Medium-term outcomes of conventional versus short uncemented femoral stems for primary total hip arthroplasty in patients younger than 55 years.

BACKGROUND: Short stems are designed with a bone preservation philosophy in mind. This study aims to compare the outcomes/complications and survival of a collarless fully hydroxyapatite (HA)-coated conventional tapered stem and a HA-coated partial neck-retaining uncemented short stem in patients ⩽55 years old at medium-term follow-up. METHODS: We retrospectively studied 247 uncemented THAs operated between 2010 and 2014, comparing 146 patients treated with the fully HA-coated collarless stem (Group A) with 101 patients treated with a partial neck preserving, HA-coated short stem (Group B). 87 and 62 males were in groups A and B, respectively (p = 0.11). The mean age of the series was 46 years (17-55) (p =0.16). The mean follow-up of groups A and B were 9.9 (7-12) years and 9.7 (7-12) years, respectively (p =0.21). RESULTS: Mean Harris Hip Score improved from 55 to 92 in group A (p <0.001) and from 54 to 95 in group B (p <0.001), without differences between groups. Mean femoral neck length preservation in groups A and B was 13.6 (0-28) mm and 26 (11-38) mm, respectively (p =0.001). 13 (8.9%) and 1 (1%) patients in groups A and B presented postoperative complications, respectively (p =0.008). The conventional stem group had more aseptic loosening (Group A 3.4% vs. Group B 0%, p =0.06) along with more Symptomatic radiolucent lines (Group A 3.4% vs. Group B 0%, p =0.06). CONCLUSIONS: Both conventional and short stems showed excellent implant survival rates and functional outcomes at a mean follow-up of 9.8 years. However, complications and radiolucent lines were more frequent with a collarless conventional-length stem. Bone preservation of the femoral neck and diaphysis may be preferred in active young patients.

Stenotrophomonas maltophilia Periprosthetic Joint Infection after Hip Revision Arthroplasty.

Stenotrophomonas maltophilia, a well-established opportunistic bacterium, primarily impacts healthcare settings. Infection of the musculoskeletal system with this bacterium is rare. We report on the first known case of hip periprosthetic joint infection (PJI) caused by S. maltophilia. The potential for development of a PJI caused by this pathogen should be considered by orthopaedic surgeons, particularly in patients with multiple severe comorbidities.

Do nonagenarians have more complications and unplanned readmissions than octogenarians following primary THA? A retrospective cohort study.

INTRODUCTION: The performance of total hip arthroplasty in elderly patients, especially nonagenarians, is challenging due to higher patient frailty and medical comorbidities. We compared 90-day postoperative complications and unplanned readmissions between nonagenarians and octogenarians undergoing elective THA. METHODS: One hundred and eleven patients undergoing elective, unilateral THA were retrospectively analyzed. Forty-four patients were nonagenarians (Group A), and 67 patients were octogenarians (Group B). Demographic data included age, gender, body mass index (BMI), ASA score and Charlson Comorbidity Index (CCI). Frailty was defined according to the Rockwood Frailty Index. All patients underwent a thorough preoperative assessment through a specific institutional clinical pathway created for this matter. Postoperative adverse events were grouped into major or minor. A regression model was used to evaluate independent risk factors for the development of complications. RESULTS: There were no differences in the ASA score (65.9% vs. 53.7% ASA III-IV), prevalence of frailty (1% vs. 9%) and comorbidities between both groups (p > .05). The CCI was higher in nonagenarians (p = 0.007). Nonagenarians had more in-hospital complications, although most were minor (p = 0.002), none of which resulted in mortality. Ninety-day unplanned readmissions were similar between groups, with 4 (9.1%) and 6 (9%) in groups A and B, respectively (p = 1). Although age was a factor associated with the development of postoperative complications in the univariate regression model (OR 3.81, 95% CI 1.31 to 11.11, p = 0.014), it lost significance after performing the multivariate analysis (OR 2.48, 95% CI 0.78 to 7.90, p = 0.125). CONCLUSION: The age of 90 years old was not a barrier to perform elective THA safely. Nonagenarians had higher in-hospital minor complications when compared to the younger cohort. However, age over 90 years was not an independent risk factor for unplanned readmissions or mortality. Multimodal protocols of perioperative care are paramount for improving outcomes after THA in very old patients.

Vástagos femorales cortos para el reemplazo total de cadera primario en pacientes jóvenes. Resultados clínicos y biomecánicos / Short femoral stems for primary total hip arthroplasty in young patients. Clinical and biomechanical outcomes

La artroplastia total de cadera es una cirugía eficaz para tratar la artrosis. Con el aumento de la necesidad de una mejor calidad de vida, este procedimiento se está realizando en pacientes más jóvenes. Pero, con la mayor expectativa de vida, también crece la demanda de múltiples cirugías de revisión para el mismo paciente. Esto plantea desafíos técnicos debido a la pérdida de hueso. Existe una necesidad creciente de identificar implantes duraderos y altamente funcionales que sean adecuados para la revisión futura. Aunque los vástagos femorales cementados eran la opción principal en el pasado, los vástagos femorales no cementados han logrado una fijación a largo plazo y excelentes resultados. Sin embargo, aún se pueden mejorar algunos problemas relacionados con la fijación. Los vástagos femorales cortos han sido desarrollados para abordar algunos de estos desafíos, mientras se mantienen los buenos resultados obtenidos con los vástagos convencionales. En este artículo, se analiza la experiencia tras 10 años de uso de vástagos femorales cortos en cirugías de cadera en pacientes jóvenes. Se comparan los resultados biomecánicos y la preservación ósea femoral, se reportan los resultados posoperatorios en relación con el regreso al deporte, y se evalúan las complicaciones relacionadas con su uso. El empleo de vástagos cortos en cirugía primaria de cadera brinda múltiples ventajas. La indicación de este tipo de implante está justificada en pacientes jóvenes y activos, con el objetivo de reproducir los resultados de los implantes convencionales con un menor consumo de hueso y la posibilidad de una revisión futura. Nivel de Evidencia: IV

Total hip arthroplasty is an effective surgery to treat osteoarthritis. Given the rising demand for a higher quality of life, this procedure is being performed on increasingly younger patients. However, a longer life expectancy is also tied to a higher demand for multiple revision surgeries for the same patient. This poses technical challenges due to bone loss. There is a growing need to identify durable and highly functional implants that are suitable for future revision. Although cemented femoral stems were the main option in the past, uncemented femoral stems have demonstrated long-term fixation and excellent results. However, some issues related to fixation can still be improved. Short femoral stems have been developed to address some of these challenges while maintaining the good results obtained with conventional stems. This study analyzes the experience after 10 years of using short femoral stems in hip surgeries on young patients. Biomechanical outcomes and femoral bone preservation are compared, postoperative outcomes regarding return to sports are reported, and complications related to their use are evaluated. Short stems have multiple advantages when used in primary hip surgery. The indication for this type of implant is justified in young and active patients, to reproduce the results of conventional implants with less bone consumption and the possibility of future revision. Level of Evidence: IV

Successful hip revision surgery following refracture of a modern femoral stem using a cortical window osteotomy technique: A case report and review of literature.

BACKGROUND: The ExeterTM Universal cemented femoral component is widely used for total hip replacement surgery. Although there have been few reports of femoral component fracture, removal of a broken femoral stem can be a challenging procedure. CASE SUMMARY: A 54-year-old man with a Dorr A femur sustained a refracture of a primary ExeterTM stem, two years after receiving a revision using a cement-within-cement technique (CWC) through an extended trochanteric osteotomy (ETO). The technical problems related to the CWC technique and the ETO played a major role in the stem fatigue refracture. We performed revision surgery and removed the distal cement using a cortical femoral window technique, followed by re-implantation with an uncemented, modular, distally-fixed uncemented stem. The patient experienced an uneventful postoperative recovery. CONCLUSION: Re-fracture of a modern femoral ExeterTM stem is a rare event, but technical complications related to revision surgery can lead to this outcome. The cortical window osteotomy technique can facilitate the removal of a broken stem and cement, allowing for prosthetic re-implantation under direct vision and avoiding ETO-related complications.

Secuenciación de próxima generación para la detección de patógenos en cirugía de cadera: experiencia y viabilidad diagnóstica en un centro de atención terciaria de la Argentina / Next generation sequencing for the detection of pathogens in hip surgery. Experience and diagnostic feasibility in a tertiary care center in Argentina

Introducción: El diagnóstico rápido y definitivo con identificación del patógeno es fundamental cuando hay una infección periprotésica. La secuenciación de próxima generación permite identificar el ADN en un germen determinado en poco tiempo. Hasta donde sabemos, no hay reportes sobre su empleo para el manejo de la infección periprotésica en Sudamérica. Nuestro objetivo fue demostrar la viabilidad diagnóstica de las muestras obtenidas de una serie de pacientes operados en Buenos Aires, Argentina, y analizadas con la técnica de secuenciación de próxima generación. materiales y métodos: Se analizó a una serie prospectiva de 20 pacientes sometidos a cirugía de revisión séptica y aséptica de cadera desde diciembre de 2019 hasta marzo de 2020. Se obtuvieron muestras intraoperatorias de líquido sinovial, tejido profundo y canal endomedular, que fueron enviadas para su análisis al laboratorio NexGen Microgen. Resultados: Se seleccionaron 17 pacientes, porque tenían una muestra apta para analizar. Los resultados se recibieron dentro de las 72 h de la cirugía. En un caso, el resultado de la secuenciación de próxima generación informó un germen distinto del identificado en los cultivos posoperatorios de partes blandas, esto permitió corregir la antibioticoterapia. En otro, esta técnica identificó Parabacteroides gordonii en una revisión aséptica, en otro, Morganella morganii, a partir de cultivos negativos en una revisión en un tiempo. Conclusión: Se demostró la viabilidad diagnóstica con la secuenciación de próxima generación, se pueden obtener resultados de microorganismos patógenos dentro de las 72 h posteriores a la cirugía en pacientes con infección periprotésica y cultivos negativos. Nivel de Evidencia: IV

Introduction: Early diagnosis of a periprosthetic joint infection (PJI) and identification of the pathogen are paramount. Next-generation sequencing (NGS) can identify the nucleic acids in a given germ in a short period. To our knowledge, there are no reports of its use in the management of PJI in South America. Our objective was to demonstrate the diagnostic feasibility of the NGS technique on the samples obtained from a series of patients operated on in Buenos Aires, Argentina. Materials and methods: A prospective series of 20 patients undergoing septic and aseptic hip revision surgery from December 2019 to March 2020 was analyzed. Intraoperative samples of synovial fluid, deep tissue, and intramedullary canal were obtained and sent to the NexGen Microgen laboratory (Texas, USA) for analysis. Results: Seventeen patients were finally eligible to present a sample suitable for analysis. In 100% of the samples, NGS results were obtained within 72 hours of surgery. In one case, the NGS result reported a germ different from the one identified in the postoperative soft tissue cultures, allowing antibiotic therapy to be corrected. In another case, NGS identified Parabacteroides gordonii in aseptic revision surgery. In another patient, the NGS identified Morganella morganii, in which conventional postoperative cultures were negative in single-stage revision surgery. Conclusion: In this study, we demonstrated the diagnostic feasibility of NGS, obtaining results within 72 hours immediately after surgery for pathogenic organisms in patients with PJI and negative cultures. Level of Evidence: IV

A Repeat Dose of Perioperative Dexamethasone Can Effectively Reduce Pain, Opioid Requirement, Time to Ambulation, and In-Hospital Stay After Total Hip Arthroplasty: A Prospective Randomized Controlled Trial.

BACKGROUND: The ideal dose of intravenous glucocorticoids to control pain in total hip arthroplasty (THA) remains unclear. This randomized controlled trial compared postoperative pain and tramadol requirement in patients undergoing unilateral primary THA who received one versus two perioperative doses of dexamethasone. METHODS: Patients consented to undergo blinded, simple randomization to either one (at anesthetic induction [1D-group]: 54 patients) or two (with an additional dose 8 hours after surgery [2D-group]: 61 patients) perioperative doses of 8-mg intravenous dexamethasone. Pain was evaluated with visual analog scale at 8, 16, and 24 hours postoperatively and with tramadol requirement. The secondary outcomes included postoperative nausea and vomiting, time to ambulation, and length of stay. RESULTS: Age (mean, 66 ± 13 years), body mass index (mean, 29 ± 5), gender (60% female), and history of diabetes were similar between groups (P >.05). Pain was higher at 16 (4 [interquartile range {IQR} 3-5] vs 2 [IQR 1-3]; P <.001) and 24 (2.5 [IQR 2-3] vs 1 [IQR 0-1] P <.001) hours postoperatively in the 1D-group patients. 1D-group patients had significantly more tramadol consumption (50 [IQR 50-100] vs 0 [IQR 0-50]; P = .01), as well as postoperative nausea and vomiting (18 [33.3%] vs 5 [8.2%]; P = .001). Fifty-five (90%) patients in the 2D-group and 32 (59%) in the 1D-group ambulated on postoperative day 0 (P = .0002). Fifty-eight (95%) patients in the 2D-group and 37 (68%) in the 1D-group were discharged on postoperative day 1 (P = .0002). CONCLUSION: An additional dose of dexamethasone at 8 hours postoperatively significantly reduced pain, tramadol consumption, time to ambulation, and length of stay after primary THA.

A comparative analysis of SLA-DRB1 genetic diversity in Colombian (creoles and commercial line) and worldwide swine populations.

Analysing pig class II mayor histocompatibility complex (MHC) molecules is mainly related to antigen presentation. Identifying frequently-occurring alleles in pig populations is an important aspect to be considered when developing peptide-based vaccines. Colombian creole pig populations have had to adapt to local conditions since entering Colombia; a recent census has shown low amounts of pigs which is why they are considered protected by the Colombian government. Commercial hybrids are more attractive regarding production. This research has been aimed at describing the allele distribution of Colombian pigs from diverse genetic backgrounds and comparing Colombian SLA-DRB1 locus diversity to that of internationally reported populations. Twenty SLA-DRB1 alleles were identified in the six populations analysed here using sequence-based typing. The amount of alleles ranged from six (Manta and Casco Mula) to nine (San Pedreño). Only one allele (01:02) having > 5% frequency was shared by all three commercial line populations. Allele 02:01:01 was shared by five populations (around > 5% frequency). Global FST indicated that pig populations were clearly structured, as 20.6% of total allele frequency variation was explained by differences between populations (FST = 0.206). This study's results confirmed that the greatest diversity occurred in wild boars, thereby contrasting with low diversity in domestic pig populations.

Osteotomía periacetabular de Ganz para el tratamiento de la displasia del desarrollo de la cadera: experiencia inicial y resultados de los primeros 44 casos / Ganz periacetabular osteotomy for the treatment of developmental dysplasia of the hip. Initial experience and results from the first 44 cases

Objetivo: Describir la técnica quirúrgica, las indicaciones y los resultados iniciales de la osteotomía periacetabular bernesa para tratar la displasia del desarrollo de la cadera. Materiales y métodos: Entre mayo de 2011 y mayo de 2020, se realizaron 44 osteotomías periacetabulares bernesas en 44 pacientes (35 mujeres, edad promedio 30 años [rango 23-38]). Todos tenían diagnóstico de displasia de cadera sintomática. El ángulo centro-borde promedio fue de 17° (rango 9°-20°) y el índice acetabular promedio, de 18° (rango 15°-20°). En 22 casos, se evaluaron y repararon los hallazgos intrarticulares por artroscopia en el mismo acto quirúrgico. Se evaluaron la corrección obtenida, la consolidación de la osteotomía y los resultados funcionales al final del seguimiento. Resultados: En 22 pacientes, se detectó hipertrofia y rotura del labrum acetabular asociadas a displasia de cadera. Diez pacientes tenían quistes paralabrales. El ángulo centro-borde promedio posoperatorio fue de 32° (rango 27°-35°) y el índice acetabular, de 6° (rango 4°-9°). El tiempo quirúrgico para la osteotomía periacetabular bernesa fue de 130 min, cuando se sumó un procedimiento artroscópico, el tiempo fue de 148 minutos. Conclusiones: La osteotomía periacetabular bernesa es técnicamente demandante, pero logra resultados predecibles en pacientes con integridad del cartílago articular y deformidades corregibles. La artroscopia antes de la osteotomía permite evaluar las condiciones del cartílago, diagnosticar y tratar lesiones intrarticulares asociadas con esta enfermedad y decidir si es necesaria la corrección del déficit de cobertura. Nivel de Evidencia: IV

Objective: To describe the surgical technique, indications, and initial results of the Bernese periacetabular osteotomy (PAO) for the treatment of developmental dysplasia of the hip. Materials and methods: Between May 2011 and May 2020, 44 PAOs were performed in 44 patients (35 women) with an average age of 30 years (23-38). All patients had a diagnosis of symptomatic hip dysplasia. The average center-edge angle was 17° (9° to 20°) and the average acetabular index was 18° (15° to 20°). In 22 cases, the intra-articular findings were evaluated and repaired by arthroscopy in the same surgical stage. The correction obtained, the consolidation of the osteotomy, and the functional outcomes at the end of the follow-up were evaluated. Results: Hypertrophy and rupture of the acetabular labrum associated with hip dysplasia were evidenced in 22 patients. Paralabral cysts were found in 10 patients in the series. The average postoperative center-edge angle was 32° (27° to 35°) and the acetabular index was 6° (4° to 9°). The surgical time for PAO was 130 minutes; in patients where an arthroscopic procedure was added, the time was 148 minutes. Conclusions: PAO is technically demanding, but has predictable outcomes in patients with articular cartilage integrity and correctable deformities. Arthroscopy before osteotomy allows assessing cartilage conditions, diagnosing and treating intra-articular lesions associated with this pathology, and deciding on the need to correct the soft tissue deficit. Level of Evidence: IV

Artrosis rápidamente progresiva de cadera secundaria a una fractura por insuficiencia subcondral del acetábulo. Reporte de un caso / Rapidly progressive osteoarthritis of the hip secondary to a subchondral insufficiency fracture of the acetabulum: A case report

Las fracturas por insuficiencia subcondral son una causa poco frecuente de cadera dolorosa. A diferencia de las fracturas traumáticas agudas, las fracturas por insuficiencia del acetábulo son menos frecuentes que las femorales. Ocurren habitualmente en mujeres posmenopáusicas con comorbilidades. Su diagnóstico inicial suele ser dificultoso y la sospecha clínica es de gran importancia. La resonancia magnética es una herramienta fundamental para detectar este cuadro. Subestimar estas lesiones puede llevar al desarrollo de una artrosis rápidamente progresiva y al reemplazo articular como desenlace. Se presenta el caso de una paciente de 68 años con una fractura por insuficiencia subcondral del acetábulo a quien se le indicó una artroplastia total de cadera no cementada. Nivel de Evidencia: IV

Subchondral insufficiency fractures are a rare cause of hip pain. Unlike acute traumatic fractures, acetabulum insufficiency fractures are less common than femoral fractures. They commonly occur in postmenopausal women with comorbidities. Its initial diagnosis is usually difficult and clinical suspicion is of great importance. Magnetic resonance imaging (MRI) is a fundamental tool for the detection of this pathology. Underestimating these injuries can lead to the development of rapidly progressive osteoarthritis and joint replacement as an outcome. We present the case of a 68-year-old patient with a subchondral insufficiency fracture of the acetabulum who underwent uncemented total hip arthroplasty. Level of Evidence: IV

Prolonged social lockdown during COVID-19 pandemic and hip fracture epidemiology.

PURPOSE: To analyse the impact of prolonged mandatory lockdown due to COVID-19 on hip fracture epidemiology. METHODS: Retrospective case-control study of 160 hip fractures operated upon between December 2019 and May 2020. Based on the date of declaration of national lockdown, the cohort was separated into two groups: 'pre-COVID time' (PCT), including 86 patients, and 'COVID time' (CT), consisting of 74 patients. All CT patients tested negative for SARS-CoV-2. Patients were stratified based on demographic characteristics. Outcome measures were 30-day complications, readmissions and mortality. A logistic regression model was run to evaluate factors associated with mortality. RESULTS: Age, female/male ratio, body mass index and American Society of Anaesthesia score were similar between both groups (p > 0.05). CT patients had a higher percentage of Charlson ≥ 5 and Rockwood Frailty Index ≥ 5 scores (p < 0.05) as well as lower UCLA and Instrumental Activities of Daily Living scores (p < 0.05). This translated into a higher hemiarthroplasty/total hip arthroplasty ratio during CT (p = 0.04). Thromboembolic disease was higher during CT (p = 0.02). Readmissions (all negative for SARS-CoV-2) were similar between both groups (p = 0.34). Eight (10.8%) casualties were detected in the CT group, whereas no deaths were seen in the control group. Logistic regression showed that frailer (p = 0.006, OR 10.46, 95%CI 8.95-16.1), less active (p = 0.018, OR 2.45, 95%CI 1.45-2.72) and those with a thromboembolic event (p = 0.005, OR 30, 95%CI 11-42) had a higher risk of mortality. CONCLUSION: Despite testing negative for SARS-CoV-2, CT patients were less active and frailer than PCT patients, depicting an epidemiological shift that was associated with higher mortality rate.

[The fisheries and growth of Ark Clams (Arcoida: Arcidae) Anadara tuberculosa in Málaga Bay, Colombian Pacific, 2005-2007]. / Pesquería y crecimiento de la piangua (Arcoida: Arcidae) Anadara tuberculosa en la Bahía de Málaga del Pacífico Colombiano, 2005-2007.

A. tuberculosa, is the most important bivalve species under exploitation in Colombia. Here, this species is found from Cabo Corrientes (Chocó) to the Ecuador border, in muddy substrates of mangrove forests. In order to determine the growth and the state of fisheries of A. tuberculosa, between December 2005 and April 2007, both, biological (in situ) and commercial studies were performed at Bahia Malaga (Colombian Pacific). The growth was estimated using the general equation of von Bertalanffy, with prior application of the methods of Bhattacharya and Powell-Wetherall. Mortality and exploitation rate were determined using the inverse model of von Bertalanffy. For the biological samplings, a total of 446 individuals of A. tuberculosa (0.64 +/- 0.13 individuals/m2) and 53 individuals (0.05 +/- 0.049 individuals/m2) of Anadara similis were collected. 79% of the catch was below 51mm. In the commercial samplings, 836 individuals of A. tuberculosa (size range: 31.1-92.2mm) were measured, but no A. similis samples were available for this. Recruitment of A. tuberculosa was higher during March, May, July and November. According to the data, A. tuberculosa might be reproducing during December, February, April and August. The data gathered with the biological samples were more reliable on explaining the growth of A. tuberculosa (K=0.332 per year, L(infinity)=88.256mm, t0=0.0556 years) than the one taken from market samples (K=0.256 per year, L(infinity)=89.77mm, t0=0733 years). The high exploitation rate (77%), the low density and the high mortality suggest that A. tuberculosa is in overexploitation state in Bahia Malaga and management strategies are urgently required.

Pesquería y crecimiento de la piangua (Arcoida: Arcidae) Anadara tuberculosa en la Bahía de Málaga del Pacífico colombiano, 2005-2007 / The fisheries and growth of Ark Clams (Arcoida: Arcidae) Anadara tuberculosa in Málaga Bay, Colombian Pacific, 2005-2007

The fisheries and growth of Ark Clams (Arcoida: Arcidae) Anadara tuberculosa in Málaga Bay, Colombian Pacific, 2005-2007. A. tuberculosa, is the most important bivalve species under exploitation in Colombia. Here, this species is found from Cabo Corrientes (Chocó) to the Ecuador border, in muddy substrates of mangrove forests. In order to determine the growth and the state of fisheries of A. tuberculosa, between December 2005 and April 2007, both, biological (in situ) and commercial studies were performed at Bahia Malaga (Colombian Pacific). The growth was estimated using the general equation of von Bertalanffy, with prior application of the methods of Bhattacharya and Powell-Wetherall. Mortality and exploitation rate were determined using the inverse model of von Bertalanffy. For the biological samplings, a total of 446 individuals of A. tuberculosa (0.64±0.13 individuals/m²) and 53 individuals (0.05±0.049 individuals/m²) of Anadara similis were collected. 79% of the catch was below 51mm. In the commercial samplings, 836 individuals of A. tuberculosa (size range: 31.1-92.2mm) were measured, but no A. similis samples were available for this. Recruitment of A. tuberculosa was higher during March, May, July and November. According to the data, A. tuberculosa might be reproducing during December, February, April and August. The data gathered with the biological samples were more reliable on explaining the growth of A. tuberculosa (K=0.332per year, L∞=88.256mm, t0=0.0556years) than the one taken from market samples (K =0.256per year, L∞=89.77mm, t0=0733years). The high exploitation rate (77%), the low density and the high mortality suggest that A. tuberculosa is in overexploitation state in Bahia Malaga and management strategies are urgently required.

Anadara tuberculosa es el bivalvo de mayor explotación en la costa pacífica de Colombia, se distribuye en Colombia desde Cabo Corrientes (Chocó) hasta los límites con el Ecuador, está asociada al bosque de manglar. Con el objetivo de determinar el estado de la pesca y su crecimiento, entre diciembre 2005 y abril 2007, se realizaron muestreos comerciales no sistemáticos y un muestreo biológico intensivo en Bahía Málaga. El crecimiento, se estimó utilizando la forma general de von Bertalanffy, con previa aplicación de los métodos de Bhattacharya & Powell-Wetherall. La mortalidad y tasa de explotación fueron determinadas usando el modelo inverso de von Bertalanffy. Se encontró una densidad de 0.64±0.13 individuos/m². En el muestreo comercial se midieron 836 individuos de Anadara tuberculosa con tallas entre 31.1mm y 92.2mm. Los datos biológicos fueron más confiables para explicar el crecimiento de Anadara tuberculosa (K=0.332 por año, L∞=88.256mm, t0=-0.0556 años) que los datos comerciales (K=0.256 por año, L∞ =89.77mm, t0=0.733 años). La tasa de explotación alta (77%), baja densidad y alta mortalidad, sugieren que Anadara tuberculosa se encuentra en un estado de sobre-explotación y requiere urgentes estrategias de manejo.

Evidence for concerted electron proton transfer in charge recombination between FADH- and 306Trp• in Escherichia coli photolyase.

Proton-coupled electron-transfer (PCET) is a mechanism of great importance in protein electron transfer and enzyme catalysis, and the involvement of aromatic amino acids in this process is of much interest. The DNA repair enzyme photolyase provides a natural system that allows for the study of PCET using a neutral radical tryptophan (Trp(•)). In Escherichia coli photolyase, photoreduction of the flavin adenine dinucleotide (FAD) cofactor in its neutral radical semiquinone form (FADH(•)) results in the formation of FADH(-) and (306)Trp(•). Charge recombination between these two intermediates requires the uptake of a proton by (306)Trp(•). The rate constant of charge recombination has been measured as a function of temperature in the pH range from 5.5 to 10.0, and the data are analyzed with both classical Marcus and semi-classical Hopfield electron transfer theory. The reorganization energy associated with the charge recombination process shows a pH dependence ranging from 2.3 eV at pH ≤ 7 and 1.2 eV at pH(D) 10.0. These findings indicate that at least two mechanisms are involved in the charge recombination reaction. Global analysis of the data supports the hypothesis that PCET during charge recombination can follow two different mechanisms with an apparent switch around pH 6.5. At lower pH, concerted electron proton transfer (CEPT) is the favorable mechanism with a reorganization energy of 2.1-2.3 eV. At higher pH, a sequential mechanism becomes dominant with rate-limiting electron-transfer followed by proton uptake which has a reorganization energy of 1.0-1.3 eV. The observed 'inverse' deuterium isotope effect at pH < 8 can be explained by a solvent isotope effect that affects the free energy change of the reaction and masks the normal, mass-related kinetic isotope effect that is expected for a CEPT mechanism. To the best of our knowledge, this is the first time that a switch in PCET mechanism has been observed in a protein.

Intraperitoneal chemotherapy for advanced ovarian and peritoneal cancers in patients following interval debulking surgery or primary cytoreductive surgery: Tom Baker Cancer Centre experience from 2006 to 2009.

OBJECTIVE: To describe our experience with cisplatin- and paclitaxel-based IP chemotherapy in patients treated initially with either neoadjuvant chemotherapy and interval debulking surgery (IDS) or primary cytoreductive surgery (PCRS). METHODS: We performed a retrospective review of the records of 67 patients (38 IDS, 29 PCRS) enrolled in the intraperitoneal (IP) chemotherapy program at the Tom Baker Cancer Centre between 2006 and 2009. Information pertaining to patient demographics, IP chemotherapy toxicity, and catheter complications was extracted, and the median time to recurrence was calculated. RESULTS: Most patients in the study were aged 50 to 70 years and had a diagnosis of stage III serous ovarian cancer. Overall, 295/393 IP cycles (75%) were successfully administered. The proportion of patients completing six cycles of chemotherapy in the IDS and PCRS groups was 53% and 59%, respectively. Frequent (> 25%) Grade 1 to 2 chemotherapy toxicities included fatigue, peripheral neuropathy, and nausea. Catheter complications were observed in 34% of patients (23/67). The recurrence rates for patients completing four or more cycles of IP chemotherapy in the IDS and PCRS groups were 58% and 35%, respectively, with the median time to recurrence approximately one year. CONCLUSION: Although IP chemotherapy is well tolerated in both IDS and PCRS patients, the median time to recurrence is shorter than expected.

Spectroscopic and thermodynamic comparisons of Escherichia coli DNA photolyase and Vibrio cholerae cryptochrome 1.

Escherichia coli DNA photolyase and cryptochrome 1 isolated from Vibrio cholerae, a member of the CRY-DASH family, are directly compared using a variety of experimental methods including UV-vis and Raman spectroscopy, reduction potential measurements, and isothermal titration calorimetry. The semiquinone form of the cryptochrome has an absorption spectrum that is red-shifted from that of the photolyase, but the Raman spectrum indicates that the FAD binding pocket is similar to that of photolyase. The FADH(-)/FADH* reduction potential of the cryptochrome is significantly higher than that of the photolyase at 164 mV vs NHE, but it also increases upon substrate binding (to 195 mV vs NHE), an increase similar to what is observed in photolyase. The FADH(-)/FADH* reduction potential for both proteins was found to be insensitive to ATP binding. Isothermal titration calorimetry found that photolyase binds tighter to substrate (K(A) approximately 10(5) M(-1) for photolyase and approximately 10(4) M(-1) for cryptochrome 1), and the binding constants for both proteins were slightly sensitive to oxidation state. Based upon this work, it appears that this cryptochrome has significant spectroscopic and electrochemical similarities to CPD photolyase. The thermodynamic cycle of the enzymatic repair in the context of this work is discussed.

[Risk factors associated to ovarian cancer]. / Factores de riesgo asociados con cáncer de ovario.

OBJECTIVE: To determine the risk factors associated to ovarian cancer. PATIENTS AND METHODS: A case-control study was carried out including 31 women with ovarian cancer and 69 patients with benign ovarian tumors corroborated with a histopathological study. We analyzed 26 independent variables, which classification was clinic, sociodemographic and ultrasonographic. The dependent variable was ovarian cancer, and it was assigned a value of 1 if it was present and 0 if it was absent. The statistical analysis was done using a logistic regression analysis, with an alpha value of 0.05. RESULTS: The malignant tumor of epithelial cells was the most common histological variety and was seen in 22 cases (71%). There were 24 cases (77.4%) in clinical stage I at the time of the diagnosis. Out of the 26 studied variables late menarche (p = 0.02), multiparity (p = 0.02), loss of weight (p = 0.04), solid tumor (p = 0.02), mixed tumor (p = 0.02) and irregularities of the tumor (p = 0.03) were significant in the applied model. CONCLUSIONS: The sociodemographic variables associated to ovarian cancer were: late menarche and multiparity; the clinical significant variable was loss of weight; and the ultrasonographic variables were solid tumor, mixed tumor and irregularities of the tumor. A population screening program is recommended in women who are in reproductive age, and it should include a gynecological ultrasonographic scanning in order to make an opportune diagnosis of this pathology.