Contribution of TRPC3-mediated Ca2+ entry to taste transduction.

The current concept of taste transduction implicates the TASR/PLCß2/IP3R3/TRPM5 axis in mediating chemo-electrical coupling in taste cells of the type II. While generation of IP3 has been verified as an obligatory step, DAG appears to be a byproduct of PIP2 cleavage by PLCß2. Here, we provide evidence that DAG-signaling could play a significant and not yet recognized role in taste transduction. In particular, we found that DAG-gated channels are functional in type II cells but not in type I and type III cells. The DAG-gated current presumably constitutes a fraction of the generator current triggered by taste stimulation in type II cells. Bitter stimuli and DAG analogs produced Ca2+ transients in type II cells, which were greatly decreased at low bath Ca2+, indicating their dependence on Ca2+ influx. Among DAG-gated channels, transcripts solely for TRPC3 were detected in the taste tissue, thus implicating this channel in mediating DAG-regulated Ca2+ entry. Release of the afferent neurotransmitter ATP from CV papillae was monitored online by using the luciferin/luciferase method and Ussing-like chamber. It was shown that ATP secretion initiated by bitter stimuli and DAG analogs strongly depended on mucosal Ca2+. Based on the overall findings, we speculate that in taste transduction, IP3-driven Ca2+ release is transient and mainly responsible for rapid activation of Ca2+-gated TRPM5 channels, thus forming the initial phase of receptor potential. DAG-regulated Ca2+ entry through apically situated TRPC3 channels extends the primary Ca2+ signal and preserves TRPM5 activity, providing a needful prolongation of the receptor potential.

Effects of chloroplast-cytoplasm exchange and lateral mass transfer on slow induction of chlorophyll fluorescence in Characeae.

Rapid cytoplasmic streaming in characean algae mediates communications between remote cell regions exposed to uneven irradiance. The metabolites exported from brightly illuminated chloroplasts spread along the internode with the liquid flow and cause transient changes in chlorophyll fluorescence at cell areas that are exposed to dim light or placed shortly in darkness. The largest distance to which the photometabolites can be transported has not yet been determined. Neither is it known if lateral transport has an influence on the induction of chlorophyll fluorescence. In this study, the relations between spatial connectivity of anchored chloroplasts in characean internodes and fluorescence induction curves were examined. Connectivity between remote cell parts was pronounced upon illumination of a cell spot at a distance up to 10 mm from the area of fluorescence measurement, provided the spot was located upstream in the cytoplasmic flow. Spatial interactions between distant cell sites were also manifested in strikingly different slow stages of fluorescence induction caused by narrow- and wide-field illumination. Cytochalasin D, cooling of bath solution, and inactivation of light-dependent envelope transporters were used to disturb cyclosis-mediated spatial interactions. Although fluorescence induction curves induced by narrow- and wide-field illumination differed greatly under control conditions, they became similar after the inhibition of cyclosis with cytochalasin D. The results indicate that cytoplasmic streaming not only drives the lateral translocation of photometabolites but also promotes the export of reducing power from illuminated chloroplasts due to flushing the chloroplast surface and keeping sharp concentration gradients.

One-year recombinant growth hormone therapy does not improve hemoglobin state and morphology of erythrocytes in growth hormone deficient children.

An increase in growth rates of children suffering from growth hormone deficiency (GHD) subjected to recombinant growth hormone treatment (rGHT) was shown to be accompanied by acceleration of metabolic processes that may stimulate oxygen consumption in various organs and tissues. Therefore, oxygen-transporting properties of RBC should undergo considerable changes during the rGHT. The aim of this study was to examine the effects of rGHT on erythrocyte shape and hemoglobin state in GHD children. The level of oxyhemoglobin (Oxy-Hb) in RBC was analyzed by Raman spectroscopy. The RBC count, mean corpuscular hemoglobin (MCH), mean corpuscular volume (MCV) and other parameters were calculated. The blood of eleven treatment-naive prepubertal children with GHD (aged 3-9, median 5.7 years) was examined and compared with control group (aged 5-7; median 6.0 years) at three time points: 0, 3 and 12 months of rGHT. Before rGHT, the MI in GHD children was higher (median 0.48 vs 0.14 p=0.0018) and the RBC count was lower (median 4.20 vs 4.96 1012 cells/L p=0.0022) than in control group. After the treatment, cell count in GHD patients did not differ significantly from the control group, but Oxy-Hb level became higher (median 0.64 vs 0.41 p=0.0075). During rGHT, MCV decreased (median 80.3 vs 83.2µm3 p=0.0231). Morphological and functional characteristics of erythrocytes in GHD children were shown to differ significantly from the healthy control group. A twelve-month rGHT partially improved some of the studied parameters but Oxy-Hb level and echinocyte count remained high.

Expression of calcium-activated chloride channels Ano1 and Ano2 in mouse taste cells.

Specialized Ca(2+)-dependent ion channels ubiquitously couple intracellular Ca(2+) signals to a change in cell polarization. The existing physiological evidence suggests that Ca(2+)-activated Cl(-) channels (CaCCs) are functional in taste cells. Because Ano1 and Ano2 encode channel proteins that form CaCCs in a variety of cells, we analyzed their expression in mouse taste cells. Transcripts for Ano1 and Ano2 were detected in circumvallate (CV) papillae, and their expression in taste cells was confirmed using immunohistochemistry. When dialyzed with CsCl, taste cells of the type III exhibited no ion currents dependent on cytosolic Ca(2+). Large Ca(2+)-gated currents mediated by TRPM5 were elicited in type II cells by Ca(2+) uncaging. When TRPM5 was inhibited by triphenylphosphine oxide (TPPO), ionomycin stimulated a small but resolvable inward current that was eliminated by anion channel blockers, including T16Ainh-A01 (T16), a specific Ano1 antagonist. This suggests that CaCCs, including Ano1-like channels, are functional in type II cells. In type I cells, CaCCs were prominently active, blockable with the CaCC antagonist CaCCinh-A01 but insensitive to T16. By profiling Ano1 and Ano2 expressions in individual taste cells, we revealed Ano1 transcripts in type II cells only, while Ano2 transcripts were detected in both type I and type II cells. P2Y agonists stimulated Ca(2+)-gated Cl(-) currents in type I cells. Thus, CaCCs, possibly formed by Ano2, serve as effectors downstream of P2Y receptors in type I cells. While the role for TRPM5 in taste transduction is well established, the physiological significance of expression of CaCCs in type II cells remains to be elucidated.

The Management of Soft Tissue and Bone Loss in Type IIIB and IIIC Pediatric Open Tibia Fractures.

PURPOSE: Type III B and C open tibia fractures in children pose a challenge to the orthopaedic surgeon. Limb salvage is the initial goal for the majority of patients, but managing soft-tissue defects and bone loss can be a challenge. The purpose of this study was to evaluate the use of circular external fixation in the management of these injuries. METHODS: In this retrospective review, we examined children with type IIIB and IIIC open tibial fractures treated with circular external fixation and soft-tissue coverage between 1990 and 2010. Chart review included: mechanism and severity of injury, degree of bone and soft-tissue loss, technique and duration of external fixation, additional procedures, clinical and radiographic outcomes, and complications. RESULTS: Eight patients were identified whose average age at the time of injury was 10.4 years (range, 3.8 to 15.3 y). There were 7 type IIIB and 1 type IIIC fractures. All patients received free or rotational soft-tissue flaps. Average bone loss was 5.4 cm (range, 0 to 12 cm). Three techniques of circular external fixation were used, including: (1) static stabilization to allow for soft-tissue coverage and fracture healing, (2) acute shortening with plan for later limb lengthening, and (3) stabilization of the extremity for soft-tissue coverage and intended bone transport. Seven of 8 limbs were salvaged. Of those 7, all were followed to skeletal maturity and ambulating without assistive devices at final follow-up. Three patients had a clinically relevant leg-length discrepancy (≥2 cm). Four of 8 patients required secondary or contralateral procedures. CONCLUSIONS: Pediatric type IIIB and IIIC tibia fractures are limb-threatening injuries that require dynamic thinking and management as the bone and soft-tissue injuries evolve. We have proposed a general algorithm to guide the treatment of these severe injuries. In our experience, circular external fixation, in conjunction with this algorithm, provides the appropriate stability and environment for managing soft tissue and bone loss and can facilitate limb salvage. LEVEL OF EVIDENCE: Level IV.

Treatment of femoral lengthening-related knee stiffness with a novel quadricepsplasty.

BACKGROUND: Knee stiffness is common after femoral lengthening. Certain patients require a quadricepsplasty when therapy does not improve flexion. A small subset of such patients may also have obligate patellar dislocation with knee flexion due to contracture of the extensor mechanism. We describe our surgical approach for both clinical situations and our outcomes in a pediatric population. METHODS: Six patients, 2 with obligate patellar dislocation, were reviewed (9% of our femoral lengthening population). Indications for surgery included persistent symptomatic restriction of flexion after at least 3 months of therapy or obligate lateral patellar dislocation with knee flexion. Knee range of motion and clinical strength were assessed. Four patients were available for gait analysis and concentric quadriceps strength testing by isokinetic dynamometer. Patient satisfaction was surveyed by questionnaire. RESULTS: All patients had full flexion before lengthening. The mean length gained (by circular external fixation and/or intramedullary motorized nail) was 10.7 cm. The mean age at the time of quadricepsplasty was 16 years. The average active flexion preoperatively was only 48 degrees. Two patients with obligate patellar dislocation and relatively good knee flexion inflated the average preoperative knee flexion. Although both had knee flexion to 100 degrees, the patella dislocated with flexion beyond 30 degrees. At follow-up (mean, 6.2 y) active flexion averaged 120 degrees (P<0.004). All patients had 5/5 clinical strength and no significant quadriceps lag. No patients had patellar instability postoperatively. Isokinetic dynamometer revealed an average weakness of 63% compared with the nonoperative quadriceps. Gait analysis indicated patients had near-normal gait patterns. All patients were satisfied and would pursue the same treatment. CONCLUSIONS: Our quadricepsplasty can significantly increase knee flexion and treat obligate patellar dislocation in the setting of extension contracture after femoral lengthening when nonoperative measures fail. LEVEL OF EVIDENCE: Level IV.

Reverse Dynamization Accelerates Regenerate Bone Formation and Remodeling in a Goat Distraction Osteogenesis Model.

UPDATE: This article was updated on December 20, 2023, because of previous errors, which were discovered after the preliminary version of the article was posted online. Figure 4 has been replaced with a figure that presents different p values. Also, on page 1943, the text that had read: "Quantitative microCT confirmed that the total volume of the regenerate in the RD group was much smaller compared with the SF (p = 0.06) and DF (p = 0.007) groups, although it was significantly smaller only compared with the DF group (Fig. 4-A). The total volume of the intact bone (contralateral tibia) was significantly smaller in the RD group compared with the other groups, but the RD group had values closest to those for the intact tibia. Similarly, the RD group had less bone volume compared with the SF and DF groups, and this value was significantly different from the DF group (p = 0.034; Fig. 4-B). Of the 3 groups, the RD group had vBMD that was the closest to that of intact bone. It also had significantly higher vBMD compared with the SF and DF groups (p < 0.0001 for both; Fig. 4-C).The results of torsional testing (Fig. 4-D) confirmed that the regenerate bone formed under conditions of RD was significantly stronger than that formed under SF or DF (p < 0.001 versus SF group, and p = 0.0493 versus DF group)."now reads: "Quantitative microCT confirmed that the total volume of the regenerate in the RD group was significantly smaller compared with the SF and DF groups (p < 0.01 for both groups; Fig. 4-A). The total volume of the intact bone (contralateral tibia) was significantly smaller compared with the SF and DF groups (p < 0.0001 for both). The RD group had values closest to those for the intact tibia, and this difference was not significant (Fig. 4-A). Similarly, the RD group had less bone volume compared with the SF and DF groups, and this value was significantly different from the DF group (p < 0.01; Fig. 4-B). Of the 3 groups, the RD group had vBMD that was the closest to that of intact bone, but the intact bone was significantly different compared with all of the other groups (p < 0.0001 for all groups). The RD group had significantly higher vBMD compared with the SF and DF groups (p = 0.042 and p = 0.046, respectively; Fig. 4-C).The results of torsional testing (Fig. 4-D) confirmed that the regenerate bone formed under conditions of RD was significantly stronger than that formed under SF or DF (p < 0.0001 versus SF group, and p = 0.0493 versus DF group). The intact group was significantly different compared with the SF group (p < 0.0001)."

The concept of reverse dynamization involves modifying the mechanical environment surrounding a fracture to influence the healing response. Initially, less rigid stabilization is performed to allow micromotion, encouraging cartilaginous callus formation. This is followed by a conversion to more rigid fixation to prevent the disruption of neovascularization, thereby accelerating bone healing and remodeling. The effect of reverse dynamization in distraction osteogenesis has not been studied, to our knowledge. The aim of this study was to determine whether reverse dynamization can accelerate the formation and maturation of regenerate bone in a goat distraction osteogenesis model. Midshaft tibial osteotomies were created in 18 goats and stabilized using circular external fixation. After a 5-day latency period, 4 weeks of limb distraction began to obtain a 2-cm gap; this was followed by 8 weeks of regenerate consolidation. The goats were divided into 3 groups: static (rigid) fixation (SF, n = 6); dynamic fixation (DF, n = 6), consisting of continuous micromotion using dynamizers; and reverse dynamization (RD, n = 6), consisting of initial micromotion during the distraction period using dynamizers followed by rigid fixation during the consolidation period. Healing was assessed using radiographs, micro-computed tomography, histological analysis, and mechanical testing. Radiographic evaluation showed earlier regenerate formation in the DF and RD groups compared with the SF group. After the distraction and consolidation periods were completed, the regenerate formed under the conditions of RD had less trabeculation, higher bone mineral density, and smaller total and bone volumes, and were stronger in torsion compared with the SF and DF groups. This appearance is characteristic of advanced remodeling, returning closest to the values of intact bone. The DF group also had evidence of an interzone (radiolucent fibrous zone) at the end of the consolidation period. Application of the reverse dynamization regimen during distraction osteogenesis accelerated formation, maturation, and remodeling of regenerate bone. The findings of this study have important implications in the clinical setting, as reverse dynamization may lead to shorter treatment times and potentially lower prevalence of complications for patients needing distraction osteogenesis.

Reverse Dynamization Accelerates Bone-Healing in a Large-Animal Osteotomy Model.

BACKGROUND: Reverse dynamization is a mechanical manipulation regimen designed to accelerate bone-healing and remodeling. It is based on the hypothesis that a fracture that is initially stabilized less rigidly allows micromotion to encourage initial cartilaginous callus formation. Once substantial callus has formed, the stabilization should then be converted to a rigid configuration to prevent the disruption of neovascularization. The aim of the present study was to investigate whether bone-healing can be accelerated using a regimen of reverse dynamization in a large-animal osteotomy model. METHODS: Transverse 2-mm tibial osteotomies were created in 18 goats, stabilized using circular external fixation, and divided into groups of 6 goats each: static fixation (rigid fixation), dynamic fixation (continuous micromotion using dynamizers), and reverse dynamization (initial micromotion using dynamizers followed by rigid fixation at 3 weeks postoperatively). Healing was assessed with the use of radiographs, micro-computed tomography, and mechanical testing. RESULTS: Radiographic evaluation showed earlier and more robust callus formation in the dynamic fixation and reverse dynamization groups compared with the static fixation group. After 8 weeks of treatment, the reverse dynamization group had reduced callus size, less bone volume, higher bone mineral density, and no evidence of radiolucent lines compared with the static fixation and dynamic fixation groups. This appearance is characteristic of advanced remodeling, returning closest to the values of intact bone. Moreover, the tibiae in the reverse dynamization group were significantly stronger in torsion compared with those in the static fixation and dynamic fixation groups. CONCLUSIONS: These findings confirmed that tibial osteotomies under reverse dynamization healed faster, healed objectively better, and were considerably stronger, all suggesting an accelerated healing and remodeling process. CLINICAL RELEVANCE: This study demonstrates that the concept of reverse dynamization challenges the current understanding regarding the optimal fixation stability necessary to maximize the regenerative capacity of bone-healing. When reverse dynamization is employed in the clinical setting, it may be able to improve the treatment of fractures by reducing the time to union and potentially lowering the risk of delayed union and nonunion.

Comparative Stiffness Characteristics of Ilizarov- and Hexapod-type External Frame Constructs.

BACKGROUND: The Ilizarov method and fixator are clinically recognised for the treatment of fractures, limb salvage and deformity correction. There have been extensive studies determining the basic mechanism for fracture healing using this technique. It is generally accepted that circular frames optimise the mechanical environment by reducing shear strain across the fracture while maintaining axial micromotion so as to promote fracture healing. There have been several new hexapod-type frames introduced into the market over the past 20 years with little comparative research into their biomechanical properties and resultant effects on the fracture environment. QUESTIONS/PURPOSES: To investigate the biomechanical behaviours of the TrueLok-Hex (TL-HEX) and Taylor spatial frame (TSF) hexapod-type circular external fixators with comparison to traditional Ilizarov-type (TL-Ilizarov and TSF-Ilizarov) constructs and potential performance in vivo. METHODS: Testing was performed on standardised four-ring TSF and TL-HEX constructs matched by identical frames using Ilizarov threaded rod constructs for each set of components. All frames were tested under physiological levels of axial, bending and torsional loading. Load-deformation properties for each construct under each mode of loading were calculated and analysed statistically using ANOVA. RESULTS: Under axial loading, the Ilizarov construct utilising TL-HEX components demonstrated the greatest rigidity followed by the Ilizarov construct using TSF components. Under bending loads, the difference in rigidity between constructs was similar but less marked. Under torsional loading, both hexapod frames were seen to be significantly more rigid than the Ilizarov constructs. Overall deformation around neutral loading was much higher in the TSF frame due to an observed significant "toe-in" laxity in the strut universal joints. The remaining deformation of both hexapod frames was similar with a higher level of TL-HEX rigidity in axial loading and a higher level of TSF rigidity in bending and torsion. CONCLUSION: In conclusion, both hexapod frame constructs were less rigid under axial loading but more rigid under bending and torsional loads than their comparative Ilizarov constructs. As a result of their Cardan universal joints, the TSF demonstrated greater overall planar strain due to the observed "toe-in" laxity around neutral loading while the TL-HEX, with ball-and-socket universal joints, demonstrated a minimal level of laxity. Beyond the initial deformation due to the preloaded laxity, both hexapod frames responded to loading in a similar manner. There were significant differences in the frames' mechanical behaviour under different loading conditions but further research is required to determine whether these translate in vivo into clinical significance. HOW TO CITE THIS ARTICLE: Fenton C, Henderson D, Samchukov M, et al. Comparative Stiffness Characteristics of Ilizarov- and Hexapod-type External Frame Constructs. Strategies Trauma Limb Reconstr 2021;16(3):138-143.

Narrative review of ring fixator management of recurrent club foot deformity.

Despite the widespread use of the Ponseti method for treatment of clubfeet, there continue to be a significant number of patients who present with a severe, stiff clubfoot as a result of extensive intra-articular soft tissue release or lack of access to care. In such patients, circular external fixators can be utilized for deformity correction with distraction across soft tissues, joints, and osteotomies. Ilizarov or hexapod circular fixators may be utilized according to surgeon preference. Indications for soft tissue release and osteotomies to aid in correction of clubfoot deformity with Ilizarov and hexapod fixators are not standardized and are guided by patient age, joint congruity, soft tissue suppleness, and osseous deformity. Correction time varies according to clubfoot deformity severity. Following deformity correction, external fixators are left in place for several weeks to stabilize the soft tissues and allow for osteotomy healing. Complications range from relatively minor pin tract infections that resolve with oral antibiotics to tarsal tunnel syndrome, osteomyelitis, or disabling arthritis requiring revision procedures. At Scottish Rite Hospital for Children, we prefer to correct severe residual clubfoot deformity with a hexapod external fixator. Acute correction and gradual correction via distraction are considered for each segmental deformity and utilized to efficiently correct deformity while minimizing soft tissue trauma. The purpose of this article is to summarize the relevant literature related to circular external fixator treatment of recurrent clubfoot deformity and outline our approach to the segmental deformities of the foot and ankle in this patient population.

Real-Time Monitoring with a Controlled Advancement Drill May Decrease Plunge Depth.

BACKGROUND: Although drill use is fundamental to orthopaedic surgery, the risk of plunging past the far cortex and potentially damaging the surrounding soft tissues remains unavoidable with conventional drilling methods. A dual motor drill may decrease that risk by providing controlled drill-bit advancement and real-time monitoring of depth and energy expenditure. We hypothesized that using the dual motor drill would decrease plunge depth regardless of the user's level of experience. METHODS: Sixty-six subjects of varying operative experience (20 attending orthopaedic surgeons, 20 orthopaedic surgery residents, and 26 senior medical students) drilled 3 holes with a conventional drill and 3 holes with a dual motor drill in a bicortical Sawbones block set in ballistic gel. The depth of drill penetration into the ballistic gel was measured for each hole using a digital caliper. RESULTS: Overall, subjects plunged less with the dual motor drill (0.9 mm) than with the conventional drill (4.2 mm) (p < 0.001). This finding was consistent within each group: attending surgeons (0.9 compared with 3.2 mm; p = 0.02), residents (1.0 compared with 3.0 mm; p < 0.001), and students (0.7 compared with 6.0 mm; p < 0.001). Plunge depths were also stratified into 3 categories: 0 to <2 mm, 2 to 5 mm, and >5 mm. Using the dual motor drill, subjects were more likely to plunge <2 mm (97% plunged, on average, 0 to <2 mm and 3% plunged, on average, 2 to 5 mm), whereas subjects were more likely to plunge deeper with the conventional drill (27% plunged, on average, 0 to <2 mm, 45% plunged, on average, 2 to 5 mm, and 27% plunged, on average, >5 mm). Notably, no subject plunged ≥2 mm on the third attempt with the dual motor drill. Attending surgeons (p = 0.02) and residents (p = 0.01) plunged less than students with the conventional drill. There was no significant difference between attending surgeons and residents with the conventional drill (p = 0.96). There was no significant difference in plunge depth between groups using the dual motor drill. CONCLUSIONS: The dual motor drill significantly decreased plunge depth for both surgically experienced and inexperienced subjects. Although inexperienced subjects performed worse with the conventional drill than those with experience, there was no difference in their performance with the dual motor drill. CLINICAL RELEVANCE: Use of a controlled advancement drill may decrease the chance of plunge-related neurovascular injury during in vivo drilling.

Cross-diffusion in a water-in-oil microemulsion loaded with malonic acid or ferroin. Taylor dispersion method for four-component systems.

We describe an improved Taylor dispersion method for four-component systems, which we apply to measure the main- and cross-diffusion coefficients in an Aerosol OT water-in-oil microemulsion loaded with one of the reactants of the Belousov-Zhabotinsky (BZ) reaction, water(1)/AOT(2)/R(3)/octane(4) system, where R is malonic acid or ferroin. With [H(2)O]/[AOT] = 11.8 and volume droplet fraction phi d = 0.18, when the microemulsion is below the percolation transition, the cross-diffusion coefficients D(13) and D(23) are large and positive ( D(13)/ D(33) congruent with 14, D(23)/ D(33) congruent with 3) for malonic acid and large and negative for ferroin ( D(13)/ D(33) congruent with -112, D(23)/ D(33) congruent with -30) while coefficients D(31) and D(32) are small and negative for malonic acid ( D(31)/ D(33) congruent with -0.01, D(32)/ D(33) congruent with -0.14) and small and positive for ferroin ( D(31)/ D(33) congruent with 5 x 10(-4), D(32)/ D(33) congruent with 8 x 10(-3)). These data represent the first direct determination of cross-diffusion effects in a pattern-forming system and of the full matrix of diffusion coefficients for a four-component system. The results should provide a basis for modeling pattern formation in the BZ-AOT system.

Discontinuously propagating waves in the bathoferroin-catalyzed Belousov-Zhabotinsky reaction incorporated into a microemulsion.

Three new types of discontinuously propagating waves are reported in the bathoferroin-catalyzed Belousov-Zhabotinsky (BZ) reaction dispersed in water-in-oil Aerosol OT microemulsion. Jumping waves (JWs) are typically observed at or above room temperature and develop from the familiar trigger waves. Bubble waves (BWs) typically emerge from trigger or JWs at similar temperatures, while rotating waves (RWs) evolve from JW at higher temperatures (>40 degrees C). All these waves propagate discontinuously in a saltatory fashion. Other characteristic features include a discontinuous front for BW consisting of small concentric waves (bubbles) and lateral rotation of annular RWs. All three types of waves, as well as segmented but continuously propagating waves, can coexist. A simple model that is able to describe both jumping and segmented waves is described.

Treatment Strategies and Frame Configurations in the Management of Foot and Ankle Deformities.

To provide standardized nomenclature for various hexapod frame configurations for foot and ankle deformity correction, a unique classification of the hexapod external fixators was proposed. This classification is based on number of correction levels, secured anatomic blocks, and direction of the strut attachment. It allows the combination of all different foot and ankle frame assemblies into a few standard hexapod configurations, irrespective of which external fixator is used.

Photoinduction of electron transport on the acceptor side of PSI in Synechocystis PCC 6803 mutant deficient in flavodiiron proteins Flv1 and Flv3.

After transferring the dark-acclimated cyanobacteria to light, flavodiiron proteins Flv1/Flv3 serve as a main electron acceptor for PSI within the first seconds because Calvin cycle enzymes are inactive in the dark. Synechocystis PCC 6803 mutant Δflv1/Δflv3 devoid of Flv1 and Flv3 retained the PSI chlorophyll P700 in the reduced state over 10 s (Helman et al., 2003; Allahverdiyeva et al., 2013). Study of P700 oxidoreduction transients in dark-acclimated Δflv1/Δflv3 mutant under the action of successive white light pulses separated by dark intervals of various durations indicated that the delayed oxidation of P700 was determined by light activation of electron transport on the acceptor side of PSI. We show that the light-induced redox transients of chlorophyll P700 in dark-acclimated Δflv1/Δflv3 proceed within 2 min, as opposed to 1-3 s in the wild type, and comprise a series of kinetic stages. The release of rate-limiting steps was eliminated by iodoacetamide, an inhibitor of Calvin cycle enzymes. Conversely, the creation with methyl viologen of a bypass electron flow to O2 accelerated P700 oxidation and made its extent comparable to that in the wild-type cells. The lack of major sinks for linear electron flow in iodoacetamide-treated Δflv1/Δflv3 mutant, in which O2- and CO2-dependent electron flows were impaired, facilitated cyclic electron flow, which was evident from the decreased steady-state oxidation of P700 and from rapid dark reduction of P700 during and after illumination with far-red light. The results show that the photosynthetic induction in wild-type Synechocystis PCC 6803 is largely hidden due to the flavodiiron proteins whose operation circumvents the rate-limiting electron transport steps controlled by Calvin cycle reactions.

Biomechanical Considerations in Foot and Ankle Circular External Fixation: Maintenance of Wire Tension.

Initial tensioning of the forefoot wires to 130 kg followed by simultaneous tensioning of the calcaneal wires to 90 kg and using the rigid double-row foot plate closed anteriorly via threaded rods produce maximum preservation of the initial wire tension during foot circular external fixation.

Self-Organization Induced by Self-Assembly in Microheterogeneous Reaction-Diffusion System.

When acrylamide (AA) monomers are added to the Belousov-Zhabotinsky (BZ) reaction incorporated into nanodroplets of water-in-oil aerosol OT (AOT) microemulsion (the BZ-AOT system), free radicals produced in the BZ reaction initiate polymerization of AA monomers and polyacrylamide particles are formed. These particles change the microstructure of the AOT microemulsion thus inducing the transition from Turing patterns to new dissipative patterns which can be either stationary "black" spots or waves.

Deformity correction in pediatric skeletal dysplasia: treatment challenges and solutions.

We reviewed our experience with limb-deformity correction in 54 children with skeletal dysplasias. Our goal was to outline common treatment strategies developed in our hospital to overcome the challenges associated with the management of these conditions. Utilization of computer-assisted preoperative planning, intraoperative monitoring of peripheral nerve function, individualized bone segment stabilization using a modular circular external fixation system, and a flexible distraction protocol improved the precision of angular deformity correction in our practice, simplified external fixator assembly, diminished postoperative frame modifications, enhanced the stability of fixation, and reduced the rate of complications.

Evaluation of complications of treatment of severe Blount's disease by circular external fixation using a novel classification scheme.

Corrective osteotomy for recalcitrant varus deformity secondary to adolescent and infantile Blount's disease can be challenging because of a combination of severity of deformity, complexity of deformity, and frequent association with patient obesity. We present here the outcome of treatment by osteotomy and gradual deformity correction by circular external fixation in 31 patients with either infantile or adolescent Blount's disease. We used a unique classification scheme to quantify and qualify complications in this patient group: category I, complications not requiring an alteration in the treatment plan, not involving unplanned return to surgery, and not influencing outcome; category II, complications requiring an alteration in the treatment plan, including unplanned returns to surgery, but that did not influence outcome; category IIIA, complications that resulted in a failure to achieve treatment goals; and category IIIB, complications that resulted in a failure to achieve treatment goals and the development of a new pathology or worsening of patient condition. All but one patient in this group incurred at least one complication. However, despite the complex nature of this patient population, 88% achieved satisfactory correction without developing category IIIA or IIIB complications. Careful selection of patients and vigilant postoperative management can result in excellent outcomes with circular external fixation and gradual correction in this challenging patient population.

Lengthening in Congenital Femoral Deficiency: A Comparison of Circular External Fixation and a Motorized Intramedullary Nail.

BACKGROUND: Circular external fixation for limb-lengthening is associated with frequent and numerous complications. Intramedullary lengthening devices represent a potential advance in limb-lengthening. The purpose of this study was to compare the outcomes of femoral lengthening in pediatric patients treated by either circular external fixation or a motorized intramedullary nail. METHODS: All patients with a diagnosis of congenital femoral deficiency who had undergone femoral lengthening with either circular external fixation or a motorized intramedullary nail were identified. The motorized intramedullary nail (FITBONE) was used with approval of the U.S. Food and Drug Administration on an individual compassionate-use basis. RESULTS: Fourteen skeletally mature patients underwent fourteen femoral lengthening sessions using circular external fixation, and thirteen patients underwent fifteen lengthening sessions using the motorized nail. The amount lengthened was similar, with a mean of 4.8 cm (range, 1.0 to 7.4 cm) in the circular fixation group and 4.4 cm (range, 1.5 to 7.0 cm) in the motorized nail group. Complications occurred in all lengthening sessions in all fourteen patients managed with the circular external fixation and in 73% of fifteen lengthening sessions in the thirteen patients managed with the motorized nail. The circular external fixation group averaged 2.36 complications per lengthening session compared with 1.2 per session in the motorized nail group. Twenty-nine percent of the circular fixation group failed to achieve a lengthening goal of at least 4 cm compared with 27% of the motorized nail group who failed to reach the goal. Eight patients had undergone eleven femoral lengthening sessions with circular external fixation prior to undergoing ten lengthening sessions by motorized nail. These patients had a comparable rate of complications with both types of lengthening, but the total number of complications averaged 2.6 per lengthening session with circular external fixation compared with 1.6 per lengthening session with the motorized nail. CONCLUSIONS: A decreased number of complications was noted with use of a motorized intramedullary nail compared with circular external fixation in pediatric patients undergoing femoral lengthening for congenital femoral deficiency. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.