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Increases in drug consumption over time, also known as escalation, is a key behavioral component of substance use disorder (SUD) that is related to potential harm to users, such as overdose. Studying escalation also allows researchers to investigate the transition from casual drug use to more SUD-like drug use. Understanding the neurobiological systems that drive this transition will inform therapeutic treatments in the aim to prevent increases in drug use and the development of SUD. The kappa opioid receptor (KOR) system is typically known for its role in negative affect, which is commonly found in SUD as well. Furthermore, the KOR system has also been implicated in drug use and importantly, modulating the negative effects of drug use. However, the specific neuronal subpopulation expressing KOR involved has not been identified. Here, we first demonstrated that pharmacologically inhibiting KOR in the nucleus accumbens core (NAcC), as a whole, blocks cocaine escalation under long-access self-administration conditions. We then demonstrated that KOR expressed on ventral tegmental area (VTA) neurons but not NAcC neurons is sufficient for blocking cocaine escalation by utilizing a novel virally-mediated CRISPR-SaCas9 knock-out of the oprk1 gene. Together, this suggests that activation of KOR on VTA terminals in the NAcC drives the transition to the SUD-like phenotype of escalation of cocaine consumption.

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Complexity in the nervous system is established by developmental genetic programs, maintained by differential genetic profiles and sculpted by experiential and environmental influence over gene expression. Determining how specific genes define neuronal phenotypes, shape circuit connectivity and regulate circuit function is essential for understanding how the brain processes information, directs behavior and adapts to changing environments. Mouse genetics has contributed greatly to current percepts of gene-circuit interfaces in behavior, but considerable work remains. Large-scale initiatives to map gene expression and connectivity in the brain, together with advanced techniques in molecular genetics, now allow detailed exploration of the genetic basis of nervous system function at the level of specific circuit connections. In this review, we highlight several key advances for defining the function of specific genes within a neural network.

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OBJECTIVE: To document the histology of Ross River virus (RRV) arthritis and to examine inflamed synovium for viral RNA. METHODS: Biopsy tissue from the inflamed knees of 12 patients with RRV infection was studied using conventional and immunostaining techniques. Reverse transcriptase-polymerase chain reaction technology was used to probe for the presence of viral RNA in the synovial biopsy samples and in serum. RESULTS: Hyperplasia of the synovial lining layer, vascular proliferation, and mononuclear cell infiltration were the main histologic changes. RRV RNA was found in knee biopsy tissue that was obtained from 2 patients at 5 weeks after the onset of symptoms. CONCLUSION: RRV RNA was identified in inflamed synovium more than a month after symptoms began. Inflammation was apparent in the absence of detectable virus in the majority of patients.

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We describe 2 patients with rheumatoid arthritis (RA) and inclusion body myositis (IBM). Examination and laboratory tests including muscle biopsy with frozen section and electron microscopy were performed. Both patients fulfilled diagnostic criteria for IBM, which is increasingly recognized in association with autoimmune disease. A high index of suspicion and early thorough investigation are required to diagnose IBM in patients with RA.

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Angiotensinogen has been assumed to be an acute-phase protein, because some forms of acute inflammation, eg, the injection of lipopolysaccharide or cellite or partial hepatectomy, increased the hepatic synthesis of angiotensinogen. In addition, the well-characterized nephrectomy-induced stimulation of angiotensinogen was thought to represent an acute-phase reaction. To evaluate this hypothesis, we examined changes in angiotensinogen secretion by the isolated perfused rat liver after the systemic administration of turpentine or lipopolysaccharide as well as in response to nephrectomy or sham nephrectomy. Comparison was made with the secretion of two typical acute-phase proteins, alpha 1-acid glycoprotein and alpha 2-macroglobulin, and with the secretion of the negative acute-phase protein albumin. All forms of experimental surgery stimulated the secretion of both control acute-phase proteins several-fold. In contrast, the response of angiotensinogen was not uniform; lipopolysaccharide and bilateral nephrectomy stimulated secretion twofold to threefold, sham nephrectomy had no effect, and turpentine decreased the secretion to 30% of the control level. A similar inhomogeneity was found in an additional experiment performed to analyze the direct effects of interleukin-1 or interleukin-6 on the secretion of angiotensinogen by freshly isolated hepatocytes. Interleukin-6 increased but interleukin-1 decreased the mRNA and secretion of angiotensinogen, whereas both cytokines increased the secretion of both acute-phase proteins. Because of this nonuniform behavior of angiotensinogen, it is premature to classify angiotensinogen as an acute-phase protein until a specific function for angiotensinogen during acute inflammation is known.

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Rheumatic manifestations are common and varied in infective endocarditis. We performed a retrospective case analysis on 87 patients with 93 episodes of infective endocarditis admitted to Flinders Medical Centre over an 11 year period (1980-1990). Disabling musculoskeletal symptoms and signs were documented in 22 (25%) of the patients. Thirteen patients developed severe or moderately severe low back pain during their illness, two with radiological evidence of a septic discitis or vertebral osteomyelitis. Two patients developed polyarthralgia/arthritis, four had septic arthritis (all with acute Staphylococcus aureus endocarditis), three developed severe loin pain, two acute gout, two had severe buttock pain and sacroiliac joint tenderness and two each developed disabling jaw/facial pain, neck/scapular pain and flank pain respectively. Five patients presented initially to the orthopaedic or rheumatological unit for management of their musculoskeletal symptoms. Four of seven patients with Streptococcus bovis endocarditis demonstrated prominent low back pain supporting a previously noted association between this organism and back symptoms. Furthermore, in one patient who had three separate episodes of endocarditis involving three different organisms, florid back symptoms were only seen in the infective episode involving Streptococcus bovis.

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Synovial tissues from inflamed and noninflamed knee joints of 13 patients with untreated rheumatoid arthritis were examined for vascular proliferation and morphological alteration of endothelial cells. Perivascular mononuclear cell infiltration and increased thickness of the synovial lining layer were noted in tissues from inflamed and noninflamed joints of patients with rheumatoid arthritis; vascular proliferation and morphological alteration of endothelial cells to resemble high endothelial venules were seen only in tissues from inflamed joints of patients with rheumatoid arthritis. These observations suggest that the migration of mononuclear cells from the peripheral blood to the perivascular areas and lining layer occurs before vascular proliferation and morphological alteration of endothelial cells.

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Immunohistological features which might predict the clinical course and outcome of rheumatoid arthritis were sought by examining multiple synovial membrane samples obtained by needle biopsy from the knee joints of 57 patients who had not received disease modifying antirheumatic drugs. Clinical measurements, but not biopsies, were repeated one year and three years after starting treatment. A correlation between both the intensity of synovial lining layer thickening and mononuclear cell infiltration and the clinical status at the time of biopsy was seen. After three years of treatment the correlations were maintained in patients who had presented and persisted with milder disease but not in patients who had presented with more active disease.

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One hundred and sixty-six patients admitted to general medical wards of a teaching hospital were examined on the day of discharge to determine whether they had been assessed for musculoskeletal disorders during their admission. Of these patients, 54.8% had musculo-skeletal symptoms with 17.5% having a significant rheumatological disorder which had been ignored. A history of musculo-skeletal symptoms was recorded in 40.4% of all patients and the examination in only 14.5%. This contrasted with the documentation of the cardiovascular (99.4%), respiratory (100%), gastrointestinal (97.6%) and central nervous (53%) systems' examination. Eighty per cent of symptomatic patients received either no treatment for their rheumatic disorder, or treatment that we regarded as suboptimal or inappropriate. Musculo-skeletal symptoms are common in patients admitted to medical wards, but are being inadequately assessed or at worst ignored. The omission of the musculo-skeletal system examination, in contrast to the almost universal inclusion of other systems' examination, demands correction. Undergraduate and postgraduate training programmes require re-evaluation. The implications of these findings are discussed.

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To test the hypothesis that early steroid pulsing augments the efficacy and decreases the toxicity of chrysotherapy 40 patients with rheumatoid arthritis were studied in a double blind, placebo controlled study. During the first three months of gold treatment group 1 received monthly intravenous methylprednisolone pulsing (steroid group) while group 2 received placebo (placebo group). All patients were assessed clinically and serologically over a 24 week period. Twelve patients were withdrawn before completion of the study and all but one of the remaining 28 patients reported clinical and serological improvements. Two patients in the steroid group were withdrawn owing to gold induced side effects while four were withdrawn in the placebo group. These small numbers were not significantly different. Minor side effects occurred more commonly in the placebo group. The clinical response was clearly better in the steroid group with statistical significance almost being achieved. In an endeavour to obtain a significant conclusion further patients will now be entered into this study.

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IgM and IgA rheumatoid factor (RF) synthesis by synovial membrane mononuclear cells was measured in 14 patients with rheumatoid arthritis (RA). The results were compared with blood mononuclear cell cultures and correlated with the intensity of lymphocyte infiltration of the synovium. IgM RF was produced by all synovial cultures compared with 56% of blood cultures; IgA RF was produced by 86% of synovial cultures and by 21% of blood cultures. A correlation was observed between synovial IgM RF synthesis, but not IgA RF synthesis, and the intensity of T cell and B cell infiltration of the synovial membrane.

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An 8-year-old boy with cystic fibrosis presented with a chronic polyarthritis. Histological examination of the synovium demonstrated multiple non-caseating granulomata. A systematic search for sarcoidosis revealed characteristic ophthalmic abnormalities and an elevated serum level of angiotensin converting enzyme. An association between cystic fibrosis and sarcoidosis is likely.

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The spectrum of immunohistological change in the affected joints of patients with rheumatoid arthritis has been well described. In this study, the immunohistological features in synovial membrane obtained from apparently uninvolved knee joints of 16 patients with active untreated rheumatoid arthritis were examined and compared to tissue from control subjects. Synovial tissue was obtained by needle biopsy. Hyperplasia of the synovial lining layer, present in 69%, was the most frequently observed abnormality in synovium obtained from uninvolved joints. Perivascular mononuclear cell infiltration was present in 31% and consisted predominantly of helper T-cells. Increased vascularity and fibrin deposition were not notable features. Clinically overt synovitis emerged in only two patients during a follow-up period of up to 36 months. In conclusion, a considerable degree of histological change was observed in the apparently uninvolved knee joints of patients with active rheumatoid arthritis. The presence of subclinical synovitis challenges current concepts of disease activity and clinical remission. Further study is required to determine whether the features described may be associated with progressive joint erosion.

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Twenty patients with intractable rheumatoid arthritis were randomized to receive 750 or 2,000 rads of lymphoid irradiation (LI) in a double-blind comparative study, and were followed for a maximum of 48 months (mean 40 months) after treatment. During followup, sustained immunomodulation (including lymphopenia, particularly of the T helper cell subset; reduced ratio of helper cells to suppressor cells; and impaired in vitro lymphocyte proliferation in response to phytohemagglutinin and pokeweed mitogen) was observed. Significant improvements in early morning stiffness, Ritchie articular index, pain score, grip strength, and 15-meter walk time were observed in both treatment groups, but these were not sustained through the followup period. Progressive joint damage was observed radiologically in both groups during followup. Thus, LI induced sustained immunosuppression, but resulted in only short-lived clinical improvement and was associated with progressive joint erosion in these patients.

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