Are biomarkers associated with sensitivity to physical activity?

BACKGROUND: Activity-based treatments play an integral role in managing musculoskeletal conditions including low back pain. However, while therapeutic exercise has been shown to reduce pain in such conditions, certain individuals experience a paradoxical pain increase in response to exercise. The physiological processes underlying this sensitivity to physical activity (SPA) are not fully understood, however stress and inflammation have been shown to contribute to SPA. The present cross-sectional study investigated whether physiological indicators of stress (cortisol) and inflammation (IL-6) help explain SPA. METHODS: Twenty-seven patients with chronic low back pain and 21 healthy controls completed a 1-h exercise session of standardized physical tasks. SPA was calculated from the difference between post- and pre-exercise pain levels. Participant's saliva was collected at several timepoints for cortisol and IL-6 levels quantification. Their waking cortisol response was calculated to reflect their cortisol regulation. Reactivity of IL-6 and cortisol was calculated to reflect changes in these measures during exercise. RESULTS: IL-6 reactivity was significantly and positively correlated with SPA among participants with low back pain. In contrast, neither cortisol waking response nor cortisol reactivity was significantly correlated within the low back pain group. No significant differences in IL-6 reactivity, cortisol reactivity or cortisol waking response were observed. CONCLUSION: These findings are the first to link SPA to an objective biomarker among people with low back pain. These findings help describe the physiological mechanisms of SPA and can support new clinical research that targets the inflammatory response of patients with chronic low-back pain and elevated SPA. SIGNIFICANCE: This study reveals a correlation between SPA and an objective salivary biomarker of IL-6 in people with low back pain, improving our understanding of this clinically relevant subjective experience.

Is immunohistochemistry more sensitive than hematoxylin-eosin staining for identifying perineural or lymphovascular invasion in oral squamous cell carcinoma? A systematic review and meta-analysis.

BACKGROUND: This study aimed to analyze whether immunohistochemistry (IHC) is more sensitive than hematoxylin-eosin (H&E) staining for identifying perineural invasion (PNI) or lymphovascular invasion (LVI) in oral squamous cell carcinoma (OSCC). MATERIAL AND METHODS: In this systematic review and meta-analysis (Prospective Register of Systematic Reviews - CRD 42021256515), data were obtained from six databases (PubMed, Scopus, LILACS, Web of Science, EBSCO, LIVIVO, Embase) and the grey literature. Cross-sectional observational studies of the diagnostic sensitivity of IHC for PNI and LVI were included. Studies were selected in two phases: first collection and reference retrieval. The Quality Assessment of Diagnostic Accuracy Studies-2 tool assessed study quality, while the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) approach assessed evidence quality. The meta-analysis (random effects model) was performed using MedCalc 18.2.1 software (MedCalc®) (p<0.05). RESULTS: Four studies (560 patients with 295 biopsies) were analyzed. The combined sensitivity was 76% (95% confidence interval [CI], 44.30-97.19%) and specificity was 42% (95% CI, 23.40-62.02%). The positive predictive value (PPV) and negative predictive value (NPV) were 61% (95% CI, 49.78-71.53%) and 70% (95% CI, 37.63-94.43%). The overall accuracy was 58% (95% CI, 45.17-70.65%). The risk of bias was low, and GRADE analysis showed a very low certainty of evidence. CONCLUSIONS: Our data suggest that IHC staining to highlight PNI/LVI may be useful in cases in which H&E analysis results in a negative decrease in the prevalence of false-negative cases and underestimated treatment.

Limiting interpedicular screw displacement increases shear forces in screws: A finite element study.

BACKGROUND CONTEXT: Screw loosening has been reported for non-fusion devices. Forces on pedicle screws could be related to kinematic parameters as the interpedicular displacement (ID), which consists of the displacement between superior and inferior screw heads from full extension to full flexion. PURPOSE: To investigate the relationship between ID and screw loosening for different designs of posterior implants using a finite element model. METHODS: An L3-sacrum previously validated spine FE model was used. Three-rod designs were considered in L4-L5 segment: a rigid screw-rod implant, a flexible one and a specific design with a sliding rod providing limited restrain in ID. In order to simulate intermediate configurations, the friction coefficient between the sliding rods and connectors were varied. The sacrum was rigidly fixed. Rotations (flexion-extension, lateral bending and axial rotation) were applied to L3, for each modeled configuration: intact, injured, injured with different implants. Model consistency was checked with existing experimental in vitro data on intact and instrumented segments. Screw loads were computed as well as ID. RESULTS: In flexion-extension, the ID was less than 2mm for rigid (R) and flexible (F) constructs and 5.5mm for intact spine and the sliding implant (S3). Screw's shear forces were 272N, 153N, 43N respectively for R, F and S3 constructs. CONCLUSIONS: Implants that allow ID presented lower screws loads. A compromise between the ability of the implant to withstand compressive forces, which requires longitudinal stiffness, and its ability to allow ID could be important for future implant designs in order to prevent screw loosening.

Associating high intensity and modulated frequency of TENS delays analgesic tolerance in rats.

BACKGROUND: Transcutaneous electrical nerve stimulation (TENS) is a non-invasive analgesic resource extensively used in painful conditions. However, preclinical studies suggest that the prolonged use of TENS results in the development of tolerance to its analgesic effect. The present study investigated the analgesic effect and development of tolerance to TENS with four different stimulation protocols. METHODS: Male Wistar rats induced with joint inflammation were divided into four groups: sensory intensity, low motor intensity, high motor intensity and sham groups. TENS was applied daily for 20 min with alternating frequency between 4 and 100 Hz until tolerance development was evidenced. Mechanical hyperalgesia was measured before and after each TENS daily application. RESULTS: After TENS, tolerance was evidenced There was a significant reduction in the mechanical withdrawal threshold in all groups 24 h after induction of inflammation (p < 0.01). We observed a loss of analgesic efficacy of TENS around the 12th, 19th and 19th days in the groups treated with sensory intensity, low motor intensity and high motor intensity, respectively (p < 0.02) when analysed using paired measurements and compared with the control. CONCLUSIONS: The association between frequency variation and intensity at motor level promotes a delay in the development of analgesic tolerance to TENS, optimizing and extending its therapeutic effectiveness.

Semi-automated stereoradiographic upper limb 3D reconstructions using a combined parametric and statistical model: a preliminary study.

PURPOSE: Quantitative assessment of 3D clinical indices may be crucial for elbow surgery planning. 3D parametric modeling from bi-planar radiographs was successfully proposed for spine and lower limb clinical investigation as an alternative for CT-scan. The aim of this study was to adapt this method to the upper limb with a preliminary validation. METHODS: CT-scan 3D models of humerus, radius and ulna were obtained from 20 cadaveric upper limbs and yielded parametric models made of geometric primitives. Primitives were defined by descriptor parameters (diameters, angles...) and correlations between these descriptors were found. Using these correlations, a semi-automated reconstruction method of humerus using bi-planar radiographs was achieved: a 3D personalized parametric model was built, from which clinical parameters were computed [orientation and projections on bone surface of trochlea sulcus to capitulum (CTS) axis, trochlea sulcus anterior offset and width of distal humeral epiphysis]. This method was evaluated by accuracy compared to CT-scan and reproducibility. RESULTS: Points-to-surface mean distance was 0.9 mm (2 RMS = 2.5 mm). For clinical parameters, mean differences were 0.4-1.9 mm and from 1.7° to 2.3°. All parameters except from angle formed by CTS axis and bi-epicondylar axis in transverse plane were reproducible. Reconstruction time was about 5 min. CONCLUSIONS: The presented method provides access to morphological upper limb parameters with very low level of radiation. Preliminary in vitro validation for humerus showed that it is fast and accurate enough to be used in clinical daily practice as an alternative to CT-scan for total elbow arthroplasty pre operative evaluation.

Postura da mão e imagética motora: um estudo sobre reconhecimento de partes do corpo / Hand posture and motor imagery: a body-part recognition study

OBJETIVOS: Assim como a imagética motora, o reconhecimento de partes do corpo aciona representações somatosensoriais específicas. Essas representações são ativadas implicitamente para comparar o corpo com o estímulo. No presente estudo, investigou-se a influência da informação proprioceptiva da postura no reconhecimento de partes do corpo (mãos) e propõe-se a utilização dessa tarefa na reabilitação de pacientes neurológicos. MATERIAIS E MÉTODOS: Dez voluntários destros participaram do experimento. A tarefa era reconhecer a lateralidade de figuras da mão apresentada, em várias perspectivas e em vários ângulos de orientação. Para a figura da mão direita, o voluntário pressionava a tecla direita e para a figura da mão esquerda, a tecla esquerda. Os voluntários realizavam duas sessões: uma com as mãos na postura prona e outra com as mãos na postura supina. RESULTADOS: Os tempos de reação manual (TRM) eram maiores para as vistas e orientações, nas quais é difícil realizar o movimento real, mostrando que durante a tarefa, existe um acionamento de representações motoras para comparar o corpo com o estímulo. Além disso, existe uma influência da postura do sujeito em vistas e ângulos específicos. CONCLUSÕES: Estes resultados mostram que representações motoras são ativadas para comparar o corpo com o estímulo e que a postura da mão influencia esta ressonância entre estímulo e parte do corpo.

OBJECTIVE: Recognition of body parts activates specific somatosensory representations in a way that is similar to motor imagery. These representations are implicitly activated to compare the body with the stimulus. In the present study, we investigate the influence of proprioceptive information relating to body posture on the recognition of body parts (hands). It proposes that this task could be used for rehabilitation of neurological patients. METHODS: Ten right-handed volunteers participated in this experiment. The task was to recognize the handedness of drawings of a hand that were presented in different perspectives and several orientations. For drawings of a right hand, the volunteers pressed the right key, and for drawings of a left hand, they pressed the left key. The volunteers underwent two sessions: one with their hands in a prone posture and the other with their hands in a supine posture. RESULTS: The manual reaction time was longer for perspectives and orientations for which the real movement was difficult to achieve. This showed that, during the task, motor representations were activated to compare the body with the stimulus. Furthermore, the subject's posture had an influence in relation to specific perspectives and orientations. CONCLUSIONS: These results showed that motor representations are activated to compare the body with the stimulus, and that the position of the hand influences this resonance between the stimulus and the body part.