Pristane-induced arthritis in mice. III. Lymphocyte phenotypic and functional abnormalities precede the development of pristane-induced arthritis.

Pristane injection caused mediastinal lymphadenopathy in arthritis-susceptible DBA/1 mice, but not in arthritis-resistant DBA/2 mice. Early DBA/1 mediastinal lymph node changes were characterized by the accumulation of surface Ig+ cells and a CD8+ (Lyt 2) lymphocyte population, causing an inversion of the CD4/CD8 ratio. Depressed mitogen responses and the appearance of a nonspecific suppressor cell population were coincidental with the CD8+ cell accumulation. Prior to the development of overt clinical arthritis, an expansion of CD4+ (L3T4) lymphocytes displaced CD8+ as the predominant phenotype in mediastinal node. Mitogen responses were restored and suppressor cell activity was abrogated concomitant with the expansion of the CD4+ cell population.     

Dynamic changes in connexin expression correlate with key events in the wound healing process

Wound healing is a complex process requiring communication for the precise co-ordination of different cell types. The role of extracellular communication through growth factors in the wound healing process has been extensively documented, but the role of direct intercellular communication via gap junctions has scarcely been investigated. We have examined the dynamics of gap junction protein (Connexins 26, 30, 31.1 and 43) expression in the murine epidermis and dermis during wound healing, and we show that connexin expression is extremely plastic between 6 hours and 12 days post-wounding. The immediate response (6 h) to wounding is to downregulate all connexins in the epidermis, but thereafter the expression profile of each connexin changes dramatically. Here, we correlate the changing patterns of connexin expression with key events in the wound healing process.     

The cerebro-morphological fingerprint of a progeroid syndrome: white matter changes correlate with neurological symptoms in xeroderma pigmentosum

Background

Xeroderma pigmentosum (XP) is a rare autosomal recessive progeroid syndrome. It has recently been shown that the underlying DNA repair defect plays a central role in the aging process. In addition to skin symptoms, various premature neurological abnormalities have been reported.

Methodology/Principal Findings

We present the clinical neurological phenotype in 14 XP patients (seven subtypes), in seven of these patients together with conventional and multiparametric advanced MRI data to assess the macrostructural and microstructural cerebral morphology in comparison to controls, including volumetric measurements, MR spectroscopy (¹H MRS), and diffusion tensor imaging (DTI). Clinical hallmarks were spinocerebellar ataxia, pyramidal tract signs, and mild cognitive deficits. DTI demonstrated significantly reduced WM directionality in all regions investigated, i.e. the thalamus, the corticospinal tracts and the dorsal corpus callosum. Single patients showed a marked relative hippocampal volume reduction, but the patients were not different from controls in the volumetric measurements of hippocampal and whole brain volumes at group level. However, ¹H MRS demonstrated that the hippocampal formation was metabolically altered.

Conclusions

The most prominent feature was the white matter affectation, as assessed by DTI, with volume and directionality reductions of the fiber projections involving both the craniocaudal fibers and the interhemispheric connections. These findings, although heterogeneous among the study sample, could be correlated with the clinico-neurological symptoms. The imaging findings support the position that myelin structures degrade prematurely in the brain of XP patients.     

Plasma leptin levels strongly correlate with plasma renin activity in patients with essential hypertension.

Previous studies demonstrated elevated plasma leptin and angiotensinogen (PRA) levels in essential hypertension. However, a few studies investigated the relationship between leptin and angiotensinogen levels in both lean and overweight/ obese hypertensives. The aim of the present study was therefore to examine the relationship between blood pressure, leptin and plasma renin activity in normotensives and in both lean and overweight/obese patients with essential hypertension. Two groups of subjects who were carefully matched for age, gender, waist:hip ratio and body mass index (BMI) were studied: 28 normotensives (NT) (age: 40.1+/-9.1 years old, BMI: 28.1+/-3.6 kg/m2, male/female: 18/10) and 33 newly diagnosed mild to moderate essential hypertensives (EHT) (age: 38.9+/-10 years old, BMI: 27.9+/-4.8 kg/m2, male/female: 22/11). No significant differences in age, gender, waist:hip ratio, fasting blood glucose and BMI were detected between EHT and NT groups. However, systolic and diastolic pressures, mean arterial blood pressures, plasma leptin levels and PRA were significantly higher in EHT group than in NT group (P = 0.001). Plasma leptin levels were strongly correlated with BMI in EHT (r=0.67, P = 0.001) and NT groups (r=0.44, P = 0.001). Plasma leptin levels were correlated with plasma PRA levels in both EHT and NT groups (r = 0.66 and r = 0.44; both P < 0.05, respectively). There was no correlation between leptin or PRA and systolic, diastolic pressures, or mean arterial blood pressures. Furthermore, the patients were divided as lean (n=16) and overweight/obese (n = 17) and compared with BMI-matched controls. In both subgroups, plasma leptin and PRA levels were also higher than those of controls. Our results showed that elevated plasma leptin and PRA are associated with hypertension in both lean and overweight/obese hypertensives. Moreover, plasma leptin was significantly correlated with plasma angiotensinogen levels. These findings suggest that adipose mass is an important determinant of blood pressure, although the mechanism is not clear.     

Synovial phenotypes in rheumatoid arthritis correlate with response to biologic therapeutics

Introduction

Rheumatoid arthritis (RA) is a complex and clinically heterogeneous autoimmune disease. Currently, the relationship between pathogenic molecular drivers of disease in RA and therapeutic response is poorly understood.

Methods

We analyzed synovial tissue samples from two RA cohorts of 49 and 20 patients using a combination of global gene expression, histologic and cellular analyses, and analysis of gene expression data from two further publicly available RA cohorts. To identify candidate serum biomarkers that correspond to differential synovial biology and clinical response to targeted therapies, we performed pre-treatment biomarker analysis compared with therapeutic outcome at week 24 in serum samples from 198 patients from the ADACTA (ADalimumab ACTemrA) phase 4 trial of tocilizumab (anti-IL-6R) monotherapy versus adalimumab (anti-TNFα) monotherapy.

Results

We documented evidence for four major phenotypes of RA synovium – lymphoid, myeloid, low inflammatory, and fibroid - each with distinct underlying gene expression signatures. We observed that baseline synovial myeloid, but not lymphoid, gene signature expression was higher in patients with good compared with poor European league against rheumatism (EULAR) clinical response to anti-TNFα therapy at week 16 (P =0.011). We observed that high baseline serum soluble intercellular adhesion molecule 1 (sICAM1), associated with the myeloid phenotype, and high serum C-X-C motif chemokine 13 (CXCL13), associated with the lymphoid phenotype, had differential relationships with clinical response to anti-TNFα compared with anti-IL6R treatment. sICAM1-high/CXCL13-low patients showed the highest week 24 American College of Rheumatology (ACR) 50 response rate to anti-TNFα treatment as compared with sICAM1-low/CXCL13-high patients (42% versus 13%, respectively, P =0.05) while anti-IL-6R patients showed the opposite relationship with these biomarker subgroups (ACR50 20% versus 69%, P =0.004).

Conclusions

These data demonstrate that underlying molecular and cellular heterogeneity in RA impacts clinical outcome to therapies targeting different biological pathways, with patients with the myeloid phenotype exhibiting the most robust response to anti-TNFα. These data suggest a path to identify and validate serum biomarkers that predict response to targeted therapies in rheumatoid arthritis and possibly other autoimmune diseases.

Trial registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT01119859","term_id":"NCT01119859"}}NCT01119859     

Toll-like receptor 3 upregulation in macrophages participates in the initiation and maintenance of pristane-induced arthritis in rats

Introduction  

Toll-like receptors (TLRs) are involved in both innate and adaptive immune responses and are likely to play a complex role in the pathogenesis of human rheumatoid arthritis (RA) and experimental arthritis. The objective of this study was to identify the key TLR in pristane-induced arthritis (PIA), a rat model for RA, and to clarify its roles in the initiation and maintenance of arthritis.     

Dynamic changes in brain lateralization correlate with human cognitive performance

Hemispheric lateralization constitutes a core architectural principle of human brain organization underlying cognition, often argued to represent a stable, trait-like feature. However, emerging evidence underlines the inherently dynamic nature of brain networks, in which time-resolved alterations in functional lateralization remain uncharted. Integrating dynamic network approaches with the concept of hemispheric laterality, we map the spatiotemporal architecture of whole-brain lateralization in a large sample of high-quality resting-state fMRI data (N = 991, Human Connectome Project). We reveal distinct laterality dynamics across lower-order sensorimotor systems and higher-order associative networks. Specifically, we expose 2 aspects of the laterality dynamics: laterality fluctuations (LF), defined as the standard deviation of laterality time series, and laterality reversal (LR), referring to the number of zero crossings in laterality time series. These 2 measures are associated with moderate and extreme changes in laterality over time, respectively. While LF depict positive association with language function and cognitive flexibility, LR shows a negative association with the same cognitive abilities. These opposing interactions indicate a dynamic balance between intra and interhemispheric communication, i.e., segregation and integration of information across hemispheres. Furthermore, in their time-resolved laterality index, the default mode and language networks correlate negatively with visual/sensorimotor and attention networks, which are linked to better cognitive abilities. Finally, the laterality dynamics are associated with functional connectivity changes of higher-order brain networks and correlate with regional metabolism and structural connectivity. Our results provide insights into the adaptive nature of the lateralized brain and new perspectives for future studies of human cognition, genetics, and brain disorders.

Hemispheric lateralization constitutes a core architectural principle of human brain organization, often argued to represent a stable, trait-like feature, but how does this fit with our increasing appreciation of the inherently dynamic nature of brain networks? This neuroimaging study reveals the dynamic nature of functional brain lateralization at resting-state and its relationship with language function and cognitive flexibility.     

Vascular changes precede tomographic changes in diabetic eyes without retinopathy and improve artificial intelligence diagnostics

The purpose of this study was to evaluate early vascular and tomographic changes in the retina of diabetic patients using artificial intelligence (AI). The study included 74 age‐matched normal eyes, 171 diabetic eyes without retinopathy (DWR) eyes and 69 mild non‐proliferative diabetic retinopathy (NPDR) eyes. All patients underwent optical coherence tomography angiography (OCTA) imaging. Tomographic features (thickness and volume) were derived from the OCTA B‐scans. These features were used in AI models. Both OCT and OCTA features showed significant differences between the groups (P < .05). However, the OCTA features indicated early retinal changes in DWR eyes better than OCT (P < .05). In the AI model using both OCT and OCTA features simultaneously, the best area under the curve of 0.91 ± 0.02 was obtained (P < .05). Thus, the combined use of AI, OCT and OCTA significantly improved the early diagnosis of diabetic changes in the retina.     

Nonrandom chromosome changes involving the Ig gene-carrying chromosomes 12 and 6 in pristane-induced mouse plasmacytomas

The karyotypes of pristane-induced mouse plasmacytomas were studied by G banding. Only primary tumors or early passage generations were analyzed. In contrast to murine T cell leukemias that showed a regular trisomy of chromosome 15, all plasmacytomas showed a consistent translocation of the distal part of chromosome 15 to either chromosome 6 [rcpT(6;15)] or 12 [T(12;15)]. The specific breakpoints were at 6C, 15D3/E ro D2/3 and 12F2. Early passage generations often showed a mixed population with two different translocations, suggesting polyclonal origin. Considered together with the known karyotypic features of murine and human lymphomas, these findings support the theory that the nonrandom chromosomal changes in lymphoproliferative malignancies are associated with the type of the target cell, rather than with the etiological agent. Moreover, the involvement of the chromosomes known to carry the heavy chain (12) and the light chain (6) determinants, respectively, raises the question of whether the translocations may be related to the DNA level rearrangements known to occur during the differentiation of normal plasma cells.     

Immune responses and histopathological changes in rabbits immunized with inactivated SARS coronavirus

To evaluate the immunogenicity of inactivated SARS coronavirus (SARS-CoV), three groups of rabbits were immunized three times at 2-week intervals with inactivated vaccine + adjuvant, adjuvant, and normal saline respectively. Eight batchs of serum were sampled from the auricular vein at day 7 to day 51, and specific IgG antibody titers and neutralizing antibody titers were detected by indirect ELISA and micro-cytopathic effect neutralizing test. Antibody specificity was identified by proteinchip assay. Histopathological changes were detected by H&E staining. The results showed that, rabbits in the experimental group immunized with inactivated SARS-CoV all generated specific IgG antibodies with neutralizing activity, which suggested the inactivated SARS-CoV could preserve its antigenicity well and elicit an effective humoral immune responses. The peak titer value of specific IgG antibody and neutralizing antibody reached 1:40960 and 1:2560 respectively. In the experimental group, no obvious histopathological changes was detected in the H&E stained slides of heart, spleen, kidney and testis samples, but the livers had slight histopathological changes, and the lungs presented remarkable histopathological changes. These findings are of importance for SARS-CoV inactivated vaccine development. Foundation item: Joint funds of National Natural Science Foundation of China (U0632010); Program of Guangdong Provincial Key Lab of Bioengineering Medicine (51207026).     

Subchondral bone and ligament changes precede cartilage degradation in guinea pig osteoarthritis

There is increasing recognition that osteoarthritis (OA) is a complex disease involving the whole synovial joint, rather than the articular cartilage alone, however its aetiology and pathogenesis is not understood. Our initial studies revealed elevated turnover of bone and ligament collagen in human and mouse OA, respectively. To investigate the relative appearance of pathology in cartilage, bone and ligament, we studied the progression of spontaneous OA in the Dunkin-Hartley (DH) guinea pig knee, and compared with age-matched control Bristol Strain 2 (BS2) knees. The classical radiographic OA score of the DH knees compared to BS2 knees was 2-fold higher at 24 weeks of age. The patella perimeter and subchondral bone density was significantly greater in the DHs at 24 and 36 weeks compared to BS2. The femoral intercondylar notch width was found to be significantly lower in the DHs at 24 and 36 weeks, compared to BS2, indicating bone remodelling at the cruciate ligament (CL) insertion site. We found significantly greater laxity of the DH anterior CL at 12, 16 and 20 weeks compared to BS2. This elevated laxity was associated with increased remodelling of the CLs, based on markers of collagen turnover, and occurred prior to bone and cartilage pathology. We propose that the laxity of the CL leads to remodelling of the subchondral bone, and intercondylar notch, due to a change in load through the joint. Remodelling of the CLs and bone occurs prior to and concomitant with histopathological changes in the articular cartilage respectively, demonstrating the fundamental role of the ligament and subchondral bone in the aetiology of knee OA.     

Differential nitric oxide synthesis and host apoptotic events correlate with bleaching susceptibility in reef corals

Coral bleaching poses a threat to coral reefs worldwide. As a consequence of the temperature-induced breakdown in coral–dinoflagellate symbiosis, bleaching can have extensive effects on reef communities. However, our understanding of bleaching at a cellular level is limited, and this is particularly true regarding differential susceptibility among coral species. Recent work suggests that bleaching may represent a host innate immune-like response to symbiont dysfunction that involves synthesis of the signalling compound nitric oxide (NO) and the induction of host apoptotic-like cell death. In this study, we examined the activity of apoptosis-regulating enzymes alongside oxidised NO accumulation (a proxy for NO synthesis) in the reef corals Acropora millepora, Montipora digitata, and Pocillopora damicornis during experimental thermal stress. P. damicornis was the most sensitive species, suffering mortality (tissue sloughing) after 5 days at 33 °C but non-lethal bleaching after 9 days at 31.5 °C. A. millepora bleached at 33 °C but remained structurally intact, while M. digitata showed little evidence of bleaching. P. damicornis and A. millepora both exhibited evidence of temperature-induced NO synthesis and, after 5 days of heating, levels of oxidised NO in both species were fivefold higher than in controls maintained at 28.5 °C. These responses preceded bleaching by a number of days and may have occurred before symbiont dysfunction (measured as chlorophyll a degradation and oxidised NO accumulation). In A. millepora, apparent NO synthesis correlated with the induction of host apoptotic-like pathways, while in P. damicornis, the upregulation of apoptotic pathways occurred later. No evidence of elevated NO production or apoptosis was observed in M. digitata at 33 °C and baseline activity of apoptosis-regulating enzymes was negligible in this species. These findings provide important physiological data in the context of the responses of corals to global change and suggest that early events in the host may be important in the collapse of the coral–dinoflagellate symbiosis.     

The rheumatoid arthritis-associated autoantigen hnRNP-A2 (RA33) is a major stimulator of autoimmunity in rats with pristane-induced arthritis

A single intradermal injection of the mineral oil pristane in susceptible DA.1F rats induces erosive arthritis closely mimicking rheumatoid arthritis (RA). Pristane-induced arthritis (PIA) is driven by autoreactive T cells but no autoantigen has been identified to date. We therefore analyzed B and T cell responses to autoantigens potentially involved in the pathogenesis of RA, including IgG, citrullinated proteins, stress proteins, glucose-6-phosphate isomerase, and heterogeneous nuclear ribonucleoprotein (hnRNP)-A2 (RA33). IgG and IgM autoantibodies to hnRNP-A2 were detectable in sera of pristane-primed DA.1F rats already 1 wk before disease onset, reached maximum levels during the acute phase, and correlated with arthritis severity. Apart from rheumatoid factor, autoantibodies to other Ags were not observed. CD4(+) lymph node cells isolated 10 days after pristane injection produced IFN-gamma but not IL-4 in response to stimulation with hnRNP-A2, whereas none of the other candidate Ags elicited cytokine secretion. Surprisingly, hnRNP-A2 also stimulated lymph node cells of naive animals to produce inflammatory cytokines in a MyD88-dependent manner. Furthermore, hnRNP-A2 was highly overexpressed in the joints of rats injected with pristane. Overexpression coincided with the appearance of anti-RA33 Abs and preceded the onset of clinical symptoms of PIA by several days. Taken together, these data suggest hnRNP-A2 to be among the primary inducers of autoimmunity in PIA. Therefore, this Ag might play a pivotal role in the pathogenesis of PIA and possibly also human RA.     

Effects of acute treatment with dexamethasone on hemodynamic and histopathological changes in rats

Abstract

We assessed the time-dependent effects of intraperitoneal (i.p.) and intravenous (i.v.) application of dexamethasone (Dexa) on the mean arterial blood pressure (MAP), heart rate (HR) and total blood volume (TBV). We evaluated also the relation between the effects and immunoreactivities of transforming growth factor-beta (TGF-β), epithelial nitric oxide synthase (eNOS), interleukin-1 beta (IL1-β) and vascular endothelial growth factor (VEGF) in rat brain, lung and kidney tissues. Rats were anesthetized and while still breathing spontaneously, a tracheotomy and femoral vein and artery catheterizations were performed. To determine TBV using the hemodilution method, 2 ml albumin-electrolyte solutions were applied by i.v. injection. Group 1 (control group) received a 1 ml bolus injection of physiologic saline, Group 2 received 15 mg/kg and Group 3 received 75 mg/kg Dexa i.p. The hematocrit was measured at 10, 20, 60 and 120 min. For each animal, the values of MAP, HR and TBV were measured within 2 h. For immunohistochemical evaluation, anti-TGF-β, anti-eNOS, anti-IL1-β and anti-VEGF primary antibodies were tested using the avidin-biotin-peroxidase method. TBV was decreased in Group 1 and the increase in MAP was statistically significant. HR values increased slightly. None of the values changed significantly in Group 2. Although TBV was unchanged in Group 3, the decrease in MAP was statistically significant. HR values increased, but the increase was not statistically significant. Mild IL1-β immunoreactivity and moderate TGF-β, eNOS and VEGF immunoreactivities were observed in the brain, lung and kidney samples in Group 1. Increased eNOS immunoreactivity in the kidney samples were observed in Group 2. eNOS immunoreactivity was as strong in the brain and the kidney samples in Group 3. Decreased VEGF immunoreactivity was observed in the lung and kidney tissues in Group 3. Significantly decreased TGF-β immunoreactivity was observed in all tissue samples in Group 3. The decreased MAP values in Group 3 differed from those in Groups 1 and 2. Despite increased eNOS immunoreactivity, especially in brain and kidney, the decrease in VEGF immunoreactivity in Group 3, especially lung and kidney, were consistent with a drop in blood pressure.     

Effects of acute treatment with dexamethasone on hemodynamic and histopathological changes in rats

We assessed the time-dependent effects of intraperitoneal (i.p.) and intravenous (i.v.) application of dexamethasone (Dexa) on the mean arterial blood pressure (MAP), heart rate (HR) and total blood volume (TBV). We evaluated also the relation between the effects and immunoreactivities of transforming growth factor-beta (TGF-β), epithelial nitric oxide synthase (eNOS), interleukin-1 beta (IL1-β) and vascular endothelial growth factor (VEGF) in rat brain, lung and kidney tissues. Rats were anesthetized and while still breathing spontaneously, a tracheotomy and femoral vein and artery catheterizations were performed. To determine TBV using the hemodilution method, 2 ml albumin-electrolyte solutions were applied by i.v. injection. Group 1 (control group) received a 1 ml bolus injection of physiologic saline, Group 2 received 15 mg/kg and Group 3 received 75 mg/kg Dexa i.p. The hematocrit was measured at 10, 20, 60 and 120 min. For each animal, the values of MAP, HR and TBV were measured within 2 h. For immunohistochemical evaluation, anti-TGF-β, anti-eNOS, anti-IL1-β and anti-VEGF primary antibodies were tested using the avidin-biotin-peroxidase method. TBV was decreased in Group 1 and the increase in MAP was statistically significant. HR values increased slightly. None of the values changed significantly in Group 2. Although TBV was unchanged in Group 3, the decrease in MAP was statistically significant. HR values increased, but the increase was not statistically significant. Mild IL1-β immunoreactivity and moderate TGF-β, eNOS and VEGF immunoreactivities were observed in the brain, lung and kidney samples in Group 1. Increased eNOS immunoreactivity in the kidney samples were observed in Group 2. eNOS immunoreactivity was as strong in the brain and the kidney samples in Group 3. Decreased VEGF immunoreactivity was observed in the lung and kidney tissues in Group 3. Significantly decreased TGF-β immunoreactivity was observed in all tissue samples in Group 3. The decreased MAP values in Group 3 differed from those in Groups 1 and 2. Despite increased eNOS immunoreactivity, especially in brain and kidney, the decrease in VEGF immunoreactivity in Group 3, especially lung and kidney, were consistent with a drop in blood pressure.     

DNA methylation changes correlate with Gleason score and tumor stage in prostate cancer

DNA methylation, a widely used epigenetic mark, has been associated with many tumors. However, few studies have addressed the role of cell-free plasma DNA methylation in discriminating aggressive prostate cancer (PCa) from indolent cases. We conducted a case series and a case-control study among histologically confirmed stage II/III cases and matched controls recruited at Columbia University Medical Center. The aim of this study was to investigate whether plasma DNA methylation levels are appropriate surrogate biomarker of PCa tumor tissue levels and whether these markers are associated with worse clinicopathological tumor characteristics, which correlate with poorer prognosis. Quantitative pyrosequencing was used to detect methylation levels of p16 (CDKN4A), APC, GSTP1, and LINE-1 in 24 pairs of prostate tumor and adjacent tissues, as well as 27 plasma samples of PCa patients and 24 of controls. DNA methylation levels were significantly higher in tumor tissue than in adjacent nontumor tissue for p16 (CDKN4A), GSTP1, and APC; GSTP1 had a higher average percentage methylation in tumor tissue (38.9%) compared with p16 (CDKN4A) (5.9%) and APC (14.5%). GSTP1, p16 (CDKN4A), and APC methylation in tumor tissue was statistically significantly higher for cases with Gleason score ≥7 compared with those with Gleason score <7 [49.0% vs. 21.9% (p=0.01), 6.6% vs. 4.5% (p=0.04), and 19.1% vs. 7.4% (p=0.02), respectively]. Plasma LINE-1 methylation levels were higher in those with higher Gleason (67.6%) than in those with Gleason's below 7 (64.6%, p=0.03). Significant plasma-tissue correlations were observed for GSTP1 and LINE-1 methylation. These data, although preliminary, suggest that aberrant methylation may be a useful marker to identify PCa patients with clinically aggressive disease.     

Quantitative changes in microtubule distribution correlate with guard cell function in Arabidopsis

Radially arranged cortical microtubules are a prominent feature of guard cells. We observed guard cells expressing GFP-tubulin (GFP-TUA6) with confocal microscopy and found recognizable changes in the appearance of microtubules when stomata open or close (Eisinger et al., 2012). In the present study, analysis of fluorescence distribution showed a dramatic increase in peak intensities of microtubule bundles within guard cells as stomata open. This increase was correlated with an increase in the total fluorescence that could be attributed to polymerized tubulin. Adjacent pavement cells did not show similar changes in peak intensities or integrated fluorescence when stomatal apertures changed. Imaging of RFP-tagged end binding protein 1 (EB1) and YFP-tagged α-tubulin expressed in the same cell revealed that the number of microtubules with growing ends remained constant, although the total amount of polymerized tubulin was higher in open than in closed guard cells. Taken together, these results indicate that the changes in microtubule array organization that are correlated with and required for normal guard cell function are characterized by changes in microtubule clustering or bundling.     

Gait and neuromuscular pattern changes are associated with differences in knee osteoarthritis severity levels

Knee osteoarthritis (OA) is a multifactoral, progressive disease process of the musculoskeletal system. Mechanical factors have been implicated in the progression of knee OA, but the role of altered joint mechanics and neuromuscular control strategies in progressive mechanisms of the disease have not been fully explored. Previous biomechanical studies of knee OA have characterized changes in joint kinematics and kinetics with the disease, but it has been difficult to determine if these biomechanical changes are involved in the development of disease, are in response to degenerative changes in the joint, or are compensatory mechanisms in response to these degenerative changes or other related factors as joint pain. The goal of this study was to explore the association between biomechanical changes and knee OA severity in an effort to understand the changing role of biomechanical factors in the progression of knee OA. A three-group cross-sectional model was used that included asymptomatic subjects, subjects clinically diagnosed with moderate knee OA and severe knee OA subjects just prior to total joint replacement surgery. Principal component analysis and discriminant analysis were used to determine the combinations of electromyography, kinematic and kinetic waveform pattern changes at the knee, hip and ankle joints during gait that optimally separated the three levels of severity. Different biomechanical mechanisms were important in discriminating between severity levels. Changes in knee and hip kinetic patterns and rectus femoris activation were important in separating the asymptomatic and moderate OA gait patterns. In contrast, changes in knee kinematics, hip and ankle kinetics and medial gastrocnemius activity were important in discriminating between the moderate and severe OA gait patterns.