Isodesmic reaction for accurate theoretical pKa calculations of amino acids and peptides.

Theoretical and quantitative prediction of pKa values at low computational cost is a current challenge in computational chemistry. We report that the isodesmic reaction scheme provides semi-quantitative predictions (i.e. mean absolute errors of 0.5-1.0 pKa unit) for the pKa1 (α-carboxyl), pKa2 (α-amino) and pKa3 (sidechain groups) of a broad set of amino acids and peptides. This method fills the gaps of thermodynamic cycles for the computational pKa calculation of molecules that are unstable in the gas phase or undergo proton transfer reactions or large conformational changes from solution to the gas phase. We also report the key criteria to choose a reference species to make accurate predictions. This method is computationally inexpensive and makes use of standard density functional theory (DFT) and continuum solvent models. It is also conceptually simple and easy to use for researchers not specialized in theoretical chemistry methods.

Development of a full-thickness acellular dermal graft from human skin: Case report of first patient rotator cuff patch augmentation repair.

The processing and initial testing of a new human tissue preparation is described. Full-thickness Acellular Dermal Matrix (ftADM) is the extracellular matrix (ECM) obtained by decellularization of full-thickness human skin from cadaveric donors. The safety, stability and usability of the graft are discussed with respect to the results of the residual cellular content, maintenance of ECM components, and biomechanical properties. Quantitative and qualitative analysis of the ECM demonstrated the absence of cell debris, while the native structure of human dermis was maintained. Biomechanical testing showed stiffness values comparable to other commercial products used for tendon reinforcement, suggesting that our ftADM could be successfully used not only in soft tissue regeneration surgeries, but also in tendon reinforcement. First case of ftADM in rotator cuff augmentation is described. Technical management of the patch during surgery and clinical outcomes are discussed.

Secondary patellar resurfacing in the treatment of patellofemoral pain after total knee arthroplasty.

PURPOSE: This paper reports a prospective review of patients who, between 2004 and 2007, underwent secondary patellar resurfacing (SPR) due to anterior knee pain after a primary total knee arthroplasty (TKA). The aim was to evaluate the clinical outcomes obtained with the SPR and to compare them with radiological findings. METHODS: A total of twenty-seven consecutive patients met the inclusion criteria. There were twenty-three (85%) women and four (15%) men with a median age of 70 years. The patients were evaluated before and after the surgery with the same functional scores and radiological parameters. Bone scintigraphy was also used in the assessment, and a CT-scan was performed in order to evaluate the femoral component rotation. The median time between TKA and SPR was 18 months. RESULTS: With a median follow-up of 23 months, seventeen patients (63%) reported a clear subjective improvement after SPR, and patellofemoral scores (primary outcome measure), KSS and WOMAC (secondary outcome measures) showed a statistically significant improvement following the procedure. There were no significant changes after SPR in the Insall-Salvati ratio, the lateral patellar displacement or the lateral patellar tilt. The mean time between TKA and SPR had no statistically significant effect on outcome. The bone scintigraphy revealed increased patellar uptake in seven cases, but this was not related to subsequent improvement after SPR. Rotational computed tomography showed a median internal rotation of the femoral component of 1º. The complications observed were a patellar component loosening and an acute post-infection. CONCLUSION: No clinical or radiological parameter was found to be related to the final outcome after SPR. There was a discrepancy between functional scale scores and the patient's subjective satisfaction.

Hyaline cartilage surface study with an environmental scanning electron microscope. An experimental study.

To obtain images of the articular surface of fresh osteochondral grafts using an environmental scanning electron microscope (ESEM). To evaluate and compare the main morphological aspects of the chondral surface of the fresh grafts. To develop a validated classification system on the basis of the images obtained via the ESEM. The study was based on osteochondral fragments from the internal condyle of the knee joint of New Zealand rabbits, corresponding to fresh chondral surface. One hundred images were obtained via the ESEM and these were classified by two observers according to a category system. The Kappa index and the corresponding confidence interval (CI) were calculated. Of the samples analysed, 62-72% had an even surface. Among the samples with an uneven surface 17-22% had a hillocky appearance and 12-16% a knobbly appearance. As regards splits, these were not observed in 92-95% of the surfaces; 4-7% showed superficial splits and only 1% deep splits. In 78-82% of cases no lacunae in the surface were observed, while 17-20% showed filled lacunae and only 1-2% presented empty lacunae. The study demonstrates that the ESEM is useful for obtaining and classifying images of osteochondral grafts.

Quadriceps muscle characteristics and subcutaneous fat assessed by ultrasound and relationship with function in patients with knee osteoarthritis awaiting knee arthroplasty.

BACKGROUND: Patients with severe knee osteoarthritis are evaluated for total knee replacement (TKR), whose main indications are persistent pain and severe functional limitations substantially affecting mobility. However, evaluation of pain intensity and functional disability is difficult to standardize. OBJECTIVE: To evaluate the relationship between quadriceps muscle thickness (QMT) and quality; the QMT and subcutaneous fat thickness (SFT) and QMT and function in patients with knee OA on a waiting list for TKR. METHODS: Cross-sectional study in consecutively-enrolled patients. Variables: SFT, QMT and rectus femoris muscle quality, assessed by echointensity (EI). Function by the Timed Up & Go Test (TUG); sociodemographic and clinical variables and physical activity were determined. Karl Pearson correlations and multiple linear regression were used. RESULTS: 61 patients (45 female, mean age 69.7 years [SD 7.2], mean BMI 33.0 [SD 5.7], mean comorbidities 3.3 [SD 2.0], 52.5% regular physical activity) were studied. Mean TUG was 15.1 (SD 6.1). Variables retained in the regression model explained 36% of variability in the TUG. Greater muscle content (percentage) (r = -0,291) was associated with better TUG scores (p = 0.001). Greater muscle EI was negatively (r = -0,364) associated with function (p = 0.006). Older age was associated with worse TUG scores while regular physical activity was associated with better TUG scores (p = 0.001 and p = 0.008, respectively). CONCLUSIONS: A higher percentage of quadriceps muscle and better muscle quality (lower EI) was associated with better function. Age and exercise levels influenced function. Ultrasound may provide.

Relationship between knee anthropometry and surgical time in total knee arthroplasty in severely and morbidly obese patients: a new prognostic index of surgical difficulty.

BACKGROUND: Total knee arthroplasty (TKA) in patients with severe and morbid obesity is one of the current challenges in prosthetic knee surgery. The body mass index (BMI) is used to identify patients who may present difficulties during surgery and postoperative complications. We carried out a prospective study with an initial hypothesis that BMI is not associated with tourniquet time in obese patients undergoing TKA and that some anthropometric parameters may be useful in predicting tourniquet time in severely and morbidly obese patients. METHODS: One hundred consecutive patients diagnosed with knee osteoarthritis with BMI > or =35 kg/m(2) scheduled for TKA were prospectively studied. Suprapatellar, infrapatellar, and supra/infrapatellar anthropometric indexes were calculated before surgery. The tourniquet time was determined. RESULTS: The mean BMI was 39.81 kg/m(2) (SD +/- 3.75). A total of 58% of patients were classified as class III obesity (BMI 35-39.99) and 42% as class IV (BMI > or = 40) Mean tourniquet time was 41.67 min (SD +/- 9.26). There was no association between the BMI and tourniquet time. The suprapatellar index was negatively associated with tourniquet time (p < 0.038). DISCUSSION: The BMI is not the only parameter that should be considered in order to identify severely and morbidly obese patients who may have more surgical difficulties during TKA. Preoperative determination of the suprapatellar index helped us to classify these patients according to the morphology of the knee and predicted a longer tourniquet time and, therefore, greater surgical difficulty, in patients with a suprapatellar ratio below 1.6 in this study.

Diaphragmatic thickness ratio (inspiratory/expiratory) as a diagnostic method of diaphragmatic palsy associated with interescalene block. / La ratio de grosor diafragmático (inspiratorio/espiratorio) como método diagnóstico de parálisis diafragmática asociada al bloqueo interescálenico.

INTRODUCTION: Diaphragmatic paralysis is a side-effect associated with interscalene block. Thickness index of the diaphragm muscle (inspiratory thickness/expiratory thickness) obtained by ultrasound has recently been introduced in clinical practice for diagnosis of diaphragm muscle atrophy. Our objective was to evaluate this index for the diagnosis of acute phrenic paresis associated with interscalene block. PATIENTS AND METHODS: We designed an observational study in 22 patients scheduled for shoulder arthroscopy. Spirometry was performed (criteria of phrenic paresis was a decrease in FVC and FEV1 ≥20%). Ultrasound apposition zone was assessed in anterior axillary line and diaphragmatic displacement was evaluated on inspiration and expiration (number of intercostal spaces; phrenic paresis considered a reduction ≥25%) and thickness of the diaphragm muscle (a phrenic paresis was considered an index <1.2). These determinations were performed before and at 20min after interscalene block at C5-C6 with 20ml of 0.5% ropivacaine. RESULTS: Twenty-one patients (95%) presented phrenic nerve block according to one or more of the methods used. One patient did not show any symptoms or signs suggestive of phrenic paralysis and was excluded. All the patients presented phrenic paresis based on the diaphragmatic thickness index, with the pre-block index being 1.8±0.5 and post-block of 1.05±0.06 (P<0.001). Ninety percent of the patients (19) presented phrenic paresis according to spirometry and all the patients had a reduction in diaphragmatic movement after the block (from 1.9±0.5 intercostal spaces to 0.5±0.3; P<0.001). CONCLUSION: The index of inspiratory / expiratory diaphragmatic thickness at cut-off <1.2 seems to be useful in the diagnosis of phrenic paresis associated with interscalene block. This index does not require a baseline pre-assessment.

Relación entre consumo de alcohol, uso de Internet y teléfono móvil, sintomatología prefrontal y mindfulnes disposicional en estudiantes universitarios / Alcohol use in relation to Internet and mobile phone use, prefrontal symptomology and dispositional mindfulness in university students

and mobile phone use, prefrontal symptomology and dispositional mindfulness in university students. This study analyzes the relationship between the type of alcohol use and parameters associated with addictive behaviors, such as abnormal use of the Internet and mobile devices, prefrontal symptoms and dispositional mindfulness in 509 university students from Madrid (Spain). The present study was multivariate, inferential, descriptive and nonexperimental, using discriminant analysis to study the predictive nature of the variables considered in weekend alcohol use, with participants classified into three groups (low, medium and high use). The results indicate that high alcohol use was related to greater Internet and mobile phone use, greater irritability and under executive control, as well as a lower mindfulness level. Longitudinal studies are needed to analyze, among other aspects, the mediating role of dispositional mindfulness in alcohol use, use of technologies and executive functioning (AU)

[Venous hemangioma of the mediastinum: apropos of a case]. / Hemangioma venoso de mediastino: a propósito de un caso.

A case of mediastinal venous hemangioma is reported. It's a benign tumor rarely found in the mediastinum. In the last six years, we only know three cases reported and none of them in our country. Clinical manifestations were cough and pleuritic pain. The diagnosis was suggested by radiologic examination and was confirmed by histologic study after thoracotomy. The mass was totally removed surgically and the evolution of the patient was favorable.

Perioperative fracture-dislocation of the humeral head during a resurfacing hemiarthroplasty.

We report a case of perioperative fracture-dislocation of the humeral head produced during the reaming for a resurfacing replacement hemiarthroplasty (RRH) in a 79-year old woman. This is a surgical complication not previously described in the literature for this type of prosthesis design. Resurfacing humeral head implant has been noted as a useful treatment for glenohumeral arthropathies, also in elderly people, with a very low incidence of complications. However, as we report, they are possible.It is advisable that conventional stemmed implants could be available when RRH is performed.

La ratio de grosor diafragmático (inspiratorio/espiratorio) como método diagnóstico de parálisis diafragmática asociada al bloqueo interescálenico / Diaphragmatic thickness ratio (inspiratory/expiratory) as a diagnostic method of diaphragmatic palsy associated with interescalene block

Introducción. La parálisis diafragmática es un efecto indeseable clásicamente asociado al bloqueo interescalénico. De forma reciente ha sido introducido en clínica el índice del grosor del músculo diafragma (grosor inspiratorio/grosor espiratorio) obtenido mediante ecografía como herramienta diagnóstica en la parálisis crónica y atrofia del músculo diafragma. Nuestro objetivo fue evaluar este índice para el diagnóstico de paresia frénica aguda asociada al bloqueo interescalénico. Pacientes y métodos. Diseñamos un estudio observacional descriptivo en 22 pacientes programados para artroscopia de hombro. Se les realizó una espirometría forzada (se consideró paresia frénica un descenso del FVC y FEV1 ≥20%), se identificó la zona de aposición en la línea axilar anterior y se evaluó el desplazamiento diafragmático en inspiración y espiración máximas (n.° de espacios intercostales; se consideró paresia frénica una reducción ≥25%) y el grosor del músculo diafragma (se consideró paresia frénica un índice<1,2). Estas determinaciones se realizaron antes y a los 20 min de realizar el bloqueo interescalénico entre C5 y C6 con 20ml de ropivacaína 0,5%. Resultados. Veintiún pacientes (95%) presentaron bloqueo del nervio frénico según alguno o varios de los métodos empleados. Un paciente no manifestó ningún síntoma ni signo sugestivo de parálisis frénica y fue excluido del análisis posterior. Todos los pacientes presentaron paresia frénica con base en el índice del grosor diafragmático, con un índice prebloqueo de 1,8±0,5 y posbloqueo de 1,05±0,06 (p<0,001). El 90% de los pacientes (19) presentó paresia frénica según la espirometría y todos los pacientes presentaron un descenso diafragmático reducido tras el bloqueo (de 1,9±0,5 espacios intercostales a 0,5±0,3; p<0,001). Conclusión. El índice del grosor diafragmático en inspiración/espiración<1,2 parece ser de utilidad en el diagnóstico de paresia frénica asociada al bloqueo interescalénico, sin que sea necesaria una evaluación basal prebloqueo (AU)

Introduction. Diaphragmatic paralysis is a side-effect associated with interscalene block. Thickness index of the diaphragm muscle (inspiratory thickness/expiratory thickness) obtained by ultrasound has recently been introduced in clinical practice for diagnosis of diaphragm muscle atrophy. Our objective was to evaluate this index for the diagnosis of acute phrenic paresis associated with interscalene block. Patients and methods. We designed an observational study in 22 patients scheduled for shoulder arthroscopy. Spirometry was performed (criteria of phrenic paresis was a decrease in FVC and FEV1 ≥20%). Ultrasound apposition zone was assessed in anterior axillary line and diaphragmatic displacement was evaluated on inspiration and expiration (number of intercostal spaces; phrenic paresis considered a reduction ≥25%) and thickness of the diaphragm muscle (a phrenic paresis was considered an index <1.2). These determinations were performed before and at 20min after interscalene block at C5-C6 with 20ml of 0.5% ropivacaine. Results. Twenty-one patients (95%) presented phrenic nerve block according to one or more of the methods used. One patient did not show any symptoms or signs suggestive of phrenic paralysis and was excluded. All the patients presented phrenic paresis based on the diaphragmatic thickness index, with the pre-block index being 1.8±0.5 and post-block of 1.05±0.06 (P<0.001). Ninety percent of the patients (19) presented phrenic paresis according to spirometry and all the patients had a reduction in diaphragmatic movement after the block (from 1.9±0.5 intercostal spaces to 0.5±0.3; P<0.001). Conclusion. The index of inspiratory / expiratory diaphragmatic thickness at cut-off <1.2 seems to be useful in the diagnosis of phrenic paresis associated with interscalene block. This index does not require a baseline pre-assessment (AU)

Knee osteotomy: navigation guided and arthroscopy assisted.

The aim of this work is to describe the procedure used, which combines navigation, arthroscopy and fluoroscopic control, and to evaluate its usefulness in complex osteotomies around the knee. The consolidation of the osteotomy was obtained without complications by obtaining a correct axis of the limb in three spatial planes. This is a precise and reproducible technique. It does not need computer support, associated with specific navigation. Simultaneous arthroscopy also allows the correction of certain intra-articular defects in the same operation, and the precise evaluation of the cartilage's state.