Additive effects of oxytocin receptor gene polymorphisms on reward circuitry in youth with autism.

Several common alleles in the oxytocin receptor gene (OXTR) are associated with altered brain function in reward circuitry in neurotypical adults and may increase risk for autism spectrum disorders (ASD). Yet, it is currently unknown how variation in the OXTR relates to brain functioning in individuals with ASD, and, critically, whether neural endophenotypes vary as a function of aggregate genetic risk. Here, for we believe the first time, we use a multi-locus approach to examine how genetic variation across several OXTR single-nucleotide polymorphisms (SNPs) affect functional connectivity of the brain's reward network. Using data from 41 children with ASD and 41 neurotypical children, we examined functional connectivity of the nucleus accumbens (NAcc) - a hub of the reward network - focusing on how connectivity varies with OXTR risk-allele dosage. Youth with ASD showed reduced NAcc connectivity with other areas in the reward circuit as a function of increased OXTR risk-allele dosage, as well as a positive association between risk-allele dosage and symptom severity, whereas neurotypical youth showed increased NAcc connectivity with frontal brain regions involved in mentalizing. In addition, we found that increased NAcc-frontal cortex connectivity in typically developing youth was related to better scores on a standardized measure of social functioning. Our results indicate that cumulative genetic variation on the OXTR impacts reward system connectivity in both youth with ASD and neurotypical controls. By showing differential genetic effects on neuroendophenotypes, these pathways elucidate mechanisms of vulnerability versus resilience in carriers of disease-associated risk alleles.

Pheochromocytoma of the Organ Zuckerkandl.

INTRODUCTION: Pheochromocytomas (PCCs);, or intra-adrenal paragangliomas (PGLs);, are neuroendocrine tumors arising within the adrenal medulla. Extra-adrenal paragangliomas may arise in the sympathetic or parasympathetic paraganglia and more rarely in other organs. One of the most common extra-adrenal sites is in the organ of Zuckerkandl, a collection of chromaffin cells near the origin of the inferior mesenteric artery or near the aortic bifurcation. The following is a case of a patient with resistant hypertension secondary to an extra-adrenal paraganglioma in the organ of Zuckerkandl. CASE: The patient is a 43 year old man with a history of depression, type 2 diabetes mellitus, and hypertension who was sent to the emergency department by his primary care physician for severely elevated blood pressures. Patient also had diaphoresis, tachycardia, and a new, fine tremor of his left hand. Upon presentation, the patient's blood pressure was 260/120 mmHg with a heart rate of 140 beats per minute. Plasma fractionated metanephrines sent on admission revealed significantly elevated levels of total plasma metanephrines (2558 pg/mL);, free metanephrine (74 pg/ml); and free normetanephrine (2484pg/mL);. An I-123 metaiodobenzylguanidine (MIBG); scan showed abnormal uptake in the lower abdomen at the level of the aortic bifurcation. Patient was started on alpha-blockade, with subsequent addition of a beta-blocker prior to surgery. Patient underwent surgical removal of the tumor with pathology consistent with a paraganglioma. DISCUSSION: Pheochromocytomas and paragangliomas are responsible for approximately 0.5 percent of cases of secondary hypertension. Many different biochemical markers have been used to aid in the diagnosis of PCC/PGL including plasma catecholamines, plasma metanephrines, urine fractionated metanephrines, urine catecholamines, total metanephrines and vanillymandellic acid. Definitive management of a PCC and PGL involves surgical removal of the tumor. Finally, there should be a discussion with each patient to determine if he or she should undergo genetic testing, as studies show that approximately 25 percent of catecholamine producing PCCs and PGLs are due to heritable genetic mutations.

Lens Epithelial Cell Proliferation in Response to Ionizing Radiation.

Lens epithelial cell proliferation and differentiation are naturally well regulated and controlled, a characteristic essential for lens structure, symmetry and function. The effect of ionizing radiation on lens epithelial cell proliferation has been demonstrated in previous studies at high acute doses, but the effect of dose and dose rate on proliferation has not yet been considered. In this work, mice received single acute doses of 0.5, 1 and 2 Gy of radiation, at dose rates of 0.063 and 0.3 Gy/min. Eye lenses were isolated postirradiation at 30 min up until 14 days and flat-mounted. Then, cell proliferation rates were determined using biomarker Ki67. As expected, radiation increased cell proliferation 2 and 24 h postirradiation transiently (undetectable 14 days postirradiation) and was dose dependent (changes were very significant at 2 Gy; P = 0.008). A dose-rate effect did not reach significance in this study (P = 0.054). However, dose rate and lens epithelial cell region showed significant interactions (P < 0.001). These observations further our mechanistic understanding of how the lens responds to radiation.

Radiation-induced DNA Damage and Repair in Lens Epithelial Cells of both Ptch1(+/-) and Ercc2(+/-) Mutated Mice.

Epidemiological studies suggest an increased incidence and risk of cataract after low-dose (<2 Gy) ionizing radiation exposures. However, the biological mechanism(s) of this process are not fully understood. DNA damage and repair are thought to have a contributing role in radiation-induced cataractogenesis. Recently we have reported an inverse dose-rate effect, as well as the low-dose response, of DNA damage and repair in lens epithelial cells (LECs). Here, we present further initial findings from two mutated strains (Ercc2+/- and Ptch1+/-) of mice, both reportedly susceptible to radiation-induced cataract, and their DNA damage and repair response to low-dose and low-dose-rate gamma rays. Our results support the hypothesis that the lens epithelium responds differently to radiation than other tissues, with reported radiation susceptibility to DNA damage not necessarily translating to the LECs. Genetic predisposition and strain(s) of mice have a significant role in radiation-induced cataract susceptibility.

Radiation-Induced Lens Opacity and Cataractogenesis: A Lifetime Study Using Mice of Varying Genetic Backgrounds.

Recent epidemiological findings and reanalysis of historical data suggest lens opacities resulting from ionizing radiation exposures are likely induced at lower doses than previously thought. These observations have led to ICRP recommendations for a reduction in the occupational dose limits for the eye lens, as well as subsequent implementation in EU member states. The EU CONCERT LDLensRad project was initiated to further understand the effects of ionizing radiation on the lens and identify the mechanism(s) involved in radiation-induced cataract, as well as the impact of dose and dose-rate. Here, we present the results of a long-term study of changes to lens opacity in male and female adult mice from a variety of different genetic (radiosensitive or radioresistant) backgrounds, including mutant strains Ercc2 and Ptch1, which were assumed to be susceptible to radiation-induced lens opacities. Mice received 0.5, 1 and 2 Gy 60Co gamma-ray irradiation at dose rates of 0.063 and 0.3 Gy min-1. Scheimpflug imaging was used to quantify lens opacification as an early indicator of cataract, with monthly observations taken postirradiation for an 18-month period in all strains apart from 129S2, which were observed for 12 months. Opacification of the lens was found to increase with time postirradiation (with age) for most mouse models, with ionizing radiation exposure increasing opacities further. Sex, dose, dose rate and genetic background were all found to be significant contributors to opacification; however, significant interactions were identified, which meant that the impact of these factors was strain dependent. Mean lens density increased with higher dose and dose rate in the presence of Ercc2 and Ptch1 mutations. This project was the first to focus on low (<1 Gy) dose, multiple dose rate, sex and strain effects in lens opacification, and clearly demonstrates the importance of these experimental factors in radiobiological investigations on the lens. The results provide insight into the effects of ionizing radiation on the lens as well as the need for further work in this area to underpin appropriate radiation protection legislation and guidance.

The experience of clinical supervision for nurses and healthcare assistants in a secure adolescent service: Affecting service improvement.

WHAT IS KNOWN ON THE SUBJECT?: Regular and effective clinical supervision for mental health nurses and healthcare assistants (HCAs) is an important tool in helping to reduce stress and burnout, and in ensuring safe, effective and high-quality mental health care. Previous studies of clinical supervision within secure mental health environments have found both a low availability of clinical supervision, and a low level of staff acceptance of its value, particularly for HCAs. WHAT DOES THIS PAPER ADD TO EXISTING KNOWLEDGE?: In previous studies, the understanding shown by HCAs and nurses around the benefits of clinical supervision may have been limited by the methods used. This study was specifically designed to help them best express their views. In contrast to previous studies, both nurses and HCAs showed a good understanding of the function and value of clinical supervision. Significant improvements in the experience of, and access to, clinical supervision for nurses and HCAs working in secure mental health services may be achieved by raising staff awareness, demonstrating organizational support and increasing monitoring of clinical supervision. WHAT ARE THE IMPLICATIONS FOR PRACTICE?: Organizations should consider reviewing their approach to supervision to include raising staff awareness, multidisciplinary supervision, group supervision, and recording and tracking of supervision rates. Organizations should be mindful of the need to provide effective clinical supervision to HCAs as well as nurses. ABSTRACT: Introduction Studies have found a low availability and appreciation of clinical supervision, especially for healthcare assistants (HCAs). Qualitative research is needed to further understand this. Aims Increase understanding of nurses' and HCAs' experiences of, and access to, clinical supervision. Identify nurses' and HCAs' perceptions of the value and function of clinical supervision. Assess how interventions affect staff's experiences of clinical supervision. Methods In 2013, HCAs and nurses in a secure adolescent service were surveyed about clinical supervision. Forty-nine HCAs and 20 nurses responded. In 2014, interventions to facilitate supervision were introduced. In 2016, the study was repeated. Forty HCAs and 30 nurses responded. Responses were analysed using a mixed methods approach. Results Significantly more HCAs found supervision to be a positive experience in 2016, and both nurses and HCAs reported significantly fewer challenges in accessing supervision. HCAs and nurses understood the value of clinical supervision. Discussion Significant improvements in the experience of clinical supervision were achieved following increased staff awareness, multidisciplinary and group supervision, and recording supervision rates. HCAs and nurses understood the consequences of inadequate supervision. Implications for practice Organizations could adopt the interventions to facilitate clinical supervision. Supervision should not be overlooked for HCAs.

Comparison of membrane-associated proteins of murine cytolytic and helper cloned T-cell lines: identification of a protein, p24, prominent in membrane fractions from cytolytic but not helper T-cells.

It has recently been reported that liposomes containing membrane components from cytolytic T-cell (TC) clones could transfer lytic activity to noncytolytic T- and B-cell lines, strongly suggesting that TC possess membrane-associated molecules which noncytolytic lymphocytes lack and which play a critical role in the lytic mechanism. It was thus of interest to compare the membrane-associated proteins from TC-lines to those of noncytolytic helper T-cell (TH) lines to determine whether any membrane-associated proteins unique to TC could be identified. Cells from three TC-lines and four TH-lines were internally labelled with [35S]methionine and then disrupted by hypotonic lysis. Low-density (plasma membrane enriched) and high-density (endoplasmic reticulum enriched) membrane fractions were isolated from each cloned cell line and analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis under reducing conditions. Two proteins were identified which were prominent in the membrane fractions from each of the three TC-lines but not in the membrane fractions from any of the four TH-lines. One of these, p215, migrated as a broad band with an apparent mol. wt of 215,000. The other, p24, migrated as a sharp band, or tightly spaced doublet, with an apparent mol. wt of 24,000. Immunoprecipitation studies using monoclonal antibodies to T200, LFA-1, Thy 1 and Lyt 2 suggested that p215 was a variant of T200 found on TC-lines but not on TH-lines. Treatment of solubilized membrane proteins from TH-lines with anti-T200 precipitated a 185-kD protein seen on each of the TH-lines but on none of the TC-lines. In contrast, p24 was not precipitated by any of these monoclonal antibodies. It therefore appears that p24 represents a previously unidentified protein which is strongly expressed by TC but not by TH and is thus deserving of further study as to its functional significance.

Increased CD8(+) T cells associated with Chlamydia pneumoniae in symptomatic carotid plaque.

BACKGROUND AND PURPOSE: The presence of Chlamydia pneumoniae has been reported in carotid atheroma, but its causative effect in the activation of an atherosclerotic plaque to a prothrombotic state remains unproved. Antigen- mediated activation of T lymphocytes within plaque may represent a mechanism by which infection can result in plaque conversion. The goal of the present study was to characterize the T-cell subtype profile related to the presence of C pneumoniae in patients with symptomatic versus asymptomatic carotid atherosclerosis. METHODS: We studied 14 plaques (5 symptomatic and 9 asymptomatic) positive for C pneumoniae confirmed by polymerase chain reaction and 14 plaques (6 symptomatic and 8 asymptomatic) from age- and stenosis-matched patients negative for C pneumoniae by polymerase chain reaction. T-cell subpopulations of T-helper, T-cytotoxic, and T-memory lymphocytes were identified through indirect enzyme immunohistochemistry with anti-CD3+, anti-CD4+, anti-CD8+, and anti-CD45RO+ monoclonal antibodies, respectively. Results are expressed as the number of positive cells per millimeter squared. RESULTS: In the absence of C pneumoniae, symptomatic plaques had a modest but significant increase of CD3+ (89.6 versus 55.3, P=0.013), CD4+ (57.3 versus 32.7, P=0.01), and CD45RO+ (82.8 versus 43.7, P=0.007), but not CD8+ T cells (28.5 versus 25.5, P=0.245) compared with asymptomatic. However, in the presence of C pneumoniae, there was significant increase of all T-lymphocyte subtypes in symptomatic plaques, including CD8+ (76.8 versus 30.3, P=0.03), CD3+ (192.1 versus 80.4, P=0.004), CD4+ (111.9 versus 37.9, P=0.003), and CD45RO+ (120.2 versus 72.9, P=0.003) cells compared with asymptomatic plaques. With use of 2-way ANOVA, both the presence of chlamydia and symptoms were associated with significantly higher T-cell counts (P<0.005 for all subtypes). CONCLUSIONS: Although all patients with symptomatic disease show a modest elevation in the concentration of intraplaque lymphocytes, a preferential increase in CD8+ class I-restricted T cells is observed in symptomatic carotid plaque positive for C pneumoniae. These data provide incentive to further explore the role of Chlamydia in the modification of immune-mediated mechanisms in active atherosclerotic plaque.

Examination of several potential mechanisms for the negative outcome in a clinical stroke trial of enlimomab, a murine anti-human intercellular adhesion molecule-1 antibody: a bedside-to-bench study.

BACKGROUND AND PURPOSE: Enlimomab, a murine monoclonal anti-human intercellular adhesion molecule (ICAM)-1 antibody, had a negative outcome in a multicenter acute-stroke trial. We did a bedside-to-bench study in standardized rat stroke models to explore mechanisms for these untoward results. METHODS: After focal brain ischemia in Wistar rats and spontaneously hypertensive rats (SHR), we administered murine anti-rat ICAM-1 antibody (1A29), subclass-matched murine immunoglobulin (IgG1), or vehicle intravenously. To examine whether rat anti-mouse antibodies were generated against the mouse protein and whether these were deleterious, we sensitized Wistar rats with 1A29 or vehicle 7 days before surgery. Infarct volume, tissue myeloperoxidase activity, neutrophil CD11b expression, and microvascular E-selectin, P-selectin, and ICAM-1 expression were examined 48 hours after surgery. Complement activation was serially assessed for 2 hours after a single injection of either 1A29 or vehicle. RESULTS: 1A29 treatment did not significantly reduce infarct size in either strain. 1A29 sensitization augmented infarct size and generated rat anti-mouse antibodies. Although 1A29 inhibited neutrophil trafficking shown by reduction in brain myeloperoxidase activity, circulating neutrophils were activated and displayed CD11b upregulation. Complement was activated in 1A29-sensitized Wistar rats and 1A29-treated SHR. E-selectin (SHR), endothelial P-selectin (Wistar and SHR), and ICAM-1 (SHR) were upregulated in animals treated with 1A29. CONCLUSIONS: Administration to rats of a murine antibody preparation against ICAM-1, 1A29, elicits the production of host antibodies against the protein, activation of circulating neutrophils, complement activation, and sustained microvascular activation. These observations provide several possible mechanisms for central nervous system-related clinical deterioration that occurred when Enlimomab was given in acute ischemic stroke.

Differential expression of HSC73 and HSP72 mRNA and proteins between young and adult gerbils after transient cerebral ischemia: relation to neuronal vulnerability.

This study presents a quantitative comparison of the time courses and regional distribution of both constitutive HSC73 and inducible HSP72 mRNA expression and their respective encoded proteins between young (3-week-old) and adult (3-month-old) gerbil hippocampus after transient global ischemia. The constitutive expression of HSC73 mRNA and protein in the hippocampus of the young sham-operated gerbils was significantly higher than in the adults. The HSC73 mRNA expression after ischemia in the CA1 layer of young gerbils was greater than in adult gerbils. HSC73 immunoreactivity was not significantly changed after ischemia-reperfusion in adult hippocampus, whereas it decreased in young gerbils. Ischemia-reperfusion led to induction of HSP72 mRNA expression throughout the hippocampus of both young and adult gerbils. HSP72 mRNA induction was more intense and sustained in the CA1 subfield of young gerbils; this was associated with a marked induction of HSP72 proteins and neuronal survival. The transient expression of HSP72 mRNA in the CA1 layer of adult gerbils was not associated with a subsequent synthesis of HSP72 protein but was linked to neuronal loss. Expression of HSP72 mRNA was shifted to an earlier period of reflow in CA3 and dentate gyrus (DG) subfields of young animals. These findings suggest that the induction of both HSP72 mRNA and proteins in the CA1 pyramidal neurons of young gerbils, as well as the higher constitutive expression of HSC73, may partially contribute to higher neuronal resistance of young animals to transient cerebral ischemia.

Nitric oxide modulates endothelin 1-induced Ca2+ mobilization and cytoskeletal F-actin filaments in human cerebromicrovascular endothelial cells.

A functional interrelation between nitric oxide (NO), the endothelial-derived vasodilating factor, and endothelin 1 (ET-1), the potent vasoconstrictive peptide, was investigated in microvascular endothelium of human brain. Nor-1 dose-dependently decreased the ET-1-stimulated mobilization of Ca2+. This response was mimicked with cGMP and abrogated by inhibitors of guanylyl cyclase or cGMP-dependent protein kinase G. These findings indicate that NO and ET-1 interactions involved in modulation of intracellular Ca2+ are mediated by cGMP/protein kinase G. In addition, Nor-1-mediated effects were associated with rearrangements of cytoskeleton F-actin filaments. The results suggest mechanisms by which NO-ET-1 interactions may contribute to regulation of microvascular function.

Quantitation of perivascular monocytes and macrophages around cerebral blood vessels of hypertensive and aged rats.

The numbers of monocytes and macrophages in the walls of cerebral blood vessels were counted on perfusion-fixed frozen brain sections (16 microns) of spontaneously hypertensive rats (SHR), stroke-prone SHR (SHR-SP), normotensive Wistar-Kyoto (WKY) rats, and young (16-week-old) and old (2-year-old) normotensive Sprague-Dawley rats (SD-16w and SD-2y, respectively) using monoclonal antibodies against rat macrophages (ED2). The staining was visualized with fluorescein-labeled second antibodies. The ED2-specific staining in brain sections was restricted to macrophages in a perivascular location. The number of perivascular cells per square millimeter of high-power field was significantly greater in SHR-SP (8.6 +/- 2.1; n = 4) and SHR (6.7 +/- 0.9; n = 6) than in normotensive WKY (4.0 +/- 0.5; n = 6; p < 0.01). The number of perivascular macrophages was also greater in SD-2y (7.5 +/- 2.7; n = 9) than in SD-16w (2.9 +/- 1.8; n = 8; p < 0.01). No ED2 staining was found in the resident microglia or in the endothelial cells, which were identified by double staining with rhodamine-labeled anti-factor VIII-related antigen antibodies. The results suggest that the stroke risk factors hypertension and advanced age are associated with increased subendothelial accumulation of monocytes and macrophages. This accumulation could increase the tendency for the endothelium to convert from an anticoagulant to a procoagulant surface in response to mediators released from these subendothelial cells.

The inhibitory effect of tumor necrosis factor and interleukin-1 on Ia induction by interferon-gamma on endothelial cells from murine central nervous system microvessels.

The effect of both tumor necrosis factor-alpha (TNF) and interleukin-1 (IL-1) on interferon-gamma (IFN)-induced Ia expression was studied using cultured endothelial cells (EC) isolated from cerebral microvessels of SJL mice. TNF inhibited Ia induction by IFN in a dose-dependent manner. The degree of inhibition by TNF was related to the IFN concentration: 200 U/ml TNF inhibited Ia expression induced by 20 U/ml IFN by 80% and Ia induced by 100 U/ml IFN by 45%. FACS analysis revealed the induction of Ia antigen on 30-40% of EC after 3 days' culture with IFN; TNF significantly reduced the percent of EC expressing Ia antigens. Identical treatment of SJL astrocytes showed TNF augmented Ia expression induced by IFN. IL-1 also inhibited Ia induction by IFN in a manner similar to that observed with TNF. The percent reduction of Ia-positive EC by Il-1 (2.0 U/ml) was 30% and 50% during incubations with 100 and 20 U/ml IFN, respectively. When combined at suboptimal concentrations IL-1 and TNF synergistically inhibited Ia expression induced by IFN. These results demonstrate that TNF acts on EC and astrocytes in a disparate manner and indicate that TNF and IL-1 can synergistically down-regulate immune responses involving central nervous system EC.

Alterations in T cell antigen specificity and class II restriction during the course of chronic relapsing experimental allergic encephalomyelitis.

In order to assess T cell antigen specificities and class II restriction requirements during the course of chronic relapsing experimental allergic encephalomyelitis (CREAE), (SJL x PL)F1 mice were used as a model. EAE can be passively transferred in these mice by F1 T cells incubated with Ia-positive antigen-presenting cells (APC) from either parent SJL (H-2s) or PL (H-2u) and MBP fragments 89-169 or 1-37, respectively. T cells purified from F1 mice immunized with MBP fragment 1-37 were positively selected for I-Au-supported proliferation by culture in the presence of irradiated Iau-positive PL spleen cells as APC. I-As-supported proliferation and proliferation to residues 89-169 were not detected following selection. Adoptive transfer of this T cell line induced CREAE in naive recipient F1 mice and 2 weeks after the second attack of EAE recipient proliferative responses were measured. Recipient T cells proliferated to both fragment 1-37 and fragment 89-169. Moreover, proliferation was supported by I-As-positive as well as I-Au-positive macrophages. These findings demonstrate that T cells with novel epitope specificities and class II restriction requirements can be generated during the course of CREAE and suggest the possibility that such cells may be involved in the pathogenesis of this chronic autoimmune illness.

Characterization of a murine central nervous system-derived cell line: infectability and presentation of viral antigen.

The cerebral endothelial cell line, 33-Mse, was characterized for its MHC antigen expression, infectability with viruses and capacity to present antigen to immune spleen cells. The cell line had interferon-gamma inducible MHC antigen expression. Infection by Theiler's murine encephalomyelitis influenced the expression of MHC molecules on the cell surface of this line. These cells could not stimulate T splenocyte proliferation or act as targets for Theiler's murine encephalomyelitis cytolytic immune spleen cells. These cells were able to present viral antigen to vaccinia virus immune spleen cells and act as targets for cytotoxic T cells from vaccinia virus immune mice.

Cytokine-regulated adhesion between encephalitogenic T lymphocytes and cerebrovascular endothelial cells.

Adhesive interactions between murine cerebrovascular endothelial cells (EC) which comprise the blood-brain barrier (BBB) and myelin basic protein (MBP)-specific encephalitogenic T lymphocytes were investigated. Adhesion was assessed by measuring the percent attachment of 51Cr-labeled T cells to EC monolayers. The basal level adhesion (20-35%) was significantly up-regulated by treating EC with recombinant murine gamma interferon (IFN-gamma), interleukin-1 alpha (IL-1 alpha) and/or tumor necrosis factor-alpha (TNF alpha). The ability of these cytokines to modulate adhesion was dose- and time-dependent and could be detected as early as 1 h after treatment. The expression of intercellular adhesion molecule-1 (ICAM-1) by EC was examined by immunofluorescence staining and ELISA. Although all unstimulated EC cultures expressed ICAM-1, treatment of EC with the above cytokines dramatically up-regulated the level of ICAM-1 expression in a dose- and time-dependent fashion similar to that observed in the adhesion assays. Treatment of EC with transforming growth factor-beta 1 (TGF beta) down-regulated the level of T cell adhesion on untreated EC in a dose-dependent manner. Pretreatment of EC with TGF beta also partially inhibited the up-regulation of adhesion induced by IFN-gamma, IL-1 alpha and/or TNF alpha. TGF beta had no effect on the up-regulation of ICAM-1 expression induced by IFN-gamma, IL-1 alpha and/or TNF alpha. These results indicate that in addition to ICAM-1, other molecules may be involved in adhesion of encephalitogenic T cells to the EC comprising the cerebral vasculature.(ABSTRACT TRUNCATED AT 250 WORDS)

Chimeric cytotoxin IL2-PE40 inhibits relapsing experimental allergic encephalomyelitis.

IL2-PE40 is a chimeric protein composed of human interleukin-2 (IL2) genetically fused to a modified form of Pseudomonas exotoxin lacking the cell recognition domain. IL2-PE40 is cytotoxic for IL2 receptor-bearing lymphocytes in culture and can inhibit activation of T cells in vivo. IL2-PE40 can significantly diminish antigen-stimulated proliferation of lymphocytes sensitized to myelin basic protein. Intraperitoneal administration of IL2-PE40 not only markedly inhibits the clinical manifestations of adoptively transferred relapsing experimental allergic encephalomyelitis but also dramatically reduces both inflammation and demyelination characteristic of the disease.

Functional characterization of endothelin receptors on cultured brain capillary endothelial cells of the rat.

This report describes the effects of endothelins (ET-1 and ET-3) on ion transport systems expressed on cultured rat brain capillary endothelial cells (RBEC) and includes investigation of pharmacological properties of ET receptors, their reactivity and induction of signal transduction pathways. ET-1 stimulated IP3 formation and Ca2+ uptake with half-maximal effective concentrations (EC50) of 0.68 and 0.93 nM, respectively; the effects of ET-3 on these responses were much weaker. ET-1-stimulated IP3 formation and Ca2+ uptake were inhibited by an ETA antagonist (BQ123) and a phospholipase C (PLC) inhibitor (U73122), indicating the presence of ETA receptors coupled to PLC. ET-1 stimulated K+ efflux (through a quinine-sensitive mechanism) and K+ uptake (through both ouabain-sensitive and bumetanide-sensitive mechanisms) with EC50 of 0.59 and 0.68 nM, respectively. The potencies of ET-3 on these responses were considerably lower than those of ET-1. By contrast, ET-1 or ET-3 stimulated Na+ uptake with similarly high potencies (EC50 = 0.80 and 1.89 nM, respectively) through EIPA (a Na+/H+ exchange inhibitor)-sensitive mechanisms. ET-stimulated K+ efflux, K+ uptake and Na+ uptake activities were all inhibited by BQ123 (but not by BQ788), suggesting the involvement of ETA (and not ETB) receptors in all these responses. ET-1 stimulated K+ uptake and efflux were inhibited by either U73122 or an intracellular Ca2+ chelator, suggesting that these two responses were mediated via PLC. In contrast, ET stimulation of Na+ uptake was unaffected by PLC inhibition or intracellular Ca2+ chelation. These data suggest the presence of two distinct subtypes of ETA receptors on RBEC; one appears to be a typical ETA receptor which is coupled to PLC and has higher binding affinity for ET-1 than ET-3. The other (ETA-like) receptor is similarly activated by ET-1 and ET-3 with high potencies but is independent of PLC. This possibility was further confirmed by the [125I]ET-1 binding studies demonstrating the presence of high- and low-affinity ET-3 binding sites.