Dopaminergic Modulation of Dynamic Emotion Perception

Emotion recognition abilities are fundamental to our everyday social interaction. A large number of clinical populations show impairments in this domain, with emotion recognition atypicalities being particularly prevalent among disorders exhibiting a dopamine system disruption (e.g., Parkinson's disease). Although this suggests a role for dopamine in emotion recognition, studies employing dopamine manipulation in healthy volunteers have exhibited mixed neural findings and no behavioral modulation. Interestingly, while a dependence of dopaminergic drug effects on individual baseline dopamine function has been well established in other cognitive domains, the emotion recognition literature so far has failed to account for these possible interindividual differences. The present within-subjects study therefore tested the effects of the dopamine D2 antagonist haloperidol on emotion recognition from dynamic, whole-body stimuli while accounting for interindividual differences in baseline dopamine. A total of 33 healthy male and female adults rated emotional point-light walkers (PLWs) once after ingestion of 2.5 mg haloperidol and once after placebo. To evaluate potential mechanistic pathways of the dopaminergic modulation of emotion recognition, participants also performed motoric and counting-based indices of temporal processing. Confirming our hypotheses, effects of haloperidol on emotion recognition depended on baseline dopamine function, where individuals with low baseline dopamine showed enhanced, and those with high baseline dopamine decreased emotion recognition. Drug effects on emotion recognition were related to drug effects on movement-based and explicit timing mechanisms, indicating possible mediating effects of temporal processing. Results highlight the need for future studies to account for baseline dopamine and suggest putative mechanisms underlying the dopaminergic modulation of emotion recognition.SIGNIFICANCE STATEMENT A high prevalence of emotion recognition difficulties among clinical conditions where the dopamine system is affected suggests an involvement of dopamine in emotion recognition processes. However, previous psychopharmacological studies seeking to confirm this role in healthy volunteers thus far have failed to establish whether dopamine affects emotion recognition and lack mechanistic insights. The present study uncovered effects of dopamine on emotion recognition in healthy individuals by controlling for interindividual differences in baseline dopamine function and investigated potential mechanistic pathways via which dopamine may modulate emotion recognition. Our findings suggest that dopamine may influence emotion recognition via its effects on temporal processing, providing new directions for future research on typical and atypical emotion recognition.

Abstract P248: Overexpression of an Intracellular Angiotensin II Fusion Protein Selectively in the Mitochondria of Mouse Proximal Tubule Cells Induces Mitochondrial Stress and Glycolytic Responses: Roles of Nitric Oxide and Superoxide

Endocrine and paracrine angiotensin II ( ANG II) activates cell surface AT 1 receptors to induce mitochondrial superoxide (O 2 - ) production and uncoupling of eNOS, leading to ANG II-induced renal and hypertensive injury. Little is known, however, whether ANG II is internalized to the mitochondria to activate AT 1 or AT 2 receptors. We tested the hypothesis that ANG II in the mitochondria exerts important dual roles on mitochondrial stress and glycolytic responses via the AT 1a /NADPH oxidase/O 2 .- and AT 2 /eNOS/NO signaling pathways. To test the hypothesis, a mitochondria-targeting ANG II protein (mito-ECFP/ANG II) was expressed selectively in the mitochondria of mouse proximal tubule cells, and treated with or without AT 1 receptor blocker losartan (10 μM), AT 2 receptor blocker PD123319 (10 μM), a non-selective NOS inhibitor L-NAME (10 mM), or a scavenger of mitochondrial superoxide, mito-TEMPO (10 μM) for 48 h, respectively. The mitochondrial stress and glycolytic responses were then determined using Seahorse XF e 24 Extracellular Flux Analyzer. Expression of mito-ECFP/ANG II alone significantly increased oxygen consumption rate (OCR) (Control: 259.8 ± 52.2 vs. mito-ECFP/ANG II: 512.5 ± 75.6 pmol/min; p <0.01, n=8) and extracellular acidification rate (ECAR) (Control: 13.5 ± 2.2 vs. mito-ECFP/ANG II: 19.3 ± 2.4 mpH/min; p <0.01, n=8), respectively. These mito-stress responses were blocked by losartan ( p <0.01, n=8), but not by PD123139 ( n.s. ). Furthermore, the mito-stress response of mito-ECFP/ANG II was significantly attenuated by mito-TEMPO (288.1 ± 10.3 pmol/min; p <0.01, n=8), and augmented by L-NAME (623.5 ± 8.7 pmol/min, p <0.05, n=8). Finally, the mito-stress response to mito-ECFP/ANG II expression was associated with significant increases in mitochondrial redox carries, Complex I (NADH coenzyme Q reductase), Complex II (succinate dehydrogenase), Complex III (cytochrome bc 1 complex) and Complex IV proteins (cytochrome c oxidase) ( p <0.01). We concluded that ANG II in the mitochondrial induces important mitochondrial stress and glycolytic responses primarily via the AT 1a /NADPH oxidase/O 2 .- signaling pathways in mouse proximal tubule cells.

Proximal patellar tendon pathology can develop during adolescence in young ballet dancers-A 2-year longitudinal study

Patellar tendinopathy (tendon pain and dysfunction), or jumper's knee, is prevalent in adult jumping athletes. Pathology in the proximal patellar tendon is a key risk factor for developing patellar tendinopathy. When pathology develops in the proximal patellar tendon is not known, although it is reported to exist in adolescent athletes. The aim of this study was to follow young jumping athletes (ballet dancers) through adolescence to identify whether pathology develops and its relation to the adolescent growth spurt. Fifty-seven elite ballet students between ages 11 and 18 were monitored for 2 years. Data were collected every 6 months, including an ultrasound scan on their left tendons using ultrasound tissue characterization (UTC) to quantify intratendinous changes, anthropometric data to calculate peak height velocity (adolescent growth spurt), participant reports of any injuries or dance modifications, and a VISA-P and single leg decline squat for patellar tendon pain. Nine percentage of adolescent dancers developed pathology during this study, and development was not associated with growth spurt. Peak height velocity and dance participation/volume both at the start and throughout the study were similar in those who did develop pathology and those who did not. Only 2 of 5 participants who developed pathology reported pain associated with their tendon. Pathology in the proximal patellar tendon can develop during adolescence.

Effectiveness of progesterone, cerclage and pessary for preventing preterm birth in singleton pregnancies: a systematic review and network meta-analysis

BACKGROUND

Preterm birth (PTB) is the leading cause of infant death, but it is unclear which intervention is best to prevent it.

OBJECTIVES

To compare progesterone, cerclage and pessary, determine their relative effects and rank them.

SEARCH STRATEGY

We searched Medline, EMBASE, CINAHL, Cochrane CENTRAL and Web of Science (to April 2016), without restrictions, and screened references of previous reviews.

SELECTION CRITERIA

We included randomised trials of progesterone, cerclage or pessary for preventing PTB in women with singleton pregnancies at risk as defined by each study.

DATA COLLECTION AND ANALYSIS

We extracted data by duplicate using a piloted form and performed Bayesian random-effects network meta-analyses and pairwise meta-analyses. We rated evidence quality using GRADE, ranked interventions using SUCRA and calculated numbers needed to treat (NNT).

MAIN RESULTS

We included 36 trials (9425 women; 25 low risk of bias trials). Progesterone ranked first or second for most outcomes, reducing PTB < 34 weeks [odds ratio (OR) 0.44; 95% credible interval (CrI) 0.22-0.79; NNT 9; low quality], <37 weeks (OR 0.58; 95% CrI 0.41-0.79; NNT 9; moderate quality), and neonatal death (OR 0.50; 95% CrI 0.28-0.85; NNT 35; high quality), compared with control, in women overall at risk. We found similar results in the subgroup with previous PTB, but only a reduction of PTB < 34 weeks in women with a short cervix. Pessary showed inconsistent benefit and cerclage did not reduce PTB < 37 or <34 weeks.

CONCLUSIONS

Progesterone was the best intervention for preventing PTB in singleton pregnancies at risk, reducing PTB < 34 weeks, <37 weeks, neonatal demise and other sequelae.

TWEETABLE ABSTRACT

Progesterone was better than cerclage and pessary to prevent preterm birth, neonatal death and more in network meta-analysis.

Revisiting the continuum model of tendon pathology: what is its merit in clinical practice and research?

The pathogenesis of tendinopathy and the primary biological change in the tendon that precipitates pathology have generated several pathoaetiological models in the literature. The continuum model of tendon pathology, proposed in 2009, synthesised clinical and laboratory-based research to guide treatment choices for the clinical presentations of tendinopathy. While the continuum has been cited extensively in the literature, its clinical utility has yet to be fully elucidated. The continuum model proposed a model for staging tendinopathy based on the changes and distribution of disorganisation within the tendon. However, classifying tendinopathy based on structure in what is primarily a pain condition has been challenged. The interplay between structure, pain and function is not yet fully understood, which has partly contributed to the complex clinical picture of tendinopathy. Here we revisit and assess the merit of the continuum model in the context of new evidence. We (1) summarise new evidence in tendinopathy research in the context of the continuum, (2) discuss tendon pain and the relevance of a model based on structure and (3) describe relevant clinical elements (pain, function and structure) to begin to build a better understanding of the condition. Our goal is that the continuum model may help guide targeted treatments and improved patient outcomes.

Social disruption alters pain and cognition in an animal model of multiple sclerosis

Although pain and cognitive deficits are widespread and debilitating symptoms of multiple sclerosis (MS), they remain poorly understood. Theiler's murine encephalomyelitis virus (TMEV) infection is an animal model of MS where disease course is exacerbated by prior stressors. Here chronic infection coupled with prior social stress increased pain behavior and impaired hippocampal-dependent memory consolidation during the demyelinating phase of disease in SJL mice. These results suggest that the TMEV model may be useful in investigating pain and cognitive impairments in MS. However, in contrast to prior Balb/cJ studies, stress failed to consistently alter behavioral and physiological indicators of disease course.

The reconstruction of the nasal ala with interpolated flaps from the cheek and forehead: design and execution modifications to improve surgical outcomes

The nasal ala, critically important in the function and appearance of the central face, has significant reconstructive demands given the lack of suitable adjacent donor tissue that can be used to repair all but the smallest surgical defects in this area. Interpolated flaps from the forehead and cheek have long been ideal reconstructive alternatives for the repair of larger or more difficult alar wounds, and with the design and execution modifications described here, the dermatological surgeon can offer more appropriate restoration of this critically important aesthetic unit.

Development and validation of a VISA tendinopathy questionnaire for greater trochanteric pain syndrome, the VISA-G

BACKGROUND

Greater trochanteric pain syndrome (GTPS) is common, resulting in significant pain and disability. There is no condition specific outcome score to evaluate the degree of severity of disability associated with GTPS in patients with this condition.

OBJECTIVE

To develop a reliable and valid outcome measurement capable of evaluating the severity of disability associated with GTPS.

METHODS

A phenomenological framework using in-depth semi structured interviews of patients and medical experts, and focus groups of physiotherapists was used in the item generation. Item and format clarification was undertaken via piloting. Multivariate analysis provided the basis for item reduction. The resultant VISA-G was tested for reliability with the inter class co-efficient (ICC), internal consistency (Cronbach's Alpha), and construct validity (correlation co-efficient) on 52 naïve participants with GTPS and 31 asymptomatic participants.

RESULTS

The resultant outcome measurement tool is consistent in style with existing tendinopathy outcome measurement tools, namely the suite of VISA scores. The VISA-G was found to be have a test-retest reliability of ICC2,1 (95% CI) of 0.827 (0.638-0.923). Internal consistency was high with a Cronbach's Alpha of 0.809. Construct validity was demonstrated: the VISA-G measures different constructs than tools previously used in assessing GTPS, the Harris Hip Score and the Oswestry Disability Index (Spearman Rho:0.020 and 0.0205 respectively). The VISA-G did not demonstrate any floor or ceiling effect in symptomatic participants.

CONCLUSION

The VISA-G is a reliable and valid score for measuring the severity of disability associated GTPS.

Does the adolescent patellar tendon respond to 5 days of cumulative load during a volleyball tournament?

Patellar tendinopathy (jumper's knee) has a high prevalence in jumping athletes. Excessive load on the patellar tendon through high volumes of training and competition is an important risk factor. Structural changes in the tendon are related to a higher risk of developing patellar tendinopathy. The critical tendon load that affects tendon structure is unknown. The aim of this study was to investigate patellar tendon structure on each day of a 5-day volleyball tournament in an adolescent population (16-18 years). The right patellar tendon of 41 players in the Australian Volleyball Schools Cup was scanned with ultrasound tissue characterization (UTC) on every day of the tournament (Monday to Friday). UTC can quantify structure of a tendon into four echo types based on the stability of the echo pattern. Generalized estimating equations (GEE) were used to test for change of echo type I and II over the tournament days. Participants played between eight and nine matches during the tournament. GEE analysis showed no significant change of echo type percentages of echo type I (Wald chi-square = 4.603, d.f. = 4, P = 0.331) and echo type II (Wald chi-square = 6.070, d.f. = 4, P = 0.194) over time. This study shows that patellar tendon structure of 16-18-year-old volleyball players is not affected during 5 days of cumulative loading during a volleyball tournament.

Studies of intracellular angiotensin II

Many extracellular signaling proteins act within their cells of synthesis and/or in target cells after internalization. This type of action is called intracrine and it plays a role in diverse biological processes. The mechanisms of intracrine intracellular action are becoming clear thanks to the application of modern techniques of molecular biology. Here, progress in this area is reviewed. In particular the intracrine biology of angiotensin II is discussed.

Abstract 405: Novel Signaling Mechanisms by Which Intracellular Angiotensin II Induces Na + /HCO 3 - CotransporterExpression In The Proximal Tubule of The Kidney

Previous studies have shown that endocrine and/or paracrine angiotensin II (ANG II) plays an important role in the regulation of sodium and bicarbonate reabsorption in the proximal tubule of the kidney. However, it is not known whether intracellular (or intracrine) ANG II also plays a role in these responses in the proximal tubule. The present study tested the hypothesis that overexpression of an intracellular cyan fluorescent fusion protein of ANG II (ECFP/ANG II) in the proximal tubule of the kidney induces the expression of the Na + /HCO 3 - cotransporter via MAPK- and NF-kB signaling pathways. To test the hypothesis, transport-competent mPCTs from wild-type and type 1a ANG II receptor-deficient mice (AT 1a -KO) were transfected with ECFP/ANG II, and treated with the AT 1 receptor blocker losartan, the MEK1/MEK2 inhibitor U0126, or the NF-κB inhibitor RO 106-9920. In wild-type mPCT cells, the expression of ECFP/ANG II more than doubled total and/or phosphorylated NHE3 antiporter and Na + /HCO 3 - cotransporter proteins (p<0.01). These response were accompanied by more than threefold increases in phospho-ERK 1/2, p65 subunit of NF-κB, and phospho-IKKα/β (Ser 176/180) proteins (p<0.01). Pretreatment of mPCT cells with losartan, U0126, or RO 106-9920 significantly blocked the effects of ECFP/ANG II (p<0.01). Furthermore, the effects of ECFP/ANG II were significantly attenuated in mPCT cells of AT 1a -KO mice (p<0.01),. In wild-type C57BL/6J mice, adenovirus-mediated overexpression of ECFP/ANG II selectively in the proximal tubule of the kidney, driven by the sodium and glucose cotransporter 2 (sglt2) promoter, significantly increased blood pressure, total and/or phosphorylated NHE3 and Na + /HCO 3 - proteins, and proximal tubular lithium reabsorption (p<0.01). These responses to ECFP/ANG II as observed in C57BL/6J mice were also attenuated in AT 1a -KO mice (p<0.01). Our results strongly suggest that intracellular ANG II may induce NHE3 and Na + /HCO 3 - expression, and increase proximal tubular sodium and bicarbonate reabsorption via AT 1a receptor-mediated activation of MAP kinases ERK 1/2 and NF-κB signaling pathways.

Animal models of cartilage repair

Cartilage repair in terms of replacement, or regeneration of damaged or diseased articular cartilage with functional tissue, is the ‘holy grail’ of joint surgery. A wide spectrum of strategies for cartilage repair currently exists and several of these techniques have been reported to be associated with successful clinical outcomes for appropriately selected indications. However, based on respective advantages, disadvantages, and limitations, no single strategy, or even combination of strategies, provides surgeons with viable options for attaining successful long-term outcomes in the majority of patients. As such, development of novel techniques and optimisation of current techniques need to be, and are, the focus of a great deal of research from the basic science level to clinical trials. Translational research that bridges scientific discoveries to clinical application involves the use of animal models in order to assess safety and efficacy for regulatory approval for human use. This review article provides an overview of animal models for cartilage repair.

Cite this article: Bone Joint Res 2014;4:89–94.

Intracellular Enhanced Cyan Fluorescent Protein/Angiotensin II Does Not Modify Angiotensinogen Accumulation in Transgenic Mice

BACKGROUND

Several studies suggest that extracellular angiotensin can upregulate renin and angiotensinogen (AGT). We have shown that enhanced cyan fluorescent protein/angiotensin II (ECFP/AngII) transgenic mice, in which AngII is fused downstream of ECFP and regulated by the mouse metallothionein housekeeping gene, possess elevated blood pressure and kidney thrombotic microangiopathy. The present study evaluated the effect of intracellular AngII on AGT messenger RNA (mRNA) and protein levels in ECFP/AngII transgenic mice.

METHODS

The traditional guanidinium thiocyanate method was used to extract total mRNA. Proteins were extracted by homogenization in a tissue extraction reagent buffer. Northern blots for AGT mRNA and an 18S ribosomal RNA control were performed. Immunoblots for AGT protein levels with actin and tubulin controls were evaluated.

RESULTS

Northern blot densitometry showed liver mRNA levels an average of 12-fold greater than levels in the brain or kidney in both Lines A and D (different copies of the transgene) with no quantifiable differences between wild-type (WT) and homozygous (HO) transgenic mice. Immunoblots showed liver AGT protein levels 3.2-fold greater than levels in the brain or kidney, with no differences observed between WT and HO transgenic mice.

CONCLUSION

ECFP/AngII transgene expression does not alter AGT mRNA or protein levels in major organs (kidney, liver, and brain) of transgenic mice. The altered blood pressure and kidney thrombosis observed in these transgenic mouse lines are not the result of increased intracellular AGT synthesis and resultant increases in free extracellular AngII. This finding is consistent with our published studies that indicate no increase in circulating AngII by radioimmunoassay.

Reduction of Blood Pressure by AT1 Receptor Decoy Peptides

BACKGROUND

We previously identified the binding of the chaperone protein gamma-aminobutyric acid receptor-associated protein (GABARAP) to a sequence on the carboxy-terminus of the angiotensin II AT1 receptor (AT1R) and showed that this binding enhances AT1R trafficking to the cell surface as well as angiotensin signaling.

METHODS

In this study, we treated sodium-depleted mice with decoy peptides consisting either of a fusion of the cell-penetrating peptide penetratin and the GABARAP/AT1R binding sequence or penetratin fused to a mutated AT1R sequence. We used telemetry to measure blood pressure.

RESULTS

Systolic and diastolic pressure fell during the 24 hours following decoy peptide injection but not after control peptide injection. Active cell-penetrating decoy peptide decreased 24-hour average systolic blood pressure from 129.8 ± 4.7 mmHg to 125.0 ± 6.0 mmHg (mean ± standard deviation). Diastolic blood pressure fell from 99.0 ± 7.1 mmHg to 95.0 ± 9.2 mmHg (n=5). Administration of the control peptide raised systolic blood pressure from 128.7 ± 1.3 mmHg to 131.7 ± 2.9 mmHg and diastolic pressure from 93.9 ± 4.5 mmHg to 95.9 ± 4.2 mmHg (n=5). The decreases in both systolic and diastolic blood pressure after active peptide administration were statistically significant compared to control peptide administration (P<0.05, two-tailed Wilcoxon rank-sum test).

CONCLUSION

These results indicate the physiological and potentially therapeutic relevance of inhibitors of GABARAP/AT1R binding.

Lessons from in vitro studies and a related intracellular angiotensin II transgenic mouse model

In the classical renin-angiotensin system, circulating ANG II mediates growth stimulatory and hemodynamic effects through the plasma membrane ANG II type I receptor, AT1. ANG II also exists in the intracellular space in some native cells, and tissues and can be upregulated in diseases, including hypertension and diabetes. Moreover, intracellular AT1 receptors can be found associated with endosomes, nuclei, and mitochondria. Intracellular ANG II can function in a canonical fashion through the native receptor and also in a noncanonical fashion through interaction with alternative proteins. Likewise, the receptor and proteolytic fragments of the receptor can function independently of ANG II. Participation of the receptor and ligand in alternative intracellular pathways may serve to amplify events that are initiated at the plasma membrane. We review historical and current literature relevant to ANG II, compared with other intracrines, in tissue culture and transgenic models. In particular, we describe a new transgenic mouse model, which demonstrates that intracellular ANG II is linked to high blood pressure. Appreciation of the diverse, pleiotropic intracellular effects of components of the renin-angiotensin system should lead to alternative disease treatment targets and new therapies.

Is compressive load a factor in the development of tendinopathy?

Tendons are designed to take tensile load, but excessive load can cause overuse tendinopathy. Overuse tendinopathy results in extensive changes to the cells and extracellular matrix, resulting in activated cells, increase in large proteoglycans and a breakdown of the collagen structure. Within these pathological changes, there are areas of fibrocartilaginous metaplasia, and mechanotransduction models suggest that this response could be due to compressive load. As load management is a cornerstone of treating overuse tendinopathy, defining the effect of tensile and compressive loads is important in optimising the clinical management of tendinopathy. This paper examines the potential role of compressive loads in the onset and perpetuation of tendinopathy, and reviews the anatomical, epidemiological and clinical evidence that supports consideration of compressive loads in overuse tendinopathy.

Social disruption induced priming of CNS inflammatory response to Theiler's virus is dependent upon stress induced IL-6 release

Chronic social disruption stress (SDR) exacerbates acute and chronic phase Theiler's murine encephalomyelitis virus (TMEV) infection, a mouse model of multiple sclerosis. However, the precise mechanism by which this occurs remains unknown. The present study suggests that SDR exacerbates TMEV disease course by priming virus-induced neuroinflammation. It was demonstrated that IL-1β mRNA expression increases following acute SDR; however, IL-6 mRNA expression, but not IL-1β, is upregulated in response to chronic SDR. Furthermore, this study demonstrated SDR prior to infection increases infection related central IL-6 and IL-1β mRNA expression, and administration of IL-6 neutralizing antibody during SDR reverses this increase in neuroinflammation.

Infective aneurysm of the inferior pancreaticoduodenal artery

INTRODUCTION

Pancreaticoduodenal (PD) artery aneurysms account for less than 2% of all splanchnic aneurysms. A mycotic aetiology is extremely uncommon.

INTRODUCTION

Two weeks following an episode of sepsis related to a prostatic biopsy, a 59-year-old man presented with abdominal pain and anaemia. Ultrasonography and computed tomography revealed an inferior PD artery pseudoaneurysm with an associated mesenteric root haematoma. This was treated successfully by transcatheter embolisation.

INTRODUCTION

Infective pseudoaneurysms of the PD artery are rare but can be associated with rupture into the gastrointestinal tract or retroperitoneum. Transcatheter embolisation remains the most effective therapy as it is associated with low morbidity and mortality rates and recurrence is very unlikely provided the aneurysm is completely excluded from the circulation.

Subchondral bone changes in three different canine models of osteoarthritis

OBJECTIVE

To test the hypothesis that changes in subchondral bone are significantly different among three canine models of osteoarthritis (OA).

DESIGN

In 21 purpose-bred mongrel dogs, OA was induced in one knee joint via either anterior cruciate ligament transection (ACLt; n = 5), medial femoral condylar groove creation (GR; n = 6), or medial meniscal release (MR; n = 5). Five dogs that had sham surgery (SH; n = 5) in one knee joint served as controls. Lameness scoring was performed every 4 weeks. Twelve weeks after surgery, the knee joints were examined by histology and histomorphometry.

RESULTS

Articular cartilage pathology as determined by Mankin scores was significantly severe in all three OA models compared to SH controls in the medial tibia (P < 0.001 to P = 0.026). ACLt had significantly thinner subchondral plate thickness (Sp.Th) in both the medial and lateral tibias while MR had significantly thicker Sp.Th in the medial tibia compared to SH controls (P < 0.001 to P = 0.011). Trabecular bone volume (BV/TV) and trabecular bone thickness (Tb.Th) for ACLt were significantly less than SH controls in the tibias (P < 0.001 to P = 0.011). Tibial Sp.Th, BV/TV, and Tb.Th were all moderately to strongly correlated with lameness scores obtained throughout the study period (r = -0.436 to r = -0.738, P < 0.001 to P = 0.047) while Mankin scores showed moderate to strong correlations with Sp.Th in each OA model (r = 0.465 to r = 0.816, P < 0.001 to P = 0.033).

CONCLUSIONS

Changes in Sp.Th are associated with articular cartilage damage while tibial Sp.Th and BV/TV and Tb.Th appear to be all influenced by joint loading alterations.

Expression of a naturally occurring angiotensin AT(1) receptor cleavage fragment elicits caspase-activation and apoptosis

Several transmembrane receptors are documented to accumulate in nuclei, some as holoreceptors and others as cleaved receptor products. Our prior studies indicate that a population of the 7-transmembrane angiotensin type-1 receptor (AT(1)R) is cleaved in a ligand-augmented manner after which the cytoplasmic, carboxy-terminal cleavage fragment (CF) traffics to the nucleus. In the present report, we determine the precise cleavage site within the AT(1)R by mass spectrometry and Edman sequencing. Cleavage occurs between Leu(305) and Gly(306) at the junction of the seventh transmembrane domain and the intracellular cytoplasmic carboxy-terminal domain. To evaluate the function of the CF distinct from the holoreceptor, we generated a construct encoding the CF as an in-frame yellow fluorescent protein fusion. The CF accumulates in nuclei and induces apoptosis in CHO-K1 cells, rat aortic smooth muscle cells (RASMCs), MCF-7 human breast adenocarcinoma cells, and H9c2 rat cardiomyoblasts. All cell types show nuclear fragmentation and disintegration, as well as evidence for phosphotidylserine displacement in the plasma membrane and activated caspases. RASMCs specifically showed a 5.2-fold increase (P < 0.001) in CF-induced active caspases compared with control and a 7.2-fold increase (P < 0.001) in cleaved caspase-3 (Asp174). Poly(ADP-ribose)polymerase was upregulated 4.8-fold (P < 0.001) in CF expressing cardiomyoblasts and colocalized with terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL). CF expression also induces DNA laddering, the gold-standard for apoptosis in all cell types studied. CF-induced apoptosis, therefore, appears to be a general phenomenon as it is observed in multiple cell types including smooth muscle cells and cardiomyoblasts.

Infrapatellar fat pad size, but not patellar alignment, is associated with patellar tendinopathy

Patellar tendinopathy (PT) is one of the most common overuse injuries of the knee. Recent reports indicate that increased body mass is frequently associated with tendinopathy, not only biomechanically but biochemically. Abnormalities of other structures within the knee extensor mechanism [patellofemoral joint (PFJ) alignment and patellar tendon length] that can directly influence the strain distribution of the patellar tendon are inconsistently implicated in PT. The aim of this study was to compare the infrapatellar fat pad volume, patellar tendon length and PFJ alignment in people with chronic PT and a group of age-, gender-, height-, and activity-matched controls with normal tendons. Axial magnetic resonance (MR) images, from 26 participants with PT and 28 control participants were obtained. Fat pad size, patellar tendon length and PFJ alignment were measured digitally from the MR images, using measurement software, and the results compared between the PT group and control group. People with PT had a significantly larger fat pad than healthy controls when controlled for height (P=0.04). Patellar tendon length was not significantly different between groups (P=0.16), nor were there between-group differences for the measures of PFJ alignment (P=0.07-0.76). Thus, the infrapatellar fat pad may play an important role in PT.

Intrarenal transfer of an intracellular fluorescent fusion of angiotensin II selectively in proximal tubules increases blood pressure in rats and mice

The present study tested the hypothesis that intrarenal adenoviral transfer of an intracellular cyan fluorescent fusion of angiotensin II (ECFP/ANG II) selectively in proximal tubules of the kidney increases blood pressure by activating AT(1) (AT(1a)) receptors. Intrarenal transfer of ECFP/ANG II was induced in the superficial cortex of rat and mouse kidneys, and the sodium and glucose cotransporter 2 (sglt2) promoter was used to drive ECFP/ANG II expression selectively in proximal tubules. Intrarenal transfer of ECFP/ANG II induced a time-dependent, proximal tubule-selective expression of ECFP/ANG II in the cortex, which peaked at 2 wk and was sustained for 4 wk. ECFP/ANG II expression was low in the glomeruli and the entire medulla and was absent in the contralateral kidney or extrarenal tissues. At its peak of expression in proximal tubules at day 14, ANG II was increased by twofold in the kidney (P < 0.01) and more than threefold in proximal tubules (P < 0.01), but remained unchanged in plasma or urine. Systolic blood pressure was increased in ECFP/ANG II-transferred rats by 28 ± 6 mmHg (P < 0.01), whereas fractional sodium excretion was decreased by 20% (P < 0.01) and fractional lithium excretion was reduced by 24% (P < 0.01). These effects were blocked by losartan and prevented in AT(1a) knockout mice. Transfer of a scrambled ECFP/ANG IIc had no effects on blood pressure, kidney, and proximal tubule ANG II, or sodium excretion. These results provide evidence that proximal tubule-selective transfer of an intracellular ANG II fusion protein increases blood pressure by activating AT(1a) receptors and increasing sodium reabsorption in proximal tubules.

The OARSI histopathology initiative - recommendations for histological assessments of osteoarthritis in the dog

The dog is a common model for study of osteoarthritis (OA). Subjective histologic scoring systems have often served as the reference standard for presence and severity of OA. However, these scoring systems have perceived shortcomings. The system developed for this report attempts to address these shortcomings by providing a standardized methodology for global assessment of the joint, versatility and the potential for relative weighting of pathology, allowing for comparison among time points, studies, and centers, and critical analysis of the system's reliability. The proposed system for assessment of canine tissues appears to provide an effective method for global assessment of articular pathology in OA. The system is versatile, comprehensive, and reliable and appears to have advantages over conventional scoring systems.

Histopathology atlas of animal model systems - overview of guiding principles

Animal model systems represent an important adjunct and surrogate for studies of osteoarthritis (OA) in humans. They provide a means to study OA pathophysiology as well as aid in the development of therapeutic agents and biological markers for diagnosing and prognosing the disease. Thus, it is of great importance for the OA scientific community, both in academic as well as industrial research, to standardize scoring systems for evaluating the OA disease process and to make results between different studies comparable. The task of the histopathology initiative of OARSI was to achieve a consensus of scoring systems for the most important species used in OA animal model research (dog, guinea pig, horse, mouse, rabbit, rat, and sheep/goat), which are presented in the various chapters in this special volume of Osteoarthritis & Cartilage together with extra chapters on basic methodology (histochemistry, statistics, morphometry), the specific terminology and a general discussion of animal models in OA research. Standardized definitions are suggested for basic but essential terms such as "grading" and "staging" in order to promote their consistent use and thereby promote improved understanding and data interpretation across all model systems. Thus, this introductory chapter presents an overview of the guiding principles for assessment of important OA animal model systems. Use of such systems, independently or in conjunction with other systems in parallel, should facilitate comparability of results across animal model studies.

The mitochondrial component of intracrine action

In recent years the actions of intracellular-acting, extracellular signaling proteins/peptides (intracrines) have become increasingly defined. General principles of intracrine action have been proposed. Mitochondria represent one locus of intracrine action, and thus far, angiotensin II, transforming growth factor-beta, growth hormone, atrial natriuretic peptide, Wnt 13, stanniocalcin, other renin-angiotensin system components, and vascular endothelial-derived growth factor, among others, have been shown to be mitochondria-localizing intracrines. The implications of this mitochondrial intracrine biology are discussed.

C-terminal processing of GABARAP is not required for trafficking of the angiotensin II type 1A receptor

OBJECTIVE

GABARAP, a small (117 aa) trafficking protein, binds to the C-terminal, cytoplasmic domain of rat angiotensin type-1A receptor (AT(1)R), the predominant effector of the octapeptide angiotensin II (Ang II) (Cook et al., Circ. Res. 2008;102:1539-47). The objectives of this study were to map the interaction domains of GABARAP and AT(1)R, to determine the effect of GABARAP association on AT(1)R signaling activity, and to determine the importance of post-translational processing of GABARAP on accumulation of AT(1)R on the plasma membrane and its signaling function.

RESULTS

Deletion analysis identified two regions within GABARAP necessary for interaction with AT(1)R in yeast two-hybrid assays: 1) a domain comprised of residues 32-51 that is nearly identical to that involved in binding and intracellular trafficking of the GABA(A) receptor and 2) a domain encompassing the C-terminal 21 aa. The GABARAP interaction domain of AT(1)R was delimited to the 15 aa immediately downstream of the last membrane spanning region. Overexpression of GABARAP in rat adrenal pheochromocytoma PC-12 cells increased the cell-surface expression of AT(1)R and Ang II-dependent activation of the cAMP signaling pathway. Residues within AT(1)R necessary for these responses were identified by mutational analysis. In PC-12 cells, GABARAP was constitutively and quantitatively cleaved at the C-terminus peptide bond and this cleavage was prevented by mutation of Gly(116). Wild-type GABARAP and the G116A mutant were, however, equally effective in stimulating AT(1)R surface expression and signaling activity.

CONCLUSIONS

GABARAP and AT(1)R interact through discrete domains and this association regulates the cell-surface accumulation and, consequently, ligand-induced function of the receptor. Unlike that observed with the GABA(A) receptor, this regulation is not dependent on C-terminal processing and modification of GABARAP.

Senescence, apoptosis, and stem cell biology: the rationale for an expanded view of intracrine action

Some extracellular-signaling peptides also at times function within the intracellular space. We have termed these peptides intracrines and have argued that intracrine function is associated with a wide variety of peptides/proteins including hormones, growth factors, cytokines, enzymes, and DNA-binding proteins among others. Here we consider the possibility that intracrines participate in the related phenomena of senescence, apoptosis, and stem cell regulation of tissue biology. Based on this analysis, we also suggest that the concept of intracrine action be expanded to include possible regulatory peptide transfer via exosomes/microvesicles and possibly by nanotubes. Moreover, the process of microvesicular and nanotube transfer of peptides and other biologically relevant molecules, which we inclusively term laterality, is explored. These notions have potentially important therapeutic implications, including implications for the therapy of cardiovascular disease.

Mechanical and biochemical characterization of cartilage explants in serum-free culture

Allografts of articular cartilage are both used clinically for tissue-transplantation procedures and experimentally as model systems to study the physiological behavior of chondrocytes in their native extracellular matrix. Long-term maintenance of allograft tissue is challenging. Chemical mediators in poorly defined culture media can stimulate cells to quickly degrade their surrounding extracellular matrix. This is particularly true of juvenile cartilage which is generally more responsive to chemical stimuli than mature tissue. By carefully modulating the culture media, however, it may be possible to preserve allograft tissue over the long-term while maintaining its original mechanical and biochemical properties. In this study juvenile bovine cartilage explants (both chondral and osteochondral) were cultured in both chemically defined medium and serum-supplemented medium for up to 6 weeks. The mechanical properties and biochemical content of explants cultured in chemically defined medium were enhanced after 2 weeks in culture and thereafter remained stable with no loss of cell viability. In contrast, the mechanical properties of explants in serum-supplemented medium were degraded by ( approximately 70%) along with a concurrent loss of biochemical content (30-40% GAG). These results suggest that long-term maintenance of allografts can be extended significantly by the use of a chemically defined medium.

The physiological basis of intracrine stem cell regulation

Intracrine peptides and proteins participate in the regulation of adult and pleuripotential embryonic-like stem cells. Included among these factors are VEGF, dynorphin, the readthrough form of acetylcholinesterase, Oct3/4, Pdx-1, Pax-6, and high-mobility group protein B1, among others. In some cases, the establishment of intracrine feedback loops can be shown to be relevant to this regulation, consistent with previously proposed principles of intracrine action. Here the role of intracrines in stem cell regulation is reviewed, with particular attention to the intracrine regulation of cardiac stem cells. The reprogramming of cells to restore the pleuripotent phenotype and the possible role of stem/progenitor cells in neoplasia are also discussed.

The trafficking protein GABARAP binds to and enhances plasma membrane expression and function of the angiotensin II type 1 receptor

Proteins that bind to the intracellular expanses, particularly cytoplasmic tail regions, of heptahelical integral membrane receptors are of particular interest in that they can mediate or modulate trafficking or intracellular signaling. In an effort to distinguish new proteins that might promote angiotensin II type 1 (AT(1)) receptor intracellular events, we screened a yeast 2-hybrid mouse brain library with the rat AT(1A) receptor (AT(1)R) carboxyl terminus and identified GABARAP, a protein involved in intracellular trafficking of the GABA(A) receptor, as a binding partner for the AT(1)R. Interaction of GABARAP with the AT(1)R carboxyl terminus was further substantiated using GST pull-down assays, and binding of the full-length tagged AT(1)R to GABARAP was verified using coimmunoprecipitation. Bioluminescence resonance energy transfer assays further confirmed specific interaction of GABARAP with AT(1)R. Moreover, GABARAP clearly increased the steady-state level of plasma membrane-associated AT(1)R in PC-12 cells. Cotransfection of GABARAP with an AT(1)R fluorescent fusion protein increased PC-12 cell surface expression of the AT(1)R more than 6-fold when standardized to the level of intracellular expression. Furthermore, GABARAP overexpression in CHO-K1 cells engineered to express AT(1)R increased angiotensin II binding sites 3.7-fold and angiotensin II-induced phospho-extracellular signal-regulated kinase 1/2 and cellular proliferation significantly over levels obtained with AT(1)R overexpression alone. In addition, small interfering RNA-mediated knockdown of GABARAP reduced the steady-state levels of the AT(1)R fluorescent fusion protein by 43% and its cell surface expression by 84%. Immunoblot analyses confirmed the quantitative image data. We conclude that GABARAP binds to and promotes trafficking of the AT(1)R to the plasma membrane.

The basis of an intracrine pharmacology

Intracrines are extracellular signaling peptide factors that can act in the intracellular space after either internalization or retention in the cells that synthesize them. They are structurally diverse and include hormones, growth factors, enzymes, DNA-binding proteins, and other peptide moieties. We have suggested principles of intracrine action and have applied those principles to forms of cellular and tissue differentiation, hormonal responsiveness, and memory. Moreover, recent findings make clear that some currently available pharmaceuticals act via the alteration of intracrine function. Thus, the beginnings of an intracrine pharmacology are at hand and we here review principles applicable to the design of such agents. The intracrine pharmacology of the renin-angiotensin system, angiogenesis, and stem cell development is discussed.