Resolving the Interactome of the Human Macrophage Immunometabolism Regulator (MACIR) with Enhanced Membrane Protein Preparation and Affinity Proteomics

Expression of the macrophage immunometabolism regulator gene (MACIR) is associated with severity of autoimmune disease pathology and with the regulation of macrophage biology through unknown mechanisms. The encoded 206 amino acid protein lacks homology to any characterized protein sequence and is a disordered protein according to structure prediction algorithms. To identify interactions of MACIR with proteins from all subcellular compartments, a membrane solubilization buffer is employed, that together with a high affinity EF hand based pull down method, increases the resolution of quantitative mass spectrometry analysis with significant enrichment of interactions from membrane bound nuclear and mitochondrial compartments compared to samples prepared with radioimmunoprecipitation assay buffer. A total of 63 significant interacting proteins are identified and interaction with the nuclear transport receptor TNPO1 and the trafficking proteins UNC119 homolog A and B are validated by immunoprecipitation. Mutational analysis in two candidate nuclear localization signal motifs in the MACIR amino acid sequence shows the interaction with TNPO1 is likely via a non-classical proline/tyrosine-nuclear localization signal motif (aa98-117). It is shown that employing a highly specific and high affinity pull down method that performs efficiently in this glycerol and detergent rich buffer is a powerful approach for the analysis of uncharacterized protein interactomes.

Single Step Purification of Glycogen Synthase Kinase Isoforms from Small Scale Transient Expression in HEK293 Cells with a Calcium-Dependent Fragment Complementation System

Purification of proteins for the biophysical analysis of protein interactions occurring in human cells can benefit from methods that facilitate the capture of small amounts of natively processed protein obtained using transient mammalian expression systems. We have used a novel calcium-dependent fragment complementation-based affinity method to effectively purify full length glycogen synthase kinase 3 (GSK3) α and β isoforms to study their interaction with amyloid β peptide (Aβ42). Using these proteins, purified from 1 mg of total cell lysate, we measured an apparent K_D of ≤100 pM between GSK3α/β and immobilized Aβ42 with surface plasmon resonance technology. This approach can be used to retrieve useful quantities of protein for biophysical experiments with small scale mammalian cell culture.

Complement Component C3 Is Highly Expressed in Human Pancreatic Islets and Prevents β Cell Death via ATG16L1 Interaction and Autophagy Regulation

We show here that human pancreatic islets highly express C3, which is both secreted and present in the cytosol. Within isolated human islets, C3 expression correlates with type 2 diabetes (T2D) donor status, HbA1c, and inflammation. Islet C3 expression is also upregulated in several rodent diabetes models. C3 interacts with ATG16L1, which is essential for autophagy. Autophagy relieves cellular stresses faced by β cells during T2D and maintains cellular homeostasis. C3 knockout in clonal β cells impaired autophagy and led to increased apoptosis after exposure of cells to palmitic acid and IAPP. In the absence of C3, autophagosomes do not undergo fusion with lysosomes. Thus, C3 may be upregulated in islets during T2D as a cytoprotective factor against β cell dysfunction caused by impaired autophagy. Therefore, we revealed a previously undescribed intracellular function for C3, connecting the complement system directly to autophagy, with a broad potential importance in other diseases and cell types.

Identification of α-helix 4 (α4) of Rab11a as a novel Rab11-binding domain (RBD): Interaction of Rab11a with the Prostacyclin Receptor

The cellular trafficking of numerous G protein-coupled receptors (GPCRs) is known to be regulated by Rab proteins that involves a direct protein:protein interaction between the receptor and the GTPase. In the case of the human prostacyclin receptor (hIP), it undergoes agonist-induced internalization and subsequent Rab11a-dependent recyclization involving an interaction between a Rab11-binding domain (RBD) localized within its carboxyl-tail domain with Rab11a. However, the GPCR-interacting domain on Rab11a itself is unknown. Hence, we sought to identify the region within Rab11a that mediates its interaction with the RBD of the hIP. The α4 helix region of Rab11 was identified as a novel binding domain for the hIP, a site entirely distinct from the Switch I/Switch II -regions that act as specific binding domain for most other Rab and Ras-like GTPase interactants. Specifically, Glu¹³⁸ within α4 helix of Rab11a appears to contact with key residues (e.g. Lys³⁰⁴) within the RBD of the hIP, where such contacts differ depending on the agonist-activated versus -inactive status of the hIP. Through mutational studies, supported by in silico homology modelling of the inactive and active hIP:Rab11a complexes, a mechanism is proposed to explain both the constitutive and agonist-induced binding of Rab11a to regulate intracellular trafficking of the hIP. Collectively, these studies are not only the first to identify α4 helix of Rab11a as a protein binding domain on the GTPase but also reveal novel mechanistic insights into the intracellular trafficking of the hIP, and potentially of other members of the GPCR superfamily, involving Rab11-dependent mechanisms.

A Microfluidic Platform for Real-Time Detection and Quantification of Protein-Ligand Interactions

The key steps in cellular signaling and regulatory pathways rely on reversible noncovalent protein-ligand binding, yet the equilibrium parameters for such events remain challenging to characterize and quantify in solution. Here, we demonstrate a microfluidic platform for the detection of protein-ligand interactions with an assay time on the second timescale and without the requirement for immobilization or the presence of a highly viscous matrix. Using this approach, we obtain absolute values for the electrophoretic mobilities characterizing solvated proteins and demonstrate quantitative comparison of results obtained under different solution conditions. We apply this strategy to characterize the interaction between calmodulin and creatine kinase, which we identify as a novel calmodulin target. Moreover, we explore the differential calcium ion dependence of calmodulin ligand-binding affinities, a system at the focal point of calcium-mediated cellular signaling pathways. We further explore the effect of calmodulin on creatine kinase activity and show that it is increased by the interaction between the two proteins. These findings demonstrate the potential of quantitative microfluidic techniques to characterize binding equilibria between biomolecules under native solution conditions.

A chromatin-independent role of Polycomb-like 1 to stabilize p53 and promote cellular quiescence

Brien et al. show that while Polycomb-like proteins PCL2 and PCL3 are E2F-regulated genes expressed in proliferating cells, PCL1 is a p53 target gene predominantly expressed in quiescent cells. PCL1 binds to and stabilizes p53 to block cellular proliferation, and depletion of PCL1 phenocopies the defects in maintaining cellular quiescence associated with p53 loss.

Polycomb-like proteins 1–3 (PCL1–3) are substoichiometric components of the Polycomb-repressive complex 2 (PRC2) that are essential for association of the complex with chromatin. However, it remains unclear why three proteins with such apparent functional redundancy exist in mammals. Here we characterize their divergent roles in both positively and negatively regulating cellular proliferation. We show that while PCL2 and PCL3 are E2F-regulated genes expressed in proliferating cells, PCL1 is a p53 target gene predominantly expressed in quiescent cells. Ectopic expression of any PCL protein recruits PRC2 to repress the INK4A gene; however, only PCL2 and PCL3 confer an INK4A-dependent proliferative advantage. Remarkably, PCL1 has evolved a PRC2- and chromatin-independent function to negatively regulate proliferation. We show that PCL1 binds to and stabilizes p53 to induce cellular quiescence. Moreover, depletion of PCL1 phenocopies the defects in maintaining cellular quiescence associated with p53 loss. This newly evolved function is achieved by the binding of the PCL1 N-terminal PHD domain to the C-terminal domain of p53 through two unique serine residues, which were acquired during recent vertebrate evolution. This study illustrates the functional bifurcation of PCL proteins, which act in both a chromatin-dependent and a chromatin-independent manner to regulate the INK4A and p53 pathways.

Characterization of the bionano interface and mapping extrinsic interactions of the corona of nanomaterials

Nanoparticles in physiological environments are known to selectively adsorb proteins and other biomolecules forming a tightly bound biomolecular 'corona' on their surface. Where the exchange times of the proteins are sufficiently long, it is believed that the protein corona constitutes the particle identity in biological milieu. Here we show that proteins in the corona retain their functional characteristics and can specifically bind to cognate proteins on arrays of thousands of immobilised human proteins. The biological identity of the nanomaterial is seen to be specific to the blood plasma concentration in which they are exposed. We show that the resulting in situ nanoparticle interactome is dependent on the protein concentration in plasma, with the emergence of a small number of dominant protein-protein interactions. These interactions are those driven by proteins that are adsorbed onto the particle surface and whose binding epitopes are subsequently expressed or presented suitably on the particle surface. We suggest that, since specific tailored protein arrays for target systems and organs can be designed, their use may be an important element in an overall study of the biomolecular corona.

Ligand-directed targeting of lymphatic vessels uncovers mechanistic insights in melanoma metastasis

Metastasis is the most lethal step of cancer progression in patients with invasive melanoma. In most human cancers, including melanoma, tumor dissemination through the lymphatic vasculature provides a major route for tumor metastasis. Unfortunately, molecular mechanisms that facilitate interactions between melanoma cells and lymphatic vessels are unknown. Here, we developed an unbiased approach based on molecular mimicry to identify specific receptors that mediate lymphatic endothelial-melanoma cell interactions and metastasis. By screening combinatorial peptide libraries directly on afferent lymphatic vessels resected from melanoma patients during sentinel lymphatic mapping and lymph node biopsies, we identified a significant cohort of melanoma and lymphatic surface binding peptide sequences. The screening approach was designed so that lymphatic endothelium binding peptides mimic cell surface proteins on tumor cells. Therefore, relevant metastasis and lymphatic markers were biochemically identified, and a comprehensive molecular profile of the lymphatic endothelium during melanoma metastasis was generated. Our results identified expression of the phosphatase 2 regulatory subunit A, α-isoform (PPP2R1A) on the cell surfaces of both melanoma cells and lymphatic endothelial cells. Validation experiments showed that PPP2R1A is expressed on the cell surfaces of both melanoma and lymphatic endothelial cells in vitro as well as independent melanoma patient samples. More importantly, PPP2R1A-PPP2R1A homodimers occur at the cellular level to mediate cell-cell interactions at the lymphatic-tumor interface. Our results revealed that PPP2R1A is a new biomarker for melanoma metastasis and show, for the first time to our knowledge, an active interaction between the lymphatic vasculature and melanoma cells during tumor progression.

CX3CL1 is up-regulated in the rat hippocampus during memory-associated synaptic plasticity

Several cytokines and chemokines are now known to play normal physiological roles in the brain where they act as key regulators of communication between neurons, glia, and microglia. In particular, cytokines and chemokines can affect cardinal cellular and molecular processes of hippocampal-dependent long-term memory consolidation including synaptic plasticity, synaptic scaling and neurogenesis. The chemokine, CX₃CL1 (fractalkine), has been shown to modulate synaptic transmission and long-term potentiation (LTP) in the CA1 pyramidal cell layer of the hippocampus. Here, we confirm widespread expression of CX₃CL1 on mature neurons in the adult rat hippocampus. We report an up-regulation in CX₃CL1 protein expression in the CA1, CA3 and dentate gyrus (DG) of the rat hippocampus 2 h after spatial learning in the water maze task. Moreover, the same temporal increase in CX₃CL1 was evident following LTP-inducing theta-burst stimulation in the DG. At physiologically relevant concentrations, CX₃CL1 inhibited LTP maintenance in the DG. This attenuation in dentate LTP was lost in the presence of GABA_A receptor/chloride channel antagonism. CX₃CL1 also had opposing actions on glutamate-mediated rise in intracellular calcium in hippocampal organotypic slice cultures in the presence and absence of GABA_A receptor/chloride channel blockade. Using primary dissociated hippocampal cultures, we established that CX₃CL1 reduces glutamate-mediated intracellular calcium rises in both neurons and glia in a dose dependent manner. In conclusion, CX₃CL1 is up-regulated in the hippocampus during a brief temporal window following spatial learning the purpose of which may be to regulate glutamate-mediated neurotransmission tone. Our data supports a possible role for this chemokine in the protective plasticity process of synaptic scaling.

Sorcin links calcium signaling to vesicle trafficking, regulates Polo-like kinase 1 and is necessary for mitosis

Sorcin, a protein overexpressed in many multi-drug resistant cancers, dynamically localizes to distinct subcellular sites in 3T3-L1 fibroblasts during cell-cycle progression. During interphase sorcin is in the nucleus, in the plasma membrane, in endoplasmic reticulum (ER) cisternae, and in ER-derived vesicles localized along the microtubules. These vesicles are positive to RyR, SERCA, calreticulin and Rab10. At the beginning of mitosis, sorcin-containing vesicles associate with the mitotic spindle, and during telophase are concentrated in the cleavage furrow and, subsequently, in the midbody. Sorcin regulates dimensions and calcium load of the ER vesicles by inhibiting RYR and activating SERCA. Analysis of sorcin interactome reveals calcium-dependent interactions with many proteins, including Polo-like kinase 1 (PLK1), Aurora A and Aurora B kinases. Sorcin interacts physically with PLK1, is phosphorylated by PLK1 and induces PLK1 autophosphorylation, thereby regulating kinase activity. Knockdown of sorcin results in major defects in mitosis and cytokinesis, increase in the number of rounded polynucleated cells, blockage of cell progression in G2/M, apoptosis and cell death. Sorcin regulates calcium homeostasis and is necessary for the activation of mitosis and cytokinesis.

Abstract PR12: CHD5 is required for neurogenesis and has a dual role in facilitating gene expression and Polycomb gene repression

The chromatin remodeler CHD5 is expressed in neural tissues and is frequently deleted in aggressive neuroblastoma. Very little is known about the normal function of CHD5, its mechanism of action or how its deletion may contribute to neuroblastoma. Here we report that depletion of CHD5 in the developing murine neocortex blocks neuronal differentiation leading to an accumulation of undifferentiated progenitors. Consistent with this, ChIP-SEQ analysis of CHD5 shows it binds a large cohort of neuronal genes and is required for facilitating their activation during differentiation. However, CHD5 also binds a cohort of Polycomb target genes and is required for the maintenance of H3K27me3 on their promoters and their sustained repression during differentiation. Finally, we show that the chromodomains of CHD5 directly bind H3K27me3 and are essential for the function of CHD5 during neuronal differentiation. These findings provide new insights into the essential role of CHD5 during neurogenesis and show how the inactivation of this candidate tumor suppressor might contribute to the progression of neuroblastoma via a defect in differentiation.

This abstract is also presented as Poster A05.

Citation Format: Christopher M. Egan, Ulrika Nyman, Julie Skotte, Gundula Streubel, Siobhán Turner, David J. O'Connell, Vilma Rraklli, Michael J. Dolan, Naomi Chadderton, Hansen Klaus, Farrar Gwyneth Jane, Kristian Helin, Johan Holmberg, Adrian P. Bracken. CHD5 is required for neurogenesis and has a dual role in facilitating gene expression and Polycomb gene repression. [abstract]. In: Proceedings of the AACR Special Conference on Chromatin and Epigenetics in Cancer; Jun 19-22, 2013; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2013;73(13 Suppl):Abstract nr PR12.

Epitope presentation is an important determinant of the utility of antigens identified from protein arrays in the development of autoantibody diagnostic assays

Autoantibodies represent an attractive biomarker for diagnostic assays principally due to the stability of immunoglobulin in patient serum facilitating measurement with conventional assays. Immune responses to tumorigenesis may facilitate detection of ovarian cancer in the early stages of the disease with identification of a panel of tumour specific autoantibodies. Despite the reporting of many tumour associated autoantibodies using arrays of tumour antigens, this has not led to the advance in diagnostic capability as rapidly as was initially expected. Here we examine the potential diagnostic utility of candidate autoantibody biomarkers identified via screening of serum samples on a high content human protein array from a unique cohort of early stage and late stage ovarian cancer patients. We analyse the performance of autoantibodies to the tumour suppressor protein p53 and the novel autoantigens alpha adducin and endosulfine alpha identified in our array screen. Each antigen has different performance characteristics using conventional ELISA format and Western blot immunoassay. The high attrition rate of promising autoantigens identified by array screening can in part be explained by the presentation of the epitope of the antigen in the subsequent method of validation and this study provides directions on maximising the potential of candidate biomarkers. This article is part of a Special Issue entitled: Translational Proteomics.

Identification of a high-affinity network of secretagogin-binding proteins involved in vesicle secretion

Secretagogin is a hexa EF-hand Ca(2+)-binding protein expressed in neuroendocrine, pancreatic endocrine and retinal cells. The protein has been noted for its expression in specific neuronal subtypes in the support of hierarchical organizing principles in the mammalian brain. Secretagogin has previously been found to interact with SNAP25 involved in Ca(2+)-induced exocytosis. Here, the cellular interaction network of secretagogin has been expanded with nine proteins: SNAP-23, DOC2alpha, ARFGAP2, rootletin, KIF5B, β-tubulin, DDAH-2, ATP-synthase and myeloid leukemia factor 2, based on screening of a high content protein array and validation and quantification of binding with surface plasmon resonance and GST pulldown assays. All targets have association rate constants in the range 10(4)-10(6) M(-1) s(-1), dissociation rate constants in the range 10(-3)-10(-5) s(-1) and equilibrium dissociation constants in the 100 pM to 10 nM range. The novel target SNAP23 is an essential component of the high affinity receptor for the general membrane fusion machinery and an important regulator of transport vesicle docking and fusion. Complementary roles in vesicle trafficking are known for ARFGAP2 and DOC2alpha in regulating fusion of vesicles to membranes, kinesin 5B and tubulin for transport of vesicles in the cell, while rootletin builds up the rootlet believed to function as a scaffold for vesicles. The identification of a discrete network of interacting proteins that mediate secretion and vesicle trafficking suggests a regulatory role for secretagogin in these processes.

Probing calmodulin protein-protein interactions using high-content protein arrays

The calcium ion (Ca(2+)) is a ubiquitous second messenger that is crucial for the regulation of a wide variety of cellular processes. The diverse transient signals transduced by Ca(2+) are mediated by intracellular -Ca(2+)-binding proteins. Calcium ions shuttle into and out of the cytosol, transported across membranes by channels, exchangers, and pumps that regulate flux across the ER, mitochondrial and plasma membranes. Calcium regulates both rapid events, such as cytoskeleton remodelling or release of vesicle contents, and slower ones, such as transcriptional changes. Moreover, sustained cytosolic calcium elevations can lead to unwanted cellular activation or apoptosis. Calmodulin represents the most significant of the Ca(2+)-binding proteins and is an essential regulator of intracellular processes in response to extracellular stimuli mediated by a rise in Ca(2+) ion concentration. To profile novel protein-protein interactions that calmodulin participates in, we probed a high-content recombinant human protein array with fluorophore-labelled calmodulin in the presence of Ca(2+). This protein array contains 37,200 redundant proteins, incorporating over 10,000 unique human proteins expressed from a human brain cDNA library. We describe the identification of a high affinity interaction between calmodulin and the single-pass transmembrane proteins STIM1 and STIM2 that localise to the ER. Translocation of STIM1 and STIM2 from the endoplasmic reticulum to the plasma membrane is a key step in store operated calcium entry in the cell.

Integrated protein array screening and high throughput validation of 70 novel neural calmodulin-binding proteins

Calmodulin is an essential regulator of intracellular processes in response to extracellular stimuli mediated by a rise in Ca(2+) ion concentration. To profile protein-protein interactions of calmodulin in human brain, we probed a high content human protein array with fluorophore-labeled calmodulin in the presence of Ca(2+). This protein array contains 37,200 redundant proteins, incorporating over 10,000 unique human neural proteins from a human brain cDNA library. We designed a screen to find high affinity (K(D) < or = 1 microm) binding partners of calmodulin and identified 76 human proteins from all intracellular compartments of which 72 are novel. We measured the binding kinetics of 74 targets with calmodulin using a high throughput surface plasmon resonance assay. Most of the novel calmodulin-target complexes identified have low dissociation rates (k(off) < or = 10(-3) s(-1)) and high affinity (K(D) </= 1 mum), consistent with the design of the screen. Many of the identified proteins are known to assemble in neural tissue, forming assemblies such as the spectrin scaffold and the postsynaptic density. We developed a microarray of the identified target proteins with which we can characterize the biochemistry of calmodulin for all targets in parallel. Four novel targets were verified in neural cells by co-immunoprecipitation, and four were selected for exploration of the calmodulin-binding regions. Using synthetic peptides and isothermal titration calorimetry, calmodulin binding motifs were identified in the potassium voltage-gated channel Kv6.1 (residues 474-493), calmodulin kinase-like vesicle-associated protein (residues 302-316), EF-hand domain family member A2 (residues 202-216), and phosphatidylinositol-4-phosphate 5-kinase, type I, gamma (residues 400-415).

Unpacking Personal Adaptability at Work

Adaptability is a key competency for career success. In this article, the authors examine how individual adaptability is associated with the accrual of human capital, the organization of the work environment, and the characteristics of individuals. They find that a number of factors are particularly strongly related to personal adaptability: gender, employability, education, and management support. By understanding the variety of factors that are intrinsic to individuals, those that can be developed within individuals, and work environment design, it seems possible to foster the development of personal adaptability in the workplace.

The role of discography in lumbar disc disease: a comparative study of magnetic resonance imaging and discography

This study reviews prospectively a series of 29 patients who were examined by magnetic resonance imaging (MRI) and discography for degenerative disc disease. All had persistent low-back pain and non-diagnostic initial investigations, including plain films, myelography and/or computed tomography (CT). The imaging characteristics for degenerative disc disease correlated in 65 out of 73 intervertebral levels. All symptomatic discs were degenerate on both MRI and discography. Features of degenerative disc disease on MRI were assessed retrospectively, with a view to identifying the symptomatic level as defined by discography. MRI could not reliably detect this level, particularly in those with multi-level degenerative disc disease. Positive reproduction of symptoms at discography was the criteria used for surgery. All 12 patients in this group had posterior spinal fusion performed. Nine improved and three were unchanged. Of the ancillary features associated with disc degeneration, only a bulging annulus fibrosis proved to be of any value on MRI. Nonetheless, MRI should be used as the primary investigation in this patient group as it can lead to a marked reduction in the number of disc levels requiring injection.

Duplex ultrasonography and selection of patients for carotid endarterectomy: plaque morphology or luminal narrowing?

Percentage of carotid stenosis and plaque morphology as determined by duplex scanning were correlated with symptoms and CT evidence of infarction in 108 patients. Severity of carotid stenosis less than 49% or greater than 50% narrowing was not associated with an increased risk of ipsilateral symptoms or CT infarction. However, a heterogeneous plaque appearance, suggesting intraplaque hemorrhage, did correlate with ipsilateral cerebral symptoms. Heterogeneous plaque appearance may be a more reliable indication for carotid endarterectomy than a hemodynamically significant stenosis.

The plain chest radiograph after acute smoke inhalation

Serial chest radiographs of 45 patients from a major fire disaster were assessed for the effects of smoke inhalation injury. Thirty-three had abnormal chest radiographs on admission. Bronchial wall thickening was present in a total of 29 patients, subglottic oedema in 13, pulmonary oedema in seven, and patchy consolidation in three. Seven patients developed pulmonary oedema following initial exposure. This was the cause of death in two patients. Serial chest radiographs were useful in monitoring this very severe complication. Bronchial wall thickening and subglottic oedema were common early findings and thus may herald more serious subsequent respiratory embarrassment. Subglottic oedema is a previously undescribed finding. It not only indicates damage to the upper airways but may also indicate damage to the lung parenchyma. It may also make endotracheal intubation difficult. Therefore, the initial chest radiograph is an important predictor of significant smoke inhalation injuries enabling selection of patients likely to need ventilatory support.

The role of CT in the management of carcinoma of the oesophagus and cardia

The role of computed tomography in assessing tumour spread and tumour resectability was evaluated in 50 patients with oesophageal carcinoma (17 middle third, 33 lower third). CT accurately identified all patients with tumour confined to the oesophagus (Stage I or II) but was limited in its ability to assess direct organ invasion (Stage III) with an overall accuracy for evaluating middle third lesions of 82% (aorta 70%, tracheobronchial tree 94%, other mediastinal structures 82%) compared to an overall accuracy for lower third lesions of 97% (aorta 97%, pancreas 100%, diaphragm 97%). Tumours deemed resectable on CT were always resectable at operation but two of seven middle third tumours and one of twelve lower third lesions deemed unresectable underwent curative resection. Preoperative CT evaluation of oesophageal tumours is useful in that it may reliably identify tumour lesions confined to the oesophagus and reliably identify distant metastases. Because of its limitations however in the assessment of organ invasion, particularly by middle third lesions, this study suggests that patients with oesophageal tumours with no evidence of distant metastases, who are otherwise fit to undergo tumour resection, should not be denied surgery on the sole basis of positive organ invasion on CT particularly if that organ is the aorta.

Solitary rectal ulcer syndrome: radiologic manifestations

The solitary rectal ulcer syndrome is a distinct clinical entity occurring mainly in young patients who experience rectal bleeding. Solitary, and occasionally multiple, ulcers occur predominantly on the anterior or anterolateral aspects of the rectum. Current theories attribute this to pelvic muscle discoordination during defecation with partial rectal mucosal prolapse and traumatic ulceration. Classical histologic changes have been demonstrated that enable accurate diagnosis by the pathologist. Ten cases of biopsy-proven solitary rectal ulcer syndrome were reviewed. The radiographic abnormalities were: nodularity of the rectal mucosa (three cases), stricture formation (two cases), polypoid rectal masses (two cases), and ulceration (two cases). Radiologically this condition must be differentiated from other more serious entities such as carcinoma or inflammatory bowel disease.

Colitis of Behçet's syndrome--radiologic and pathologic features

Three patients with Behçet's syndrome and colitis are described. The radiologic and histologic appearances of the colitis are discussed. The similarities of Behçet's colitis to Crohn's disease are outlined. The cases demonstrate the necessity to consider Behçet's syndrome in the differential diagnosis of inflammatory bowel disease.

Congenital intrathoracic bronchopulmonary foregut malformations in childhood

Bronchopulmonary foregut malformations (BPFM) are a group of related disorders. They include tracheoesophageal fistula with or without atresia, bronchopulmonary sequestration, intestinal duplication cyst, bronchogenic cyst, aberrant systemic arterial supply to the lung, and bronchial mucosal rests in the esophagus. This paper describes 12 cases which illustrate the spectrum of clinical and radiographic features of these anomalies. The embryogenesis of these malformations is reviewed and appropriate radiographic investigation is discussed.

Intrathoracic rib: radiographic features of two cases

Two cases of intrathoracic rib are presented. In one of these the anomalous rib was not supernumerary, and the investing layers of pleura caused the rib to appear abnormally dense. The relevant literature is briefly reviewed.

Arthritis of primary biliary cirrhosis

We describe the clinical and roentgenographic findings in the hands of 13 patients with primary biliary cirrhosis. A nondeforming, generally asymptomatic erosive arthritis was present in 12 of 13 patients. The erosions were asymmetrically distributed and mainly involved the distal small joints of the hands. Seven patients had osteopenia due to hepatic osteodystrophy. Intraosseous lytic defects were present in three patients, chondrocalcinosis in two patients, and hypertrophic osteoarthropathy in one patient. We discuss the importance of the clinical and roentgenographic features of the arthritis of primary biliary cirrhosis.

The arthritis of mixed connective tissue disease

Twenty patients with mixed connective tissue disease were followed for 5 years. Arthritis occurred in all 20 patients, being the presenting complaint in 11 patients. The joints most frequently involved were the proximal interphalangeal (PIP), metacarpophalangeal (MCP), wrists, metatarsophalangeal (MTP), and knee; the distribution tended to be symmetrical, mimicking early rheumatoid arthritis. Joint deformities occurred in 6 patients, but apart from 1 patient with arthritis mutilans, significant functional impairment was not encountered. Radiologically small punched out bone erosions, asymmetrically distributed, were the most characteristic finding; other notable changes were aseptic necrosis, tuft erosions, and periarticular calcification. Joint effusions were non-inflammatory, the cellular content was predominantly lymphocytic and the C3 level was normal. Most cases were controlled with non-steroidal anti-inflammatory agents and invariably responded to prednisone less than or equal to 7.5 mg/day.

Hand changes in primary biliary cirrhosis

The radiographic findings in the hands of 13 patients with primary biliary cirrhosis are described. Erosive arthritis was present in 12 of the 13 cases. Seven patients hand osteopenia due to hepatic osteodystrophy. Intraosseous lytic defects were present in 3 cases. Chondrocalcinosis, a previously unreported finding, was seen in 2 patients, and one exhibited hypertrophic osteoarthropathy. The significance of these radiographic findings is discussed.

Multicentric tracheobronchial and oesophageal granular cell myoblastoma

Two patients with multiple intrathorcic granular cell myoblastomas are described. In one case multiple tumours were present in the major airways and oesophagus. The patient presented with recurrent pulmonary infections and stridor due to airway obstruction. In the other case dysphagia caused by multiple oesophageal granular cell myoblastomas was the major symptom. Granular cell myoblastoma is a rare tumour of neurogenic origin with a characteristic histological appearance. The pattern of multiple tracheobranchial and oesophageal tumours is uncommon and forms the basis of this report.

Pneumatosis coli in non-Hodgkins lymphoma

Two patients with poorly differentiated lymphoma who developed pneumatosis coli are described. In one case, the intramural gas was associated with diffuse nodular submucosal deposits of tumour. An annular stricture due to lymphoma was the underlying aetiology of the pneumatosis coli in the second case. The pathogenesis of pneumatosis coli in the context of malignant lymphoma is discussed.

Lymphoma of the colon: the spectrum of radiologic changes

Primary lymphoma of the colon is rare and comprises less than 1% of large bowel malignancies. Secondary colonic involvement in patients with advanced lymphoma is not uncommon and is frequently undetected. The radiographic findings of 34 patients with colonic lymphoma were reviewed. Thirteen patients had primary tumors, while the remaining 21 had colonic involvement secondary to systemic disease. The radiologic features were classified as mucosal nodularity, endo-exoenteric mass, intraluminal mass, mural infiltration, and mesenteric invasion. One patient with diffuse mucosal nodularity developed acute colonic dilatation, while two other patients had pneumatosis coli secondary to local tumor depositions. Lymphoma is now a well-described complication of chronic ulcerative colitis, and a further case is described here. Although colonic lymphoma is a relatively rare tumor, the spectrum of radiologic changes reviewed here may enable a more accurate radiologic diagnosis.

Pneumatosis cystoides intestinalis and obstructing intussusception in celiac disease

Spontaneous penumoperitoneum and pneumatosis cystoides intestinalis have been undescribed complications of celiac disease. In the case reported, small bowel gas cysts caused an obstructing intussusception. The etiology of the pneumatosis cystoides intestinalis is discussed.

Mixed connective tissue disease--clinical and radiological aspects of 20 cases

The clinical and radiological features of 20 cases of mixed connective tissue disease (MCTD), a newly defined disorder, are described. MCTD shares a number of abnormalities with other collagen diseases, notably diffuse systemic sclerosis and systemic lupus erythematosus. However, patients with MCTD have a specific circulating antibody to extractable nuclear antigen (ENA). Most of the cases described exhibited multi-system involvement with radiological changes in the skeleton, chest, and gastro-intestinal tract. Twelve of the 20 cases had an erosive arthritis. This finding has not been previously noted in the radiological literature.

Cranio-carpo-tarsal dysplasia. A report of seven cases

Clinical and radiographic features of seven cases of cranio-carpo-tarsal dysplasia are presented. Radiographs show bilateral dislocation of the hips, bilateral vertical talus deformity hand deformities, and characteristic skull changes.

Unusual gastrointestinal features in a child with pernicious anemia

Pernicious anemia in childhood is a rare disease. The radiologic demonstration of gastric mucosal atrophy led directly to this diagnosis in an 11-year-old girl. In addition, there was deformity of the pyloric antrum and superficial ulceration in the stomach and duodenum. Endoscopy and biopsy confirmed these findings.

The plain abdominal radiograph in pneumatosis coli

The clinical features and plain film findings in 14 patients with pneumatosis coli are described. Nine had oxygen treatment. The plain radiographic appearances are analysed and their value in diagnosis is presented. It is concluded that the plain abdominal radiograph is a simple and effective way of monitoring the progress of patients undergoing oxygen therapy.

Autologous radioiodinated fibrinogen, simplified

A method for the rapid preparation of radioiodinated autologous fibrinogen has been improved. Plasma is separated from cells by a single centrifugation. Fibrinogen is isolated in two salting-out steps at a 1:4 dilution of plasma and 22.5% saturated ammonium sulfate. Iodination is accomplished with chloramine T at a chloramine T-to-fibrinogen molar ratio of 12:1. Free iodide is removed by a single dilution and salting-out step at 29% saturated ammonium sulfate. Preparation time is about 1 hr; clottable radioactivity is 90-95%. Denaturation due to storage is undetectable at 6 weeks. Advantages of this procedure are (A) a short preparation time and (B) a purified autologous radioiodinated fibrinogen preparation.

The fate of Wurster's red free radical in tissues with high and low oxygen utilizations (heart muscle and gingiva)

When N,N-dimethyl p-phenylenediamine is incubated with fresh frozen sections of rat heart muscle, there is a rapid, enzymatic, single electron oxidation of the diamine to form the pink Wurster's free radical with absorption maxima at 550 and 510 nm. This is followed by radical dimerization and other interactions to form a purple color accompanied by a new peak at 660-670 nm and finally a substantive blue dye. In contrast, with frozen sections of gingiva, instead of the pink color of the Wurster's free radical, one first sees a green color which slowly changes to blue. If heart muscle is kept at room temperature for 30-60 min or in a deep freeze for several days prior to use, it also exhibits formation of the green color. Spectrophotometric studies of the above tissue systems reveal that the new green color does not represent formation of a new compound with new absorption maxima. The same absorption maxima are present in each of the above systems; however, there are differences among the systems with respect to the rates of formation of the absorption maxima in different regions of the spectrum. The latter phenomena produce the color changes seen by the eye. It is suggested that the kinetics of Wurster's Red free radical interactions in tissue may be dependent upon the metabolic (redox) status of the tissue.