Recombinant Aspergillus fumigatus antigens Asp f 3 and Asp f 9 in liposomal vaccine protect mice against invasive pulmonary aspergillosis

Invasive pulmonary aspergillosis caused by the ubiquitous mold Aspergillus fumigatus is a major threat to immunocompromised patients, causing unacceptably high mortality despite standard of care treatment, and costing an estimated $1.2 billion annually. Treatment for this disease has been complicated by the emergence of azole resistant strains of A. fumigatus, rendering first-line antifungal therapy ineffective. The difficulties in treating infected patients using currently available drugs make immunotherapeutic vaccination an attractive option. Here, we demonstrate the efficacy of VesiVax® adjuvant liposomes, consisting of a combination of two individual liposome preparations, to which two recombinant A. fumigatus surface antigens, Asp f 3 and Asp f 9 (VesiVax® Af3/9), have been chemically conjugated. Using a murine model, we demonstrate that VesiVax® Af3/9 is protective against infection by azole resistant strains of A. fumigatus in both steroid-suppressed and neutropenic mice as quantified by improved survival and reduced fungal burden in the lungs. This protection correlates with upregulation of IL-4 produced by splenocytes, and the presence of Asp f 3 and Asp f 9 specific IgG2a antibodies in the serum of mice given VesiVax® Af3/9. Furthermore, mice given VesiVax® Af3/9 with a subsequent course of liposomal amphotericin B (AmBisome®) had improved survival over those given either treatment alone, indicating a benefit to VesiVax® Af3/9 vaccination even in the case of infections that require follow-up antifungal treatment. These data demonstrate that prophylactic vaccination with VesiVax® Af3/9 is a promising method of protection against invasive pulmonary aspergillosis even as the changing face of the disease renders current therapies ineffective.

Nano- and Macroscale Imaging of Cholesterol Linoleate and Human Beta Defensin 2-Induced Changes in Pseudomonas aeruginosa Biofilms

The biofilm production of Pseudomonas aeruginosa (PA) is central to establishing chronic infection in the airways in cystic fibrosis. Epithelial cells secrete an array of innate immune factors, including antimicrobial proteins and lipids, such as human beta defensin 2 (HBD2) and cholesteryl lineolate (CL), respectively, to combat colonization by pathogens. We have recently shown that HBD2 inhibits biofilm production by PA, possibly linked to interference with the transport of biofilm precursors. Considering that both HBD2 and CL are increased in airway fluids during infection, we hypothesized that CL synergizes with HBD2 in biofilm inhibition. CL was formulated in phospholipid-based liposomes (CL-PL). As measured by atomic force microscopy of single bacteria, CL-PL alone and in combination with HBD2 significantly increased bacterial surface roughness. Additionally, extracellular structures emanated from untreated bacterial cells, but not from cells treated with CL-PL and HBD2 alone and in combination. Crystal violet staining of the biofilm revealed that CL-PL combined with HBD2 effected a significant decrease of biofilm mass and increased the number of larger biofilm particles consistent with altered cohesion of formed biofilms. These data suggest that CL and HBD2 affect PA biofilm formation at the single cell and community-wide level and that the community-wide effects of CL are enhanced by HBD2. This research may inform future novel treatments for recalcitrant infections in the airways of CF patients.

Enhancing Efficacy and Stability of an Antiheroin Vaccine: Examination of Antinociception, Opioid Binding Profile, and Lethality

In recent years, drug conjugate vaccines have shown promise as therapeutics for substance use disorder. As a means to improve the efficacy of a heroin conjugate vaccine, we systematically explored 20 vaccine formulations with varying combinations of carrier proteins and adjuvants. In regard to adjuvants, we explored a Toll-like receptor 9 (TLR9) agonist and a TLR3 agonist in the presence of alum. The TLR9 agonist was cytosine-guanine oligodeoxynucleotide 1826 (CpG ODN 1826), while the TLR3 agonist was virus-derived genomic doubled-stranded RNA (dsRNA). The vaccine formulations containing TLR3 or TLR9 agonist alone elicited strong antiheroin antibody titers and blockade of heroin-induced antinociception when formulated with alum; however, a combination of TLR3 and TLR9 adjuvants did not result in improved efficacy. Investigation of month-long stability of the two lead formulations revealed that the TLR9 but not the TLR3 formulation was stable when stored as a lyophilized solid or as a liquid over 30 days. Furthermore, mice immunized with the TLR9 + alum heroin vaccine gained significant protection from lethal heroin doses, suggesting that this vaccine formulation is suitable for mitigating the harmful effects of heroin, even following month-long storage at room temperature.

Monomeric M2e antigen in VesiVax® liposomes stimulates protection against type a strains of influenza comparable to liposomes with multimeric forms of M2e

Given the interest in the ectodomain of the matrix 2 (M2e) channel protein as a target for development of a universal influenza vaccine, we examined the role of the antigen configuration of M2e in generating a protective immune response. A series of M2e mutations and a truncated M2e segment were prepared as a means of controlling the formation of monomer, dimer, and higher order multimeric forms of M2e. Each of these M2e peptides was incorporated into a liposome-based vaccine technology platform previously shown to stimulate a protective response to influenza A infection using M2e as a mixture of monomers, dimers and multimers (L-M2e1-HD/MPL). Our results using these modified forms of M2e produced 90-100% survival following lethal challenge with H1N1 (A/PR/8/34) in both inbred BALB/c and outbred Swiss Webster mice vaccinated with a truncated monomeric form of the M2 protein, M2e_1-15 in liposomes. These observations show that a tetrameric configuration is not required to elicit significant protection when the M2e antigen is formulated in immunogenic liposomes and further, that the first 15 amino acids of M2e likely play a primary role in providing the protective immune response.

Toll-like receptor 3 adjuvant in combination with virus-like particles elicit a humoral response against HIV

Human Immunodeficiency Virus (HIV) Virus-Like Particles (VLPs) composed of HIV_IIIB Gag and HIV_BaL gp120/gp41 envelope are a pseudovirion vaccine capable of presenting antigens in their native conformations. To enhance the immunogenicity of the HIV Env antigen, VLPs were coupled to VesiVax Conjugatable Adjuvant Lipid Vesicles (CALV) containing one of four toll-like-receptor (TLR) ligands, each activating a receptor with distinct cellular localization and downstream pathways. C57BL/6 mice were vaccinated by intranasal prime followed by two sub-cheek boosts and their sera immunoglobulin and neutralizing potency were measured over a duration of 3months after vaccination. PBS control, VLPs alone, CALV+VLPs, and VLPs complexed with CALV and ligands for TLR2 (PAM3CAG), TLR3 (dsRNA), TLR4 (MPLA), or TLR7/8 (resiquimod) were evaluated based on antibody titer, IgG1 and IgG2c class switching, germinal center formation, T follicular cells and potency of neutralizing antibodies. Consistently, the TLR3 ligand dsRNA complexed to CALV and in combination with VLPs (CALV(dsRNA)+VLPs) induced the strongest response. CALV(dsRNA)+VLPs induced the highest titers against the recombinant vaccine antigens clade B Bal gp120 and pr55 Gag. Additionally, CALV(dsRNA)+VLPs induced cross-clade antibodies, represented by high titers of antibody to clade c 96ZM651 gp120. CALV(dsRNA)+VLPs induced predominantly IgG2c over IgG1, a response associated with T helper type 1 (Th1)-like cytokines. In turn, CALV(dsRNA)+VLP immunized mice generated the most potent neutralizing antibodies against HIV strain MN.3. Finally, at time of sacrifice, a significant increase in germinal center B cells and T follicular cells was detected in mice which received CALV(dsRNA)+VLPs compared to PBS. Our results indicate that CALV(dsRNA) is a superior adjuvant for HIV VLPs in generating a Th1-like immunoglobulin profile, while prolonging lymph node germinal centers, T follicular cells and generating neutralizing antibodies to a highly sensitive tier 1A variant of HIV.

Stability of an amphipathic helix-hairpin surfactant peptide in liposomes

Surfactant protein B (SP-B; 79 residues) is a member of the saposin superfamily and plays a pivotal role in lung function. The N- and C-terminal regions of SP-B, cross-linked by two disulfides, were theoretically predicted to fold as charged amphipathic helices, suggesting participation in surfactant activities. Previous studies with oxidized Super Mini-B (SMB), a construct based on the N- and C-regions of SP-B (i.e., residues 1-25 and 63-78) joined with a designer turn (-PKGG-) and two disulfides, indicated that freshly prepared SMB in lipids folded as a surface active, α-helix-hairpin. Because other peptides modeled on α-helical SP domains lost helicity and surfactant activity on storage, experiments were here performed on oxidized SMB in surfactant liposomes stored at ~2-8°C for ≤5.5years. Captive bubble surfactometry confirmed low minimum surface tensions for fresh and stored SMB preparations. FTIR spectroscopy of fresh and stored SMB formulations showed secondary structures compatible with the peptide folding as α-helix-hairpin. A homology (I-TASSER) model of oxidized SMB demonstrated a globular protein, exhibiting a core of hydrophobic residues and a surface of polar residues. Since mass spectroscopy indicated that the disulfides were maintained on storage, the stability of SMB may be partly due to the disulfides bringing the N- and C-α-helices closer. Mass spectroscopy of stored SMB preparations showed some methionine oxidation, and also partial deacylation of surfactant phospholipids to form lyso-derivatives. However, the stable conformation and activity of stored SMB surfactant suggest that the active helix-hairpin resists these chemical changes which otherwise may lead to surfactant inhibition.

Assessment of free fatty acids and cholesteryl esters delivered in liposomes as novel class of antibiotic

BACKGROUND

Healthcare associated infections (HAI) with multidrug-resistant (MDR) bacteria continue to be a global threat, highlighting an urgent need for novel antibiotics. In this study, we assessed the potential of free fatty acids and cholesteryl esters that form part of the innate host defense as novel antibacterial agents for use against MDR bacteria.

METHODS

Liposomes of six different phospholipid mixtures were employed as carrier for six different fatty acids and four different cholesteryl esters. Using a modified MIC assay based on DNA quantification with the fluoroprobe Syto9, formulations were tested against Gram-positive and Gram-negative bacteria implicated in HAI. Formulations with MIC values in the low μg/mL range were further subjected to determination of minimal bactericidal activity, hemolysis assay with sheep erythrocytes, and cytotoxicity testing with the human liver cell line HepG2. The potential for synergistic activity with a standard antibiotic was also probed.

RESULTS

Palmitic acid and stearic acid prepared in carrier 4 (PA4 and SA4, respectively) were identified as most active lipids (MIC against MDR Staphylococcus epidermidis was 0.5 and 0.25 μg/mL, respectively; MIC against vancomycin resistant Enterococcus faecalis (VRE) was 2 and 0.5 μg/mL, respectively). Cholesteryl linoleate formulated with carrier 3 (CL3) exhibited activity against the S. epidermidis strain (MIC 1 μg/mL) and a Pseudomonas aeruginosa strain (MIC 8 μg/mL) and lowered the vancomycin MIC for VRE from 32-64 μg/mL to as low as 4 μg/mL. At 90 μg/mL PA4, SA4, and CL3 effected less than 5 % hemolysis over 3 h and PA4 and CL3 did not exhibit significant cytotoxic activity against HepG2 cells when applied at 100 μg/mL over 48 h.

CONCLUSIONS

Our results showed that selected fatty acids and cholesteryl esters packaged with phospholipids exhibit antibacterial activity against Gram-positive and Gram-negative bacteria and may augment the activity of antibiotics. Bactericidal activity could be unlinked from hemolytic and cytotoxic activity and the type of phospholipid carrier greatly influenced the activity. Thus, fatty acids and cholesteryl esters packaged in liposomes may have potential as novel lipophilic antimicrobial agents.

A Novel Prime and Boost Regimen of HIV Virus-Like Particles with TLR4 Adjuvant MPLA Induces Th1 Oriented Immune Responses against HIV

HIV virus-like particles (VLPs) present the HIV envelope protein in its native conformation, providing an ideal vaccine antigen. To enhance the immunogenicity of the VLP vaccine, we sought to improve upon two components; the route of administration and the additional adjuvant. Using HIV VLPs, we evaluated sub-cheek as a novel route of vaccine administration when combined with other conventional routes of immunization. Of five combinations of distinct prime and boost sequences, which included sub-cheek, intranasal, and intradermal routes of administration, intranasal prime and sub-cheek boost (IN+SC) resulted in the highest HIV-specific IgG titers among the groups tested. Using the IN+SC regimen we tested the adjuvant VesiVax Conjugatable Adjuvant Lipid Vesicles (CALV) + monophosphoryl lipid A (MPLA) at MPLA concentrations of 0, 7.5, 12.5, and 25 μg/dose in combination with our VLPs. Mice that received 12.5 or 25 μg/dose MPLA had the highest concentrations of Env-specific IgG2c (20.7 and 18.4 μg/ml respectively), which represents a Th1 type of immune response in C57BL/6 mice. This was in sharp contrast to mice which received 0 or 7.5 μg MPLA adjuvant (6.05 and 5.68 μg/ml of IgG2c respectively). In contrast to IgG2c, MPLA had minor effects on Env-specific IgG1; therefore, 12.5 and 25 μg/dose of MPLA induced the optimal IgG1/IgG2c ratio of 1.3. Additionally, the percentage of germinal center B cells increased significantly from 15.4% in the control group to 31.9% in the CALV + 25 μg MPLA group. These mice also had significantly more IL-2 and less IL-4 Env-specific CD8⁺ T cells than controls, correlating with an increased percentage of Env-specific central memory CD4⁺ and CD8⁺ T cells. Our study shows the strong potential of IN+SC as an efficacious route of administration and the effectiveness of VLPs combined with MPLA adjuvant to induce Env specific Th1-oriented HIV-specific immune responses.

Enhancing nicotine vaccine immunogenicity with liposomes

A major liability of existing nicotine vaccine candidates is the wide variation in anti-nicotine immune responses among clinical trial participants. In order to address this liability, significant emphasis has been directed at evaluating adjuvants and delivery systems that confer more robust potentiation of the anti-nicotine immune response. Toward that end, we have initiated work that seeks to exploit the adjuvant effect of liposomes, with or without Toll-like receptor agonist(s). The results of the murine immunization study described herein support the hypothesis that a liposomal nicotine vaccine formulation may provide a means for addressing the immunogenicity challenge.

Diagnostic and prognostic significance of the alternatively spliced ACTN4 variant in high-grade neuroendocrine pulmonary tumours

BACKGROUND

High-grade neuroendocrine tumours (HGNTs) of the lung manifest a wide spectrum of clinical behaviour, but no method for predicting their outcome has been established.

MATERIALS AND METHODS

We newly established a monoclonal antibody specifically recognizing the product of the alternatively spliced ACTN4 transcript (namely, variant actinin-4), and used it to examine the expression of variant actinin-4 immunohistochemically in a total of 609 surgical specimens of various histological subtypes of lung cancer.

RESULTS

Variant actinin-4 was expressed in 55% (96/176) of HGNTs, but in only 0.8% (3/378) of non-neuroendocrine (NE) lung cancers. The expression of variant actinin-4 was significantly associated with poorer overall survival in HGNT patients (P=0.00021, log-rank test). Multivariate analysis using the Cox proportional hazards model showed that the expression of variant actinin-4 was the most significant independent negative predictor of survival in HGNT patients (hazard ratio (HR), 2.15; P=0.00113) after the presence of lymph node metastasis (HR, 2.25; P=0.00023).

CONCLUSIONS

The expression of variant actinin-4 is an independent prognostic factor for patients with HGNTs. This protein has a high affinity for filamentous actin polymers and likely promotes aggressive behaviour of cancer cells. The present clinical findings clearly support this notion.

Characterization of the murine Th2 response to immunization with liposomal M2e influenza vaccine

While the current influenza vaccine strategy is dependent on eliciting neutralizing antibodies to the hemagglutinin (H or HA) surface glycoprotein, antigenic drifts and occasional antigenic shifts necessitate constant surveillance and annual updates to the vaccine components. The ectodomain of the matrix 2 (M2e) channel protein has been proposed as a universal vaccine candidate, although it has not yet been shown to elicit neutralizing antibodies. Utilizing a liposome-based vaccine technology, an M2e vaccine (L-M2e-HD/MPL) was tested and shown to stimulate the production of anti-M2e antibodies which precipitated with whole virus and inhibited viral cell lysis by multiple type A strains of influenza virus using a novel in vitro assay. The anti-M2e antibodies also conferred complete protection following passive transfer from L-M2e-HD/MPL vaccinated mice to naïve mice challenged with H1N1 virus. Significantly higher levels of IL-4 compared to IFN-γ were secreted by the splenocytes of L-M2e-HD/MPL vaccinated mice incubated with M2e. In addition, depletion of CD4 cells or CD4 cells plus CD8 cells from L-M2e-HD/MPL vaccinated mice using monoclonal antibodies markedly decreased the level of protection of the vaccine when compared to just CD8 depletion of L-M2e-HD/MPL vaccinated mice. These results suggest that the protective immune response elicited by this vaccine is mediated primarily by a Th2 mechanism.

Lipids including cholesteryl linoleate and cholesteryl arachidonate contribute to the inherent antibacterial activity of human nasal fluid

Mucosal surfaces provide first-line defense against microbial invasion through their complex secretions. The antimicrobial activities of proteins in these secretions have been well delineated, but the contributions of lipids to mucosal defense have not been defined. We found that normal human nasal fluid contains all major lipid classes (in micrograms per milliliter), as well as lipoproteins and apolipoprotein A-I. The predominant less polar lipids were myristic, palmitic, palmitoleic, stearic, oleic, and linoleic acid, cholesterol, and cholesteryl palmitate, cholesteryl linoleate, and cholesteryl arachidonate. Normal human bronchioepithelial cell secretions exhibited a similar lipid composition. Removal of less-polar lipids significantly decreased the inherent antibacterial activity of nasal fluid against Pseudomonas aeruginosa, which was in part restored after replenishing the lipids. Furthermore, lipids extracted from nasal fluid exerted direct antibacterial activity in synergism with the antimicrobial human neutrophil peptide HNP-2 and liposomal formulations of cholesteryl linoleate and cholesteryl arachidonate were active against P. aeruginosa at physiological concentrations as found in nasal fluid and exerted inhibitory activity against other Gram-negative and Gram-positive bacteria. These data suggest that host-derived lipids contribute to mucosal defense. The emerging concept of host-derived antimicrobial lipids unveils novel roads to a better understanding of the immunology of infectious diseases.

The VesiVax system: a method for rapid vaccine development

The VesiVax system is based upon the concept that highly potent vaccines can be designed by engineering proteins that are capable of stably inserting themselves into liposomes. Such a nanoscale liposomal particle can then serve as an immunogen for vaccine development. The VesiVax vaccine technology platform is designed to make it relatively easy to engineer and produce new vaccines quickly. Vaccines based on the VesiVax system have been designed against the influenza virus and herpes simplex type 2 virus, the causative agents of the "flu" and genital herpes, respectively. Both vaccines have been tested in animal models and have demonstrated significant protective efficacy from challenge with lethal doses of virus. Assays of the immunological parameters suggest that both T and B cell responses can be elicited by VesiVax vaccines. The safety profile of the VesiVax vaccines is expected to be much better than that of vaccines prepared by conventional techniques. Taken together, the inherent flexibility of the VesiVax platform is expected to facilitate the rapid development of new vaccines which are effective at stimulating protective immune responses.

Contortrostatin, a snake venom disintegrin with anti-angiogenic and anti-tumor activity

Disintegrins are soluble peptides found in snake venom. They bind to Arg-Gly-Asp (RGD)-responsive integrins with high affinity (nM range) and block integrin function. Contortrostatin (CN), the disintegrin from southern copperhead venom, is a homodimer with a molecular weight of 13,500. Each chain contains 65 amino acids with an Arg-Gly-Asp motif. CN has anti-invasive and anti-adhesive activity on tumor cells and endothelial cells in vitro, and binds to integrins alphavbeta3, alphavbeta5, and/or alpha5beta1. In vivo studies using the human metastatic breast cancer cell line MDA-MB-435, in an orthotopic xenograft model in nude mice, revealed that CN has potent anti-tumor and anti-angiogenic activity. Recent studies have employed an intravenous liposomal delivery procedure. Liposomal delivery of CN has also been shown to provide effective in vivo anti-tumor and anti-angiogenic activity in a human ovarian cancer animal model.

Protection against H1, H5, H6 and H9 influenza A infection with liposomal matrix 2 epitope vaccines

The recent emergence of multiple avian influenza A subtypes that cause human disease (i.e., H5N1, H9N2 and H7N7), coupled with the fear that one of these strains might precipitate a new pandemic, underscores the need to develop new technological approaches to immunization which elicit protective immune responses against multiple subtypes of influenza A. In response to this demand, several matrix 2 protein ectodomain segments (M2eA) corresponding to the H1N1, H5N1 and H9N2 influenza strains were formulated using a novel liposome-based vaccine technology and evaluated as potential immunogens for developing a "universal" influenza vaccine. Mice immunized with liposomal M2eA survived homologous challenges with H1N1 (100% survival) or H9N2 (80% survival) influenza strains. There were significant reductions in their lung viral load as well as in immunized mice challenged with the H5N1 subtype. The mice vaccinated with an M2eA segment corresponding to the H1N1 and H6N2 (a reassortant influenza A virus carrying the M2eA from PR8/34) strains elicited elevated IgG ELISA antibody titers to this M2eA epitope segment and antiserum from these immunized mice provided passive protection (100% survival) to naïve mice receiving a lethal dose of H6N2 influenza virus. These results provide the first evidence that recombinant M2eA epitopes to multiple subtypes elicited immune protection against a homologous challenge and provides further evidence in favor of the development of a "universal" influenza vaccine based on M2eA.

Surgical treatment of late developmental displacement of the hip. Results after 33 years

The outcome of displaced hips treated by Somerville and Scott's method was assessed after more than 25 years. A total of 147 patients (191 displaced hips) was reviewed which represented an overall follow-up of 65.6%. The median age at the index operation was two years. During the first five years, 25 (13%) hips showed signs of avascular change. The late development of valgus angulation of the neck, after ten years, was seen in 69 (36%) hips. Further operations were frequently necessary. Moderate to severe osteoarthritis developed at a young age in 40% of the hips. Total hip replacement or arthrodesis was necessary in 27 (14%) hips at a mean age of 36.5 years. Risk factors identified were high dislocation, open reduction, and age at the original operation. Two groups of patients were compared according to outcome. All the radiographic indices were different between the two groups after ten years, but most were similar before. It takes a generation to establish the prognosis, although some early indicators may help to predict outcome.

[The efficacy of function water (electrolyzed strong acid solution) on open heart surgery; postoperative mediastinitis due to methicillin-resistant Staphylococcus aureus]

Methicillin-resistant Staphylococcus aureus (MRSA) infection after cardiac surgery has recently increased. We compared the anti-inflammatory effect of an electrolyzed strong acid solution and a warm saline solution in patients with open heart surgery. These solutions were used for mediastinal irrigation before closing the sternum. Group A patients were irrigated by a warm saline solution, and group B patients were irrigated by an electrolyzed strong acid solution, administration of this water is safe, feasible, and easy for the prevention of MRSA infection. Postoperative infection was significantly decreased in the group B as compared in the group A. An electrolyzed strong acid solution may be effective on postoperative infection, particularly MRSA infection following open heart surgery.

Intravenous liposomal delivery of the snake venom disintegrin contortrostatin limits breast cancer progression

Despite significant research in this area, metastatic breast cancer remains a disease with a poor prognosis. Until an effective therapy is developed, it is imperative that new treatment modalities be investigated. In this report, we describe an effective method for delivery of a novel snake venom disintegrin, contortrostatin (CN), in an orthotopic, xenograft model of human mammary cancer in immunodeficient mice. CN (Mr 13,500) is a homodimeric disintegrin isolated from venom of the Southern Copperhead snake. The homodimer possesses two Arg-Gly-Asp sites, which modulate its interaction with integrins on tumor cells and angiogenic vascular endothelial cells. Although our laboratory has previously described the antitumor activity of CN in a mouse model of human mammary cancer, the method of delivery, daily intratumor injection, was not translatable to clinical application. We now describe a clinically relevant method of administering CN, liposomal delivery (LCN). A unique liposomal system has been designed for i.v. administration of a biologically active protein with full retention of biological activity. Pharmacokinetics, biodistribution, platelet reactivity, and immunogenicity of LCN were determined and compared with similar characteristics of native, unencapsulated CN. There are several advantages to liposomal delivery of CN: (1) LCN has a significantly prolonged circulatory half-life compared with native CN; (2) LCN is passively accumulated in the tumor; (3) LCN has no platelet reactivity; and (4) LCN is not recognized by the immune system. Finally, antiangiogenic activity is an important component of CN's mechanism of antitumor action. We have demonstrated that i.v. delivery of LCN leads to potent antiangiogenic activity in the orthotopic, xenograft human mammary tumor model.

[Successful treatment for tachyarrhythmia with ultra short acting beta-blocker during beating coronary artery bypass grafting; report of a case]

A 62-year-old man with supraventricular/ventricular tachycardia associated with myocardial infarction developed tachycardia during beating coronary artery bypass grafting (CABG). Intravenous administration of an ultra short acting beta-blocker, landiolol hydrochloride, controlled heart rate and improved tachyarrhythmia without significant change of blood pressure. Landiolol hydrochloride is effective and useful for the treatment of tachyarrhythmia during beating CABG.

Closed reduction of developmental dislocation of the hip by prolonged traction

The efficacy of traction before an attempted closed reduction for patients with developmental dislocation of the hip remains controversial. We treated 55 children (62 dislocations of the hip) by preliminary, prolonged traction for a mean of eight weeks. All were followed up for at least two years in order to observe the development of any avascular changes within the femoral head. Of the 55 children, 27 (31 dislocations) were followed up until they were over six years of age. Fifty-seven of the 62 hips (92%) showed a successful closed reduction. Only one had radiological evidence of avascular necrosis of the femoral head. Of the 31 hips which were followed up to over six years of age, 15 (48%) showed residual subluxation. Our method of prolonged preliminary traction leads to a high rate of successful closed reduction, a low incidence of avascular necrosis and a reduced need for secondary operations.

Avascular necrosis associated with fractures of the femoral neck in children: histological evaluation of core biopsies of the femoral head

There is no well-documented effective treatment for avascular necrosis following fractures of the femoral neck in children. Six children who suffered avascular necrosis following these fractures were treated with a long period of non-weight bearing. We tried to predict the advisable period of non-weight bearing by histological finding on core biopsy taken from the femoral head and present long-term follow-up results. The time interval for the biopsy ranged from 4 to 21 months after injury. Two specimens obtained within 1 year after injury showed total necrosis. The other four specimens taken more than 1 year after injury showed partial repair. Two specimens obtained from patients who had minimally displaced fractures also revealed necrotic tissue. Four patients were initially placed non-weight bearing for over 1 year. Two patients started weight bearing immediately after surgery, and late segmental collapse occurred within 1 year. They were then placed non-weight bearing for a further period in excess of 1 year. All patients, including those who had severely displaced fractures, avoided severe collapse of the femoral head. To avoid severe collapse of the femoral head due to avascular necrosis after pediatric femoral neck fractures, a long period of non-weight bearing of at least 1 year may be recommended treatment.

Detection of genes expressed in primary colon cancers by in situ hybridisation: overexpression of RACK 1

AIMS

The isolation of various genes that are expressed in a region specific manner is considered useful for research in molecular pathology. In situ hybridisation (ISH) was used in a screening procedure to isolate these genes efficiently, using colon cancer as a model.

METHODS

Suppression subtractive hybridisation (SSH) between colon cancer tissue samples and corresponding non-cancerous tissues was performed. Genes showing high expression in the cancers were selected using macro-DNA array analysis. As a final screening procedure, conventional ISH was performed to isolate genes expressed specifically in colon cancers.

RESULTS

Sixty nine clones were selected by SSH and macro-DNA array analyses. These clones were then analysed by ISH to examine their expression patterns. ISH screening revealed that all the clones screened showed more intense signals in colon cancers than in non-cancerous tissues. Among them, RACK 1, which is a protein kinase C receptor and a homologue of the G protein beta subunit, was expressed intensely in colon cancer cells. RACK 1 expression was evaluated in multiple samples by ISH, and the results confirmed that RACK 1 was universally overexpressed in cells of all 11 colon cancers examined.

CONCLUSIONS

Many genes, including RACK 1, expressed in colon cancer cells can be isolated efficiently by this method, and their precise expression pattern can be evaluated. These results indicate that ISH is an excellent technique for systemic screening of genes expressed in a region specific manner.

Diplopia after limited macular translocation surgery

PURPOSE

Full macular translocation surgery relocates the fovea away from choroidal neovascularization, inducing significant postoperative torsional diplopia. In "limited macular translocation," a saline-induced retinal detachment is followed by scleral imbrication with mattress sutures and spontaneous retinal reattachment. In this study, diplopia was characterized in patients treated with limited macular translocation.

METHODS

Two surgeons performed retinal translocation surgery on 250 patients over an 18-month time span. The extent and direction of the retinal translocation, and the amount and location of scleral imbrication, were recorded. All patients complaining of diplopia were referred for ocular motility evaluation and treatment.

RESULTS

Thirteen (5.2%) patients complained of occasional or constant diplopia. Imbricating sutures were placed supero-temporally in all cases. Inferior foveal translocation ranged from 200 to 2115 microm (median, 1750 microm). Visual acuity ranged from 20/40 to 20/400 in the operated eye. Prism-and-cover testing underestimated the strabismus when compared with subjective testing. In 3 patients, there was no shift on alternate-cover testing despite binocular diplopia. Excyclotorsion ranged from 0 degrees to 16 degrees. Diplopia resolved in 10 cases with prism; 3 required an occlusive filter for distortion or aniseikonia. One patient underwent successful strabismus surgery to eliminate dependence on prism glasses.

CONCLUSIONS

Limited macular translocation only rarely produces symptomatic diplopia. Suprisingly, traditional prism-and-cover testing does not reliably quantify the misalignment. This may result from the combination of a persistent macular scotoma and a repositioned fovea relative to the peripheral retina. Prism therapy is generally satisfactory in the absence of retinal distortion or aniseikonia.

Reliability of the Severin classification in the assessment of developmental dysplasia of the hip

This study was undertaken to investigate the reliability of Severin's classification at various ages, and to determine whether the reliability is improved by careful measurement rather than subjective assessment. The radiographs taken at ages 6, 10 and 16 years of 20 randomly selected patients treated for developmental dysplasia of the hip were graded by six observers on two separate occasions using parameters measured according to Severin's criteria. In addition, four of these observers regraded the same radiographs using subjective assessment without measurements being made on two other separate occasions. Agreements between and within observers were evaluated using the weighted Cohen's kappa statistic for each age group. Intraobserver reliability was good, there being a close association between the measured and the subjectively observed ratings. This accords with the subjective nature of this classification. The interobserver reliability was found to be poor although it improved when direct measurements were made. Overall agreement between observers improves as patient age increases. It is concluded that comparisons between different observers using the Severin classification system are not reliable. However, a single investigator comparing treatment modalities in the same study allowing for individual bias in assessing deformity and subluxation would produce reliable results.

Transplantation of the en bloc vascular system for coronary revascularization

OBJECTIVES

Use of the free gastroepiploic artery graft for coronary revascularization has not been very popular because of its inclination toward vasospasm. We hypothesized that the cause of free gastroepiploic artery spasm was the graft damage caused by an interruption of venous drainage from the graft. To solve this problem, we developed a new method of free gastroepiploic artery grafting.

METHODS

From January 1997 to October 1999, 33 patients underwent coronary artery bypass grafting with the free gastroepiploic artery according to our new method. The gastroepiploic artery graft was harvested en bloc with its satellite veins. The gastroepiploic vein was anastomosed to the right atrial appendage for venous drainage simultaneously with the gastroepiploic artery being grafted in the aortocoronary position.

RESULTS

A total of 96 distal anastomoses were performed, including 33 free gastroepiploic artery grafts according to our method, 33 in situ left internal thoracic artery grafts, 26 saphenous vein grafts, and 4 radial artery grafts. Neither operative nor hospital death occurred. Early postoperative angiography revealed that all of the 33 free gastroepiploic artery grafts performed with our method were patent without spasm, and flow competition occurred only in 2 of those grafts. On late angiography, all 15 free gastroepiploic artery grafts were patent without spasm.

CONCLUSIONS

The free gastroepiploic artery grafting with venous drainage technique we developed can prevent graft spasm, leading to improved patency rate.

Cloning and characterization of a novel gene, DRH1, down-regulated in advanced human hepatocellular carcinoma

Few genes related to carcinogenesis and progression of hepatocellular carcinoma (HCC) have been identified to date. In the present study, we report the cloning and characterization of a novel gene, DRH1, which is frequently down-regulated in HCC. The full-length DRH1 clone contains an open reading frame of 1257 nucleotides encoding 419 amino acids. The deduced DRH1 protein shows 41% identity to VDUP1, expression of which is rapidly induced by 1,25-dihydroxyvitamin D3. The DRH1 gene was localized to chromosome 15, and DRH1 protein was mainly observed in the cytoplasm of transiently transfected cells. Real-time quantitative reverse transcription-PCR analysis showed that the expression level of DRH1 was reduced in 29 of 35 (83%) HCCs compared with corresponding noncancerous liver tissue. The average (mean +/- SE) ratio of DRH1 expression level in tumor to corresponding noncancerous tissue was significantly different between well, moderately, and poorly differentiated HCCs (1.15 +/- 0.23, 0.69 +/- 0.10, and 0.19 +/- 0.04, respectively) and between HCCs without and with vascular invasion (0.94 +/- 0.16 and 0.46 +/- 0.07, respectively). These results indicate that the down-regulation of DRH1 occurs not at an early stage but rather at a late stage of HCC progression. Although the function of DRH1 protein is still unknown, our findings suggest that DRH1 is related to the progression of HCC and may provide a new prognostic factor.

Analysis of nuclear localization signals using a green fluorescent protein-fusion protein library

We describe here an efficient method for identifying intracellular localization signals in proteins with stereospecific intracellular localizations in culture cells. The method involves rapid fluorescence screening of cells transfected with a cDNA library in which cDNAs are fused to the gene encoding the Aequorea victoria green fluorescent protein (GFP). We analyzed nuclear localization and nuclear localization signals (NLSs) in a model application of this method. As a result, we identified classical NLSs in 75% of nuclear localized proteins. We identified some novel NLS candidates among the classical NLS-negative sequences whose nuclear localization was also identified in another cell line and with other molecular tag sequences. This method will be useful for identifying intracellular localization signals and for more detailed analysis of intracellular architecture.

To fuse or not to fuse: the effects of electrostatic interactions, hydrophobic forces, and structural amphiphilicity on protein-mediated membrane destabilization

The development of lipid-based delivery vehicles for therapeutic molecules has become a topic of intense research. Recently, much of this effort has been directed towards mimicking the characteristics of viruses that give them an advantage for the delivery of genetic medicines. One of the most desirable properties of viral-based vectors is the ability to promote the destabilization of the host cell membrane to allow the entry of the genetic medicine into the target cell. This has been found to be largely controlled by the coat proteins on the surface of enveloped viruses. Although the exact mechanism by which proteins involved in the fusion process are able to promote the destabilization of membranes has yet to be elucidated, much understanding based upon information gained from a wide variety of studies is advancing the state of knowledge in this area. Parameters such as hydrophobic and electrostatic interactions as well as structural amphiphilicity, control to a large extent, the nature of the interaction of proteins with membranes. Thus, membrane fusion is mediated primarily by these forces acting in concert with one another. Ultimately, the knowledge gained from these studies will help to develop the ideal delivery system for the next generation of therapeutics.

Failure of anti-Forssman antibodies to induce rejection of mouse heart xenografts

The Forssman antigen has been proposed to be a target for the xenograft reaction in selected species combinations, including the rat and mouse, which are Forssman-negative and -positive species respectively. The mouse represents an important experimental model for a variety of immune-mediated disease processes, and the availability of a simple, inexpensive target antigen could provide an important tool for studying a selected portion of the immunologic basis for the rejection of xenografts. We have examined the potential that antibodies directed against mouse Forssman antigen could cause the hyperacute rejection of mouse heart xenografts in naive rat recipients. The Forssman antibodies tested included rat anti-mouse (R-anti-M) antiserum, R-anti-M antiserum depleted of anti-Forssman (anti-F) antibodies, rat anti-sheep red blood cell (SRBC) antiserum containing anti-F antibodies and a rat monoclonal anti-F IgM antibody. Our results demonstrate that the R-anti-M antiserum at day 4 post transplantation displayed significant titers (1:512-4096) of hemagglutinating antibodies for SRBC and mild to moderate levels of IgM that specifically binds to Forssman glycolipid (GalNAcalpha1-3GalNAcbeta1-3Galalpha1-4Galbeta1- 4Glcbeta1-1ceramide) as measured by an enzyme-linked immunosorbent assay (ELISA). Passive transfer of the R-anti-M serum to rats receiving mouse cardiac grafts immediately after transplantation caused hyperacute rejection of the xenografts. Sequential immunoabsorption of R-anti-M sera with SRBCs resulted in total removal of the anti-Forssman activity (as defined by negative hemagglutination titer and minimal binding to Forssman glycolipid in ELISA). The anti-F Ab-depleted R-anti-M antisera, however, retained the capacity to induce hyperacute rejection of the mouse hearts [n = 6, median survival time (MST) 13 min] when passively transferred to rat recipients. Anti-Forssman antibodies induced by immunization of LEW rats with SRBCs or a rat anti-Forssman monoclonal antibody, mAb M.1.22.25, exhibited substantial anti-Forssman activity (hemagglutinating titer 1:512-4096 and moderate-to-strong binding to Forssman glycolipid in ELISA respectively). These antibodies also failed, however, to trigger hyperacute rejection of mouse cardiac xenografts. In conclusion, our results suggest that the rat anti-Forssman antibodies, including those stimulated by mouse cardiac xenografts, do not appear to play a role in the immediate (hyperacute) rejection of mouse heart xenografts.

Molecular cloning and expression of Xenopus p300/CBP

Transcriptional coactivators act as signal committers from transcriptional regulators to basal transcriptional machineries. We isolated the cDNA for p300/CBP, one of the most important transcriptional coactivators, of Xenopus. We also report its regulated expression, and the effects of microinjection of its truncated form. Xenopus p300/CBP (Xp300) encodes a 2483 amino acid protein which is highly homologous with human p300. Northern hybridization analyses indicated that Xp300 mRNA is stored in the oocyte, and is present throughout early embryogenesis of this species. In situ hybridization studies have revealed that Xp300 mRNA localization is ubiquitous throughout early embryogenesis, but that in later stages it is predominant in the neural region. Among adult tissues, Xp300 mRNA was clearly detected in some tissues, suggesting that Xp300 functions as a transcriptional regulator in various tissues. Microinjection of a carboxy-terminal-truncated form of Xp300 RNA into both cells of Xenopus two-blastomere stage embryos invoked the malformation of the embryos. The neural plates of Xp300 RNA-injected embryos were loose and the trunk area was heavily contracted. These results suggest that Xp300 is indispensable for normal development of the early embryo, especially in neural formation.

cFKBP/SMAP; a novel molecule involved in the regulation of smooth muscle differentiation

During embryogenesis, smooth muscle cells of the gut differentiate from mesenchymal cells derived from splanchnic mesoderm. We have isolated a gene involved in the differentiation of smooth muscle cells in the gut using differential display between the chicken proventriculus in which the smooth muscle layer develops poorly and the gizzard in which smooth muscles develop abundantly. The protein encoded by this gene showed highest similarity to mouse FK506 binding protein, FKBP65, and from the function of this protein it was designated chicken FKBP/smooth muscle activating protein (cFKBP/SMAP). cFKBP/SMAP was first expressed in smooth muscle precursor cells of the gut and, after smooth muscles differentiate, expression was restricted to smooth muscle cells. In organ culture of the gizzard, the differentiation of smooth muscle cells was inhibited by the addition of FK506, the inhibitor of FKBPs. Moreover, overexpression of cFKBP/SMAP in lung and gizzard mesenchymal cells induced smooth muscle differentiation. In addition, cFKBP/SMAP-induced smooth muscle differentiation was inhibited by FK506. We postulate therefore that cFKBP/SMAP plays a crucial role in smooth muscle differentiation in the gut and provides a powerful tool to study smooth muscle differentiation mechanisms, which have been poorly analyzed so far.

MMAC1/PTEN mutations in primary tumor specimens and tumor cell lines

A candidate tumor suppressor gene, MMAC1/PTEN, located in human chromosome band 10q23, was recently identified based on sequence alterations observed in several glioma, breast, prostate, and kidney tumor specimens or cell lines. To further investigate the mutational profile of this gene in human cancers, we examined a large set of human tumor specimens and cancer cell lines of many types for 10q23 allelic losses and MMAC1 sequence alterations. Loss of heterozygosity (LOH) at the MMAC1 locus was observed in approximately one-half of the samples examined, consistent with the high frequency of 10q allelic loss reported for many cancers. Of 124 tumor specimens exhibiting LOH that have been screened for MMAC1 alterations to date, we have detected variants in 13 (approximately 10%) of these primary tumors; the highest frequency of variants was found in glioblastoma specimens (approximately 23%). Novel alterations identified in this gene include a missense variant in a melanoma sample and a splicing variant and a nonsense mutation in pediatric glioblastomas. Of 76 tumor cell lines prescreened for probable LOH, microsequence alterations of MMAC1 were detected in 12 (approximately 16%) of the lines, including those derived from astrocytoma, leukemia, and melanoma tumors, as well as bladder, breast, lung, prostate, submaxillary gland, and testis carcinomas. In addition, in this set of tumor cell lines, we detected 11 (approximately 14%) homozygous deletions that eliminated coding portions of MMAC1, a class of abnormality not detected by our methods in primary tumors. These data support the occurrence of inactivating MMAC1 alterations in multiple human cancer types. In addition, we report the discovery of a putative pseudogene of MMAC1 localized on chromosome 9.

The reliability of measurements of pelvic radiographs in infants

We have evaluated the reliability of the measurement of radiological indicators in developmental dysplasia of the hip. Three observers each independently assessed 60 pelvic radiographs from infants aged from 3 to 36 months. Errors from the true value of a single measurement made by a single observer (E1), of the average of two measurements by a single observer (E2), and of the average of two single measurements by two different observers (E3) were established for the acetabular index of Hilgenreiner, for the assessment of superior and lateral femoral displacement and for indicators of pelvic alignment. The errors for the assessment of the acetabular index were E1 +/- 5 degrees, E2 +/- 5 degrees, and E3 +/- 3.5 degrees. There was a significant correlation between the presence of an acetabular notch on the radiograph and an increased error in measurement (p = 0.01). Yamamuro's measurement of lateral femoral displacement was more reliable than the Hilgenreiner distance. The errors of indicators of pelvic alignment showed a correlation with the age of the infant; the quotient of pelvic rotation was more reliable after seven months of age (p < 0.0001). The errors of the measurement of the symphysis os-ischium angle tended to increase with age and those of the measurement of the index of pelvic tilt decreased with skeletal maturation (p = 0.002).

THE RELIABILITY OF MEASUREMENTS OF PELVIC RADIOGRAPHS IN INFANTS

We have evaluated the reliability of the measurement of radiological indicators in developmental dysplasia of the hip. Three observers each independently assessed 60 pelvic radiographs from infants aged from 3 to 36 months. Errors from the true value of a single measurement made by a single observer (E1), of the average of two measurements by a single observer (E2), and of the average of two single measurements by two different observers (E3) were established for the acetabular index of Hilgenreiner, for the assessment of superior and lateral femoral displacement and for indicators of pelvic alignment.

The errors for the assessment of the acetabular index were E1 ± 5°, E2 ± 5°, and E3 ± 3.5°. There was a significant correlation between the presence of an acetabular notch on the radiograph and an increased error in measurement (p = 0.01). Yamamuro’s measurement of lateral femoral displacement was more reliable than the Hilgenreiner distance. The errors of indicators of pelvic alignment showed a correlation with the age of the infant; the quotient of pelvic rotation was more reliable after seven months of age (p < 0.0001). The errors of the measurement of the symphysis os-ischium angle tended to increase with age and those of the measurement of the index of pelvic tilt decreased with skeletal maturation (p = 0.002).

The formation of amphotericin B ion channels in lipid bilayers

The ability of amphotericin B (AmB) to form ion-permeable channels in cholesterol containing lipid bilayers was studied by UV/visible absorbance, circular dichroism, and fluorescence spectroscopy. Stable liposomes composed of distearoylphosphatidylcholine, cholesterol, distearoylphosphatidylglycerol, and AmB were prepared so that a wide range of AmB concentrations in the bilayer could be studied. Singular value decomposition analysis (Henry & Hofrichter, 1992) of the circular dichroism spectra of AmB at different AmB/lipid ratios suggests that AmB exists primarily in only two states in the bilayer, a "monomeric" state and an "aggregated" state. The transition from the "monomeric" to the "aggregated" state begins to occur at a critical concentration of 1 AmB per 1000 lipids in the membrane and coincides with the appearance of channel activity. The data support the recent theoretical conclusions of Weakliem et al. (1995) which predict that pore formation in the lipid bilayer will occur when the drug molecule concentration exceeds a critical value. At this critical concentration, it is calculated that a minimum number of 16 AmB molecules per liposome are required to observe channel activity. The results are consistent with the sterol-dependent AmB channel models proposed by de Kruijff and Demel (1974), Andreoli (1974), and Khutorsky (1992). To further elucidate the effects of sterol on AmB-mediated channel formation, liposomes were prepared with varying ratios of cholesterol and AmB. At cholesterol mole percentages greater than 1, channel activity was observed to occur at AmB concentrations just above the critical value. Previous reports show that cholesterol forms "tail-to-tail" dimers at mole percentages greater than 2 (Harris et al., 1995). This suggests that formation of the bilayer-spanning channels by AmB is initiated most efficiently when the tail-to-tail dimer of cholesterol is present. Although the structural nature of the AmB channel could not be unambiguously determined, these experiments provide further evidence in support of the widely held view that AmB's primary mechanism of killing fungal cells occurs by forming ion-permeable channels.

Molecular cloning of cDNA for XTCAD-1, a novel Xenopus cadherin, and its expression in adult tissues and embryos of Xenopus laevis

We have isolated from a Xenopus tailbud cDNA library a novel cadherin cDNA, denoted as XTCAD-1, which contained an open reading frame including the entire coding region. XTCAD-1 codes for 714 amino acids (molecular mass: 96 kDa), which include five characteristic extracellular cadherin motifs, a single putative transmembrane domain, and a cytoplasmic domain. In each domain, XTCAD-1 shared extensive homologies with other cadherins, and was related to EP-, E-, and P-cadherins more closely than to N- and M-cadherins. In adult Xenopus, XTCAD-1 mRNA was strongly expressed in intestine/stomach, kidney and skin, which are respectively derived from endoderm, mesoderm, and ectoderm. In Xenopus embryogenesis, expression of XTCAD-1 mRNA was first detected at blastula stage, and the level of the expression increased gradually during gastrula stage, reached a peak at tailbud stage and then decreased slightly at tadpole stage. These results suggest that in Xenopus laevis XTCAD-1 plays an important role in the maintenance of adult tissues that contain epithelial cells abundantly and also in morphogenesis in early embryonic development.

Molecular cloning of cDNAs for two Xenopus proteasome subunits and their expression in adult tissues

Proteasome, a large protein complex with ATP-dependent protease activities, is composed of non-identical but closely related multi-subunits. Using cDNAs for rat proteasome subunits as probes, we obtained three cDNA clones for two Xenopus proteasome subunits from ovary cDNA library. The primary structures of the three cDNAs showed high homology to the corresponding proteasome subunits of other mammalian species (above 90%) and also considerable homology to those of Drosophila and yeast. These results indicate that the sequences of proteasome subunits are well conserved during evolution. Northern blot hybridization revealed that RNAs for the newly isolated subunits (XC8 and XC9) and the previously isolated subunit (XC3) occur at very high levels in testis and ovary, at moderately high levels in lung, skin kidney and spleen, and at low levels in liver, stomach and muscle. It was also shown that relative amounts of the mRNAs for the three subunits are similar in all the adult tissues examined. From these results, we concluded that the expression of the genes for the three subunits (XC3 XC8 and XC9-1) takes place in a roughly coordinated manner in different adult tissues.

Defensins promote fusion and lysis of negatively charged membranes

Defensins, a family of cationic peptides isolated from mammalian granulocytes and believed to permeabilize membranes, were tested for their ability to cause fusion and lysis of liposomes. Unlike alpha-helical peptides whose lytic effects have been extensively studied, the defensins consist primarily of beta-sheet. Defensins fuse and lyse negatively charged liposomes but display reduced activity with neutral liposomes. These and other experiments suggest that fusion and lysis is mediated primarily by electrostatic forces and to a lesser extent, by hydrophobic interactions. Circular dichroism and fluorescence spectroscopy of native defensins indicate that the amphiphilic beta-sheet structure is maintained throughout the fusion process. Taken together, these results support the idea that protein-mediated membrane fusion depends not only on hydrophobic and electrostatic forces but also on the spatial arrangement of the amino acid residues to form a three-dimensional amphiphilic structure, which promotes the efficient mixing of the lipids between membranes. A molecular model for membrane fusion by defensins is presented, which takes into account the contributions of electrostatic forces, hydrophobic interactions, and structural amphiphilicity.

A molecular model for membrane fusion based on solution studies of an amphiphilic peptide from HIV gp41

The mechanism of protein-mediated membrane fusion and lysis has been investigated by solution-state studies of the effects of peptides on liposomes. A peptide (SI) corresponding to a highly amphiphilic C-terminal segment from the envelope protein (gp41) of the human immunodeficiency virus (HIV) was synthesized and tested for its ability to cause lipid membranes to fuse together (fusion) or to break open (lysis). These effects were compared to those produced by the lytic and fusogenic peptide from bee venom, melittin. Other properties studied included the changes in visible absorbance and mean particle size, and the secondary structure of peptides as judged by CD spectroscopy. Taken together, the observations suggest that protein-mediated membrane fusion is dependent not only on hydrophobic and electrostatic forces but also on the spatial arrangement of the amino acid residues to form an amphiphilic structure that promotes the mixing of the lipids between membranes. A speculative molecular model is proposed for membrane fusion by alpha-helical peptides, and its relationship to the forces involved in protein-membrane interactions is discussed.

[A case of malignant localized visceral pleural mesothelioma]

We experienced malignant localized mesothelioma of which origin was visceral pleura. According to, 1) the preoperative chest X-ray and chest CT which showed extra-pleural sign, 2) the rapid tumor growth, and 3) the result from needle biopsy, we diagnosed malignant localized mesothelioma of which origin was parietal pleura. Surgical treatment was performed, and diagnosed that its origin was visceral pleura. The tumor invaded the lung. It is dangerous to diagnose by means of needle biopsy because of malignant cell implantation. We recommend that firstly the surgical treatment should be carried out for malignant mesothelioma, which needs extended resection for preventing its recurrence.

The crystal structure of diphtheria toxin

The crystal structure of the diphtheria toxin dimer at 2.5 A resolution reveals a Y-shaped molecule of three domains. The catalytic domain, called fragment A, is of the alpha + beta type. Fragment B actually consists of two domains. The transmembrane domain consists of nine alpha-helices, two pairs of which are unusually apolar and may participate in pH-triggered membrane insertion and translocation. The receptor-binding domain is a flattened beta-barrel with a jelly-roll-like topology. Three distinct functions of the toxin, each carried out by a separate structural domain, can be useful in designing chimaeric proteins, such as immunotoxins, in which the receptor-binding domain is substituted with antibodies to target other cell types.

Crystallization of diphtheria toxin

Two new crystal forms (forms III and IV) have been grown of diphtheria toxin (DT), which kills susceptible cells by catalyzing the ADP-ribosylation of elongation factor 2, thereby stopping protein synthesis. Forms III and IV diffract to 2.3 A and 2.7 A resolution, respectively. Both forms belong to space group C2; the unit cell parameters for form III are a = 107.3 A, b = 91.7 A, c = 66.3 A and beta = 94.7 degrees and those for form IV are a = 108.3 A, b = 92.3 A, c = 66.1 A and beta = 90.4 degrees. Both forms have one protein chain per asymmetric unit with the dimeric molecule on a twofold axis of symmetry. Form IV is exceptional among all crystal forms of DT in that it can be grown reproducibly. Thus the form IV crystals should yield a crystallographic structure giving insight into the catalytic, receptor-binding and membrane-insertion properties of DT.

Activin receptor mRNA is expressed early in Xenopus embryogenesis and the level of the expression affects the body axis formation

Activin is a member of the transforming growth factor beta (TGF-beta) and possesses various activities in cellular control phenomena. During Xenopus embryonic development, activin is thought to act as a natural mesoderm-inducing factor. We isolated here the Xenopus activin receptor cDNA from Xenopus tadpole cDNA library and examined the expression of the Xenopus activin receptor gene during the course of early embryonic development. The Xenopus activin receptor has an 87% homology at the level of deduced amino acid sequence with the mouse activin receptor, and using the cDNA obtained, three bands of mRNA with different lengths were detected in Xenopus embryos throughout early embryogenesis. We synthesized activin receptor mRNA in vitro and tested the effect of the injection of the mRNA into Xenopus fertilized eggs on subsequent development. When the synthetic mRNA was injected into uncleaved fertilized eggs, embryos with reduced trunk structure were formed. However, when the mRNA was injected into the ventral blastomeres at the 16-cell stage, embryos with a secondary body axis were formed. These results indicate the importance of the function of activin receptor in the regulatory mechanism for body axis formation.

Deduced primary structure of a Xenopus proteasome subunit XC3 and expression of its mRNA during early development

Proteasome is a non-lysosomal proteinase complex ubiquitously distributed in eukaryotic cells. We isolated here the cDNA clone for one of the proteasome subunits (XC3) from Xenopus ovary cDNA libraries using rat RC3 cDNA as a prove. The cDNA is 885 bp long and encodes 234 amino acids. The deduced amino acid sequence is highly homologous (95.3%) to those of rat RC3 and human HC3 subunits. The mRNA for XC3 is one of the maternal mRNAs and detected at all the embryonic stages investigated, but its level changes in a characteristic way especially at the gastrula stage. We suggest that the highly conserved XC3 subunit plays an essential role in proteasome function and also that during Xenopus embryogenesis mRNA for XC3 subunit is replaced from maternal to newly-synthesized one probably around the gastrula stage.

Effects of repeated exposure to cyclophosphamide on drug resistance and biological properties of a newly autonomy-acquired mouse mammary tumor (T4-OI320)

T4-OI320 tumors, the autonomous but estrogen receptor (ER-)-positive subline recently established from the pregnancy-dependent TPDMT-4 mouse mammary tumor, were characterized by moderate sensitivity to 1 mg cyclophosphamide (CY) and high sensitivity to 20 micrograms mitomycin C (MMC) and 1.5 mg 5-fluorouracil (5FU) twice weekly, the modal chromosome number of 40, the mean ER level of 20.8 fmol/mg protein, and a population of cells with one exogenous mouse mammary tumor virus (MMTV) genome. Serial tumor passages under CY treatment were conducted to investigate the effects of continued chemotherapy on growth habit, drug resistance, ER, karyotype, proviral MMTV genome and 22 oncogenes including int-1 and int-2. The growth rate was 2.9- and 4.5-fold increased after 10 and 20 passages, respectively. Along with this, the tumors acquired greater or complete resistance to CY and MMC similar to each other in antitumor mechanism, but maintained similarly high sensitivity to 5FU different from CY in antitumor mechanism. The ER level remained the same as but declined to half of the initial level after 10 and 20 passages, respectively. Tumor cells became more heterogenous in karyotype and the proportion of hyperdiploid cells with 41 to 47 chromosomes increased, resulting in shift of the modal number to 42 after 20 passages: Cells with 42 chromosomes accounted for 41% of the population. The exogenous MMTV bands in the Southern blotting became more intense after CY treatment accompanying neither amplification nor rearrangement of any cellular oncogenes. The tumors transplanted under no treatment for 20 generations had 1.5-fold higher growth rate, slightly stronger resistance to CY and MMC, similarly high sensitivity to 5FU, 4-fold lower ER level, the same distribution of chromosome numbers compared to the original tumors and similar intensity of the exogenous MMTV bands. Thus, acquisition of higher growth potential and greater drug resistance in the course of CY treatment appeared to be associated with chromosomal changes and selective overgrowth of the particular cell population with exogenous MMTV information in this model.