PCAF ubiquitin ligase activity inhibits Hedgehog/Gli1 signaling in p53-dependent response to genotoxic stress.

The Hedgehog (Hh) signaling regulates tissue development, and its aberrant activation is a leading cause of malignancies, including medulloblastoma (Mb). Hh-dependent tumorigenesis often occurs in synergy with other mechanisms, such as loss of p53, the master regulator of the DNA damage response. To date, little is known about mechanisms connecting DNA-damaging events to morphogen-dependent processes. Here, we show that genotoxic stress triggers a cascade of signals, culminating with inhibition of the activity of Gli1, the final transcriptional effector of Hh signaling. This inhibition is dependent on the p53-mediated elevation of the acetyltransferase p300/CBP-associated factor (PCAF). Notably, we identify PCAF as a novel E3 ubiquitin ligase of Gli1. Indeed PCAF, but not a mutant with a deletion of its ubiquitination domain, represses Hh signaling in response to DNA damage by promoting Gli1 ubiquitination and its proteasome-dependent degradation. Restoring Gli1 levels rescues the growth arrest and apoptosis effect triggered by genotoxic drugs. Consistently, DNA-damaging agents fail to inhibit Gli1 activity in the absence of either p53 or PCAF. Finally, Mb samples from p53-null mice display low levels of PCAF and upregulation of Gli1 in vivo, suggesting PCAF as potential therapeutic target in Hh-dependent tumors. Together, our data define a mechanism of inactivation of a morphogenic signaling in response to genotoxic stress and unveil a p53/PCAF/Gli1 circuitry centered on PCAF that limits Gli1-enhanced mitogenic and prosurvival response.

Numb activates the E3 ligase Itch to control Gli1 function through a novel degradation signal.

Hedgehog pathway regulates tissue patterning and cell proliferation. Gli1 transcription factor is the major effector of Hedgehog signaling and its deregulation is often associated to medulloblastoma formation. Proteolytic processes represent a critical mechanism by which this pathway is turned off. Here, we characterize the regulation of an ubiquitin-mediated mechanism of Gli1 degradation, promoted by the coordinated action of the E3 ligase Itch and the adaptor protein Numb. We show that Numb activates the catalytic activity of Itch, releasing it from an inhibitory intramolecular interaction between its homologous to E6-AP C-terminus and WW domains. The consequent activation of Itch, together with the recruitment of Gli1 through direct binding with Numb, allows Gli1 to enter into the complex, resulting in Gli1 ubiquitination and degradation. This process is mediated by a novel Itch-dependent degron, composed of a combination of two PPXYs and a phospho-serine/proline motifs, localized in Gli1 C-terminal region, indicating the role of two different WW docking sites in Gli1 ubiquitination. Remarkably, Gli1 protein mutated in these modules is no longer regulated by Itch and Numb, and determines enhanced Gli1-dependent medulloblastoma growth, migration and invasion abilities, as well as in vitro transforming activity. Our data reveal a novel mechanism of regulation of Gli1 stability and function, which influences Hedgehog/Gli1 oncogenic potential.

I Conferencia Nacional de Consenso sobre el Injerto Óseo del Seno Maxilar / 1st National Consensus Conference on maxillar sinus bone grafts

Objetivo: El objetivo de la I Conferencia Española de Consenso sobre el Injerto Óseo Sinusal era intentar llegar a puntos de acuerdo sobre las principales controversias de esta técnica, aplicada de forma muy variada y con el empleo de materiales muy diversos, y conseguir plasmar los mismos en un documento resumen consensuado por todos los autores. Material y método: Durante los días 17 y 18 de octubre de 2008 se celebró en Oviedo la citada conferencia, auspiciada por la Sociedad Española de Cirugía Oral y Maxilofacial. En ella se dieron cita un total de 50 ponentes de reconocido prestigio nacional e internacional que repasaron en 6 mesas de trabajo las principales controversias sobre los injertos óseos sinusales. Tras las conferencias de los ponentes, los moderadores establecían las principales conclusiones de cada mesa y se abría un turno de debate donde participaban todos los asistentes. Resultado: Este documento y sus conclusiones emanan de las presentaciones realizadas por los ponentes y de las deliberaciones y acuerdos de cada mesa de trabajo. Ambos han sido aprobados tras varias correcciones por todos los autores antes de ser enviados para su publicación. Además, han obtenido el reconocimiento científico oficial de la Sociedad Española de Cirugía Oral y Maxilofacial y deben servir como base para futuros estudios y reuniones científicas. Conclusiones: El objetivo fundamental cuando se realiza un injerto óseo sinusal es la formación de hueso vital en el seno maxilar, para conseguir la supervivencia a largo plazo de los implantes tras su carga protésica. Para ello, la técnica y la secuencia de tratamiento deben orientarse a conseguir resultados predecibles y estables en el tiempo, aunque esto suponga un mayor tiempo de espera hasta la colocación de la prótesis. La estabilidad inicial del implante es el factor clave para la osteointegración y debe ser el principal criterio para indicar implantes simultáneos o diferidos en el seno maxilar(AU)

Objective: The objectives of the first Spanish Consensus Conference on Sinus Bone Graft were trying to reach agreements points on the major controversies of this technique, and translate them in a summary document. Material and method: During the 17th and 18th of October of 2008 took place in Oviedo (Spain) the Conference, sponsored by the Spanish Society of Oral and Maxillofacial Surgery. There, 50 national and international speakers reviewed in 6 workshops the major controversies of sinus bone grafts. Following the conferences, the moderators proposed the main conclusions of each workshop and opened a round of discussion where all attendees participated. Results: This document and its conclusions emanate from the presentations made by the speakers and the discussions and agreements of each workshop. Both have been approved after several corrections by all authors before being submitted for publication. They have also obtained the official scientific recognition of the Spanish Society of Oral and Maxillofacial Surgery and should serve as a basis for future scientific studies and meetings. Conclusions: The main objective when we perform a sinus bone graft is vital bone formation in the maxillary sinus, to achieve long-term survival of the implants after prosthetic loading. To do this, the technique and sequence of treatment should aim to achieve predictable and stable results over time, although this involves a longer waiting time. The initial implant stability is the key factor for osseointegration and should be the main criterion to indicate simultaneous or delayed implants in the maxillary sinus(AU)

Osteotomía de Le Fort I segmentada para acceso a la base craneal: Cordoma de clivus

No disponible

Severe cervical chyle fistula after radical neck dissection.

The case of a chylous cervical fistula detected immediately after radical neck dissection is presented. The flow and metabolic derangements secondary to depletion of fluid, electrolytes, and protein required the ligation of the thoracic duct at the thoracic cavity. The various possible treatments of chylous fistula are reviewed.

Evidence against chronic antigen-specific T lymphocyte activation in myasthenia gravis.

Myasthenia gravis (MG) is an antigen-specific autoimmune disease caused by antibodies against acetylcholine receptors (AChR) at the post-synaptic membrane of the neuromuscular junction. Clinical and immunological data imply the involvement of AChR-specific T lymphocytes as helper cells for autoantibody production. Direct data to support this hypothesis, however, remain sparse. In the present study, a large population of MG patients was studied for evidence of peripheral blood T cell activation by several assays. Assays based on non-specific measurements of T cell activation as well as assays of antigen-specific clonal expansion were utilized. Levels of soluble IL-2 receptor in serum were modestly elevated in some patients, suggesting T cell activation. However, peripheral blood cells did not show evidence of IL-2 receptor expression or enhanced reactivity to IL-2 in culture. Clonable T cells selected for hypoxanthine phosphoribosyl transferase (hprt) mutation, another non-antigen-specific marker for T cell activation, were not seen with increased frequency except in patients treated with purine analogs. Antigen-specific T cell activation was measured by proliferation assays using heterologous and autologous sources of AChR. Antigen-restimulated peripheral blood cell cultures were cloned by limiting dilution. The vast majority of patients failed to show convincing evidence of AChR specific T cell activation or clonal expansion; only 2 of 44 patients demonstrated clonable autologous AChR-specific T cells. An alternative hypothesis of T cell involvement in MG is proposed in which T cell activation is discontinuous and predominantly directed at antigens other than AChR.

Fibrous glass insulation and cancer: response and rebuttal.

In response to our commentary on fibrous glass and cancer [Infante et al., 1994], three letters have been received by the journal. The arguments put forth in these letters do not lead us to alter our scientific view that fibrous glass insulation is carcinogenic. No information is given in the letters that has not previously been stated. Even though these letters raise the same diaphanous arguments, we believe that to preserve occupational and public health we must respond in detail to ensure that the contentions of the fibrous glass industry do not gain further acceptance. Thus, we respond to each letter in turn: The first by Weiss questions and distorts epidemiologic findings, the second by McConnell attempts to recant his past views on the carcinogenicity of fibrous glass and on the value of rodent bioassays in general, and the third by Hesterberg and Chase impugns our analyses demonstrating a positive cancer response in their study. Lastly, we have not debated every issue raised in these three letters because of space limitations, and have centered our responses on what we consider the major incongruities and falsities in each letter. Likewise, we have been selective in citing only relevant literature, or those reports used by the industry or its consultants to support their views.

Appearance of resistance to beta-lactam antibiotics during therapy for Streptococcus pneumoniae meningitis.

A young boy had meningitis caused by Streptococcus pneumoniae that was relatively resistant to penicillin and susceptible to cefotaxime. After 10 days of therapy with penicillin and cefotaxime, fever recurred and a second lumbar puncture revealed a pneumococcus that was resistant to all beta-lactam antibiotics. We now add vancomycin to empiric third-generation cephalosporin therapy for meningitis in children when gram-positive cocci are seen on the cerebrospinal fluid smear.

Fibrous glass and cancer.

Some argue that fibrous glass (glass wool) should not be considered as a likely human carcinogen and hence should not be listed in the Seventh Annual Report on Carcinogens (ARC) prepared by the National Toxicology Program (NTP) and mandated by the U.S. Congress. In examining this issue, data from both laboratory experiments (animal studies) and epidemiologic studies (human data) are reviewed with the results evaluated according to the criteria established by the International Agency for Research on Cancer (IARC) and adopted in slightly modified form by the NTP for classifying substances as human carcinogens or likely human carcinogens. From our comprehensive review of the available information, we conclude that fibrous glass materials are carcinogenic, and in view of the NTP and IARC definitions should be listed in the ARC. Our review then examines the carcinogenic potency of glass fibers to humans in comparison with asbestos fibers and concludes that on a fiber-per-fiber basis, glass fibers may be as potent or even more potent than asbestos. The implications of these findings are then presented for regulatory purposes in the occupational setting.

A historical perspective of some occupationally related diseases of women.

The study of occupational diseases among women has been minimal, and when observations of adverse health effects have been made, they often have been obscured, ignored, or mismanaged. Occupational exposures of women to beryllium, benzene, and vinyl chloride serve as past examples of indifference to the plight of women in the workplace. The lack of regulation for waste anesthetic gases and antineoplastic drugs to protect health care workers and veterinarians indicates that this indifference continues today.

Use of rodent carcinogenicity test results for determining potential cancer risk to humans.

A high proportion of "human" and "probable human" carcinogens as categorized by the International Agency for Research on Cancer have been identified through observations in workers. The excess cancer risk has often been quite high. Most substances known to cause cancer in humans are now known to cause cancer in animals. In the past two decades, an increasing number of substances first shown to cause cancer in animals are now known to cause or are highly suspected of causing cancer in humans (and quite often in workers). The observations necessitate the use of rodent cancer test results for identifying and regulating potential environmental carcinogens. The role of cell proliferation (CP) in the carcinogenic response is important from a regulatory view in terms of both qualitative and quantitative evidence. If CP influences the carcinogenic response, the use of such data to modify dose response in the low-dose range is another factor that needs to be considered. Presentations at this symposium, however, indicate that CP data at the present time should not be incorporated into cancer risk assessments. More simple concepts that affect quantitative dose response and that may result in an artificially low estimated risk but could be adjusted for in the bioassay protocol have usually been ignored. A balanced approach would be to incorporate all known factors that influence quantitative estimates of cancer risk when conducting animal cancer bioassays and extrapolating those results to humans.

State of the science on the carcinogenicity of gasoline with particular reference to cohort mortality study results.

As a result of the content of benzene in various streams of refinery products, including gasoline, it is not surprising that over the years studies and case reports have linked gasoline exposure to lymphopoietic cancers (LPC), particularly leukemia and multiple myeloma (MM). Of three recently conducted studies of gasoline-exposed workers, one shows strong associations with leukemia and MM, a second suggests some association with leukemia and did not analyze data for MM, and the third study is not possible to evaluate because of a major problem with study design. Other diseases of particular interest in relation to gasoline exposure are kidney cancer, malignant melanoma, and heart disease. One study suggests an association with kidney cancer, but the second study did not. There appears to be no association between employment in refineries or gasoline exposure and heart disease. However, evaluation of risk of kidney cancer and heart disease is somewhat difficult because investigators did not control for cigarette smoking, even though it is related to these diseases. This is of particular concern when studying gasoline-exposed workers, who because of the explosive nature of gasoline probably smoke less than the general population used for comparison of mortality. Some studies of refinery workers and gasoline-exposed workers in particular show an excess risk of death from malignant melanoma. Whether this latter association is the result of benzene/gasoline exposure, sunlight exposure, or a combination of the two cannot be determined with the data currently available.(ABSTRACT TRUNCATED AT 250 WORDS)