Tallo: A global tree allometry and crown architecture database.

Data capturing multiple axes of tree size and shape, such as a tree's stem diameter, height and crown size, underpin a wide range of ecological research-from developing and testing theory on forest structure and dynamics, to estimating forest carbon stocks and their uncertainties, and integrating remote sensing imagery into forest monitoring programmes. However, these data can be surprisingly hard to come by, particularly for certain regions of the world and for specific taxonomic groups, posing a real barrier to progress in these fields. To overcome this challenge, we developed the Tallo database, a collection of 498,838 georeferenced and taxonomically standardized records of individual trees for which stem diameter, height and/or crown radius have been measured. These data were collected at 61,856 globally distributed sites, spanning all major forested and non-forested biomes. The majority of trees in the database are identified to species (88%), and collectively Tallo includes data for 5163 species distributed across 1453 genera and 187 plant families. The database is publicly archived under a CC-BY 4.0 licence and can be access from: https://doi.org/10.5281/zenodo.6637599. To demonstrate its value, here we present three case studies that highlight how the Tallo database can be used to address a range of theoretical and applied questions in ecology-from testing the predictions of metabolic scaling theory, to exploring the limits of tree allometric plasticity along environmental gradients and modelling global variation in maximum attainable tree height. In doing so, we provide a key resource for field ecologists, remote sensing researchers and the modelling community working together to better understand the role that trees play in regulating the terrestrial carbon cycle.

National level E-Resource Centre for Tobacco Control (E-RCTC): One stop solution to information on tobacco control in India.

The existing information on tobacco control, though highly valuable, is lying scattered at different sources. Post Graduate Institute of Medical Education and Research (PGIMER) Chandigarh in collaboration and technical support of International Union against TB and Lung Diseases (The Union) undertook an initiative to start a national level E-Resource Centre for Tobacco Control (E-RCTC) with an aim to provide relevant information on tobacco control under one roof thereby countering the misleading facts on tobacco control which exist on various web engines. The national level E-Resource Centre for Tobacco Control was developed in three stages. In the span of less than 3 years, the portal is open in public domain with over 2,36,019 visitors from around 80+ countries (as on 23rd July 2020), and growing. The portal showcases an array of valuable and vital information related to tobacco control initiatives under various heads like: Policies and Legislations, Circulars and Orders, National Tobacco Control Programme (NTCP), Publications and IEC Materials. India's first national level Resource Centre for Tobacco Control has proved to be a much-needed step in the country for facilitating speedy implementation of World Health Organization- Framework Convention on Tobacco Control (WHO-FCTC), MPOWER and other tobacco control interventions. Even with its limitations like absence of an interactive mechanism among a few others, the Resource Centre is nothing less than a storehouse of knowledge as it showcases content that are immensely helpful for the tobacco control community. Constant efforts are being made to improve the national level E-Resource Centre for Tobacco Control website and minimize the drawbacks.

Second-harmonic generation microscopy analysis reveals proteoglycan decorin is necessary for proper collagen organization in prostate.

Collagen remodeling occurs in many prostate pathologies; however, the underlying structural architecture in both normal and diseased prostatic tissues is largely unexplored. Here, we use second-harmonic generation (SHG) microscopy to specifically probe the role of the proteoglycan decorin (Dcn) on collagen assembly in a wild type (wt) and Dcn null mouse (Dcn - / - ). Dcn is required for proper organization of collagen fibrils as it regulates size by forming an arch-like structure at the end of the fibril. We have utilized SHG metrics based on emission directionality (forward-backward ratio) and relative conversion efficiency, which are both related to the SHG coherence length, and found more disordered fibril organization in the Dcn - / - . We have also used image analysis readouts based on entropy, multifractal dimension, and wavelet transforms to compare the collagen fibril/fiber architecture in the two models, where all these showed that the Dcn - / - prostate comprised smaller and more disorganized collagen structures. All these SHG metrics are consistent with decreased SHG phase matching in the Dcn - / - and are further consistent with ultrastructural analysis of collagen in this model in other tissues, which show a more random distribution of fibril sizes and their packing into fibers. As Dcn is a known tumor suppressor, this work forms the basis for future studies of collagen remodeling in both malignant and benign prostate disease.

RNA Aptamers Rescue Mitochondrial Dysfunction in a Yeast Model of Huntington's Disease.

Huntington's disease (HD) is associated with the misfolding and aggregation of mutant huntingtin harboring an elongated polyglutamine stretch at its N terminus. A distinguishing pathological hallmark of HD is mitochondrial dysfunction. Any strategy that can restore the integrity of the mitochondrial environment should have beneficial consequences for the disease. Specific RNA aptamers were selected that were able to inhibit aggregation of elongated polyglutamine stretch containing mutant huntingtin fragment (103Q-htt). They were successful in reducing the calcium overload, which leads to mitochondrial membrane depolarization in case of HD. In one case, the level of Ca2+ was restored to the level of cells not expressing 103Q-htt, suggesting complete recovery. The presence of aptamers was able to increase mitochondrial mass in cells expressing 103Q-htt, along with rescuing loss of mitochondrial genome. The oxidative damage to the proteome was prevented, which led to increased viability of cells, as monitored by flow cytometry. Thus, the presence of aptamers was able to inhibit aggregation of mutant huntingtin fragment and restore mitochondrial dysfunction in the HD cell model, confirming the advantage of the strategy in a disease-relevant parameter.

Polarization-resolved second harmonic generation imaging of human ovarian cancer.

Remodeling of the extracellular matrix in human ovarian cancer can be manifested in increased collagen concentration, changes in alignment within fibrils/fibers and/or up-regulation of different collagen isoforms. We used pixel-based second harmonic generation (SHG) polarization microscopy analyses to probe these molecular changes in human ovarian tissues [normal stroma, benign tumors, and high-grade serous (HGS) tumors] by: (i) determination of the α-helical pitch angle via the single-axis molecular model, (ii) collagen alignment within fibrils via SHG anisotropy, and (iii) chirality via SHG circular dichroism (SHG-CD). Pixel approaches are required due to the complex structure of the matrix that lacks a high degree of fiber alignment. The largest differences in the helical pitch angle were between normal stroma and benign tumors, consistent with gene expression showing the Col III isoform is up-regulated in the latter. The data were not consistent with up-regulation of Col III in HGS tumors as previous reports have suggested. The different tissues also displayed differing SHG anisotropies and SHG-CD responses, consistent with either Col III incorporation or randomization of Col I alignment within benign and malignant tumors. Additionally, the high-grade tumors displayed higher collagen concentration, where this desmoplasia is consistent with the higher fiber density in these tissues. These results collectively indicate that the fibril assemblies are distinct in all tissues, where these differences likely result from the synthesis of collagen rather than remodeling of existing collagen. Importantly, these analyses are label-free and interrogate subresolution collagen structure on intact tissues, without the need for conventional structural biology tools.

Maternal Diets Deficient in Vitamin D Increase the Risk of Kyphosis in Offspring: A Novel Kyphotic Porcine Model.

BACKGROUND: The purpose of this study was to explore the role of perinatal vitamin-D intake on the development and characterization of hyperkyphosis in a porcine model. METHODS: The spines of 16 pigs were assessed at 9, 13, and 17 weeks of age with radiography and at 17 weeks with computed tomography (CT), magnetic resonance imaging (MRI), histology, and bone-density testing. An additional 169 pigs exposed to 1 of 3 maternal dietary vitamin-D levels from conception through the entire lactation period were fed 1 of 4 nursery diets supplying different levels of vitamin D, calcium, and phosphorus. When the animals were 13 weeks of age, upright lateral spinal radiography was performed with use of a custom porcine lift and sagittal Cobb angles were measured in triplicate to determine the degree of kyphosis in each pig. RESULTS: The experimental animals had significantly greater kyphotic sagittal Cobb angles at all time points when compared with the control animals. These hyperkyphotic deformities demonstrated no significant differences in Hounsfield units, contained a slightly lower ash content (46.7% ± 1.1% compared with 50.9% ± 1.6%; p < 0.001), and demonstrated more physeal irregularities. Linear mixed model analysis of the measured kyphosis demonstrated that maternal diet had a greater effect on sagittal Cobb angle than did nursery diet and that postnatal supplementation did not completely eliminate the risk of hyperkyphosis. CONCLUSIONS: Maternal diets deficient in vitamin D increased the development of hyperkyphosis in offspring in this model. CLINICAL RELEVANCE: This study demonstrates that decreased maternal dietary vitamin-D intake during pregnancy increases the risk of spinal deformity in offspring. In addition, these data show the feasibility of generating a large-animal spinal-deformity model through dietary manipulation alone.

Advanced quantitative imaging and biomechanical analyses of periosteal fibers in accelerated bone growth.

PURPOSE: The accepted mechanism explaining the accelerated growth following periosteal resection is that the periosteum serves as a mechanical restraint to restrict physeal growth. To test the veracity of this mechanism we first utilized Second Harmonic Generation (SHG) imaging to measure differences of periosteal fiber alignment at various strains. Additionally, we measured changes in periosteal growth factor transcription. Next we utilized SHG imaging to assess the alignment of the periosteal fibers on the bone both before and after periosteal resection. Based on the currently accepted mechanism, we hypothesized that the periosteal fibers adjacent to the physis should be more aligned (under tension) during growth and become less aligned (more relaxed) following metaphyseal periosteal resection. In addition, we measured the changes in periosteal micro- and macro-scale mechanics. METHODS: 30 seven-week old New Zealand White rabbits were sacrificed. The periosteum was imaged on the bone at five regions using SHG imaging. One centimeter periosteal resections were then performed at the proximal tibial metaphyses. The resected periosteal strips were stretched to different strains in a materials testing system (MTS), fixed, and imaged using SHG microscopy. Collagen fiber alignment at each strain was then determined computationally using CurveAlign. In addition, periosteal strips underwent biomechanical testing in both circumferential and axial directions to determine modulus, failure stress, and failure strain. Relative mRNA expression of growth factors: TGFß-1, -2, -3, Ihh, PTHrP, Gli, and Patched were measured following loading of the periosteal strips at physiological strains in a bioreactor. The periosteum adjacent to the physis of six tibiae was imaged on the bone, before and after, metaphyseal periosteal resection, and fiber alignment was computed. One-way ANOVA statistics were performed on all data. RESULTS: Imaging of the periosteum at different regions of the bone demonstrated complex regional differences in fiber orientation. Increasing periosteal strain on the resected strips increased periosteal fiber alignment (p<0.0001). The only exception to this pattern was the 10% strain on the tibial periosteum, which may indicate fiber rupture at this non-physiologic strain. Periosteal fiber alignment adjacent to the resection became less aligned while those adjacent to the physes remained relatively unchanged before and after periosteal resection. Increasing periosteal strain on the resected strips increased periosteal fiber alignment (p<0.0001). The only exception to this pattern was the 10% strain on the tibial periosteum, which may indicate fiber rupture (and consequent retraction) at this non-physiologic strain. Increasing periosteal strain revealed a significant increase in relative mRNA expression for Ihh, PTHrP, Gli, and Patched, respectively. CONCLUSION: Periosteal fibers adjacent to the growth plate do not appear under tension in the growing limb, and the alignments of these fibers remain unchanged following periosteal resection. SIGNIFICANCE: The results of this study call into question the long-accepted role of the periosteum acting as a simple mechanical tether restricting growth at the physis.

Specific detection of tetanus toxoid using an aptamer-based matrix.

Batch-to-batch variation of therapeutic proteins produced by biological means requires rigorous monitoring at all stages of the production process. A large number of animals are employed for risk assessment of biologicals, which has low ethical and economic acceptability. Research is now focussed on the validation of in vitro and ex vivo tests to replace live challenges. Among in vitro methods, enzyme-linked immunosorbent assay (ELISA) is considered to be the gold standard for estimation of integrity of tetanus toxoid. ELISA utilizes antibodies for detection, which, because of their biological origin and limited modifiability, may have low stability and result in irreproducibility. We have developed a method using highly specific and selective RNA aptamers for detection of tetanus toxoid. Using displacement assay, we first identified aptamers which bind to different aptatopes on the surface of the toxoid. Pairs of these aptamers were employed as capture-detection ligands in a sandwich-ALISA (aptamer-linked immobilized sorbent assay) format. The binding efficiency was confirmed by the fluorescence intensity in each microtire plate well. Using aptamers alone, detection of tetanus toxoid was possible with the same level of sensitivity as antibody. Aptamers were also used in the capture ALISA format. Adjuvanted tetanus toxoid was subjected to accelerated stress testing, including thermal, mechanical and freeze-thawing stress conditions. The loss in antigenicity of the preparation determined by ALISA in each case was found to be similar to that determined by conventional ELISA. Thus, it is possible to replace antibodies with aptamers to develop a more robust detection tool for tetanus toxoid.

Accuracy of model-based tracking of knee kinematics and cartilage contact measured by dynamic volumetric MRI.

The purpose of this study was to determine the accuracy of knee kinematics and cartilage contact measured by volumetric dynamic MRI. A motor-actuated phantom drove femoral and tibial bone segments through cyclic 3D motion patterns. Volumetric images were continuously acquired using a 3D radially undersampled cine spoiled gradient echo sequence (SPGR-VIPR). Image data was binned based on position measured via a MRI-compatible rotary encoder. High-resolution static images were segmented to create bone models. Model-based tracking was performed by optimally registering the bone models to the volumetric images at each frame of the SPGR-VIPR series. 3D tibiofemoral translations and orientations were reconstructed, and compared to kinematics obtained by tracking fiducial markers. Imaging was repeated on a healthy subject who performed cyclic knee flexion-extension. Cartilage contact for the subject was assessed by measuring the overlap between articular cartilage surfaces. Model-based tracking was able to track tibiofemoral angles and translations with precisions less than 0.8° and 0.5mm. These precisions resulted in an uncertainty of less than 0.5mm in cartilage contact location. Dynamic SPGR-VIPR imaging can accurately assess in vivo knee kinematics and cartilage contact during voluntary knee motion performed in a MRI scanner. This technology could facilitate the quantitative investigation of links between joint mechanics and the development of osteoarthritis.

Periosteal Fiber Transection During Periosteal Procedures Is Crucial to Accelerate Growth in the Rabbit Model.

BACKGROUND: Disruption of the periosteum has been used to explain overgrowth after long bone fractures. Clinically, various periosteal procedures have been reported to accelerate growth with varied results. Differences between procedures and study populations, in these prior studies, make drawing conclusions regarding their effectiveness difficult. QUESTIONS/PURPOSES: The purpose of this study was to (1) determine if all reported periosteal procedures accelerate growth and increase the length of bones; (2) study the relative duration of these growth-accelerating effects at two time points; and (3) identify the periosteal procedure that results in the most growth. METHODS: Periosteal stripping (N = 8), periosteal transection (N = 8), periosteal resection (N = 8), (and) full periosteal release (N = 8) were performed on the tibiae of skeletally immature rabbits. Tibiae were collected 2 weeks postoperatively. The tibiae of additional cohorts of periosteal transection (N = 8), periosteal resection (N = 8), full periosteal release (N = 8), and repetitive periosteal transection (N = 8) were collected 8 weeks postoperatively. The contralateral tibiae served as an operative sham control in all cohorts. Fluorochrome bone labeling was used to measure growth rates, whereas high-resolution Faxitron imaging was performed to measure tibial lengths. Comparisons were then made between (1) experimental and sham controls; and (2) different procedures. Eight additional nonsurgical animals were included as age-matched controls. RESULTS: Growth (in microns) was accelerated at the proximal tibial physis on the tibia undergoing the periosteal surgical procedures versus the contralateral control limb after the transection (411 ± 27 versus 347 ± 18, p < 0.001 [mean ± SD]), resection (401 ± 33 versus 337 ± 31, p < 0.001), and full periosteal release (362 ± 45 versus 307 ± 33, p < 0.001), 2 weeks after the index procedure. Conversely, the periosteal stripping cohort trended toward less growth (344 ± 35) than the controls (356 ± 25; p = 0.08). No differences were found between limbs in the nonoperative controls. Tibial lengths for the experimental tibiae were longer at 2 weeks in the transection (1.6 ± 0.4 mm, p < 0.001), resection (1.6 ± 0.9 mm, p = 0.03), and full periosteal release (1.7 ± 0.5 mm, p < 0.001), whereas negligible differences were found between the tibiae of the nonoperative controls (0.13 ± 0.7 mm, p = 0.8) and stripping cohorts (0.10 ± 0.6 mm, p = 0.7). At 8 weeks, growth acceleration ceased at the proximal tibial physes in the transection cohort (174 ± 11 versus 176 ± 21, p = 0.8), and the control limbs actually grew faster than the experimental limbs after resection (194 ± 24 versus 178 ± 23, p = 0.02) and full periosteal release (193 ± 16 versus 175 ± 19, p < 0.01) cohorts. Growth rates were increased over control limbs, only in the repetitive transection cohort (190 ± 30 versus 169 ± 19, p = 0.01) at 8 weeks. Tibial lengths for the experimental tibiae remained longer at 8 weeks in the transection (1.4 ± 0.70 mm, p < 0.001), resection (2.2 ± 0.82 mm, p < 0.001), full periosteal release (1.6 ± 0.42 mm, p < 0.001), and repetitive periosteal transection (3.3 ± 1.1 mm, p < 0.001), whereas negligible differences were found between the tibiae of the nonoperative controls (-0.08 ± 0.58 mm, p = 0.8). Comparing the procedures at 2 weeks postoperatively, no differences were found in tibial lengths among the transection (2.1% ± 0.5% increase), resection (2.1% ± 1.1% increase), and full periosteal release (2.1% ± 0.6 %); however, all three demonstrated greater increased growth when compared with the stripping cohort (-0.10% ± 0.7%; p < 0.05). At 8 weeks no differences could be found between increased tibial lengths among the transection (1.5% ± 0.7%), resection (2.3% ± 0.9%), and full periosteal release (1.7% ± 0.4%). The repetitive transection produced the greatest over length increase (3.5% ± 1%), and this was greater than the acceleration generated by the single resection (p < 0.001) or the full periosteal release (p = 0.001). All four demonstrated an increase greater than the nonoperative control (0.09% ± 0.6%; p < 0.05). CONCLUSIONS: Transection of the longitudinally oriented periosteal fibers appears critical to accelerate growth in a rabbit model. CLINICAL RELEVANCE: These findings in an animal model support previous claims that limb overgrowth occurs as the result of periosteal disruption. Based on these findings in rabbits, we believe that less invasive procedures like periosteal transection are a promising avenue to explore in humans; clinical studies should seek to determine whether it is equally effective as more invasive procedures and its role as an adjunct to guided growth or distraction osteogenesis.

Multicomponent T2 analysis of articular cartilage with synovial fluid partial volume correction.

PURPOSE: To investigate the use of a three-pool model to account for the confounding effects of synovial fluid on multicomponent T2 analysis of articular cartilage using Multicomponent Driven Equilibrium Single Shot Observation of T1 and T2 (mcDESPOT). MATERIALS AND METHODS: mcDESPOT was performed on the knee of eight asymptomatic volunteers and eight patients with osteoarthritis at 3.0T with multicomponent T2 maps created using the two-pool model and a three-pool model containing a nonexchanging synovial fluid water pool. The fraction of the fast-relaxing water component (FF ) and the T2 relaxation times for the fast-relaxing (T2F ) and slow-relaxing (T2S ) water components were measured in the superficial and deep layers of patellar cartilage using the two-pool and three-pool models in asymptomatic volunteers and patients with osteoarthritis and were compared using Wilcoxon signed rank tests. RESULTS: Within the superficial layer of patellar cartilage, FF was 22.5% and 25.6% for asymptomatic volunteers and 21.3% and 22.8% for patients with osteoarthritis when using the two-pool and three-pool models, respectively, while T2S was 73.9 msec and 62.0 msec for asymptomatic volunteers and 72.0 msec and 63.1 msec for patients with osteoarthritis when using the two-pool and three-pool models, respectively. For both asymptomatic volunteers and patients with osteoarthritis, the two-pool model provided significantly (P < 0.05) lower FF and higher T2S than the three-pool model, likely due to the effects of synovial fluid partial volume averaging. CONCLUSION: The effects of partial volume averaging between superficial cartilage and synovial fluid may result in biased multicomponent T2 measurements that can be corrected using an mcDESPOT three-pool model containing a nonexchanging synovial fluid water pool.

Inhibition of Aggregation of Mutant Huntingtin by Nucleic Acid Aptamers In Vitro and in a Yeast Model of Huntington's Disease.

Elongated polyglutamine stretch in mutant huntingtin (mhtt) correlates well with the pathology of Huntington's disease (HD). Inhibition of aggregation of mhtt is a promising strategy to arrest disease progression. In this work, specific, high-affinity RNA aptamers were selected against monomeric mhtt (51Q-htt). Some of them inhibited its aggregation in vitro by stabilizing the monomer. They also recognized 103Q-htt but not 20Q-htt (nonpathogenic length). Inhibition of aggregation corresponded with reduced leakage of a fluorescent probe from liposomes and diminished oxidative stress in RBCs. The presence of aptamers was able to rescue the sequestration of the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH) by aggregated mhtt. Some of the aptamers were able to enhance the partitioning of mhtt in the soluble fraction in a yeast model of HD. They were also able to rescue endocytotic defect due to aggregation of mhtt. The beneficial effect of a combination of aptamers was enhanced with improvement in cell survival. Since HD is a monogenic autosomal dominant disorder, aptamers may be developed as a viable strategy to slow down the progress of the disease. Since they are nonimmunogenic and nontoxic, aptamers may emerge as strong candidates to reduce protein-protein interaction and hence protein aggregation in protein misfolding disorders in general.

Articular cartilage zonal differentiation via 3D Second-Harmonic Generation imaging microscopy.

PURPOSE: The collagen structure throughout the patella has not been thoroughly investigated by 3D imaging, where the majority of the existing data come from histological cross sections. It is important to have a better understanding of the architecture in normal tissues, where this could then be applied to imaging of diseased states. METHODS: To address this shortcoming, we investigated the combined use of collagen-specific Second-Harmonic Generation (SHG) imaging and measurement of bulk optical properties to characterize collagen fiber orientations of the histologically defined zones of bovine articular cartilage. Forward and backward SHG intensities of sections from superficial, middle and deep zones were collected as a function of depth and analyzed by Monte Carlo simulations to extract the SHG creation direction, which is related to the fibrillar assembly. RESULTS: Our results revealed differences in SHG forward-backward response between the three zones, where these are consistent with a previously developed model of SHG emission. Some of the findings are consistent with that from other modalities; however, SHG analysis showed the middle zone had the most organized fibril assembly. While not distinct, we also report bulk optical property values for these different zones within the patella. CONCLUSIONS: Collectively, these results provide quantitative measurements of structural changes at both the fiber and fibril assembly of the different cartilage zones and reveals structural information not possible by other microscope modalities. This can provide quantitative insight to the collagen fiber network in normal cartilage, which may ultimately be developed as a biomarker for osteoarthritis.

Quantitative magnetic resonance imaging of the articular cartilage of the knee joint.

Osteoarthritis is characterized by a decrease in the proteoglycan content and disruption of the highly organized collagen fiber network of articular cartilage. Various quantitative magnetic resonance imaging techniques have been developed for noninvasive assessment of the proteoglycan and collagen components of cartilage. These techniques have been extensively used in clinical practice to detect early cartilage degeneration and in osteoarthritis research studies to monitor disease-related and treatment-related changes in cartilage over time. This article reviews the role of quantitative magnetic resonance imaging in evaluating the composition and ultrastructure of the articular cartilage of the knee joint.

Roles of Hsp104 and trehalose in solubilisation of mutant huntingtin in heat shocked Saccharomyces cerevisiae cells.

Inhibition of huntingtin aggregation, either in the nucleus and/or in the cytosol, has been identified as a major strategy to ameliorate the symptoms of Huntington's disease. Chaperones and other protein stabilisers would thus be key players in ensuring the correct folding of the amyloidogenic protein and its expression in the soluble form. By transient activation of the global heat stress response in Saccharomyces cerevisiaeBY4742, we show that heterologous expression of mutant huntingtin (103Q-htt) could be modulated so that the protein was partitioned off in the soluble fraction of the cytosol. This led to lower levels of reactive oxygen species and improved cell viability. Previous reports had speculated on the relationship between trehalose and the heat shock response in ensuring enhanced cell survival but no direct evidence of such an interaction was available. Using mutants of an isogenic strain which do not express the major trehalose synthetic or metabolising enzymes or the chaperone, heat shock protein 104 (Hsp104), we were able to identify the functions of Hsp104 and the osmoprotectant trehalose in solubilising mutant huntingtin. We propose that the beneficial effect of the protein refolding machinery in solubilising the aggregation-prone protein is exerted by maintaining a tight balance between the trehalose synthetic enzyme, trehalose-6-phosphate synthase 1 and Hsp104. This ensures that the level of the osmoprotectant, trehalose, does not exceed the limit beyond which it is reported to inhibit protein refolding.

Deciphering the roles of trehalose and Hsp104 in the inhibition of aggregation of mutant huntingtin in a yeast model of Huntington's disease.

Despite the significant amount of experimental data available on trehalose, the molecular mechanism responsible for its intracellular stabilising properties has not emerged yet. The repair of cellular homeostasis in many protein-misfolding diseases by trehalose is credited to the disaccharide being an inducer of autophagy, a mechanism by which aggregates of misfolded proteins are cleared by the cell. In this work, we expressed the pathogenic N-terminal fragment of huntingtin in Δnth1 mutant (unable to degrade trehalose) of Saccharomyces cerevisiae BY4742 strain. We show that the presence of trehalose resulted in the partitioning of the mutant huntingtin in the soluble fraction of the cell. This led to reduced oxidative stress and improved cell survival. The beneficial effect was independent of the expression of the major cellular antioxidant enzyme, superoxide dismutase. Additionally, trehalose led to the overexpression of the heat shock protein, Hsp104p, in mutant huntingtin-expressing cells, and resulted in rescue of the endocytotic defect in the yeast cell. We propose that at least in the initial stages of aggregation, trehalose functions as a stabiliser, increasing the level of monomeric mutant huntingtin protein, with its concomitant beneficial effects, in addition to its role as an inducer of autophagy.

Rapid multicomponent T2 analysis of the articular cartilage of the human knee joint at 3.0T.

PURPOSE: To determine the feasibility of using multicomponent-driven equilibrium single-shot observation of T1 and T2 (mcDESPOT) for evaluating the human knee joint at 3.0T and to investigate depth-dependent and regional-dependent variations in multicomponent T2 parameters within articular cartilage. MATERIALS AND METHODS: mcDESPOT was performed on the knee joint of 10 asymptomatic volunteers at 3.0T. Single-component T2 relaxation time (T2single ), multicomponent T2 relaxation time for water tightly bound to proteoglycan (T2PG ) and bulk water loosely bound to the macromolecular matrix (T2BW ), and fraction of water tightly bound to proteoglycan (FPG ) were measured in eight cartilage subsections and within the superficial and deep layers of patellar cartilage. Statistical analysis was used to investigate depth-dependent and regional-dependent variations in parameters. RESULTS: There was lower (P = 0.001) T2single and T2PG and higher (P < 0.001) FPG in the deep than superficial layer of patellar cartilage. There was higher (P < 0.001) FPG on the weight-bearing surfaces than nonweight-bearing surfaces. There was higher (P < 0.001) T2single , T2PG , and T2BW on the trochlea and posterior medial and lateral femoral condyles than the patella, central medial and lateral femoral condyles, and medial and lateral tibia plateaus. CONCLUSION: Multicomponent T2 parameters of the articular cartilage of the human knee joint can be measured at 3.0T using mcDESPOT and show depth-dependent and regional-dependent variations.

Bioball universal modular neck adapter as a salvage for failed revision total hip arthroplasty.

Management of recurrent dislocation of total hip arthroplasty is often a challenging and daunting task. Re-revision of such a total hip prosthesis may not be easy as the removal of a well-fixed, fully coated stem is extremely difficult. We managed to salvage instability in three revision hip cases in which the fully coated stem had subsided by using a bioball universal neck adapter without changing the femoral stem or acetabular cup.

Length of polyglutamine tract affects secondary and tertiary structures of huntingtin protein.

The role of polyglutamine (polyQ) tract on protein stability and disease pathology remains ambiguous. We monitored the unfolding/refolding patterns of huntingtin proteins with varying polyQ lengths. In the presence of urea, minor differences in unfolding and refolding efficiencies were observed. However, in the presence of guanidinium hydrochloride, the protein with a longer polyQ stretch was able to regain its secondary but not tertiary structure on step-wise removal of denaturant. Thus, in case of Huntington's disease, the higher aggregation propensity of the mutant protein is likely to be due to the lower stability of the protein due to elongated polyQ tract.

Effect of pesticides on the aggregation of mutant huntingtin protein.

The classical reports on neurodegeneration concentrate on studying disruption of signalling cascades. Although it is now well recognized that misfolding and aggregation of specific proteins are associated with a majority of these diseases, their role in aggravating the symptoms is not so well understood. Huntington's disease (HD) is a neurodegenerative disorder that results from damage to complex II of mitochondria. In this work, we have studied the effect of mitochondrial complex I inhibitors, viz. 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine and rotenone, and complex II inhibitor, viz. 3-nitropropionic acid, on the aggregation of mutant huntingtin (mthtt) protein, whose misfolding and aggregation results in cellular abnormalities characteristic of HD. All three inhibitors were found to accelerate the aggregation of mthtt in vitro, although the amounts of aggregates formed were different in all cases. Thus, apart from their effect on mitochondrial viability, these neurotoxins are capable of interfering with the protein aggregation process and thus, hastening the onset of the disease.