Monoclonal antibody (WT 1) directed against a T cell surface glycoprotein: characteristics and immunosuppressive activity

WT 1, an IgG2a subclass monoclonal antibody, recognizes a human T lineage specific antigen (mol. wt 40,000). This antigen is strongly expressed on thymic T blasts, and on peripheral T cells activated by phytohaemagglutinin, whereas cortical thymocytes and peripheral T cells are moderately positive for WT 1. In contrast, B lymphocytes, myeloid and erythroid cells, including the progenitor cells of these lineages, and terminal deoxynucleotidyl transferase positive cells in the bone marrow, are all WT 1 negative. Binding of WT 1 to T cells is blocked by a previously described antibody (3A1) suggesting that both antibodies bind to the same antigen present on human T cells. WT 1, however, is also reactive with T lymphocytes from rhesus monkeys whereas 3A1 is not. Therefore, the biological effects of WT 1 could be studied in a monkey model. In a skin allograft model, WT 1 was immunosuppressive and induced a marked prolongation of graft survival.     

Transmission electron microscopic demonstration of vimentin in rat osteoblast and osteocyte cell bodies and processes using the immunogold technique

Background: The immunogold labeling technique and transmission electron microscopy were used to demonstrate the expression and position of the intermediate filament vimentin in rat osteoblast and osteocyte cell bodies and cell processes. Conventional light and transmission electron microscopic studies of bone cells demonstrated adjacent cell linkage to be mediated by osteoblast and osteocyte processes present within the canalicular system traversing the bone matrix. The cell processes were filled with densely packed filaments, many of which have been shown previously to be actin microfilaments. The appearance, however, of 10 nm diameter filaments in some cell processes and the fact that the intermediate filament vimentin has been defined in many cells of mesenchymal origin raised the possibility that some of these filaments might be vimentin. The ultrastructural colloidal gold immunochemical technique allowed for demonstration in situ of the expression of vimentin filaments plus accurate definition of their position. Methods: The studies were performed in newborn rat femoral and tibial diaphyseal cortical bone and in 1-week-old repair bone from 2.4 mm diameter defects made through the lateral cortex in 6-week-old rat femurs and tibias. The bone tissues for the immunochemical study were fixed in 1% glutaraldehyde, 4% paraformaldehyde, and 0.1 M phosphate buffer (pH 7.4) for 2 days. Decalcification was performed in 6% EDTA for 2–3 days. Infiltration involved use of Lowicryl resin K4M, and the embedding and curing processes were performed in a cryostat with temperatures ?30°C. An antivimentin monoclonal antibody was used for labeling using the postembedding technique. Effective antibody dilutions ranged from 1:10 to 1:200, with the dilutions of 1:25 and 1:100 showing the best combination of filament labeling with the least matrix background. The grids were exposed to 10 nanometer gold colloid conjugated goat anti-mouse IgM for demonstration of binding. Results: Vimentin immunolabeling was defined clearly in relation to filaments within the osteoblast and osteocyte cell body cytoplasm, throughout the entire length of the osteoblast and osteocyte cell processes, and in close relationship to the intercellular gap junctions which were present within the cell processes both close to the cell bodies and within the canaliculi well away from them. Conclusions: Immunogold labeling demonstrates the presence of the intermediate filament vimentin in osteoblast and osteocyte cell bodies and processes of rat bone. Vimentin distribution is not concentrated to specific areas, is present throughout the extent of the bodies and processes, and is seen immediately adjacent to gap junctions. © 1995 Wiley-Liss, Inc.     

Effect of sensory stimulus on striatal dopamine release in humans and cats: a [(11)C]raclopride PET study

BACKGROUND: Sensory stimulation of the forelimb extremities constitutes a well-established experimental model that has consistently shown to activate dopamine (DA) neurotransmission in the mammals' forebrain. OBJECTIVES: To visualize in vivo this modification of striatal DA release in healthy human volunteers using Positron Emission Tomography (PET) and [(11)C]raclopride. Experiments in humans were paralleled by experiments in anesthetized cats. Changes in endogenous DA release were assessed through its competition with [(11)C]raclopride binding (BP(raclo)), a radioligand probing DA D2-receptors. RESULTS: In humans no significant difference of BP(raclo) in caudate (with sensory stimulation: 2.0 +/- 0.3 versus without sensory stimulation: 2.2 +/- 0.3; P = 0.3) or putamen (2.6 +/- 0.3 versus 2.6 +/- 0.2; P = 0.9) ipsilateral to the stimulus was disclosed as a result of sensory stimulation. Similarly, no change of BP(raclo) was observed contralaterally to the stimulation in the caudate nucleus (with sensory stimulation: 2.0 +/- 0.4 versus without sensory stimulation: 2.1 +/- 0.2; P = 0.5) and the putamen (2.5 +/- 0.4 versus 2.6 +/- 0.2; P = 0.4). In cats the same results were obtained in the ipsilateral to stimulation striatum (with sensory stimulation: 2.5 +/- 0.03 versus without sensory stimulation: 2.4 +/- 0.05; P = 0.7). No change was also observed contralaterally to the stimulation (2.4 +/- 0.04 versus 2.5 +/- 0.06; P = 0.6). The [(11)C]raclopride binding remained unchanged by sensory stimuli in both humans and cats. CONCLUSION: This suggests that the DA release induced by sensory stimulus is mostly extrasynaptic whereas the synaptic DA release is probably small, which fits well with the absence of [(11)C]raclopride displacement. The mechanism of this extrasynaptic DA release could be related to a local action of glutamate on dopaminergic terminals via a thalamo-cortico-striatal loop. Present results also underline homology between cat and human responses to sensory stimuli and validate the use of cat brain to find physiological concepts in humans.     

The blocking effect of antibodies against the products of the H-2 gene complex on lymphocyte complement (C3d) receptors. complement dependence and specificity

Antisera against the products of the major histocompatibility system (MHS), produced by immunization between congenic mouse strains differing only at that segment of the 17th chromosome rosettes which bears the H-2gene complex, exert a reproducible blocking effect on formation of with EACm (C3d rosettes). In many instances this effect is probably due to specific antibodies reactive with the lymphocytes, as indicated by immunochemical and adsorption experiments. Purified antibodies from the C3H anti-C3H.B10 immune ascites failed to exert this blocking effect. The blocking capacity can be restored, however, by addition of fresh normal mouse, rabbit or fetal calf serum, but not by heat inactivated serum. These experiments show that the presently defined H-2K, H-2D and H-2L antigens as well as some Ia antigens are themselves not the C3d receptors. The blocking effects observed in the presence of complement are possibly due to the proximity of H-2 or Ia molecules and C3d receptors, or to a rearrangement of membrane components after reaction with anti-MHC anti-MHC antibodies and complement.     

Autonomy and developing physicians: Reimagining supervision using self-determination theory

In this article, we address the question, ‘What is the role of autonomy in physician development?’ Medical education is a developmental process, and autonomy plays a motivational role in physician development. Calls for increased supervision of residents have raised concerns that the resulting decreased autonomy might interfere with resident development, leading the authors to explore the relationship between supervision and autonomy. The medical education literature posits a simple inverse relationship between supervision and autonomy. Within competency frameworks, autonomy is operationalised as independence and viewed as the end goal of training. Alternatively, there is emerging empirical literature describing autonomy and supervision as dynamic and developmental constructs and point towards more complex relationship between supervision and autonomy. Self-determination theory (SDT) presents a framework for understanding this dynamic relationship and the role of autonomy in physician development. Within SDT, autonomy is a fundamental psychological need, associated with motivation for learning, self-regulation and an internal locus of control. Supporting learner autonomy can afford learners the opportunity to internalise the values and norms of the profession, leading to an integrated regulation of their behaviours and actions. Conceptualising autonomy through the lens of SDT provides an avenue for education interventions and future research on supervision and autonomy. Educators can integrate supervision and autonomy support in the clinical setting, seeking to motivate learner development by balancing optimal challenge and support and integrating autonomy support with ‘hands-on’ approaches to supervision. SDT also provides a theoretical framework relevant to current discussions regarding feedback conversations and coaching in medical education. Lastly, conceptualising autonomy using SDT opens new avenues for investigation, exploring the complex relationship between supervision and autonomy and developing efforts to integrate autonomy support with clinical supervision.     

Urinary calprotectin,NGAL, and KIM-1 in the differentiation of primarily inflammatory vs. non-inflammatory stable chronic kidney diseases

Introduction It has been demonstrated that urinary neutrophil gelatinase-associated lipocalin (NGAL) and calprotectin are helpful biomarkers in the differentiation of intrinsic and prerenal acute kidney injury.Objective The present cross-sectional study investigates, whether urinary biomarkers are able to differentiate primarily inflammatory from non-inflammatory entities in chronic kidney disease (CKD).Methods Urinary calprotectin, NGAL, and kidney injury molecule-1 (KIM-1) concentrations were assessed in a study population of 143 patients with stable CKD and 29 healthy controls. Stable renal function was defined as an eGFR fluctuation ≤5 ml/min/1.73 m² in the past 12 months. Pyuria, metastatic carcinoma, and renal transplantation were regarded as exclusion criteria. Diabetic nephropathy, hypertensive nephropathy, and polycystic kidney disease were categorized as ‘primarily non-inflammatory renal diseases’ (NIRD), whereas glomerulonephritis and vasculitis were regarded as ‘primarily inflammatory renal diseases’ (IRD).Results Urinary calprotectin and NGAL concentrations significantly differed between CKD and healthy controls (p < 0.05 each), whereas KIM-1 concentrations did not (p = 0.84). The three biomarkers did neither show significant differences in-between the individual entities, nor the two categories of IRD vs. NIRD (calprotectin 155.7 vs. 96.99 ng/ml; NGAL 14 896 vs. 11 977 pg/ml; KIM-1 1388 vs. 1009 pg/ml; p > 0.05 each). Albumin exceeds the diagnostic power of the investigated biomarkers by far.Conclusions The urinary biomarkers calprotectin, NGAL, and KIM-1 have no diagnostic value in the differentiation of primarily inflammatory vs. non-inflammatory etiologies of CKD.