Merkel cell carcinoma: value of sentinel lymph-node status and adjuvant radiation therapy

BACKGROUND

Sentinel lymph-node (LN) biopsy (SLNB) is a valuable tool to assess the regional LN status in Merkel cell carcinoma (MCC). However, its prognostic value is still debated. This study was undertaken to assess SLNB usefulness for MCC management and to determine the impact of SLNB status on disease-free survival (DFS) and overall survival (OS) by comparing SLNB-positive versus -negative patients according to demographic, clinical and treatment characteristics.

PATIENTS AND METHODS

In this retrospective, multicenter observational study, SLNB was proposed to all patients referred for clinically N0 MCC. Treatment schedule consisted of wide-margin surgical resection of primary MCC followed by adjuvant radiation therapy (aRT) to the primary site and, for SLNB-positive patients, radical LN dissection followed by regional aRT. Univariate and multivariate analyses determined factors associated with DFS and OS.

RESULTS

Among 87 patients with successful SLNB, 21 (24.1%) were SLNB-positive. Median follow-up for the entire series was 39 months; respective 3-year DFS and OS rates were 73% and 81.4%, respectively. Univariate analysis (all patients) identified SLNB-negativity as being associated with prolonged OS (P = 0.013) and aRT (all sites considered) was associated with longer DFS (P = 0.004) and OS (P = 0.018). Multivariate analysis (all patients) retained SLNB status and aRT (all sites considered) as being associated with improved DFS (P = 0.014 and 0.0008) and OS (P = 0.0020 and 0.0019). Moreover, for SLNB-negative patients, tumor-bed irradiation was also significantly associated with prolonged DFS (P = 0.006) and OS (P = 0.014).

CONCLUSIONS

The present study demonstrates that SLNB-negativity is a strong predictor of longer DFS and OS in stage I and II MCC patients. The similar benefit for aRT on tumor bed observed in this study has to be confirmed by a prospective study. The results advocate for SLNB being considered to all MCC patients.

The reporting of clinical signs in laboratory animals

Observing and reporting clinical signs in laboratory animals is necessary for many reasons: the assessment of animal welfare, compliance with the principle of refinement (e.g. humane endpoints), regulatory compliance (e.g. reporting severity) and, importantly, as a scientific outcome, e.g. in animal models of disease or safety studies. Developments in the reporting of clinical signs will enhance the scientific value gained from animal experiments and further address the ethical cost. This paper discusses systematic approaches to the observation and reporting of clinical signs in animals (to be) used for research. Glossaries from public and corporate institutions have been consulted and a reference glossary has been set up, providing terminology to be tailored for institutional or project-specific use. The clinical examination of animals must be carried out by competent and specifically trained staff in a systematic way and repeated at adequate intervals and clinical observations must be registered effectively to allow this information to be used. The development of institutional or project-specific glossaries and the use of handwritten records or automated databases are discussed in detail. Among the users are animal care staff, veterinarians and researchers who will need to agree on a given set of clinical signs to be monitored routinely or as a scientific read-out and to train for the proper application. The paper introduces a long list of clinical signs with scientific terminology, descriptions and explanations as a reference glossary to be published and maintained online as a living document supported by the authors as an editorial committee.

Intérêt de la prise en charge nutritionnelle des patients traités par irradiation des voies aérodigestives supérieures: la consultation diététique est-elle utile?

AIMS

The head and neck tumors are most often associated with a precarious nutritional status. Radiotherapy increases the risk of denutrition because of its secondary effects on the secretory and sensorial mucous membranes. The purpose of our retrospectively study was to evaluate the interest of a precocious and regular nutritional therapy on the ability to maintain the nutritional status of the patient during the radiotherapy.

PATIENTS AND METHODS

The fifty-two patients included in the survey have been classified retrospectively in two different groups based on their observance to the nutritional therapy: group 1 "good observance", group 2 "bad observance".

RESULTS

The 31 patients of group 1 have lost an average of 1.9 kg by the end of the irradiation, whereas the 21 patients of group 2 have lost an average of 6.1 kg (p<0.001). The almost stability in weight of patients in group 1 was linked to a lower frequency of breaks in the radiotherapy (6 vs 33% p=0.03) and in a decrease in grade of inflammatory mucous membranes (10% of grade 3 in group 1 vs 52% in group 2, p=0.006). The quantity of calories ingested in form of nutritional supplements was greater in group 1 and consequently enabled patients to stabilized their weight (1200 calories in group 1 versus 850 calories in group 2, p<0.005).

CONCLUSIONS

The given nutritional advice and the prescription of adapted nutritional supplements consequently allowed limiting efficiently the weight lost during the irradiation and the grade of mucositis. The systematization of a precocious nutritional therapy for patients irradiated for head and neck tumors seems absolutely essential.

Swiss DVI at the tsunami disaster: Expect the unexpected

The conclusions reached while considering various aspects of the implemented strategy in the identification procedures in the wake of the tsunami disaster of December 26, 2004 are outlined. The lessons to be learned are discussed.

[Two cases of malignant tumors of the face after hematopoietic stem cell transplantation]

INTRODUCTION

Malignant solid tumors are a complication of hematopoietic stem cell transplantation (HSCT).

OBSERVATION

Two patients underwent HSCT for acute leukemia. Chronic graft-versus-host disease (GVHD) developed. At 5 years one patient developed squamous cell carcinoma of the tongue and the other mucoepidermoid carcinoma of the parotid gland.

DISCUSSION

Several factors are involved in the development of secondary malignant tumors after HSCT. Pre- and post-graft immunosuppressive treatment inhibits the defence system and cell repair and can trigger chronic GVHD with chronic inflammation of the epithelial tissue leading to accelerated cell turn over and a risk of genetic anomalies favoring penetration of viral particles. Squamous cell carcinoma of the oral cavity after HSCT presents the same clinical, histological and prognostic features as in the non-grafted patient. These patients require prolonged surveillance. Improved grafting and ant-HPV vaccination techniques may reduce the risk of cancer after HSCT.

Détection du ganglion sentinelle par lymphoscintigraphie dans les cancers epidermoïdes de la cavité buccale : étude prospective de 31 patients

INTRODUCTION

This study aimed at evaluating the relevance of sentinel node detection by lymphoscintigraphy in patients diagnosed with squamous-cell carcinoma of the oral cavity in the absence of neck adenopathy.

PATIENTS AND METHODS

A prospective study was carried out in 31 patients diagnosed with T1 to T3 squamous-cell carcinoma of the oral cavity without any clinically detectable neck adenopathy. A lymphoscintigraphy was performed the day before surgery. All patients underwent sentinel lymph node biopsy guided by a gamma-ray detecting probe and modified neck dissection. Pathologic evaluation of the sentinel lymph node included, in addition to the standard protocol, immunohistochemical analysis and thin sections of E stained preparations.

RESULTS

In 3 patients, the lymphoscintigraphy failed to detect any sentinel lymph node. In the remaining group of 28 patients, 20 patients showed a negative sentinel node concordant with a histologically negative neck dissection. In 5 patients, a positive lymph node was found although the rest of the neck dissection was negative. In 3 patients, sentinel lymph node was found to be negative but other neck nodes were positive. The overall sensitivity of lymphoscintigraphy in our study was 62%.

DISCUSSION

Surprisingly, the results of our study do not support the clinical usefulness of sentinel lymph node detection as a reliable and accurate staging method in patients with oral squamous cell carcinoma. We observed that lymphoscintigraphy was not a reliable method for detecting micrometastases in patients diagnosed with a squamous-cell carcinoma of the oral cavity without clinical evidence of neck matastases.

Reconstruction mandibulaire par lambeau osseux vascularisé après ostéoradionécrose

INTRODUCTION

The reconstruction of mandibular continuity destroyed by osteoradionecrosis can be a difficult task. The aim of this study was to evaluate the reliability and contribution of vascular osseous flaps for mandibular reconstruction after osteoradionecrosis.

MATERIAL AND METHOD

A retrospective study of patients undergoing mandibular reconstruction after osteoradionecrosis between 1989 and 2002 was performed. Twenty-five mandibular reconstructions were performed in 23 patients: 16 fibular free flaps, 5 osteomuscular serrato-costal free flaps, 1 osteocutaneous external brachial free flap, 1 medial femoral condylar free flap and 2 armed pectoralis major pediculed flaps.

RESULTS

We observed two major complications (8%): loss of one fibular flap and one medial femoral condylar free flap. We observed 42% minor complications. Overall quality of life was constantly enhanced.

DISCUSSION

Fibular flap is definitely a good method for immediate or secondary mandibular reconstruction. A serratocostal flap must be considered as an alternative flap when the fibular flap is unavailable.

Genetic modifications of the adeno-associated virus type 2 capsid reduce the affinity and the neutralizing effects of human serum antibodies

The high prevalence of human serum antibodies against adeno-associated virus type 2 (AAV) vectors represents a potential limitation for in vivo applications. Consequently, the development of AAV vectors able to escape antibody binding and neutralization is of importance. To identify capsid domains which contain major immunogenic epitopes, six AAV capsid mutants carrying peptide insertions in surface exposed loop regions (I-261, I-381, I-447, I-534, I-573, I-587) were analyzed. Two of these mutants, I-534 and I-573, showed an up to 70% reduced affinity for AAV antibodies as compared to wild-type AAV in the majority of serum samples. In addition, AAV mutant I-587 but not wild-type AAV efficiently transduced cells despite the presence of neutralizing antisera. Taken together, the results show that major neutralizing effects of human AAV antisera might be overcome by the use of AAV capsid mutants.

In vitro selection of viral vectors with modified tropism: the adeno-associated virus display

Improving the efficiency and specificity of gene vectors is critical for the success of gene therapy. In an effort to generate viral mutants with controlled tropism we produced a library of adeno-associated virus (AAV) clones with randomly modified capsids and used it for the selection of receptor-targeting mutants. After several rounds of selection on different cell lines that were resistant to infection by wild-type (wt) AAV, infectious mutants were harvested at high titers. These mutants transduced target cells with an up to 100-fold increased efficiency, in a receptor-specific manner and without interacting with the primary receptor for wt AAV. The results demonstrate for the first time that a combinatorial approach based on a eukaryotic virus library allows one to generate efficient, receptor-specific targeting vectors with desired tropism.

Analysis of site-specific transgene integration following cotransduction with recombinant adeno-associated virus and a rep encodingplasmid

BACKGROUND

Recombinant adeno-associated virus (rAAV) has many advantages for gene therapeutic applications in comparison with other vector systems. One of the most promising features is the ability of wild-type (wt) AAV to integrate site-specifically into human chromosome 19. However, this feature is lost in rAAV vectors due to the removal of the rep-coding sequences.

METHODS

HeLa cells were transfected with a rep expression plasmid, infected by rAAV and grown with or without selection pressure. Single cell clones were generated and genomic DNA was analyzed for site-specific integration by Southern blotting analysis and fluorescence in situ hybridization (FISH).

RESULTS

Transfection of HeLa cells with a rep expression plasmid followed by transduction with a rAAV vector resulted in site-specific integration of the transgene at AAVS1 on human chromosome 19 in 7 of 10 cell clones analyzed. In marked contrast, transduction of cells with rAAV alone did not result in any site-specific integration of the transgene.

CONCLUSIONS

The high frequency with which the site-specific integration took place in the presence of Rep protein is comparable with the results observed with wtAAV. These results offer opportunities for the development of specifically integrating rAAV vectors.

Aptamers as tools for target prioritization and lead identification

The increasing number of potential drug target candidates has driven the development of novel technologies designed to identify functionally important targets and enhance the subsequent lead discovery process. Highly specific synthetic nucleic acid ligands--also known as aptamers--offer a new exciting route in the drug discovery process by linking target validation directly with HTS. Recently, aptamers have proven to be valuable tools for modulating the function of endogenous cellular proteins in their natural environment. A set of technologies has been developed to use these sophisticated ligands for the validation of potential drug targets in disease models. Moreover, aptamers that are specific antagonists of protein function can act as substitute interaction partners in HTS assays to facilitate the identification of small-molecule lead compounds.

The VP1 capsid protein of adeno-associated virus type 2 is carrying a phospholipase A2 domain required for virus infectivity

The unique region of the VP1 protein of parvoviruses was proposed to contain a parvoviral phospholipase A2 (pvPLA2) motif. Here, PLA2 activity is shown in the unique region of adeno-associated virus type 2 (AAV-2) VP1 when expressed as an isolated domain in bacteria. Mutations in this region of the capsid protein strongly reduced the infectivity of mutant virions in comparison to wild-type AAV-2. This correlated with effects on the activity of PLA2. The mutations had no influence on capsid assembly, packaging of viral genomes into particles or binding to and entry into HeLa cells. However, a delayed onset and reduced amount of early gene expression, as measured by Rep immunofluorescence, was observed. These results suggest that pvPLA2 activity is required for a step following perinuclear accumulation of virions but prior to early gene expression.

Adeno-associated virus capsids displaying immunoglobulin-binding domains permit antibody-mediated vector retargeting to specific cell surface receptors

Recombinant adeno-associated virus type 2 (rAAV2) is a promising vector for human somatic gene therapy. However, its broad host range is a disadvantage for some applications, because it reduces the specificity of the gene transfer. To overcome this limitation, we sought to create a versatile rAAV vector targeting system which would allow us to redirect rAAV binding to specific cell surface receptors by simple coupling of different ligands to its capsid. For this purpose, an immunoglobulin G (IgG) binding domain of protein A, Z34C, was inserted into the AAV2 capsid at amino acid position 587. The resulting AAV2-Z34C mutants could be packaged and purified to high titers and bound to IgG molecules. rAAV2-Z34C vectors coupled to antibodies against CD29 (beta(1)-integrin), CD117 (c-kit receptor), and CXCR4 specifically transduced distinct human hematopoietic cell lines. In marked contrast, no transduction was seen in the absence of antibodies or in the presence of specific blocking reagents. These results demonstrate for the first time that an immunoglobulin binding domain can be inserted into the AAV2 capsid and coupled to various antibodies, which mediate the retargeting of rAAV vectors to specific cell surface receptors.

The VP1 capsid protein of adeno-associated virus type 2 is carrying a phospholipase A2 domain required for virus infectivity

The unique region of the VP1 protein of parvoviruses was proposed to contain a parvoviral phospholipase A2 (pvPLA2) motif. Here, PLA2 activity is shown in the unique region of adeno-associated virus type 2 (AAV-2) VP1 when expressed as an isolated domain in bacteria. Mutations in this region of the capsid protein strongly reduced the infectivity of mutant virions in comparison to wild-type AAV-2. This correlated with effects on the activity of PLA2. The mutations had no influence on capsid assembly, packaging of viral genomes into particles or binding to and entry into HeLa cells. However, a delayed onset and reduced amount of early gene expression, as measured by Rep immunofluorescence, was observed. These results suggest that pvPLA2 activity is required for a step following perinuclear accumulation of virions but prior to early gene expression.

[Cutaneous angiosarcoma of the head: three cases]

Cutaneous angiosarcoma of the head is an uncommon finding. We report three cases, two women with a scalp localization and a man with a facial (frontal) localization. Recurrence was observed in one woman after surgery; this patient was given palliative treatment due to her poor health condition. The other women experienced three recurrences. After the last surgery, latissmus dorsi free flap graft, she has been disease free. The man was treated with surgery and radiotherapy. Regional lymph node metastasis appeared 5 years after the initial treatment. He is now disease free after surgery and cervical radiotherapy. Wide surgery and careful long-term follow-up are essential. The latissimus dorsi free flap can provide successful cure.

[Primary osseous leiomyosarcoma of the jaw. Apropos of a case]

Primary leiomyosarcoma of bone is a malignant smooth muscle tumour uncommonly found in the jaws. We report a case of primary leiomyosarcoma of the mandible in a 31-year-old man treated with wide resection and radiotherapy then secondary reconstruction with a fibula free flap. No recurrence or distant metastasis has developed four years after the initial surgery. We review the literature on primary leiomyosarcoma of the jaws.

Efficient and selective AAV2-mediated gene transfer directed to human vascular endothelial cells

Gene therapy vectors based on adeno-associated virus-2 (AAV2) offer considerable promise for human gene therapy. Applications for AAV vectors are limited to tissues efficiently transduced by the vector due to its natural tropism, which is predominantly skeletal muscle, neurons, and hepatocytes. Tropism modification to elevate efficiency and/or selectivity to individual cell types would enhance the scope of AAV for disease therapies. The vascular endothelium is implicitly important in cardiovascular diseases and cancer, but is relatively poorly transduced by AAV vectors. We therefore genetically incorporated the peptide SIGYPLP, which targets endothelial cells (EC), into position I-587 of AAV capsids. SIGYPLP-modified AAV (AAVsig) showed enhanced transduction of human EC compared with AAV with a wild-type capsid (AAVwt), a phenotype independent of heparan sulphate proteoglycan (HSPG) binding. In contrast, AAVsig did not enhance transduction of primary human vascular smooth muscle cells or human hepatocytes, principal targets for AAV vectors in local or systemic gene delivery applications, respectively. Furthermore, infection of EC in the presence of bafilomycin A(2) indicated that intracellular trafficking of AAV particles was altered by targeting AAV by means of SIGYPLP. AAV vectors with enhanced tropism for EC will be useful for diverse gene therapeutics targeted at the vasculature.

[Complications of orthognathic surgery. Apropos of a series of 84 patients]

BACKGROUND

Patients demand satisfactory functional and esthetic results from orthognatic surgery. The aim of this study as to assess adverse outcomes after orthognatic surgery.

PATIENTS AND METHODS

We retrospectively reviewed 84 patients who underwent maxillary (22.6%), mandibular (29.8%) or bimaxillary (38.1%) osteotomy in 1997. We re-examined 76 of these patients at a mean 21 months follow-up. Data were recorded for the preoperative, early postoperative, secondary postoperative and late postoperative periods.

RESULTS

Infectious complications occurred in 2% of the cases of maxillary surgery. For mandibular surgery there were 10.5% infectious complications including 83% that resolved spontaneously, 3.5% neurological complications and 1.7% temporomandibular joint complications.

DISCUSSION

Maxillary osteotomy has proven reliable. Major adverse outcome is infrequent but serious. Adverse outcomes in mandibular surgery are more common but less problematic.

Monoclonal antibodies against the adeno-associated virus type 2 (AAV-2) capsid: epitope mapping and identification of capsid domains involved in AAV-2-cell interaction and neutralization of AAV-2 infection

The previously characterized monoclonal antibodies (MAbs) A1, A69, B1, and A20 are directed against assembled or nonassembled adeno-associated virus type 2 (AAV-2) capsid proteins (A. Wistuba, A. Kern, S. Weger, D. Grimm, and J. A. Kleinschmidt, J. Virol. 71:1341-1352, 1997). Here we describe the linear epitopes of A1, A69, and B1 which reside in VP1, VP2, and VP3, respectively, using gene fragment phage display library, peptide scan, and peptide competition experiments. In addition, MAbs A20, C24-B, C37-B, and D3 directed against conformational epitopes on AAV-2 capsids were characterized. Epitope sequences on the capsid surface were identified by enzyme-linked immunoabsorbent assay using AAV-2 mutants and AAV serotypes, peptide scan, and peptide competition experiments. A20 neutralizes infection following receptor attachment by binding an epitope formed during AAV-2 capsid assembly. The newly isolated antibodies C24-B and C37-B inhibit AAV-2 binding to cells, probably by recognizing a loop region involved in binding of AAV-2 to the cellular receptor. In contrast, binding of D3 to a loop near the predicted threefold spike does not neutralize AAV-2 infection. The identified antigenic regions on the AAV-2 capsid surface are discussed with respect to their possible roles in different steps of the viral life cycle.

A statistical study of air bubbles on athletic shoesoles

Comparisons of a shoemark with a shoesole (and standards) sometimes lead to associations based on air bubbles (among other manufacturing or acquired characteristics). Today, the assessment of the evidential value of air bubbles coincidences relies largely upon the examiner's experience and/or follows sometimes a verification based on the examination of a small number of analogous pairs collected for the case at hand. Statistical data related to the occurrence and characteristics of air bubbles on shoesoles in an attempt to model the potential variability have been gathered. Seventy-one pairs of shoes with the same design, brand, model and size were obtained. Right and left soles were photographed. An image-processing algorithm was developed to allow the systematic acquisition of data such as: (1) the number of air bubbles on the sole and around given structural elements; (2) the measure of air bubbles characteristics such as their surface and position. These data allow a discussion of the assessment of the probability of finding on shoesoles (same design, brand, model and size) a certain number of air bubbles on a surface with the same positions and morphology.

The p24 family member p23 is required for early embryonic development

The p24 family of type I integral-membrane proteins, which are localised in the endoplasmic reticulum (ER), the intermediate compartment and the Golgi apparatus, are thought to function as receptors for cargo exit from the ER and in transport vesicle formation. Members of the p24 family have been found in a molecular complex and are enriched in COPI-coated vesicles, which are involved in membrane traffic between the ER and Golgi complex. Although expressed abundantly, simultaneous deletion of several family members does not appear to affect cell viability and protein secretion in yeast. In order to gain more insights into the physiological roles of different p24 proteins, we generated mice deficient in the expression of one family member, p23 (also called 24delta1, see for alternative nomenclature). In contrast to yeast genetics, in mice disruption of both p23 alleles resulted in early embryonic lethality. Inactivation of one allele led not only to reduced levels of p23 itself but also to reduced levels of other family members. The reduction in steady-state protein levels also induced structural changes in the Golgi apparatus, such as the formation of dilated saccules. The generation of mice deficient in p23 expression has revealed an essential and non-redundant role for p23 in the earliest stages of mammalian development. It has also provided genetic evidence for the participation of p24 family members in oligomeric complexes and indicates a structural role for these proteins in maintaining the integrity of the early secretory pathway.

Dyskerin localizes to the nucleolus and its mislocalization is unlikely to play a role in the pathogenesis of dyskeratosis congenita

Mutations in the DKC1 gene are responsible for causing the bone marrow failure syndrome, dyskeratosis congenita (DKC; OMIM 305000). The majority of mutations identified to date are missense mutations and are clustered in exons 3, 4 and 11. It is predicted that the corresponding protein dyskerin is a nucleolar phosphoprotein which functions in both pseudo-uridylation and cleavage of precursor rRNA. Dyskerin contains multiple putative nuclear localization signals (NLSs) at the N-terminus (KKHKKKKERKS) and C-terminus [KRKR(X)(17)KKEKKKSKKDKKAK(X)(17)-KKKKKKKKAKEVELVSE]. By fusing dyskerin with the enhanced green fluorescent protein (EGFP) and by following a time course of expression in mammalian cell lines, we showed that full-length dyskerin initially localizes to the nucleoplasm and subsequently accumulates in the nucleoli. A co-localization to the coiled bodies was observed in some cells where dyskerin-EGFP had translocated to the nucleoli. Analysis of a series of mutant constructs indicated that whereas the most C-terminal lysine-rich clusters [KKEKKKS-KKDKKAK(X)(17)KKKKKKKKAKEVELVSE] influence the rate of nucleoplasmic and nucleolar accumulation, the KRKR sequence is primarily responsible for the nuclear import. Nucleolar localization was maintained when either the N- or C-terminal motifs were mutated, but not when all NLSs were removed. We conclude that the intranuclear localization of dyskerin is accomplished by the synergistic effect of a number of NLSs and that the nucleolar localization signals are contained within the NLSs. Further, examination of dyskerin-EGFP fusions mimicking mutations detected in patients indicated that the intracellular mislocalization of dyskerin is unlikely to cause DKC.

Rab6 coordinates a novel Golgi to ER retrograde transport pathway in live cells

We visualized a fluorescent-protein (FP) fusion to Rab6, a Golgi-associated GTPase, in conjunction with fluorescent secretory pathway markers. FP-Rab6 defined highly dynamic transport carriers (TCs) translocating from the Golgi to the cell periphery. FP-Rab6 TCs specifically accumulated a retrograde cargo, the wild-type Shiga toxin B-fragment (STB), during STB transport from the Golgi to the endoplasmic reticulum (ER). FP-Rab6 TCs associated intimately with the ER, and STB entered the ER via specialized peripheral regions that accumulated FP-Rab6. Microinjection of antibodies that block coatomer protein I (COPI) function inhibited trafficking of a KDEL-receptor FP-fusion, but not FP-Rab6. Additionally, markers of COPI-dependent recycling were excluded from FP-Rab6/STB TCs. Overexpression of Rab6:GDP (T27N mutant) using T7 vaccinia inhibited toxicity of Shiga holotoxin, but did not alter STB transport to the Golgi or Golgi morphology. Taken together, our results indicate Rab6 regulates a novel Golgi to ER transport pathway.

Evidence for a COP-I-independent transport route from the Golgi complex to the endoplasmic reticulum

The cytosolic coat-protein complex COP-I interacts with cytoplasmic 'retrieval' signals present in membrane proteins that cycle between the endoplasmic reticulum (ER) and the Golgi complex, and is required for both anterograde and retrograde transport in the secretory pathway. Here we study the role of COP-I in Golgi-to-ER transport of several distinct marker molecules. Microinjection of anti-COP-I antibodies inhibits retrieval of the lectin-like molecule ERGIC-53 and of the KDEL receptor from the Golgi to the ER. Transport to the ER of protein toxins, which contain a sequence that is recognized by the KDEL receptor, is also inhibited. In contrast, microinjection of anti-COP-I antibodies or expression of a GTP-restricted Arf-1 mutant does not interfere with Golgi-to-ER transport of Shiga toxin/Shiga-like toxin-1 or with the apparent recycling to the ER of Golgi-resident glycosylation enzymes. Overexpression of a GDP-restricted mutant of Rab6 blocks transport to the ER of Shiga toxin/Shiga-like toxin-1 and glycosylation enzymes, but not of ERGIC-53, the KDEL receptor or KDEL-containing toxins. These data indicate the existence of at least two distinct pathways for Golgi-to-ER transport, one COP-I dependent and the other COP-I independent. The COP-I-independent pathway is specifically regulated by Rab6 and is used by Golgi glycosylation enzymes and Shiga toxin/Shiga-like toxin-1.

Genetic capsid modifications allow efficient re-targeting of adeno-associated virus type 2

The human parvovirus adeno-associated virus type 2 (AAV2) has many features that make it attractive as a vector for gene therapy. However, the broad host range of AAV2 might represent a limitation for some applications in vivo, because recombinant AAV vector (rAAV)-mediated gene transfer would not be specific for the tissue of interest. This host range is determined by the binding of the AAV2 capsid to specific cellular receptors and/or co-receptors. The tropism of AAV2 might be changed by genetically introducing a ligand peptide into the viral capsid, thereby redirecting the binding of AAV2 to other cellular receptors. We generated six AAV2 capsid mutants by inserting a 14-amino-acid targeting peptide, L14, into six different putative loops of the AAV2 capsid protein identified by comparison with the known three-dimensional structure of canine parvovirus. All mutants were efficiently packaged. Three mutants expressed L14 on the capsid surface, and one efficiently infected wild-type AAV2-resistant cell lines that expressed the integrin receptor recognized by L14. The results demonstrate that the AAV2 capsid tolerates the insertion of a nonviral ligand sequence. This might open new perspectives for the design of targeted AAV2 vectors for human somatic gene therapy.

The KDEL retrieval system is exploited by Pseudomonas exotoxin A, but not by Shiga-like toxin-1, during retrograde transport from the Golgi complex to the endoplasmic reticulum

To investigate the role of the KDEL receptor in the retrieval of protein toxins to the mammalian cell endoplasmic reticulum (ER), lysozyme variants containing AARL or KDEL C-terminal tags, or the human KDEL receptor, have been expressed in toxin-treated COS 7 and HeLa cells. Expression of the lysozyme variants and the KDEL receptor was confirmed by immunofluorescence. When such cells were challenged with diphtheria toxin (DT) or Escherichia coli Shiga-like toxin 1 (SLT-1), there was no observable difference in their sensitivities as compared to cells which did not express these exogenous proteins. By contrast, the cytotoxicity of Pseudomonas exotoxin A (PE) is reduced by expressing lysozyme-KDEL, which causes a redistribution of the KDEL receptor from the Golgi complex to the ER, and cells are sensitised to this toxin when they express additional KDEL receptors. These data suggest that, in contrast to SLT-1, PE can exploit the KDEL receptor in order to reach the ER lumen where it is believed that membrane transfer to the cytosol occurs. This contention was confirmed by microinjecting into Vero cells antibodies raised against the cytoplasmically exposed tail of the KDEL receptor. Immunofluorescence confirmed that these antibodies prevented the retrograde transport of the KDEL receptor from the Golgi complex to the ER, and this in turn reduced the cytotoxicity of PE, but not that of SLT-1, to these cells.

Recombinant adeno-associated virus vectors

Recombinant adeno-associated virus (rAAV) is a promising vector for somatic gene therapy due to the ability to transduce terminally-differentiated and non-dividing cells, the lack of any apparent pathogenicity, a low immunogenicity, a relatively high stability of transgene expression, and the potential for targeted integration. Improved methods of rAAV packaging allow the generation of concentrated and highly purified rAAV for clinical trials. Preclinical studies with rAAV are currently in progress for the treatment of a variety of inherited monogenic defects, but also for acquired diseases like HIV infection and cancer. Because of the broad host range of wild type AAV, rAAV is able to transduce a variety of human tissues, preferentially those of epitheloid origin, with high efficiency and therefore may be used for various clinical applications. Whilst several issues including safety, tissue tropism and methods to achieve site-specific integration need further improvement, rAAV certainly has a sufficient number of advantages to be seriously considered as a gene therapy vector.

A conserved deamidation site at Asn 2 in the catalytic subunit of mammalian cAMP-dependent protein kinase detected by capillary LC-MS and tandem mass spectrometry

The N-terminal sequence myr-Gly-Asn is conserved among the myristoylated cAPK (protein kinase A) catalytic subunit isozymes Calpha, Cbeta, and Cgamma. By capillary LC-MS and tandem MS, we show that, in approximately one third of the Calpha and Cbeta enzyme populations from cattle, pig, rabbit, and rat striated muscle, Asn 2 is deamidated to Asp 2. This deamidation accounts for the major isoelectric variants of the cAPK C-subunits formerly called CA and CB. Deamidation also includes characteristic isoaspartate isomeric peptides from Calpha and Cbeta. Asn 2 deamidation does not occur during C-subunit preparation and is absent in recombinant myristoylated Calpha (rCalpha) from Escherichia coli. Deamidation appears to be the exclusive pathway for introduction of an acidic residue adjacent to the myristoylated N-terminal glycine, verified by the myristoylation negative phenotype of an rCalpha(Asn 2 Asp) mutant. This is the first report thus far of a naturally occurring myr-Gly-Asp sequence. Asp 2 seems to be required for the well-characterized (auto)phosphorylation of the native enzyme at Ser 10. Our results suggest that the myristoylated N terminus of cAPK is a conserved site for deamidation in vivo. Comparable myr-Gly-Asn sequences are found in several signaling proteins. This may be especially significant in view of the recent knowledge that negative charges close to myristic acid in some proteins contribute to regulating their cellular localization.

Staurosporine-induced conformational changes of cAMP-dependent protein kinase catalytic subunit explain inhibitory potential

BACKGROUND

Staurosporine inhibits most protein kinases at low nanomolar concentrations. As most tyrosine kinases, along with many serine/threonine kinases, are either proto oncoproteins or are involved in oncogenic signaling, the development of protein kinase inhibitors is a primary goal of cancer research. Staurosporine and many of its derivatives have significant biological effects, and are being tested as anticancer drugs. To understand in atomic detail the mode of inhibition and the parameters of high-affinity binding of staurosporine to protein kinases, the molecule was cocrystallized with the catalytic subunit of cAMP-dependent protein kinase.

RESULTS

The crystal structure of the protein kinase catalytic subunit with staurosporine bound to the adenosine pocket shows considerable induced-fit rearrangement of the enzyme and a unique open conformation. The inhibitor mimics several aspects of adenosine binding, including both polar and nonpolar interactions with enzyme residues, and induces conformational changes of neighboring enzyme residues.

CONCLUSIONS

The results explain the high inhibitory potency of staurosporine, and also illustrate the flexibility of the protein kinase active site. The structure, therefore, is not only useful for the design of improved anticancer therapeutics and signaling drugs, but also provides a deeper understanding of the conformational flexibility of the protein kinase.

Phosphorylation of protein kinase Cdelta (PKCdelta) at threonine 505 is not a prerequisite for enzymatic activity. Expression of rat PKCdelta and an alanine 505 mutant in bacteria in a functional form

A structural feature shared by many protein kinases is the requirement for phosphorylation of threonine or tyrosine in the so-called activation loop for full enzyme activity. Previous studies by several groups have indicated that the isotypes alpha, betaI, and betaII of protein kinase C (PKC) are synthesized as inactive precursors and require phosphorylation by a putative "PKC kinase" for permissive activation. Expression of PKCalpha in bacteria resulted in a nonfunctional enzyme, apparently due to lack of this kinase. The phosphorylation sites for the PKC kinase in the activation loop of PKCalpha and PKCbetaII could be identified as Thr497 and Thr500, respectively. We report here that PKCdelta, contrary to PKCalpha, can be expressed in bacteria in a functional form. The activity of the recombinant enzyme regarding substrate phosphorylation, autophosphorylation, and dependence on activation by 12-O-tetradecanoylphorbol-13-acetate as well as the Km values for two substrates are comparable to those of recombinant PKCdelta expressed in baculovirus-infected insect cells. By site-directed mutagenesis we were able to show that Thr505, corresponding to Thr497 and Thr500 of PKCalpha and PKCbetaII, respectively, is not essential for obtaining a catalytically competent conformation of PKCdelta. The mutant Ala505 can be activated and does not differ from the wild type regarding activity and several other features. Ser504 can not take over the role of Thr505 and is not prerequisite for the kinase to become activated, as proven by the unaffected enzyme activity of respective mutants (Ala504 and Ala504/Ala505). These results indicate that phosphorylation of Thr505 is not required for the formation of functional PKCdelta and that at least this PKC isoenzyme differs from the isotypes alpha, betaI, and betaII regarding the permissive activation by a PKC kinase.

Crystal structures of catalytic subunit of cAMP-dependent protein kinase in complex with isoquinolinesulfonyl protein kinase inhibitors H7, H8, and H89. Structural implications for selectivity

The discovery of several hundred different protein kinases involved in highly diverse cellular signaling pathways is in stark contrast to the much smaller number of known modulators of cell signaling. Of these, the H series protein kinase inhibitors (1-(5-isoquinolinesulfonyl)-2-methylpiperazine (H7), N-[2-(methylamino)ethyl]-5-isoquinolinesulfonamide (H8) N-[2-(p-Bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide (H89)) are frequently used to block signaling pathways in studies of cellular regulation. To elucidate inhibition mechanisms at atomic resolution and to enable structure-based drug design of potential therapeutic modulators of signaling pathways, we determined the crystal structures of corresponding complexes with the cAPK catalytic subunit. Complexes with H7 and H8 (2.2 A) and with H89 (2.3 A) define the binding mode of the isoquinoline-sulfonamide derivatives in the ATP-binding site while demonstrating effects of ligand-induced structural change. Specific interactions between the enzyme and the inhibitors include the isoquinoline ring nitrogen ligating to backbone amide of Val-123 and an inhibitor side chain amide bonding to the backbone carbonyl of Glu-170. The conservation of the ATP-binding site of protein kinases allows evaluation of factors governing general selectivity of these inhibitors among kinases. These results should assist efforts in the design of protein kinase inhibitors with specific properties.

In vivo activation of recombinant cAPK catalytic subunit active site mutants by coexpression of the wild-type enzyme, evidence for intermolecular cotranslational phosphorylation

The catalytic subunit of cAMP dependent protein kinase (cAPK) carries two stable autophosphorylated residues. One of them, Thr197, resides in the so-called protein kinase activation segment, and needs to be phosphorylated for full activity and protein kinase inhibitor binding of the enzyme. While wild-type recombinant mammalian C-subunit, expressed in E. coli, can fully autoactivate itself by phosphorylation at Thr197, many active site mutants lack this autophosphorylation activity, so that the primary effects of the mutations become obscured. Two active site mutants of bovine C-subunit, defective in protein kinase inhibitor peptide binding, were activated by wild-type enzyme in vivo, but could not be activated in vitro, demonstrating intermolecular and presumably cotranslational autophosphorylation. The results may delineate strategies for the expression and mutagenesis of other protein kinases with requirements for activation segment phosphorylation.

Homologous and nonhomologous retroviral recombinations are both involved in the transfer by infectious particles of defective avian leukosis virus-derived transcomplementing genomes

We previously described avian leukosis virus-based packaging cell lines that produce stocks of retroviral vectors in which replication-competent viruses were not detectable. However, following infection of target cells with these retroviral stocks, we recently obtained colonies resulting from the transmission of recombinant genomes. Here, we have analyzed their genetic structure and shown that (i) each of them results from recombination between the packaging- and integration-defective transcomplementing genomes and the retroviral vector; (ii) recombination probably occurred during the reverse transcription step, involving strand switching of the reverse transcription growing point from the infectious retroviral vector to the transcomplementing RNA; and (iii) sequence identity and nonhomologous sequences were both used for the strand switching.

Analysis of ALV-based packaging cell lines for production of contaminant defective viruses

We have previously described avian leukosis virus-based packaging cell lines that express gag, pol, and env proteins from two transcomplementing genomes and produce helper-free stocks of retroviral vectors with different host ranges. In this report, we demonstrated that (i) despite the deletion of the psi packaging sequence, the packaging-defective transcomplementing retroviral transcripts were packaged into virions at a level that could reach 2.3% of a wild-type virus packaging level and (ii) despite deletion of the 3' LTR, these genomes were transferred along with the vector to target cells. As these genomes were also bearing a selectable gene, titers of the resulting contaminant particles could be estimated, depending on the cell line to be between 0 and 6 infectious particles/ml of supernatant.

Defective retroviral endogenous RNA is efficiently transmitted by infectious particles produced on an avian retroviral vector packaging cell line

This report describes the contamination of "helper-free" stocks of defective retroviral vector with particles bearing retroviral endogenous RNA. An avian leukosis virus-based packaging cell line was developed from LMH cells that bear the ev1, ev3, and ev6 retroviral endogenous loci. The results show that an endogenous retroviral transcript (ev3) was packaged into virions produced by this packaging cell line and was efficiently transferred along with the vector to target cells. The titer of the ev contaminant particles was estimated at 50-100 CA-p27gag-expressing units/ml of supernatant.

Use of helper cells with two host ranges to generate high-titer retroviral vectors

We have recently described Avian Leukosis Virus (ALV)-based packaging cell lines that can produce helper-free ALV-based retrovirus vectors with A, B, C, and E envelope host ranges. Here, we report that lacZ retroviral vectors of subgroup C or E can infect helper cells of subgroup A (Isolde) which are then able to produce high titers of lacZ recombinant viruses of subgroup A. Superinfection of helper cells by lacZ recombinant virus was performed by cocultivating packaging cells with two subgroup specificities (A and E), but this did not result in increased recombinant virus titers. This "ping-pong" process caused the emergence of replication-competent (RC) viruses which are shown to result from recombination between the viral sequences of the helper cell lines and the cis-acting sequences of the lacZ recombinant virus.

[Two-years' experience of ambulatory anesthesia in otorhinolaryngology in children]

Three hundred children were anaesthetized for E.N.T. operations. The anaesthetic consultation took place one week prior to operation. The anaesthetic comprises premedication, inhalation of halothane for infants, or propofol drip for the others with tracheal tubing for 10% of them. Recovery in every case is supervised in the recovery room. There are few setbacks with this method. Eleven children were not accepted for operation for sociological or medical reasons (Willebrand diseases) and only 3 had to remain in hospital until the following day due to slow recovery from anaesthetic.

[Use of propofol in ophthalmological anesthesia in elderly patients]

Forty patients more than 65 years old were anaesthetized with propofol for cataract surgery. Patients were divided into two groups: those intubated after topical oropharyngeal anaesthesia and those intubated after muscle relaxation obtained with suxamethonium. Induction and maintenance of anaesthesia were carried out with 2.5 mg . kg-1 and 4 mg . kg-1 . h-1 respectively. Concurrent use of muscle relaxants had no effect on the action and characteristics of the general anaesthesia or recovery. Relative bradycardia (7%) and arterial hypotension (25%) occurred rapidly following induction and continued during the entire period of anaesthesia despite the systematic infusion of 500 ml of electrolyte solutions. Recovery was extremely rapid. The original Glasgow score was obtained within 20 min. The only negative side-effects were generally late occurring (4-6 h): postanaesthetic nausea or vomiting. Otherwise, tolerance was excellent. Use of propofol was ideal for this type of surgery due to its strong and durable ocular hypotensive effect.