Impact of COVID-19 on Dental Practices in El Salvador and Mexico: A Comprehensive Survey Analysis.

BACKGROUND AND OBJECTIVES: This study aimed to identify the relationship between prevention measures and protective barriers in dental practice in El Salvador and Mexico during the COVID-19 pandemic in 2020 and 2021. MATERIALS AND METHODS: A longitudinal study was conducted from June 2020 to December 2021, involving 1,719 dentists divided into four groups based on location and year. A 20-question survey in Spanish was utilized and validated with a Cronbach's alpha value of 0.84. RESULTS: The use of phone triage (OR = 1.3), thermometers (OR = 1.4), physical distancing (OR = 1.7), and face shields (OR = 2.6) was significantly associated with dental practice in both countries during the pandemic. CONCLUSIONS: During 2020 and 2021, dental care in El Salvador and Mexico was significantly linked to COVID-19 preventive measures. Phone triage, thermometers, distancing, and face shields positively correlated with dental services. National health agencies should promote the use of minimum preventive measures in dental care, preparing for potential reinfections or new pandemics from emerging virus variants.

Identifying Activities from an Intervention to Promote Sleep in Hospitalised Patients Using the Focus Mapping Technique.

BACKGROUND: Sleep is an essential element for patients' recovery during a period of hospitalisation. Hospital Clínic de Barcelona has developed the ClíNit project to promote patients' sleep by identifying elements that affect the quality of sleep and implementing actions to improve rest at night. OBJECTIVE: Our aim is to select actions to improve sleep quality. METHODS: The study population included night-shift nurses from two clinical units where the pilot actions were to be carried out (n: 14). The nurses prioritised actions to improve sleep quality using the methodology proposed by Fogg: clarification, magic wand, crispification, and the focus-mapping technique. RESULTS: Two sessions were organised for each unit and 32 actions considered high impact and easy to implement were proposed, of which 43.75% (14/32) were directly dependent on nurses. It was then agreed to implement four of these pilot studies. CONCLUSIONS: One aspect worth highlighting is that using prioritization techniques such as the Fogg technique is a good strategy to implement the general objectives of intervention programmes in large organizations in an easy way.

Condicionantes de calidad de los cuidados enfermeros durante el turno de noche / Factors Influencing Quality of Nursing Care during the Night Shifts

Introducción: El turno nocturno provoca efectos físicos y psicológicos en las enfermeras. Fatiga, estrés, ansiedad, alteraciones del sueño y percepción negativa del entorno laboral pueden condicionar la calidad del cuidado. Objetivo: Identificar las condiciones relacionadas con la calidad de los cuidados enfermeros durante los turnos de noche en los hospitales. Métodos: Se realiza una revisión sistemática según criterios PRISMA. Se utilizó como estrategia común en las bases consultadas la combinación de las palabras clave y booleanos: ("Quality of Care") AND ("Nurse"OR"Nurses") AND ("Night shift"OR"Shift"). Se exploraron las bases de datos PubMed, Cinahl, Scopus y Cochrane. Se Incluyeron ensayos, estudios transversales, revisiones y estudios cualitativos entre 2009 y 2018. Se excluyeron los que no cumplieron requisitos de contenido y criterios de evaluación de calidad metodológica descritos a priori. Se incluyeron 20 trabajos. Conclusiones: Para la mayoría de autores la calidad de los cuidados nocturnos es menor que durante el día y puede estar condicionada por exceso de horas trabajadas, percepción de salud, fatiga, calidad del sueño, menor ratio enfermera-paciente, menor apoyo institucional y menor satisfacción profesional. Los indicadores de calidad más utilizados fueron incidencia de úlceras por presión, errores en identificación de pacientes, errores de medicación, errores de comunicación, cuidados sin realizar, desmotivación profesional, despersonalización y retención institucional. La heterogeneidad de los estudios hace que pueda aumentar el sesgo en los resultados. Muchos indicadores descritos son evaluados mediante percepciones, ocasionalmente por métodos objetivos. La identificación de condicionantes clave en la calidad de cuidados nocturnos permite iniciativas institucionales de gran impacto(AU)

Introduction: The night shift causes physical and psychological effects on nurses. Fatigue, stress, anxiety, sleep disturbances and negative perception of the work environment can affect the quality of care. Objective: To identify the conditions related to the quality of nursing care during night shifts in hospitals. Methods: A systematic review was carried out according to PRISMA criteria. As a common strategy in the consulted databases, the combination of the following keywords and Booleans was used: ("Quality of Care") AND ("Nurse "OR "Nurses") AND ("Night shift "OR "Shift"). The PubMed, Cinahl, Scopus and Cochrane databases were explored. Trials, cross-sectional studies, reviews and qualitative studies between 2009 and 2018 were included. Those that did not meet content requirements and methodological quality assessment criteria described a priori were excluded. Twenty papers were included. Conclusions: For most authors, the quality of night care is lower than during the day and may be affected by an excess of working hours, health perception, fatigue, sleep quality, lower nurse-patient ratio, lower institutional support and lower professional satisfaction. The most frequently used quality indicators were incidence of pressure ulcers, patient identification errors, medication errors, communication errors, unperformed care, professional demotivation, depersonalization and institutional retention. The heterogeneity of the studies may increase bias in the results. Many of the indicators described are assessed by perceptions, occasionally using objective methods. The identification of key determinants in the quality of night care allows for high-impact initiatives at the institutional level(AU)

Evaluación de una intervención para mejora en la administración segura de medicación en el turno de noche / An Intervention to Improve Safe Administration of Medication in the Night Shift

Introducción: Uno de cada siete pacientes hospitalizados experimenta un evento adverso relacionado con la administración de medicación. Los errores de medicación son una de las causas más importantes de mortalidad y morbilidad prevenible. Objetivo: Evaluar la eficacia de una intervención formativa sobre la población de enfermeras de turno de noche de un hospital de agudos para mejorar el cumplimiento del protocolo de administración segura de medicación. Métodos: Ensayo experimental, pre-post intervención formativa, realizado en Hospital Clínic de Barcelona, durante 2015-2016. Población: 268 enfermeras en dos turnos de noche, muestra: 177 participantes (88 Grupo Control y 89 Grupo Experimental). La intervención consistió en sesiones informativas y acceso a Procedimiento escrito. El instrumento de medida fue el Procedimiento Normalizado de Trabajo de la institución mediante check-list de cumplimiento. Se realzó estudio uni-bivariable, mediante Chi2 y test de Fisher con significancia para p < 0,05. Resultados: Se realizaron 219 observaciones en Grupo Control y 207 en Grupo Experimental. De 17 variables analizadas, solo tres mostraron diferencias significativas: en Grupo Experimental mejoró el conocimiento del Procedimiento; se incrementó el uso del agua y jabón sobre la solución hidroalcohólica; y empeoró la identificación normalizada de fármacos pendientes de administrar. Ninguna de las 14 variables restantes mostró diferencias significativas. De 426 observaciones, solo se produjeron 3 errores de medicación en Grupo control, subsanados antes de su administración, y 0 en Grupo Experimental. Conclusiones: Las intervenciones formativas clásicas con receptores pasivos pueden no ser eficaces para mejorar la práctica enfermera en administración segura de medicación(AU)

Introduction: One in seven hospitalized patients experiences an adverse event related to administration of medication. Medication errors are one of the most important causes of preventable mortality and morbidity. Objective: To assess the efficacy of a training intervention with the population of night shift nurses in an acute care hospital, in order to improve compliance with the protocol for the safe administration of medication. Methods: Experimental trial, pre-post training intervention, carried out at Hospital Clínic of Barcelona, during 2015-2016. The population consisted of 268 nurses in two night shifts. The sample consisted of 177 participants (88 from the control group and 89 from the experimental group). The intervention consisted in information sessions and access to a written procedure. The measurement instrument was the Institution's Standard Work Procedure by means of a compliance check-list. Uni-bivariate study was performed, using chi-square and Fisher's test with a significance of P < 0.05. Results: 219 observations were carried out in the control group and 207, in the experimental group. Of seventeen variables analyzed, only three showed significant differences: in the experimental group, knowledge of the procedure improved, increase in the use of soap and water over hydroalcoholic solution, and worsening of standardized identification of drugs pending from being administered. None of the fourteen remaining variables showed significant differences. Of 426 observations, only three medication errors occurred in the control group, corrected before its administration, and zero occurred in the experimental group. Conclusions: Classic training interventions with passive receptors may not be effective to improve nursing practice in safe administration of medication(AU)

Impacto sobre entorno laboral de un proyecto de gestión de enfermería en el turno de noche / A Nursing Management Project's Impact on the Work Environment during the Night Shift

Introducción: Para garantizar los cuidados 24h en instituciones hospitalarias es esencial la existencia de Equipos de Enfermería cuya actividad se desarrolle en horario nocturno. Existen factores organizativos que provocan, entre los equipos nocturnos, la percepción de menos oportunidades de desarrollo profesional y menos atención institucional. Esto puede repercutir en la calidad de los cuidados e incluso en la salud de los profesionales. Las enfermeras líderes tienen la responsabilidad de crear y mantener un entorno laboral con influencia positiva. Objetivo: Evaluar un proyecto de gestión de enfermería mediante el impacto sobre la percepción del entorno laboral en el turno de noche. Métodos: Estudio casi-experimental pre-post, con intervención sobre la población. De una población de enfermeras del turno de noche n = 268 se obtuvo muestra n = 159. Se utilizó el instrumento "Practice Environment Scale of the Nursing Work Index", que permite evaluar y comparar factores del entorno de la práctica de enfermería. Se realizaron estadísticos univariables de tendencia central y dispersión, y estadísticos de contraste con significancia p < 0,05. Resultados: En el 41,94 por ciento de las cuestiones obtuvieron diferencias significativas, destacando el Factor 3 "Habilidad, liderazgo y apoyo a las enfermeras por parte de sus responsables". El valor medio global obtenido en la prueba PRE fue de 2,37 (IC95 por ciento 2,22 2,52) y la media global para el valor POST fue 2,49 (IC95 por ciento 2,34 2,95), con p = 0,0254. Conclusiones: La evaluación de un proyecto de gestión de enfermería mediante el impacto sobre la percepción del entorno laboral en turno de noche muestra mejoras con diferencias significativas(AU)

Introduction: To guarantee 24 hours of care in hospital institutions, the existence of nursing teams is essential whose activity is carried out at night. There are organizational factors that provoke, among night teams, the perception of fewer opportunities for professional development and less institutional attention. This can have an impact on the quality of care and even on the health of professionals. Leader nurses are responsible for creating and maintaining a positively influencing work environment. Objective: To evaluate a nursing management project through the impact on the perception about the work environment on the night shift. Methods: Pre-post quasi-experimental study carried out with intervention on the population. From a population of night-shift nurses (n=268), we obtained a sample of 268. The instrument "Practice Environment Scale of the Nursing Work Index" was used, which allows evaluating and comparing factors from the nursing practice setting. Univariate statistics of central tendency and dispersion were determined, as well as contrast statistics with significance p < 0.05. Results: In 41.94 percent of the questions, significant differences were obtained, highlighting factor 3 (nurses' skill, leadership and support by their heads). The global mean value obtained in the PRE test was 2.37 (95 percent CI, 2.22-2.52) and the global mean for the POST value was 2.49 (95 percent CI, 2.34-2.95), with p=0.0254. Conclusions: A nursing management project's evaluation through the impact on the perception about the work environment in the night shift shows improvements with significant differences(AU)

[SURGICAL HAND WASHING: HANDSCRUBBING OR HANDRUBBING]. / LAVADO QUIRÚRGICO DE MANOS: FRICCIÓN ALCOHÓLICA O FROTADO JABONOSO.

The importance of protocols for preoperative antisepsis of the hands is given by the risk of transferring bacteria from the hands of the surgical team to the patient during surgery and it is relationship with infection of surgical wound site (SSI). Careful surgical scrub reduces the number of bacteria on the skin, but does not eliminate them completely, remaining transient microorganisms on hands after the surgical scrub. There fore if micropuncture in surgical gloves occurs, the correct preoperative preparation of hands and double gloving will be essential to reduce the risk of bacterial transmission to patients. The protocols for surgical hand antisepsis are two: Surgical scrub with antiseptic soap (hand scrubbing). Surgical scrub by rubbing alcohol (handrubbing). The hand antisepsis by rubbing with an alcohol solution has proved to be significantly more effective compared to soap solutions. We must also see that in surgical hand antisepsis with soap, you must rinse them with water. And often hospitals' taps and keys are contaminated by Pseudomonas spp., including P. aeuinosa.

Apical Closure in Apexification: A Review and Case Report of Apexification Treatment of an Immature Permanent Tooth with Biodentine.

Materials such as calcium hydroxide paste and mineral trioxide aggregate are used in apexification treatment of immature permanent teeth, but the search for improved materials with higher characteristics of biocompatibility results in different materials. Biodentine is a tricalcium silicate cement that possesses adequate handling characteristics and acceptable mechanical and bioactivity properties. This report describes the case of a 9-year-old boy who was referred to the Department of Dental Clinic of Querétaro Autonomous University of Mexico. One month prior the patient had suffered a dental trauma of his upper left central incisor and had been treated by another dentist. The clinical diagnosis was previously initiated therapy and symptomatic apical periodontitis. The treatment was apexification with Biodentine. At follow-ups performed at 3, 6, and 18 months after treatment the tooth was asymptomatic. The cone-beam computed tomography scan at 18-month postoperative follow-up revealed continuity of periodontal ligament space, absence of periapical rarefactions, and a thin layer of calcified tissue formed apical to the Biodentine barrier. On the basis of sealing ability and biocompatibility, apexification treatment with Biodentine was applied in the present case report. The favorable clinical and radiographic outcome in this case demonstrated that Biodentine may be an efficient alternative to the conventional apexification materials.

Lavado quirúrgico de manos. Fricción alcohólica o frotado jabonoso / Surgical hand washing: handscrubbing or handrubbing

La importancia de los protocolos para la antisepsia prequirúrgica de las manos viene dada por el riesgo de transferencia de bacterias presentes en las manos del equipo quirúrgico al paciente durante la intervención y su relación con la infección de la herida quirúrgica (SSI). Un cuidadoso lavado quirúrgico reduce el número de bacterias en la piel, aunque no las elimina completamente, pues algunos microorganismos transitorios permanecen en las manos después del lavado quirúrgico. Por este motivo, en caso de micropunciones en los guantes quirúrgicos, la correcta preparación prequirúrgica de las manos y el doble enguantado será fundamental para reducir el riesgo de transmisión de bacterias a los pacientes. Los protocolos para la antisepsia quirúrgica de las manos son dos: • Lavado quirúrgico con jabón antiséptico. • Lavado quirúrgico por fricción alcohólica. La antisepsia de las manos por fricción con una solución alcohólica ha demostrado ser significativamente más eficaz, frente a las soluciones jabonosas. Esto es debido a que en la antisepsia de las manos con jabón se requiere su enjuague con agua, y a menudo en las llaves y grifos de los hospitales se encuentran colonias de las pseudomonas spp., en particular la P. aeruginosa. Los dos métodos son adecuados para la prevención de las infecciones de la herida quirúrgica (SSI. Sin embargo, los jabones antisépticos se han utilizado y se siguen utilizando por muchos equipos quirúrgicos en todo el mundo para la preparación prequirúrgica de las manos, es importante señalar que la eficacia antibacteriana de los productos que contienen las formulaciones alcohólicas es superior a la que cualquier jabón antiséptico disponible en la actualidad. Por lo tanto, el objetivo principal de este artículo es difundir estos conocimientos, que, pese a toda la literatura escrita [1-7,13], aún requieren más difusión (AU)

The importance of protocols for preoperative antisepsis of the hands is given by the risk of transferring bacteria from the hands of the surgical team to the patient during surgery and it is relationship with infection of surgical wound site (SSI). Careful surgical scrub reduces the number of bacteria on the skin, but does not eliminate them completely, remaining transient microorganisms on hands after the surgical scrub. Therefore if micropuncture in surgical gloves occurs, the correct preoperative preparation of hands and double gloving will be essential to reduce the risk of bacterial transmission to patients. The protocols for surgical hand antisepsis are two: • Surgical scrub with antiseptic soap (handscrubbing). • Surgical scrub by rubbing alcohol (handrubbing). The hand antisepsis by rubbing with an alcohol solution has proved to be significantly more effective compared to soap solutions. We must also see that in surgical hand antisepsis with soap, you must rinse them with water. And often hospitals’ taps and keys are contaminated by Pseudomonas spp., including P. aeruginosa. Both methods are suitable for the prevention of surgical site infections (SSI). However, antiseptic soaps have been and are still used by many surgical teams around the world to the preoperative preparation of hands. Importantly, the antibacterial efficacy of products containing alcoholic formulations is higher than any currently available antibacterial soap. Therefore, the main objective of this article is to spread these knowledges, that, despite all the literature written [1-7,13], still require further spreanding (AU)

Distinct eRF3 requirements suggest alternate eRF1 conformations mediate peptide release during eukaryotic translation termination.

Organisms that use the standard genetic code recognize UAA, UAG, and UGA as stop codons, whereas variant code species frequently alter this pattern of stop codon recognition. We previously demonstrated that a hybrid eRF1 carrying the Euplotes octocarinatus domain 1 fused to Saccharomyces cerevisiae domains 2 and 3 (Eo/Sc eRF1) recognized UAA and UAG, but not UGA, as stop codons. In the current study, we identified mutations in Eo/Sc eRF1 that restore UGA recognition and define distinct roles for the TASNIKS and YxCxxxF motifs in eRF1 function. Mutations in or near the YxCxxxF motif support the cavity model for stop codon recognition by eRF1. Mutations in the TASNIKS motif eliminated the eRF3 requirement for peptide release at UAA and UAG codons, but not UGA codons. These results suggest that the TASNIKS motif and eRF3 function together to trigger eRF1 conformational changes that couple stop codon recognition and peptide release during eukaryotic translation termination.

Mortalidad por causas accidentales en niños menores de 5 años en el Hospital Nacional de Niños "Dr. Carlos Sáenz Herrera", 2002-2004 / Mortality due to accidental causes in children younger than 5 years of age at the Hospital Nacional de Niños "Dr. Carlos Sáenz Herrera”, 2002-2004

Las lesiones traumáticas por causas externas corresponden en Costa Rica a la segunda causa de muerte en niños menores de 5 años, con una tasa para 2004 de 9.23 X 100000 habitantes, y la primera causa de años de vida potencialmente perdidos, 37 por ciento, para esta edad. El objetivo de esta investigación fue evaluar el impacto de este tipo de lesiones como causa de muerte en niños menores de 5 años, atendidos en el Hospital Nacional de Niños, HNN, y caracterizar esta población. Materiales y métodos: Se realizó un estudio caso control pareado, donde se incluyeron todos los niños menores de 5 años egresados del HNN desde diciembre de 2001 a diciembre de 2004, con diagnóstico de lesión no intencional por causas externas. Los casos los constituyeron los niños que egresaron fallecidos y para cada uno se eligió al azar un control de la misma edad y sexo que no hubiera fallecido por causa de la lesión traumática. Resultados: Hubo un total de 36 casos distribuidos igualmente por sexo. Las principales causas de muerte resultaron, en orden de importancia: los accidentes de tránsito y los ahogamientos. La mayoría de los casos provinieron de la provincia de San José. No se encontraron diferencias estadísticamente significativas en la mayoría de variables estudiadas entre casos y controles. La mayoría de muertes ocurrieron durante los meses de verano y típicos de vacaciones escolares; además, el 35 por ciento de éstas ocurrieron durante el fin de semana. La mayoría de los niños ingresó al hospital durante el segundo turno, 2pm-10pm, y la gran mayoría de las lesiones, 64 por ciento ocurrieron en la casa, p<0.05. La no supervisión figuró, dentro del estudio, como un factor de riesgo de ocurrencia de una lesión no intencional, p<0.05. Conclusiones: El registro de este tipo de lesiones es aún muy deficiente en Costa Rica, lo cual dificulta la realización de un estudio analítico sobre prevalencia y factores de riesgo de lesiones no intencionales por causas externas.

Tpa1p is part of an mRNP complex that influences translation termination, mRNA deadenylation, and mRNA turnover in Saccharomyces cerevisiae.

In this report, we show that the Saccharomyces cerevisiae protein Tpa1p (for termination and polyadenylation) influences translation termination efficiency, mRNA poly(A) tail length, and mRNA stability. Tpa1p is encoded by the previously uncharacterized open reading frame YER049W. Yeast strains carrying a deletion of the TPA1 gene (tpa1Delta) exhibited increased readthrough of stop codons, and coimmunoprecipitation assays revealed that Tpa1p interacts with the translation termination factors eRF1 and eRF3. In addition, the tpa1Delta mutation led to a 1.5- to 2-fold increase in the half-lives of mRNAs degraded by the general 5'-->3' pathway or the 3'-->5' nonstop decay pathway. In contrast, this mutation did not have any affect on the nonsense-mediated mRNA decay pathway. Examination of mRNA poly(A) tail length revealed that poly(A) tails are longer than normal in a tpa1Delta strain. Consistent with a potential role in regulating poly(A) tail length, Tpa1p was also found to coimmunoprecipitate with the yeast poly(A) binding protein Pab1p. These results suggest that Tpa1p is a component of a messenger ribonucleoprotein complex bound to the 3' untranslated region of mRNAs that affects translation termination, deadenylation, and mRNA decay.

Distinct paths to stop codon reassignment by the variant-code organisms Tetrahymena and Euplotes.

The reassignment of stop codons is common among many ciliate species. For example, Tetrahymena species recognize only UGA as a stop codon, while Euplotes species recognize only UAA and UAG as stop codons. Recent studies have shown that domain 1 of the translation termination factor eRF1 mediates stop codon recognition. While it is commonly assumed that changes in domain 1 of ciliate eRF1s are responsible for altered stop codon recognition, this has never been demonstrated in vivo. To carry out such an analysis, we made hybrid proteins that contained eRF1 domain 1 from either Tetrahymena thermophila or Euplotes octocarinatus fused to eRF1 domains 2 and 3 from Saccharomyces cerevisiae. We found that the Tetrahymena hybrid eRF1 efficiently terminated at all three stop codons when expressed in yeast cells, indicating that domain 1 is not the sole determinant of stop codon recognition in Tetrahymena species. In contrast, the Euplotes hybrid facilitated efficient translation termination at UAA and UAG codons but not at the UGA codon. Together, these results indicate that while domain 1 facilitates stop codon recognition, other factors can influence this process. Our findings also indicate that these two ciliate species used distinct approaches to diverge from the universal genetic code.

Obstrucción intestinal secundaria a vólvulo espléndico en un paciente pediátrico / Secundary intestinal obstruction a splenic volvulous in a pediatric patient

La torsión de un bazo errante es rara. La forma de presentación varia desde dolor abdominal intermitente hasta un cuadro de abdomen agudo. Se presenta caso clínico de un paciente pediátrico con obstrucción intestinal secundaria a la torsión de un bazo errante. Descriptores: vólvulo de intestino medio, vólvulo esplénico, bazo errante.

Discrimination between defects in elongation fidelity and termination efficiency provides mechanistic insights into translational readthrough.

The suppression of stop codons (termed translational readthrough) can be caused by a decreased accuracy of translation elongation or a reduced efficiency of translation termination. In previous studies, the inability to determine the extent to which each of these distinct processes contributes to a readthrough phenotype has limited our ability to evaluate how defects in the translational machinery influence the overall termination process. Here, we describe the combined use of misincorporation and readthrough reporter systems to determine which of these mechanisms contributes to translational readthrough in Saccharomyces cerevisiae. The misincorporation reporter system was generated by introducing a series of near-cognate mutations into functionally important residues in the firefly luciferase gene. These constructs allowed us to monitor the incidence of elongation errors by monitoring the level of firefly luciferase activity from a mutant allele inactivated by a single missense mutation. In this system, an increase in luciferase activity should reflect an increased level of misincorporation of the wild-type amino acid that provides an estimate of the overall fidelity of translation elongation. Surprisingly, we found that growth in the presence of paromomycin stimulated luciferase activity for only a small subset of the mutant proteins examined. This suggests that the ability of this aminoglycoside to induce elongation errors is limited to a subset of near-cognate mismatches. We also found that a similar bias in near-cognate misreading could be induced by the expression of a mutant form of ribosomal protein (r-protein) S9B or by depletion of r-protein L12. We used this misincorporation reporter in conjunction with a readthrough reporter system to show that alterations at different regions of the ribosome influence elongation fidelity and termination efficiency to different extents.

GTP hydrolysis by eRF3 facilitates stop codon decoding during eukaryotic translation termination.

Translation termination in eukaryotes is mediated by two release factors, eRF1 and eRF3. eRF1 recognizes each of the three stop codons (UAG, UAA, and UGA) and facilitates release of the nascent polypeptide chain. eRF3 is a GTPase that stimulates the translation termination process by a poorly characterized mechanism. In this study, we examined the functional importance of GTP hydrolysis by eRF3 in Saccharomyces cerevisiae. We found that mutations that reduced the rate of GTP hydrolysis also reduced the efficiency of translation termination at some termination signals but not others. As much as a 17-fold decrease in the termination efficiency was observed at some tetranucleotide termination signals (characterized by the stop codon and the first following nucleotide), while no effect was observed at other termination signals. To determine whether this stop signal-dependent decrease in the efficiency of translation termination was due to a defect in either eRF1 or eRF3 recycling, we reduced the level of eRF1 or eRF3 in cells by expressing them individually from the CUP1 promoter. We found that the limitation of either factor resulted in a general decrease in the efficiency of translation termination rather than a decrease at a subset of termination signals as observed with the eRF3 GTPase mutants. We also found that overproduction of eRF1 was unable to increase the efficiency of translation termination at any termination signals. Together, these results suggest that the GTPase activity of eRF3 is required to couple the recognition of translation termination signals by eRF1 to efficient polypeptide chain release.

Leaky termination at premature stop codons antagonizes nonsense-mediated mRNA decay in S. cerevisiae.

The Nonsense-Mediated mRNA Decay (NMD) pathway mediates the rapid degradation of mRNAs that contain premature stop mutations in eukaryotic organisms. It was recently shown that mutations in three yeast genes that encode proteins involved in the NMD process, UPF1, UPF2, and UPF3, also reduce the efficiency of translation termination. In the current study, we compared the efficiency of translation termination in a upf1Delta strain and a [PSI(+)] strain using a collection of translation termination reporter constructs. The [PSI(+)] state is caused by a prion form of the polypeptide chain release factor eRF3 that limits its availability to participate in translation termination. In contrast, the mechanism by which Upf1p influences translation termination is poorly understood. The efficiency of translation termination is primarily determined by a tetranucleotide termination signal consisting of the stop codon and the first nucleotide immediately 3' of the stop codon. We found that the upf1Delta mutation, like the [PSI(+)] state, decreases the efficiency of translation termination over a broad range of tetranucleotide termination signals in a unique, context-dependent manner. These results suggest that Upf1p may associate with the termination complex prior to polypeptide chain release. We also found that the increase in readthrough observed in a [PSI(+)]/upf1Delta strain was larger than the readthrough observed in strains carrying either defect alone, indicating that the upf1Delta mutation and the [PSI(+)] state influence the termination process in distinct ways. Finally, our analysis revealed that the mRNA destabilization associated with NMD could be separated into two distinct forms that correlated with the extent the premature stop codon was suppressed. The minor component of NMD was a 25% decrease in mRNA levels observed when readthrough was >/=0.5%, while the major component was represented by a larger decrease in mRNA abundance that was observed only when readthrough was

Regulation of prelamin A endoprotease activity by prelamin A.

The maturation of lamin A is completed by the endoproteolytic cleavage of its farnesylated precursor protein, prelamin A. In the absence of this cleavage, prelamin A can neither give rise to lamin A nor assemble into the nuclear lamina. We call the enzyme which catalyzes this endoproteolytic step the 'prelamin A endoprotease'. In this study, we begin characterization of the regulation of prelamin A endoprotease. In particular, we address the question as to whether prelamin A endoprotease activity is constitutive in cells or responds to expression of prelamin A. To do this, we compared the activity of this novel endoprotease in cells which express prelamin A with those that do not. Our data shows that the enzymatic activity of prelamin A endoprotease is enhanced by the expression of prelamin A.