEM, consistent with the depletion of thiols and the consequent alteration of the redox status.

CONCLUSION

Using redox-sensitive paramagnetic contrast agents, EPRI can non-invasively discriminate redox status differences between normal tissue and tumors.

Feasibility and assessment of non-invasive in vivo redox status using electron paramagnetic resonance imaging

PURPOSE

To test the feasibility of electron paramagnetic resonance imaging (EPRI) to provide non-invasive images of tissue redox status using redox-sensitive paramagnetic contrast agents.

MATERIAL AND METHODS

Nitroxide free radicals were used as paramagnetic agents and a custom-built 300 MHz EPR spectrometer/imager was used for all studies. A phantom was constructed consisting of four tubes containing equal concentrations of a nitroxide. Varying concentrations of hypoxanthine/xanthine oxidase were added to each tube and reduction of the nitroxide was monitored by EPR as a function of time. Tumor-bearing mice were intravenously infused with a nitroxide and the corresponding reduction rate was monitored on a pixel-by-pixel basis using 2D EPR of the tumor-bearing leg and normal leg serving as control. For animal studies, nitroxides were injected intravenously (1.25 mmol/kg) and EPR projections were collected every 3 min after injection using a magnetic field gradient of 2.5 G/cm. The reduction rates of signal intensity on a pixel-by-pixel basis were calculated and plotted as a redox map. Redox maps were also collected from the mice treated with diethylmaleate (DEM), which depletes tissue thiols and alters the global redox status.

RESULTS

Redox maps obtained from the phantoms were in agreement with the intensity change in each of the tubes where the signals were decreasing as a function of the enzymatic activity, validating the ability of EPRI to accurately access changes in nitroxide reduction. Redox imaging capability of EPR was next evaluated in vivo. EPR images of the nitroxide distribution and reduction rates in tumor-bearing leg of mice exhibited more heterogeneity than in the normal tissue. Reduction rates were found to be significantly decreased in tumors of mice treated with DEM, consistent with the depletion of thiols and the consequent alteration of the redox status.

CONCLUSION

Using redox-sensitive paramagnetic contrast agents, EPRI can non-invasively discriminate redox status differences between normal tissue and tumors.

Malignant adenomyoepithelioma of the breast with lung metastases: report of a case

Adenomyoepithelioma of the breast is a rare lesion, and has a bicellular pattern of epithelial and myoepithelial cells which are regularly distributed in the tubular structures based on the histologic and ultrastructural features. It is thought to be a benign or a low-grade malignant disease. We herein describe a case of malignant adenomyoepithelioma of the breast with lung metastases in an 86-year-old woman. A primary massive tumor in the left breast grew rapidly within a short period of time. A simple mastectomy with sampling of the axillary lymph nodes was performed. The obtained lymph nodes did not include any metastatic lesions. Malignancy was evidenced by the presence of a high mitotic rate and severe nuclear atypia. Three months after the operation, radiology showed multiple lung metastases, and the patient died 2 weeks thereafter. Reviewing the literature, nine similar cases were reported, and the prognosis of malignant adenomyoepithelioma of the breast with distant metastases was very poor with the time of recurrence varying after initial treatments. Malignant adenomyoepithelioma should be followed up with careful screening for distant metastases.

p53 Mutation in bladder cancer patients in Japan and inhibition of growth by in vitro adenovirus-mediated wild-type p53 transduction in bladder cancer cells

BACKGROUND

Altered expression of p53 has been described in nearly half of bladder cancers, and p53 mutations are presumed to play a role in the multistep progression of these tumors.

MATERIALS AND METHODS

The incidence of mutation in the p53 gene and its correlation with histopathologic findings and patient survival were evaluated in 105 Japanese patients with bladder cancer. Laboratory experiments were also performed to confirm the infectivity and efficacy in tumor growth inhibition of an adenovirus expressing wild-type p53 in EJ bladder cancer cells.

RESULTS

Mutations of p53 were observed in 38 bladder cancer specimens (36%), with a significantly higher incidence of mutation being seen in tumors of higher stage and grade. The overall survival was worse in patients with the p53 mutation. In laboratory experiments, adenoviral vectors infected bladder cancer cells in a dose- and cell density-dependent manner. The adenovirus-mediated transduction of wild-type p53 resulted in dose-dependent growth inhibition of bladder cancer cells in vitro. No significant cytotoxicity was observed after infection by a control adenovirus.

CONCLUSION

Transduction of wild-type p53 might be a potential therapeutic option for bladder cancer.

Antitumor effect of bcl-2 antisense phosphorothioate oligodeoxynucleotides on human renal-cell carcinoma cells in vitro and in mice

BACKGROUND AND PURPOSE

Programmed cell death is a genetically regulated pathway that is altered in many cancers. This process is, in part, regulated by the bcl-2 oncogene. Antisense oligodeoxynucleotides (ODNs) targeted to specific oncogenes have been used with some therapeutic success in animal models of leukemia and melanoma cells and human Hodgkin's lymphoma. We evaluated the effects of antisense ODNs targeted to the bcl-2 oncogene on the proliferation of human renal-cell carcinoma (RCC) cells in vitro and on the growth of human RCC xenografts in BALBc nude (nu/nu) mice.

MATERIALS AND METHODS

Expression bcl-2 mRNA in five RCC cell lines (ACHN, Caki-1, RCZ, RCW, and OS-RC-2) was analyzed by reverse transcriptase-polymerase chain reaction. The effects of phosphorothioated ODNs containing human bcl-2 sense and bcl-2 antisense sequences that were transfected with Lipofectin on the proliferation and viability of cultures of established human RCC cell lines were determined by MTS assay. The expression of Bcl-2 protein in ACHN tumor cells following antisense bcl-2 (AS2) ODN treatment was evaluated by Western blot analysis, and the extent of apoptosis in these cells was determined by fluorescence-activated cell sorter (FACS) analysis. The antitumor activity in ACHN xenografts in nu/nu mice was monitored by measuring differences in tumor weight in treated and control mice.

RESULTS

Expression of bcl-2 mRNA was detected in all five RCC lines. Treatment with antisense bcl-2 ODNs inhibited the growth of all tested RCC cells and decreased Bcl-2 protein expression in ACHN cells. The AS2 antisense ODN complementary to the coding region of bcl-2 mRNA showed a superior antiproliferative effect compared with AS1 ODN complementary to the translation initiation region. Inhibition by antisense bcl-2 ODNs of ACHN cells was dose dependent. The FACS analysis revealed that growth inhibition was associated with the induction of programmed cell death. In vivo, AS2 ODN antitumor activity was noted in locally injected groups.

CONCLUSIONS

Treatment of human RCC with antisense ODNs targeted to bcl-2 inhibits growth and is associated with the induction of programmed cell death. These results suggest therapeutic use of antisense bcl2 in the treatment of RCC.

Comparative evaluation of 99mTc-MIBI and 99mTc-HMDP scintimammography for the diagnosis of breast cancer and its axillary metastases

The purpose of the present study was to compare scintimammography using technetium-99m hexakis 2-methoxyisobutylisonitrile (MIBI) with that using 99mTc-hydroxymethylene diphosphonate (HMDP) in the detection of breast cancer and its axillary lesions. The study population comprised 50 consecutive females with breast cancer who were scheduled for surgery. All patients underwent scintimammography with 99mTc-MIBI and 99mTc-HMDP. The images were acquired 5 min (early) and 2 h (delayed) after injection of each radiopharmaceutical. Regions of interest were placed over the breast tumour (T), the axillary lesion (A) and the normal ipsilateral breast tissue (N). The two count ratios were calculated, i.e. the tumour to normal breast tissue ratio (T/N) and the axillary lymph node to normal breast tissue ratio (A/N). For the breast tumours, using 99mTc-MIBI the positive rate was 86% (43/50) for the early and 72% (36/50) for the delayed images. The corresponding values using 99mTc-HMDP were 72% (36/50) and 40% (20/50), respectively. Histopathological examination revealed metastatic lymph node involvement in 22 patients. For the axillary lesions, using 99mTc-MIBI the positive rate was 72.7% (16/22) for the early and 54.5% (12/22) for the delayed images. Using 99mTc-HMDP, the positive rate was only 18.2% (4/22) for the early and 4.5% (1/22) for the delayed images. Using 99mTc-MIBI, the mean T/N (+/- SD) ratios on early and delayed images were 2.69 +/- 1.64 and 2.03 +/- 1.16, respectively, and the mean A/N (+/- SD) ratios on early and delayed images were 2.20 +/- 1.23 and 1.80 +/- 1.20, respectively. The corresponding values using 99mTc-HMDP were 1.77 +/- 0.91, 1.42 +/- 0.72, 1.27 +/- 0.63 and 1.08 +/- 0.25, respectively. The T/N and A/N ratios on the early and delayed 99mTc-MIBI images were both significantly higher than those obtained using 99mTc-HMDP. 99mTc-MIBI scintimammography is more sensitive than 99mTc-HMDP scintimammography for the detection of breast cancer and its axillary lymph node metastases.

Amino acid residues in the alpha IIb subunit that are critical for ligand binding to integrin alpha IIbbeta 3 are clustered in the beta-propeller model

Several distinct regions of the integrin alpha(IIb) subunit have been implicated in ligand binding. To localize the ligand binding sites in alpha(IIb), we swapped all 27 predicted loops with the corresponding sequences of alpha(4) or alpha(5). 19 of the 27 swapping mutations had no effect on binding to both fibrinogen and ligand-mimetic antibodies (e.g. LJ-CP3), suggesting that these regions do not contain major ligand binding sites. In contrast, swapping the remaining 8 predicted loops completely blocked ligand binding. Ala scanning mutagenesis of these critical predicted loops identified more than 30 discontinuous residues in repeats 2-4 and at the boundary between repeats 4 and 5 as critical for ligand binding. Interestingly, these residues are clustered in the predicted beta-propeller model, consistent with this model. Most of the critical residues are located at the edge of the upper face of the propeller, and several critical residues are located on the side of the propeller domain. None of the predicted loops in repeats 1, 6, and 7, and none of the four putative Ca(2+)-binding predicted loops on the lower surface of the beta-propeller were important for ligand binding. The results map an important ligand binding interface at the edge of the top and on the side of the beta-propeller toroid, centering on repeat 3.

Toxicity and health-related quality of life during and after high dose rate brachytherapy followed by external beam radiotherapy for prostate cancer

BACKGROUND

The optimal protocol for combining high dose rate brachytherapy and external beam irradiation as treatment for localized prostate cancer is unknown. Toxicity rates and clinical and biochemical outcomes should be evaluated to validate the current treatment protocol.

METHODS

Fifty-eight patients were treated for prostate cancer with high dose rate brachytherapy followed by 30 Gy of external beam radiation therapy. Toxicity during treatment and for 12-18 months thereafter, and treatment-related morbidity, were evaluated. Physician-assessed treatment-related toxicity was graded at the time of occurrence using the Radiation Therapy Oncology Group morbidity criteria. Four separate self-administered questionnaires were used to collect longitudinally demographic data and general and prostate disease-related measures of quality of life.

RESULTS

Various degrees of rectal bleeding due to radiation proctitis were experienced by 13 patients (22%) at a median time of 11 months. Two of these patients needed hospitalization to undergo laser coagulation of the rectal mucosa. Study patients had statistically significant decreases in five SF-36 domains during the first month of treatment. All measures recovered by 12 months. Sexual function was not affected by irradiation. Lower urinary tract symptoms assessed by IPSS/QOL scores worsened significantly during the first month of treatment but later recovered to baseline levels. Physician-assessed RTOG scores failed to detect these changes.

CONCLUSIONS

Morbidity associated with combined radiation therapy was greatest during the first month of treatment and affected quality of life significantly. Most measures recovered to baseline levels by 12 months following radiation therapy. Although the current protocol appears acceptable, measures should be taken to decrease treatment-related morbidity further.

Retroperitoneoscopic radical nephrectomy by the posterior lumber approach for renal-cell carcinoma associated with chronic renal failure

PURPOSE

To evaluate the efficacy and invasiveness of retroperitoneoscopic radical nephrectomy for renal-cell carcinoma (RCC) in patients with chronic renal failure (CRF), a group known to have relatively high surgical risk.

PATIENTS AND METHODS

Between May 1996 and September 1999, six CRF patients maintained on hemodialysis underwent retroperitoneoscopic radical nephrectomy for clinically localized RCC by the posterior lumber approach. The excised kidneys were evacuated via a posterior skin incision (5 cm) between two port sites; the muscle layers were not incised.

RESULTS

The procedure was completed in all patients with no major complications. The mean operative time was 162 (range 135-210) minutes, and the estimated blood loss was 58 (15-100) mL; none of the patients required a blood transfusion. Regular hemodialysis was restarted on postoperative day 2 or 3.

CONCLUSIONS

This procedure seems to be minimally invasive and suitable for the treatment of small RCC in atrophic kidneys, especially in patients with CRF.

Spontaneous rupture of a parathyroid adenoma presenting as a massive cervical hemorrhage: report of a case

We report an unusual case of spontaneous rupture of a parathyroid adenoma causing cervical hemorrhage. A 60-year-old woman presented to our hospital after the sudden development of extensive ecchymosis of her neck and upper anterior chest wall. Computed tomography (CT) scanning revealed a hematoma in the left retrotracheal space, and laboratory examinations revealed significant hypercalcemia, hypophosphatemia, and a high level of intact parathyroid hormone. Primary hyperparathyroidism was diagnosed, but it was not until the hematoma had subsided, 4 months after her initial presentation, that a parathyroid adenoma was revealed by CT. An operation was performed, and a parathyroid adenoma with hemosiderin deposition was histologically diagnosed. Although this phenomenon is unusual, all endocrine surgeons should be well aware of the possibility of its occurrence.

Application of the membrane filter technique to bromodeoxyuridine immunochemistry for exfoliative cytology

The membrane filter technique for smear specimens of tumors in bromodeoxyuridine (BrdU) immunochemistry is described. The staining results of Raji cells processed using the filter technique was compared with that obtained by the conventional cytospin method. Although the BrdU mean labeling index (LI) for in cytospin specimens was almost the same as the LI in membrane filter specimens, filter specimens showed excellent staining and less cell destruction compared with those processed by cytospin. Small amounts of tumor specimens such as squamous cell carcinoma and polymorphous low-grade adenocarcinoma also were processed using the membrane filter appliance. For squamous cell carcinoma, the LI for the filter specimens was 5.36+/-0.38 and that of the paraffin sections was 5.56+/-0.38. The membrane filter technique provided relatively undamaged specimens for exfoliative cytology and will be useful for immunohistochemical evaluation of tumor cells and for routine, noninvasive cytological screening.

Differences between T-cell reactivities to major myelin protein-derived peptides in opticospinal and conventional forms of multiple sclerosis and healthy controls

In Japanese, susceptibility to the conventional form of multiple sclerosis (C-MS) is associated with the HLA-DRB1*1501-DRB5*0101 haplotype while susceptibility to the opticospinal form of MS (OS-MS) is associated with HLA-DPA1*0202-DPB1*0501. To clarify the characteristics of T cells autoreactive to myelin proteins in each MS subtype, we established T-cell lines reactive to such myelin antigens as myelin basic protein (MBP), proteolipid protein (PLP) and myelin oligodendrocyte glycoprotein (MOG) from 5 of 10 OS-MS patients, 6 of 11 C-MS patients and 7 of 13 healthy controls (HCs), and T-cell epitopes and their restriction molecules were determined. We found that (a) intermolecular epitope spreading was found to be significantly more frequent in MS patients than in HCs (P=0.0128), (b) intramolecular epitope spreading also tended to occur more frequently in MS patients than in HCs (P=0.0584), (c) in OS-MS, HLA-DR-restricted and MOG-autoreactive T cells were more frequently established as compared with those reactive to MBP or PLP epitopes and (d) in C-MS, HLA-DQ-restricted and PLP-autoreactive T cells dominated those autoreactive to MBP or MOG epitopes. A DPB1*0501-restricted MBP-reactive T-cell clone from a patient with OS-MS provided evidence that the first HLA class II anchor amino acid of peptide bound to disease-susceptible DP5 molecule was distinct from that for the DR2 molecule. Taken together, these differences in specificities of myelin-autoreactive T cells between C-MS and OS-MS as well as the difference in the anchor motif of the binding peptides between each MS subtype-susceptible HLA class II molecule may contribute to the development of distinct clinical phenotypes.

Bilateral pneumothorax with extensive subcutaneous emphysema manifested during third molar surgery. A case report

This report describes a case of bilateral pneumothorax with extensive subcutaneous emphysema in a 45-year-old man that occurred during surgery to extract the left lower third molar, performed with the use of an air turbine dental handpiece. Computed tomographic scanning showed severe subcutaneous emphysema extending bilaterally from the cervicofacial region and the deep anatomic spaces (including the pterygomandibular, parapharyngeal, retropharyngeal, and deep temporal spaces) to the anterior wall of the chest. Furthermore, bilateral pneumothorax and pneumomediastinum were present. In our patient, air dissection was probably caused by pressurized air being forced through the operating site into the surrounding connective tissue.

The role of alpha and beta chains in ligand recognition by beta 7 integrins

Integrins alpha(E)beta(7) and alpha(4)beta(7) are involved in localization of leukocytes at mucosal sites. Although both alpha(E)beta(7) and alpha(4)beta(7) utilize the beta(7) chain, they have distinct binding specificities for E-cadherin and mucosal addressin cell adhesion molecule-1 (MAdCAM-1), respectively. We found that mutation of the metal ion-dependent adhesion site (MIDAS) in the alpha(E) A-domain (D190A) abolished E-cadherin binding, as did mutation F298A on the A-domain surface near the MIDAS cleft. A docking model of the A-domain with E-cadherin domain 1 indicates that coordination of the alpha(E) MIDAS metal ion by E-cadherin Glu(31) and a novel projection of Phe(298) into a hydrophobic pocket on E-cadherin provide the basis for the interaction. The location of the binding site on the alpha(E) A-domain resembles that on other integrins, but its structure appears distinctive and particularly adapted to recognize the tip of E-cadherin, a unique integrin ligand. Additionally, mutation of the beta(7) MIDAS motif (D140A) abolished alpha(E)beta(7) binding to E-cadherin and alpha(4)beta(7)-mediated adhesion to MAdCAM-1, and alpha(4) chain mutations that abrogated binding of alpha(4)beta(1) to vascular cell adhesion molecule-1 and fibronectin similarly reduced alpha(4)beta(7) interaction with MAdCAM-1. Thus, although specificity can be determined by the integrin alpha or beta chain, common structural features of both subunits are required for recognition of dissimilar ligands.

Adenovirus-mediated ribozyme targeting of HER-2/neu inhibits in vivo growth of breast cancer cells

HER-2/neu is overexpressed in 25-30% of human breast cancers. We prepared an anti-HER-2/neu hammerhead ribozyme expressed by a recombinant adenovirus (rAdHER-Rz). Human breast cancer cell lines were transduced with high efficiency, resulting in decreased HER-2/neu expression. In vivo injections of rAdHER-Rz into BT-474 tumors established in nude mice inhibited tumor growth to 20% of mock-treated controls. Similar in vivo effects were shown in MCF-7 cells, which do not overexpress HER-2/neu. The growth inhibitory effects of rAdHER-Rz were greater than those of an antisense-expressing vector. These results suggest the utility of anti-HER-2/neu ribozymes as a rational strategy for gene therapy of breast cancer. Gene Therapy (2000) 7, 241-248.

The crystal structure of calcium-free human m-calpain suggests an electrostatic switch mechanism for activation by calcium

Calpains (calcium-dependent cytoplasmic cysteine proteinases) are implicated in processes such as cytoskeleton remodeling and signal transduction. The 2.3-A crystal structure of full-length heterodimeric [80-kDa (dI-dIV) + 30-kDa (dV+dVI)] human m-calpain crystallized in the absence of calcium reveals an oval disc-like shape, with the papain-like catalytic domain dII and the two calmodulin-like domains dIV+dVI occupying opposite poles, and the tumor necrosis factor alpha-like beta-sandwich domain dIII and the N-terminal segments dI+dV located between. Compared with papain, the two subdomains dIIa+dIIb of the catalytic unit are rotated against one another by 50 degrees, disrupting the active site and the substrate binding site, explaining the inactivity of calpains in the absence of calcium. Calcium binding to an extremely negatively charged loop of domain dIII (an electrostatic switch) could release the adjacent barrel-like subdomain dIIb to move toward the helical subdomain dIIa, allowing formation of a functional catalytic center. This switch loop could also mediate membrane binding, thereby explaining calpains' strongly reduced calcium requirements in vivo. The activity status at the catalytic center might be further modulated by calcium binding to the calmodulin domains via the N-terminal linkers.

Ganglioside GT1b in rat brain binds to p58, a brain-specific sodium-dependent inorganic phosphate cotransporter: expression cloning with a specific monoclonal antibody to ganglioside GT1b-binding protein

To evidence the notion that gangliosides involve neuronal cell interactions in the brain, we surveyed the presence of ganglioside-binding proteins in membrane lysates of adult rat cerebellum. Three proteins (p58, p90, and p160) were identified as GT1b-binding proteins by incubation of the blot of the membrane lysate with GT1b micelles. We generated a monoclonal antibody (mAb) specific to the polypeptide portion of the GT1b-binding proteins (YAK-2). The YAK-2 mAb specifically reacted with all three proteins on blots of proteins pretreated under nonreducing conditions for SDS-PAGE, but reacted mainly with p58 under reducing conditions, showing that p90 and p160 are oligomeric forms of p58. The binding activity of the YAK-2 mAb was completely inhibited by the presence of GT1b micelles, indicating the specificity of YAK-2 mAb for p58 and its oligomers. Immunohistochemical investigations revealed that both p58 and GT1b colocalize within the granular layer of adult rat cerebellum. Expression cloning of p58 cDNA was performed using YAK-2 mAb, and five putative clones were obtained. Among them, the nucleotide sequence of one cDNA completely matched that of rat brain-specific sodium-dependent inorganic phosphate cotransporter (rBNPI), a 61 kDa membrane protein. COS7 cells were transfected with a Flag-chimeric construct containing the rBNPI/p58 cDNA, and the membrane lysate was subjected to immunoprecipitation with anti-Flag antibody. One protein (64 kDa) was detected only with YAK-2 mAb, and the membrane lysate specifically bound to GT1b micelles. Taking together, we propose that rBNPI/p58 functions as a GT1b-binding protein in neuronal cells.