Osteoprotegerin ligand is a cytokine that regulates osteoclast differentiation and activation

The ligand for osteoprotegerin has been identified, and it is a TNF-related cytokine that replaces the requirement for stromal cells, vitamin D3, and glucocorticoids in the coculture model of in vitro osteoclastogenesis. OPG ligand (OPGL) binds to a unique hematopoeitic progenitor cell that is committed to the osteoclast lineage and stimulates the rapid induction of genes that typify osteoclast development. OPGL directly activates isolated mature osteoclasts in vitro, and short-term administration into normal adult mice results in osteoclast activation associated with systemic hypercalcemia. These data suggest that OPGL is an osteoclast differentiation and activation factor. The effects of OPGL are blocked in vitro and in vivo by OPG, suggesting that OPGL and OPG are key extracellular regulators of osteoclast development.

Osteoprotegerin: a novel secreted protein involved in the regulation of bone density

A novel secreted glycoprotein that regulates bone resorption has been identified. The protein, termed Osteoprotegerin (OPG), is a novel member of the TNF receptor superfamily. In vivo, hepatic expression of OPG in transgenic mice results in a profound yet nonlethal osteopetrosis, coincident with a decrease in later stages of osteoclast differentiation. These same effects are observed upon administration of recombinant OPG into normal mice. In vitro, osteoclast differentiation from precursor cells is blocked in a dose-dependent manner by recombinant OPG. Furthermore, OPG blocks ovariectomy-associated bone loss in rats. These data show that OPG can act as a soluble factor in the regulation of bone mass and imply a utility for OPG in the treatment of osteoporosis associated with increased osteoclast activity.

Activated T cells regulate bone loss and joint destruction in adjuvant arthritis through osteoprotegerin ligand

Bone remodelling and bone loss are controlled by a balance between the tumour necrosis factor family molecule osteoprotegerin ligand (OPGL) and its decoy receptor osteoprotegerin (OPG). In addition, OPGL regulates lymph node organogenesis, lymphocyte development and interactions between T cells and dendritic cells in the immune system. The OPGL receptor, RANK, is expressed on chondrocytes, osteoclast precursors and mature osteoclasts. OPGL expression in T cells is induced by antigen receptor engagement, which suggests that activated T cells may influence bone metabolism through OPGL and RANK. Here we report that activated T cells can directly trigger osteoclastogenesis through OPGL. Systemic activation of T cells in vivo leads to an OPGL-mediated increase in osteoclastogenesis and bone loss. In a T-cell-dependent model of rat adjuvant arthritis characterized by severe joint inflammation, bone and cartilage destruction and crippling, blocking of OPGL through osteoprotegerin treatment at the onset of disease prevents bone and cartilage destruction but not inflammation. These results show that both systemic and local T-cell activation can lead to OPGL production and subsequent bone loss, and they provide a novel paradigm for T cells as regulators of bone physiology.

Tumor necrosis factor receptor family member RANK mediates osteoclast differentiation and activation induced by osteoprotegerin ligand

A receptor that mediates osteoprotegerin ligand (OPGL)-induced osteoclast differentiation and activation has been identified via genomic analysis of a primary osteoclast precursor cell cDNA library and is identical to the tumor necrosis factor receptor (TNFR) family member RANK. The RANK mRNA was highly expressed by isolated bone marrow-derived osteoclast progenitors and by mature osteoclasts in vivo. Recombinant OPGL binds specifically to RANK expressed by transfected cell lines and purified osteoclast progenitors. Transgenic mice expressing a soluble RANK-Fc fusion protein have severe osteopetrosis because of a reduction in osteoclasts, similar to OPG transgenic mice. Recombinant RANK-Fc binds with high affinity to OPGL in vitro and blocks osteoclast differentiation and activation in vitro and in vivo. Furthermore, polyclonal Ab against the RANK extracellular domain promotes osteoclastogenesis in bone marrow cultures suggesting that RANK activation mediates the effects of OPGL on the osteoclast pathway. These data indicate that OPGL-induced osteoclastogenesis is directly mediated through RANK on osteoclast precursor cells.

Evolving guidelines for publication of qualitative research studies in psychology and related fields

We present a set of evolving guidelines for reviewing qualitative research, to serve four functions: to contribute to the process of legitimizing qualitative research; to ensure more appropriate and valid scientific reviews of qualitative manuscripts, theses, and dissertations; to encourage better quality control in qualitative research through better self- and other-monitoring; and to encourage further developments in approach and method. Building on a review of existing principles of good practice in qualitative research, we used an iterative process of revision and feedback from colleagues who engage in qualitative research, resulting in a set of seven guidelines common to both qualitative and quantitative research and seven guidelines especially pertinent to qualitative investigations in psychology and related social sciences. The Evolving Guidelines are subject to continuing revision and should not be used in a rigid manner, in order to avoid stifling creativity in this rapidly evolving, rich research tradition.

RANK is the intrinsic hematopoietic cell surface receptor that controls osteoclastogenesis and regulation of bone mass and calcium metabolism

We have generated RANK (receptor activator of NF-kappaB) nullizygous mice to determine the molecular genetic interactions between osteoprotegerin, osteoprotegerin ligand, and RANK during bone resorption and remodeling processes. RANK(-/-) mice lack osteoclasts and have a profound defect in bone resorption and remodeling and in the development of the cartilaginous growth plates of endochondral bone. The osteopetrosis observed in these mice can be reversed by transplantation of bone marrow from rag1(-/-) (recombinase activating gene 1) mice, indicating that RANK(-/-) mice have an intrinsic defect in osteoclast function. Calciotropic hormones and proresorptive cytokines that are known to induce bone resorption in mice and human were administered to RANK(-/-) mice without inducing hypercalcemia, although tumor necrosis factor alpha treatment leads to the rare appearance of osteoclast-like cells near the site of injection. Osteoclastogenesis can be initiated in RANK(-/-) mice by transfer of the RANK cDNA back into hematopoietic precursors, suggesting a means to critically evaluate RANK structural features required for bone resorption. Together these data indicate that RANK is the intrinsic cell surface determinant that mediates osteoprotegerin ligand effects on bone resorption and remodeling as well as the physiological and pathological effects of calciotropic hormones and proresorptive cytokines.

Dissociable functions in the medial and lateral orbitofrontal cortex: evidence from human neuroimaging studies

Recent imaging studies show that the orbitofrontal cortex (OFC) is activated during a wide variety of paradigms, including guessing tasks, simple delayed matching tasks and sentence completion. We suggest that, as with other regions of the prefrontal cortex, activity in the OFC is most likely to be observed when there is insufficient information available to determine the appropriate course of action. In these circumstances the OFC, rather than other prefrontal regions, is more likely to be activated when the problem of what to do next is best solved by taking into account the likely reward value of stimuli and responses, rather than their identity or location. We suggest that selection of stimuli on the basis of their familiarity and responses on the basis of a feeling of 'rightness' are also examples of selection on the basis of reward value. Within the OFC, the lateral regions are more likely to be involved when the action selected requires the suppression of previously rewarded responses.

The osteoclast differentiation factor osteoprotegerin-ligand is essential for mammary gland development

Osteoprotegerin-ligand (OPGL) is a key osteoclast differentiation/activation factor essential for bone remodeling. We report that mice lacking OPGL or its receptor RANK fail to form lobulo-alveolar mammary structures during pregnancy, resulting in death of newborns. Transplantation and OPGL-rescue experiments in opgl-/- and rank-/- pregnant females showed that OPGL acts directly on RANK-expressing mammary epithelial cells. The effects of OPGL are autonomous to epithelial cells. The mammary gland defect in female opgl-/- mice is characterized by enhanced apoptosis and failures in proliferation and PKB activation in lobulo-alveolar buds that can be reversed by recombinant OPGL treatment. These data provide a novel paradigm in mammary gland development and an evolutionary rationale for hormonal regulation and gender bias of osteoporosis in females.

Arthritic pain is processed in brain areas concerned with emotions and fear

OBJECTIVE

Functional neuroimaging studies have shown that experimentally induced acute pain is processed within at least 2 parallel networks of brain structures collectively known as the pain matrix. The relevance of this finding to clinical pain is not known, because no direct comparisons of experimental and clinical pain have been performed in the same group of patients. The aim of this study was to compare directly the brain areas involved in processing arthritic pain and experimental pain in a group of patients with osteoarthritis (OA).

METHODS

Twelve patients with knee OA underwent positron emission tomography of the brain, using (18)F-fluorodeoxyglucose (FDG). Scanning was performed during 3 different pain states: arthritic knee pain, experimental knee pain, and pain-free. Significant differences in the neuronal uptake of FDG between different pain states were investigated using statistical parametric mapping software.

RESULTS

Both pain conditions activated the pain matrix, but arthritic pain was associated with increased activity in the cingulate cortex, the thalamus, and the amygdala; these areas are involved in the processing of fear, emotions, and in aversive conditioning.

CONCLUSION

Our results suggest that studies of experimental pain provide a relevant but quantitatively incomplete picture of brain activity during arthritic pain. The search for new analgesics for arthritis that act on the brain should focus on drugs that modify this circuitry.

floricaula: a homeotic gene required for flower development in antirrhinum majus

Plants carrying the floricaula (flo) mutation cannot make the transition from inflorescence to floral meristems and have indeterminate shoots in place of flowers. The flo-613 allele carries a Tam3 transposon insertion, which allowed the isolation of the flo locus. The flo gene encodes a putative protein (FLO) containing a proline-rich N-terminus and a highly acidic region. In situ hybridization shows that the flo gene is transiently expressed in the very early stages of flower development. The earliest expression seen is in bract primordia, followed by sepal, petal, and carpel primordia, but no expression is detected in stamen primordia. This pattern of expression has implications for how flo affects phyllotaxis, organ identity, and determinacy. We propose that flo interacts in a sequential manner with other homeotic genes affecting floral organ identity.

Response inhibition and impulsivity: an fMRI study

Aggressive, suicidal and violent behaviour have been associated with impulsive personality and difficulty in inhibiting responses. We used functional magnetic resonance imaging (fMRI) of the whole brain to examine the neural correlates of response inhibition in 19 normal subjects as they performed a Go/NoGo task. Subjects completed Eysenck's Impulsivity Scale, Barratt's Impulsivity Scale (BIS) and behavioural impulsivity tasks. Associations between blood oxygen level dependent (BOLD) response, trait impulsivity, task performance and National Adult Reading Test (NART) IQ were investigated. Neural response during response inhibition was most prominent in the right lateral orbitofrontal cortex. Responses were also seen in superior temporal gyrus, medial orbitofrontal cortex, cingulate gyrus, and inferior parietal lobule, predominantly on the right side. Subjects with greater scores on impulsivity scales and who made more errors had greater activation of paralimbic areas during response inhibition, while less impulsive individuals and those with least errors activated higher order association areas. Exploratory factor analysis of orbital activations, personality measures and errors of commission did not reveal a unitary dimension of impulsivity. However, the strong association between posterior orbital activation and Eysenck's impulsivity score on a single factor suggests that greater engagement of right orbitofrontal cortex was needed to maintain behavioural inhibition in impulsive individuals. Lower IQ was more important than impulsivity scores in determining errors of commission during the task. Neuroimaging of brain activity during the Go/NoGo task may be useful in understanding the functional neuroanatomy and associated neurochemistry of response inhibition. It may also allow study of the effects of physical and psychological interventions on response inhibition in clinical conditions such as antisocial personality disorder.

A systematic review and meta-analysis of exercise interventions in schizophrenia patients

BACKGROUND

The typically poor outcomes of schizophrenia could be improved through interventions that reduce cardiometabolic risk, negative symptoms and cognitive deficits; aspects of the illness which often go untreated. The present review and meta-analysis aimed to establish the effectiveness of exercise for improving both physical and mental health outcomes in schizophrenia patients.

METHOD

We conducted a systematic literature search to identify all studies that examined the physical or mental effects of exercise interventions in non-affective psychotic disorders. Of 1581 references, 20 eligible studies were identified. Data on study design, sample characteristics, outcomes and feasibility were extracted from all studies and systematically reviewed. Meta-analyses were also conducted on the physical and mental health outcomes of randomized controlled trials.

RESULTS

Exercise interventions had no significant effect on body mass index, but can improve physical fitness and other cardiometabolic risk factors. Psychiatric symptoms were significantly reduced by interventions using around 90 min of moderate-to-vigorous exercise per week (standardized mean difference: 0.72, 95% confidence interval -1.14 to -0.29). This amount of exercise was also reported to significantly improve functioning, co-morbid disorders and neurocognition.

CONCLUSIONS

Interventions that implement a sufficient dose of exercise, in supervised or group settings, can be feasible and effective interventions for schizophrenia.

Neuropsychological impairments in unipolar depression: the influence of perceived failure on subsequent performance

The CANTAB battery of neuropsychological tests was used to compare the performance of 28 patients with unipolar depression with that of 22 age and IQ matched controls. The patients were impaired on almost all tests studied with deficits in pattern and spatial recognition memory, matching to sample, spatial span, spatial working memory and planning. Most of the patients showed at least some impairment and deficits were seen across cognitive domains. An important finding was the detrimental effect of failure on subsequent performance; having solved one problem incorrectly, patients were far more likely than controls to fail the subsequent problem. Superimposed on the general deficits, there were also specific deficits in executive tasks characteristic of frontostriatal dysfunction and deficits in mnemonic tasks characteristic of temporal lobe dysfunction. This combination of a specific form of motivational deficit, resulting in oversensitivity to negative feedback, and superimposed specific neuropsychological deficits were correlated with severity of depression. The most significant correlations were seen between mnemonic deficits and clinical rating scores. Comparisons of the deficits seen in the depressed patients in this study with other patient groups assessed with the CANTAB neuropsychological battery, showed that one of the hypotheses of the neuropsychological deficits in depression, that of "frontosubcortical' or "frontostriatal' dysfunction, was not supported. These findings are discussed in relation to the likely neural substrates of depression.

Attention to pain localization and unpleasantness discriminates the functions of the medial and lateral pain systems

Functional imaging studies have identified a matrix of structures in the brain that respond to noxious stimuli. Within this matrix, a division of function between sensory-discriminative and affective responses has so far been demonstrated by manipulating either pain intensity or unpleasantness under hypnosis in two different normal volunteer groups studied on separate occasions. Our study used positron emission tomography (PET) to demonstrate this division of function under more natural conditions in a healthy group of volunteers, using a CO(2) laser to provide nociceptive stimuli that selectively activate A-delta and C-fibres without contamination by touch sensations. We measured the differential cerebral responses to noxious and innocuous laser stimuli during conditions of selective attention to either the unpleasantness or location of the stimuli. Attention to location increased responses in the contralateral (right) primary somatosensory and inferior parietal cortices. This result implies that these components of the lateral pain system are concerned mainly with the localization of pain. In contrast, attention to unpleasantness increased responses in bilateral perigenual cingulate and orbitofrontal cortices, contralateral (right) amygdala, ipsilateral (left) hypothalamus, posterior insula, M1 and frontal pole. These areas comprise key components of the medial pain and neuroendocrine systems and the results suggest that they have a role in the affective response to pain. Our results indicate the importance of attentional effects on the pattern of nociceptive processing in the brain. They also provide the first clear demonstration, within a single experiment, of a major division of function within the neural pain matrix.

Effects of methylphenidate on spatial working memory and planning in healthy young adults

Previous studies of the effects of the psychomotor stimulant, methylphenidate, have concentrated on vigilance and reaction time tasks. In this study, the effects of methylphenidate on more complex aspects of cognition were studied using tasks from the CANTAB battery and related tests which have been shown to be sensitive to frontal lobe dysfunction. Twenty-eight young healthy men participated in a counterbalanced, double-blind, placebo-controlled study of the effects of methylphenidate. Cognitive assessment included tests of spatial working memory, planning, verbal fluency, attentional set-shifting and sustained attention. Methylphenidate had significant effects on performance of the tests of spatial working memory and planning but not on the attentional and fluency tests. When the drug was taken on the first test session, performance on the spatial tests was enhanced by the drug compared to placebo. However, when the drug was taken second, performance accuracy was impaired whereas response latencies were decreased. These results are consistent with a hypothesis that methylphenidate influences performance in two conflicting ways; enhancing executive aspects of spatial function on novel tasks but impairing previously established performance. This pattern of effects is discussed within the framework of dual, interacting arousal mechanisms.

Empathy

After defining empathy, discussing its measurement, and offering an example of empathy in practice, we present the results of an updated meta-analysis of the relation between empathy and psychotherapy outcome. Results indicated that empathy is a moderately strong predictor of therapy outcome: mean weighted r = .31 (p < .001; 95% confidence interval: .28-.34), for 59 independent samples and 3599 clients. Although the empathy-outcome relation held equally for different theoretical orientations, there was considerable nonrandom variability. Client and observer perceptions of therapist empathy predicted outcomes better than therapist perceptions of empathic accuracy measures, and the relation was strongest for less experienced therapists. We conclude with practice recommendations, including endorsing the different forms that empathy may take in therapy.

Neuropsychological evidence for frontostriatal dysfunction in schizophrenia

Schizophrenics and controls were compared on a computerized test of attentional set-shifting which provides a componential analysis of the Wisconsin Card Sort Test and has previously been shown to be sensitive to frontal lobe dysfunction and Parkinson's disease. The main test was of extra-dimensional shifting where subjects are required to shift response to an alternative perceptual dimension. In one condition, termed 'perseveration', subjects are required to shift to a novel dimension and ignore the previously relevant one. In the other condition, termed 'learned irrelevance', subjects are required to shift to the previously irrelevant dimension and ignore a novel one. Chronic medicated schizophrenics (N = 32) show a highly significant impairment on the perseveration but not the learned irrelevance condition, as compared to normal age and IQ matched controls (N = 24). This was true even of a subgroup of patients with preserved IQ. The impairments in attentional set-shifting failed to correlate with patients' scores on the Mini-Mental State Examination (mean; S.D. 26.8; 1.8) or with scores on a test of recognition memory. These results provide evidence for a specific deficit in a set-shifting test of executive function and support a hypothesis of frontostriatal dysfunction in schizophrenia.

Prefrontal dysfunction in depressed patients performing a complex planning task: a study using positron emission tomography

INTRODUCTION

Patients with unipolar depression show impaired performance on the Tower of London planning task. Positron emission tomography, which has previously identified resting state blood flow abnormalities in depression, was used to investigate neural activity associated with performance of this task in depressed patients and normal controls.

METHODS

Six patients with unipolar depression and six matched controls were scanned while performing easy and hard Tower of London problems in a one-touch computerized paradigm and while performing a perceptuomotor control task.

RESULTS

The patients in this study showed an expected task-related performance deficit compared with normal subjects. In normal subjects, the task engaged a network of prefrontal cortex, anterior cingulate, posterior cortical areas and subcortical structures including the striatum, thalamus and cerebellum. Depressed patients failed to show significant activation in the cingulate and striatum; activation in the other prefrontal and posterior cortical regions was significantly attenuated relative to controls. Crucially, patients also failed to show the normal augmentation of activation in the caudate nucleus, anterior cingulate and right prefrontal cortex associated with increasing task difficulty.

CONCLUSIONS

These findings provide evidence for cingulate, prefrontal and striatal dysfunction associated with impaired task performance in depression. The present results are consistent with a central role of cingulate dysfunction in depression as well as suggesting impaired frontostriatal function.

State-dependent changes in hippocampal grey matter in depression

Reduced hippocampal volume has been reported in depression and may be involved in the aetiology of depressive symptoms and vulnerability to depressive relapse. Neuroplasticity following antidepressant drug treatment in the hippocampus has been demonstrated in animal models but adaptive changes after such treatment have not been shown in humans. In this study, we determined whether grey matter loss in the hippocampus in depression (1) is present in medication-free depressed (2) changes in response to antidepressant treatment and (3) is present as a stable trait in medication-free remitted patients. Sixty-four medication-free unipolar depressed patients: 39 currently depressed and 25 in remission, and 66 healthy controls (HC) underwent structural magnetic resonance imaging in a cross-sectional and longitudinal design. Thirty-two currently depressed participants were then treated with the antidepressant citalopram for 8 weeks. Adherence to treatment was evaluated by measuring plasma citalopram concentration. We measured regional variation in grey matter concentration by using voxel-based morphometry-Diffeomorphic Anatomical Registration Through Exponentiated Lie algebra. Patients with current depression had bilaterally reduced grey matter in the hippocampus compared with HC and untreated patients in stable remission with the latter groups not differing. An increase in grey matter was observed in the hippocampus following treatment with citalopram in currently depressed patients. Grey matter reduction in the hippocampus appears specific to the depressed state and is a potential biomarker for a depressive episode.

Abnormal response to negative feedback in unipolar depression: evidence for a diagnosis specific impairment

OBJECTIVES

To assess in further detail the specific form of motivational impairment influencing neuropsychological performance in depression-oversensitivity to perceived failure. The present study considers two questions: firstly whether this is specific to depression and secondly how the effect relates to clinical features.

METHODS

Unipolar depressed patients and matched controls were assessed on two neuropsychological tests giving explicit performance feedback. The data were analysed in two separate studies to consider the questions above. The first study considered the specificity of the effect to depressed patients, using data on the same tests collected from other patient groups. The second study was a longitudinal assessment of the depressed patients on clinical recovery to determine whether the effect is specific to the depressed state.

RESULTS

The effect was not seen in non-depressed patient groups, either neurological or psychiatric groups. The longitudinal study showed a residual abnormal response to negative feedback on clinical recovery.

CONCLUSIONS

Abnormal response to negative feedback is specific to a primary diagnosis of depression and may be a trait rather than a state factor of the disorder. These results are discussed in relation to the putative neuropathology of depression and also to cognitive and behavioural accounts of the disorder. The findings presented here have important implications for establishing a link between mood and cognition in unipolar depression.