Slower respiration rate is associated with higher self-reported well-being after wellness training.

Mind-body interventions such as mindfulness-based stress reduction (MBSR) may improve well-being by increasing awareness and regulation of physiological and cognitive states. However, it is unclear how practice may alter long-term, baseline physiological processes, and whether these changes reflect improved well-being. Using respiration rate (RR), which can be sensitive to effects of meditation, and 3 aspects of self-reported well-being (psychological well-being [PWB], distress, and medical symptoms), we tested pre-registered hypotheses that: (1) Lower baseline RR (in a resting, non-meditative state) would be a physiological marker associated with well-being, (2) MBSR would decrease RR, and (3) Training-related decreases in RR would be associated with improved well-being. We recruited 245 adults (age range = 18-65, M = 42.4): experienced meditators (n = 42), and meditation-naïve participants randomized to MBSR (n = 72), active control (n = 41), or waitlist control (n = 66). Data were collected at pre-randomization, post-intervention (or waiting), and long-term follow-up. Lower baseline RR was associated with lower psychological distress among long-term meditators (p* = 0.03, b = 0.02, 95% CI [0.01, 0.03]), though not in non-meditators prior to training. MBSR decreased RR compared to waitlist (p = 0.02, Cohen's d = - 0.41, 95% CI [- 0.78, - 0.06]), but not the active control. Decreased RR related to decreased medical symptoms, across all participants (p* = 0.02, b = 0.57, 95% CI [0.15, 0.98]). Post-training, lower RR was associated with higher PWB across training groups compared to waitlist (p* = 0.01, b = 0.06, 95% CI [0.02, 0.10]), though there were no significant differences in change in PWB between groups. This physiological marker may indicate higher physical and/or psychological well-being in those who engage in wellness practices.

Surface immobilization of neural adhesion molecule L1 for improving the biocompatibility of chronic neural probes: In vitro characterization.

Silicon-based implantable neural electrode arrays are known to experience failure during long-term recording, partially due to host tissue responses. Surface modification and immobilization of biomolecules may provide a means to improve their biocompatibility and integration within the host brain tissue. Previously, the laminin biomolecule or laminin fragments have been used to modify the neural probe's silicon surface to promote neuronal attachment and growth. Here we report the successful immobilization of the L1 biomolecule on a silicon surface. L1 is a neuronal adhesion molecule that can specifically promote neurite outgrowth and neuronal survival. Silane chemistry and the heterobifunctional coupling agent 4-maleimidobutyric acid N-hydroxysuccinimide ester (GMBS) were used to covalently bind these two biomolecules onto the surface of silicon dioxide wafers, which mimic the surface of silicon-based implantable neural probes. After covalent binding of the biomolecules, polyethylene glycol (PEG)-NH(2) was used to cap the unreacted GMBS groups. Surface immobilization was verified by goniometry, dual polarization interferometry, and immunostaining techniques. Primary murine neurons or astrocytes were used to evaluate the modified silicon surfaces. Both L1- and laminin-modified surfaces promoted neuronal attachment, while the L1-modified surface demonstrated significantly enhanced levels of neurite outgrowth (p<0.05). In addition, the laminin-modified surface promoted astrocyte attachment, while the L1-modified surface showed significantly reduced levels of astrocyte attachment relative to the laminin-modified surface and other controls (p<0.05). These results demonstrate the ability of the L1-immobilized surface to specifically promote neuronal growth and neurite extension, while inhibiting the attachment of astrocytes, one of the main cellular components of the glial sheath. Such unique properties present vast potentials to improve the biocompatibility and chronic recording performance of neural probes.

Biomechanical properties of the superficial fascial system.

BACKGROUND: Surgical repair of the superficial fascial system (SFS) has been claimed to both increase wound strength and enhance surgical outcome through anchoring of deeper tissues. OBJECTIVE: The authors assessed the biomechanical properties of the SFS to determine whether repair of the SFS layer improved early and long-term postoperative wound strength. METHODS: Four complementary studies were conducted to study the dermis and SFS junctional architecture and connective tissue content: gross dissection using a dehydrating agent (Pen-Fix; Richard-Allan Scientific, Kalamazoo, MI), a histologic study with hemotoxylin and eosin staining, soft tissue radiography, and immunofluorescence staining. Freshly excised human abdominal and lower back/buttock tissues underwent a midline incision, followed by repair using dermal sutures only (DRM), dermal sutures plus SFS sutures (DRM/SFS) or repair of the SFS only (SFS). Fresh swine abdominal tissues were similarly excised and repaired. Biomechanical tests were undertaken to compare the ex vivo human and swine tissues. Three types of closure-dermal sutures only (DRM), dermal sutures plus permanent 0-braided nylon suture in the SFS (DRM/SFS/N), and dermal sutures plus absorbable 0-vicryl suture in the SFS (DRM/SFS/V) were also tested in an in vivo swine model. RESULTS: Immunofluorescence studies showed collagen and elastin content and ratios to be comparable in the dermis and SFS. In ex vivo studies of human abdominal and back tissues, cyclic creep did not vary significantly among the different types of repair. DRM/SFS repair had a significantly higher failure load than dermal repair alone in both human abdominal and back tissues. In the in vivo swine study, normal tissue had a significantly higher failure load than all repair groups. The wounds where SFS had been repaired in addition to dermis exhibited an increased tensile strength and, among these, the wounds closed with SFS repair with a nonabsorbable suture exhibited greater tensile strength compared to absorbable suture repair. However, no statistically significant difference was noted, due to the small sample size. CONCLUSIONS: We have determined, using an ex vivo model, that repair of the SFS layer in addition to dermis repair significantly increases the initial biomechanical strength of wound repair. This has the potential to decrease early wound dehiscence. In our in vivo model, the use of a nonabsorbable suture to approximate the SFS demonstrated a trend toward increased long-term wound strength. We believe our studies provide scientific data documenting that SFS is a key contributory strength layer in the early postoperative period, and is likely to be a strength layer even in the later stages of wound healing.

Bi-directional mechanical properties of the posterior region of the glenohumeral capsule.

The objective of this study was to determine the mechanical properties of the posterior region of the glenohumeral capsule in the directions perpendicular (transverse) and parallel (longitudinal) to the longitudinal axis of the posterior band of the inferior glenohumeral ligament. A punch was used to excise one transverse and one longitudinal tissue sample from the posterior capsule of 11 cadaveric shoulders. All tissue samples exhibited the typical nonlinear behavior reported for ligaments and tendons. Significant differences (p < 0.05) were detected between the transverse and longitudinal tissue samples for ultimate stress (1.5+/-1.4 and 4.9+/-2.9 MPa, respectively) and tangent modulus (10.3+/-6.6 and 31.5+/-12.7 MPa, respectively). No significant differences (p > 0.05) were observed between the ultimate strain (transverse: 22.3+/-12.5%, longitudinal: 22.8+/-11.1%) and strain energy density (transverse: 27.2+/-52.8 MPa, longitudinal: 67.5+/-88.2 MPa) of the transverse and longitudinal tissue samples. The ratio of the longitudinal to transverse moduli (4.8+/-4.2) was similar to that found for the axillary pouch (3.3+/-2.8) in a previous study. Thus, both the axillary pouch and the posterior capsule function to stabilize the joint multi-axially. Future analytical models of the glenohumeral joint should consider the properties of the posterior capsule in its transverse and longitudinal directions to fully describe the behavior of the glenohumeral capsule. These models will be clinically important by providing a more accurate representation of the intact capsule as well as simulated capsular injuries and surgical repair procedures.

The surface immobilization of the neural adhesion molecule L1 on neural probes and its effect on neuronal density and gliosis at the probe/tissue interface.

Brain tissue inflammatory responses, including neuronal loss and gliosis at the neural electrode/tissue interface, limit the recording stability and longevity of neural probes. The neural adhesion molecule L1 specifically promotes neurite outgrowth and neuronal survival. In this study, we covalently immobilized L1 on the surface of silicon-based neural probes and compared the tissue response between L1 modified and non-modified probes implanted in the rat cortex after 1, 4, and 8 weeks. The effect of L1 on neuronal health and survival, and glial cell reactions were evaluated with immunohistochemistry and quantitative image analysis. Similar to previous findings, persistent glial activation and significant decreases of neuronal and axonal densities were found at the vicinity of the non-modified probes. In contrast, the immediate area (100 µm) around the L1 modified probe showed no loss of neuronal bodies and a significantly increased axonal density relative to background. In this same region, immunohistochemistry analyses show a significantly lower activation of microglia and reaction of astrocytes around the L1 modified probes when compared to the control probes. These improvements in tissue reaction induced by the L1 coating are likely to lead to improved functionality of the implanted neural electrodes during chronic recordings.

Seeding neural progenitor cells on silicon-based neural probes.

OBJECT: Chronically implanted neural electrode arrays have the potential to be used as neural prostheses in patients with various neurological disorders. While these electrodes perform well in acute recordings, they often fail to function reliably in clinically relevant chronic settings because of glial encapsulation and the loss of neurons. Surface modification of these implants may provide a means of improving their biocompatibility and integration within host brain tissue. The authors proposed a method of improving the brain-implant interface by seeding the implant's surface with a layer of neural progenitor cells (NPCs) derived from adult murine subependyma. Neural progenitor cells may reduce the foreign body reaction by presenting a tissue-friendly surface and repair implant-induced injury and inflammation by releasing neurotrophic factors. In this study, the authors evaluated the growth and differentiation of NPCs on laminin-immobilized probe surfaces and explored the potential impact on transplant survival of these cells. METHODS: Laminin protein was successfully immobilized on the silicon surface via covalent binding using silane chemistry. The growth, adhesion, and differentiation of NPCs expressing green fluorescent protein (GFP) on laminin-modified silicon surfaces were characterized in vitro by using immunocytochemical techniques. Shear forces were applied to NPC cultures in growth medium to evaluate their shearing properties. In addition, neural probes seeded with GFP-labeled NPCs cultured in growth medium for 14 days were implanted in murine cortex. The authors assessed the adhesion properties of these cells during implantation conditions. Moreover, the tissue response around NPC-seeded implants was observed after 1 and 7 days postimplantation. RESULTS: Significantly improved NPC attachment and growth was found on the laminin-immobilized surface compared with an unmodified control before and after shear force application. The NPCs grown on the laminin-immobilized surface showed differentiation potential similar to those grown on polylysine-treated well plates, as previously reported. Viable (still expressing GFP) NPCs were found on and in proximity to the neural implant after 1 and 7 days postimplantation. Preliminary examinations indicated that the probe's NPC coating might reduce the glial response at these 2 different time points. CONCLUSIONS: The authors' findings suggest that NPCs can differentiate and strongly adhere to laminin-immobilized surfaces, providing a stable matrix for these cells to be implanted in brain tissue on the neural probe's surface. In addition, NPCs were found to improve the astrocytic reaction around the implant site. Further in vivo work revealing the mechanisms of this effect could lead to improvement of biocompatibility and chronic recording performance of neural probes.