ANATOMICAL AND FUNCTIONAL STUDY OF THE MEDIAL COLLATERAL LIGAMENT COMPLEX OF THE ELBOW

Objective: To carry out an anatomical study of the medial collateral ligament, an important elbow stabilizer in different degrees of elbow flexion-extension. Methods: Forty elbows were dissected in order to analyze the functional behavior of the anterior, posterior and transverse ligament bands during valgus stress maneuvers of the elbow in different degrees of flexion and extension. Two groups were determined; in the group GPA the posterior band of the ligament was sectioned initially, then the articular capsule and finally the anterior band; in group GAP this order was reversed. Results: Instability was observed in GPA only in the third stage, when there was a greater mean elbow's opening during the flexion (between 50 degrees and 70 degrees); in GAP the instability was present since the first stage; the degrees of flexion with greater instability were the same as in group GPA. Conclusion: The anterior band of the medial collateral ligament of the elbow is the most important stabilizer of the elbow valgus instability, and its principal action occurs between 50 degrees and 70 degrees of elbow flexion. Level of Evidence III, Diagnostic Studies Investigating a diagnostic test.

Estudo anatômico e funcional do complexo ligamentar colateral medial do cotovelo

OBJETIVO: Realizar um estudo anatômico do ligamento colateral medial, um importante estabilizador do cotovelo, em diferentes graus de flexo-extensão do cotovelo. MÉTODOS: Foram dissecados 40 cotovelos para analisar o comportamento funcional das bandas anterior, posterior e transversa do ligamento nas manobras de estresse em valgo do cotovelo durante seu movimento de flexão e extensão em diferentes graus. Determinou-se dois grupos: no GPA foi seccionado, a banda posterior do ligamento, depois a cápsula articular e, por fim, a banda anterior; no GAP, a ordem de dissecação foi inversa. RESULTADOS: No GPA observou-se instabilidade somente na terceira etapa e a média de abertura foi maior entre 50&º e 70&º de flexão de cotovelo; no GAP, a instabilidade apareceu desde a primeira etapa e os graus de flexão com maior instabilidade foram nos mesmos do grupo A. CONCLUSÃO: A banda anterior do ligamento colateral medial do cotovelo é o mais importante estabilizador na instabilidade em valgo do cotovelo e sua atuação principal acontece entre 50º e 70º de flexão do cotovelo. Nível de evidência III, Estudo Diagnóstico - Investigação de um exame para diagnóstico.

ANTERIOR SHOULDER INSTABILITY: CORRELATION BETWEEN MAGNETIC RESONANCE ARTHROGRAPHY, ULTRASOUND ARTHROGRAPHY AND INTRAOPERATIVE FINDINGS

The purpose of the present study was to determine ultrasound (US) arthrography diagnostic accuracy in patients with recurrent shoulder dislocation by comparing US arthrography and magnetic resonance arthrography (MRA) with intraoperative findings. Fifty-six consecutive patients with diagnosis of chronic anterior instability of the shoulder were evaluated for assessment of bone and soft tissue lesions by three radiologists. Twenty-five cases were confirmed by surgery. Sensitivity, specificity, inter-and intraobserver agreement were calculated. Ultrasound sensitivity ranged from 20% to 100% and specificity from 25% to 90%. MRA sensitivity ranged from 80% to 100% and specificity from 50% to 100%. Interobserver agreement was good for MRA (0.54-0.70) and fair for US arthrography (0.19-0.40). Despite a higher interobserver variability for US arthrography than for MRA, our results indicate that US is capable of demonstrating bone and soft tissue lesions related to chronic instability of the shoulder in the presence of intra-articular fluid. (E-mail: marcelo_simao@hotmail.com) (C) 2012 World Federation for Ultrasound in Medicine & Biology.

Is the meander growth in the Brazil Current system off Southeast Brazil due to baroclinic instability?

Temporally-growing frontal meandering and occasional eddy-shedding is observed in the Brazil Current (BC) as it flows adjacent to the Brazilian Coast. No study of the dynamics of this phenomenon has been conducted to date in the region between 22 degrees S and 25 degrees S. Within this latitude range, the flow over the intermediate continental slope is marked by a current inversion at a depth that is associated with the Intermediate Western Boundary Current (IWBC). A time series analysis of 10-current-meter mooring data was used to describe a mean vertical profile for the BC-IWBC jet and a typical meander vertical structure. The latter was obtained by an empirical orthogonal function (EOF) analysis that showed a single mode explaining 82% of the total variance. This mode structure decayed sharply with depth, revealing that the meandering is much more vigorous within the BC domain than it is in the IWBC region. As the spectral analysis of the mode amplitude time series revealed no significant periods, we searched for dominant wavelengths. This search was done via a spatial EOF analysis on 51 thermal front patterns derived from digitized AVHRR images. Four modes were statistically significant at the 95% confidence level. Modes 3 and 4, which together explained 18% of the total variance, are associated with 266 and 338-km vorticity waves, respectively. With this new information derived from the data, the [Johns, W.E., 1988. One-dimensional baroclinically unstable waves on the Gulf Stream potential vorticity gradient near Cape Hatteras. Dyn. Atmos. Oceans 11, 323-350] one-dimensional quasi-geostrophic model was applied to the interpolated mean BC-IWBC jet. The results indicated that the BC system is indeed baroclinically unstable and that the wavelengths depicted in the thermal front analysis are associated with the most unstable waves produced by the model. Growth rates were about 0.06 (0.05) days(-1) for the 266-km (338-km) wave. Moreover, phase speeds for these waves were low compared to the surface BC velocity and may account for remarks in the literature about growing standing or stationary meanders off southeast Brazil. The theoretical vertical structure modes associated with these waves resembled very closely to the one obtained for the current-meter mooring EOF analysis. We interpret this agreement as a confirmation that baroclinic instability is an important mechanism in meander growth in the BC system. (C) 2008 Elsevier B.V. All rights reserved.

Laser locking to the Hg-199 S-1(0)-P-3(0) clock transition with 5.4x10(-15)/root tau fractional frequency instability

With Hg-199 atoms confined in an optical lattice trap in the Lamb-Dicke regime, we obtain a spectral line at 265.6 nm for which the FWHM is similar to 15 Hz. Here we lock an ultrastable laser to this ultranarrow S-1(0) - P-3(0) clock transition and achieve a fractional frequency instability of 5.4 x 10(-15) / root tau for tau <= 400 s. The highly stable laser light used for the atom probing is derived from a 1062.6 nm fiber laser locked to an ultrastable optical cavity that exhibits a mean drift rate of -6.0 x 10(-17) s-(1) (-16.9 mHzs(-1) at 282 THz) over a six month period. A comparison between two such lasers locked to independent optical cavities shows a flicker noise limited fractional frequency instability of 4 x 10(-16) per cavity. (c) 2012 Optical Society of America

How Should the Articular Disk Position Be Analyzed?

Purpose: To compare 2 methods used to determine the disk position based on sagittal magnetic resonance images. Patients and Methods: A cross-sectional study of patients with the signs and symptoms of temporomandibular disorders was conducted. The patients' ages and gender distributions were collected. The disk position diagnosis from the clinical examination was considered the primary outcome. Three observers evaluated the presence of anterior displacement on magnetic resonance images according to 2 criteria: method 1 (12-o'clock position) and method 2 (location of the intermediate zone). To assess the intraobserver variability of the 2 methods, the examiners evaluated the same magnetic resonance images at the beginning of the study (time 1) and 40 days later (time 2). The intraobserver agreement was assessed using the observed agreement and the kappa statistic. McNemar's test was used to assess the differences between each method and the clinical examination findings (P < .05). The accuracy, sensitivity, specificity, and positive and negative predictive values were calculated by comparing the diagnosis from each method with that from the clinical examination (considered the reference standard). Results: The final sample was composed of 20 subjects with a mean age of 33.0 +/- 33.7 years; 3 were men (15%) and 17 were women (85%). A statistically significant difference between the 2 methods was found. Method 1 yielded a greater percentage of anterior displaced disks (52.5%). The agreement between the clinical diagnosis and method 1 was lower (70.0%) than that between the clinical diagnosis and method 2 (87.5%). No statistically significant difference was found between the clinical diagnosis and method 2. Conclusion: The disk position should be judged according to the intermediate zone criterion. (C) 2012 American Association of Oral and Maxillofacial Surgeons J Oral Maxillofac Surg 70:1534-1539, 2012

Particle creation due to tachyonic instability in relativistic stars

Dense enough compact objects were recently shown to lead to an exponentially fast increase of the vacuum energy density for some free scalar fields properly coupled to the spacetime curvature as a consequence of a tachyonic-like instability. Once the effect is triggered, the star energy density would be overwhelmed by the vacuum energy density in a few milliseconds. This demands that eventually geometry and field evolve to a new configuration to bring the vacuum back to a stationary regime. Here, we show that the vacuum fluctuations built up during the unstable epoch lead to particle creation in the final stationary state when the tachyonic instability ceases. The amount of created particles depends mostly on the duration of the unstable epoch and final stationary configuration, which are open issues at this point. We emphasize that the particle creation coming from the tachyonic instability will occur even in the adiabatic limit, where the spacetime geometry changes arbitrarily slowly, and therefore is quite distinct from the usual particle creation due to the change in the background geometry.

Cytogenetic instability of dental pulp stem cell lines

Human adult stem cells (hASCs) offer a potentially renewable source of cell types that are easily isolated and rapidly expanded for use in regenerative medicine and cell therapies without the complicating ethical problems that are associated with embryonic stem cells. However, the eventual therapeutic use of hASCs requires that these cells and their derivatives maintain their genomic stability. There is currently a lack of systematic studies that are aimed at characterising aberrant chromosomal changes in cultured ASCs over time. However, the presence of mosaicism and accumulation of karyotypic abnormalities within cultured cell subpopulations have been reported. To investigate cytogenetic integrity of cultured human dental stem cell (hDSC) lines, we analysed four expanded hDSC cultures using classical G banding and fluorescent in situ hybridisation (FISH) with X chromosome specific probe. Our preliminary results revealed that about 70% of the cells exhibited karyotypic abnormalities including polyploidy, aneuploidy and ring chromosomes. The heterogeneous spectrum of abnormalities indicates a high frequency of chromosomal mutations that continuously arise upon extended culture. These findings emphasise the need for the careful analysis of the cytogenetic stability of cultured hDSCs before they can be used in clinical therapies.

MRI analysis of the relationship between bone changes in the temporomandibular joint and articular disc position in symptomatic patients

Objectives: The aim of this study was to investigate bone changes in the condyle, articular eminence and glenoid fossa in relation to the position of the articular disc. Methods: 148 temporomandibular joints (TMJs) of 74 symptomatic patients who underwent MRI were evaluated. The position of the disc was classified as either normal (N), disc displacement with reduction (DDwR), disc displacement without reduction (DDwoR) and posterior displacement (PD). Bone changes were investigated in the condyle and temporal components of the TMJ and classified as osteophytosis, sclerosis or erosion. Results: There were no bone changes in the glenoid fossa of the temporal bone. Of the total number of TMJs studied, 94 (63.5%) were N, 34 (23%) presented DDwoR, 19 (12.8%) presented DDwR and 1 (0.7%) presented PD. The bone changes in the condyle and posterior aspect of the articular eminence were associated with the position of the disc. The bone changes in the anterior aspect of the articular eminence were not associated with the position of the disc. Conclusion: In cases of DDwoR, bone changes in the condyles were more common. The combination of erosion and osteophytosis in the condyle and the bone changes of the posterior aspect of the articular eminence were associated with disc position. Dentomaxillofacial Radiology (2012) 41, 367-372. doi: 10.1259/dmfr/79317853

The uncertain consequences of transferring bacterial strains between laboratories - rpoS instability as an example

Abstract Background Microbiological studies frequently involve exchanges of strains between laboratories and/or stock centers. The integrity of exchanged strains is vital for archival reasons and to ensure reproducible experimental results. For at least 50 years, one of the most common means of shipping bacteria was by inoculating bacterial samples in agar stabs. Long-term cultures in stabs exhibit genetic instabilities and one common instability is in rpoS. The sigma factor RpoS accumulates in response to several stresses and in the stationary phase. One consequence of RpoS accumulation is the competition with the vegetative sigma factor σ70. Under nutrient limiting conditions mutations in rpoS or in genes that regulate its expression tend to accumulate. Here, we investigate whether short-term storage and mailing of cultures in stabs results in genetic heterogeneity. Results We found that samples of the E. coli K-12 strain MC4100TF exchanged on three separate occasions by mail between our laboratories became heterogeneous. Reconstruction studies indicated that LB-stabs exhibited mutations previously found in GASP studies in stationary phase LB broth. At least 40% of reconstructed stocks and an equivalent proportion of actually mailed stock contained these mutations. Mutants with low RpoS levels emerged within 7 days of incubation in the stabs. Sequence analysis of ten of these segregants revealed that they harboured each of three different rpoS mutations. These mutants displayed the classical phenotypes of bacteria lacking rpoS. The genetic stability of MC4100TF was also tested in filter disks embedded in glycerol. Under these conditions, GASP mutants emerge only after a 3-week period. We also confirm that the intrinsic high RpoS level in MC4100TF is mainly due to the presence of an IS1 insertion in rssB. Conclusions Given that many E. coli strains contain high RpoS levels similar to MC4100TF, the integrity of such strains during transfers and storage is questionable. Variations in important collections may be due to storage-transfer related issues. These results raise important questions on the integrity of bacterial archives and transferred strains, explain variation like in the ECOR collection between laboratories and indicate a need for the development of better methods of strain transfer.

Mechanisms of ring chromosome formation, ring instability and clinical consequences

Background The breakpoints and mechanisms of ring chromosome formation were studied and mapped in 14 patients. Methods Several techniques were performed such as genome-wide array, MLPA (Multiplex Ligation-Dependent Probe Amplification) and FISH (Fluorescent in situ Hybridization). Results The ring chromosomes of patients I to XIV were determined to be, respectively: r(3)(p26.1q29), r(4)(p16.3q35.2), r(10)(p15.3q26.2), r(10)(p15.3q26.13), r(13)(p13q31.1), r(13)(p13q34), r(14)(p13q32.33), r(15)(p13q26.2), r(18)(p11.32q22.2), r(18)(p11.32q21.33), r(18)(p11.21q23), r(22)(p13q13.33), r(22)(p13q13.2), and r(22)(p13q13.2). These rings were found to have been formed by different mechanisms, such as: breaks in both chromosome arms followed by end-to-end reunion (patients IV, VIII, IX, XI, XIII and XIV); a break in one chromosome arm followed by fusion with the subtelomeric region of the other (patients I and II); a break in one chromosome arm followed by fusion with the opposite telomeric region (patients III and X); fusion of two subtelomeric regions (patient VII); and telomere-telomere fusion (patient XII). Thus, the r(14) and one r(22) can be considered complete rings, since there was no loss of relevant genetic material. Two patients (V and VI) with r(13) showed duplication along with terminal deletion of 13q, one of them proved to be inverted, a mechanism known as inv-dup-del. Ring instability was detected by ring loss and secondary aberrations in all but three patients, who presented stable ring chromosomes (II, XIII and XIV). Conclusions We concluded that the clinical phenotype of patients with ring chromosomes may be related with different factors, including gene haploinsufficiency, gene duplications and ring instability. Epigenetic factors due to the circular architecture of ring chromosomes must also be considered, since even complete ring chromosomes can result in phenotypic alterations, as observed in our patients with complete r(14) and r(22).

Método de ensaio biomecânico para análise da isometricidade na reconstrução do ligamento patelofemoral medial

OBJETIVO: Apresentar um dispositivo biomecânico para o estudo da reconstrução do ligamento patelofemoral medial (LPFM) e sua isometricidade. MÉTODOS: Foi desenvolvido um sistema biomecânico acessível, que permite a aplicação de forças fisiológicas e não fisiológicas no joelho, através de um braço mecânico e aplicação de pesos e contrapesos, possibilitando a execução de diferentes estudos, além de ter um sistema de medidas bastante preciso de aferição de distâncias entre diferentes estruturas para análise dos experimentos. Este artigo descreve a montagem deste sistema, além de sugerir algumas aplicações práticas. Foram estudados seis joelhos de cadáveres. Os joelhos foram preparados em uma máquina de ensaios desenvolvida no Laboratório de Biomecânica do IOT HC FMUSP, que permitiu a avaliação dinâmica do comportamento patelar, quantificando a sua lateralização entre 0 e 120 graus. A diferença entre as distâncias encontradas, com e sem carga, aplicada na patela foram agrupadas segundo o ângulo de fixação do enxerto (0°, 30°, 60° e 90°) e situação do joelho (íntegro, reconstruído e lesado). RESULTADOS: Houve uma tendência em ocorrer menor desvio lateral em ângulos de fixação acima de 30 graus de flexão, principalmente entre os ângulos entre 45° e 60° graus de flexão, após a reconstrução. Para os demais ângulos não houve significância estatística. CONCLUSÃO: O método desenvolvido é uma ferramenta útil para os estudos da articulação patelofemoral, além de ter um sistema de medidas bastante preciso de aferição de distâncias entre diferentes estruturas e permitir a sua utilização em instituições com menos recursos disponíveis.

Necrose avascular da cabeça femoral em pacientes HIV positivos: resultados iniciais do tratamento cirúrgico por substituição articular cerâmica-cerâmica

OBJETIVOS: Avaliar os resultados funcionais iniciais e o índice de complicações precoces das artroplastias totais do quadril cerâmica-cerâmica em pacientes que convivem com o HIV e apresentam osteonecrose da cabeça femoral. MÉTODO: Doze pacientes HIV+ com diagnóstico de osteonecrose da cabeça do fêmur incongruente foram avaliados através de critérios clínicos, laboratoriais, pela escala funcional WOMAC antes e após o tratamento com substituição articular. RESULTADOS: Observamos que 83,3% dos indivíduos faziam uso de inibidores de protease, 75% apresentavam dislipidemia e 66,6% síndrome lipodistrófica, a melhora na evolução no escore WOMAC foi estatisticamente significativa para seis e 12 meses de pós-operatório em comparação com o escore pré-operatório e não observamos complicações secundárias a esse procedimento. CONCLUSÃO: A artroplastia total do quadril com implante de cerâmica-cerâmica para o tratamento da necrose avascular do quadril nessa parcela da população é opção cirúrgica adequada, apresenta melhora funcional inicial significativa e baixo índice de complicação precoce.

Avaliação do torque de resistência passiva em atletas femininas com entorse de tornozelo

INTRODUÇÃO: A entorse de tornozelo é uma das lesões mais comuns em atletas. Uma forma de avaliar a frouxidão ligamentar pode ser através da medida da amplitude passiva dos movimentos de inversão e eversão do pé para estimar a resistência passiva das estruturas capsuloligamentares do tornozelo, o qual pode ser chamado de torque de resistência passiva. Existem poucos estudos que utilizam a avaliação do torque passivo do tornozelo para avaliar a resistência da cápsula e dos ligamentos. OBJETIVO: O objetivo deste estudo foi comparar o torque passivo dos movimentos de inversão e eversão do pé em atletas com e sem história de entorse de tornozelo. MÉTODO: Participaram do estudo 32 atletas de basquetebol e voleibol feminino (16,06 ± 0,8 anos, 67,63 ± 8,17kg, 177,8 ± 6,47cm). Seus tornozelos foram divididos em dois grupos: grupo controle (29), composto por tornozelos sem sintomas, e grupo entorse de tornozelo, composto por tornozelos que sofreram lesão (29). O torque dos movimentos passivos do tornozelo foi registrado por um dinamômetro isocinético, e a atividade dos músculos fibular longo e tibial anterior foi medida por um eletromiógrafo. As atletas realizaram duas repetições do movimento de inversão e eversão, nas velocidades de 5, 10 e 20°/s e, em seguida, o mesmo protocolo foi repetido apenas para o movimento de inversão máxima do pé. RESULTADOS: O torque de resistência passiva durante os movimentos de inversão e eversão do pé foi menor no grupo com entorse do tornozelo. Este grupo também mostrou menor torque durante o movimento de inversão máxima do pé. Não foram observadas diferenças entre o movimento de inversão e eversão. CONCLUSÕES: A entorse de tornozelo leva a um menor torque de resistência passiva, indicando redução da resistência dos ligamentos colaterais do tornozelo e uma frouxidão articular mecânica.