Pulse labeling of small nuclear ribonucleoproteins in vivo reveals distinct patterns of antigen recognition by human autoimmune antibodies.

Antibodies directed against small nuclear ribonucleoprotein ( snRNP ) particles are found in the Sm and RNP autoimmune sera from numerous patients with systemic lupus erythematosus (SLE) and mixed connective tissue disease (MCTD). These two reactivities differ in disease distribution as well as antigen specificity. Although sera from both of these autoimmune syndromes contain snRNP reactive antibodies, distinction in antigen binding specificity have been difficult to define because of the particulate nature of the snRNP antigen. To overcome this problem, while retaining the antigen in a native state, cells were pulse-labeled with [35S]methionine for 8 min to generate radioactive snRNP proteins in forms reflecting incomplete de novo particle assembly. Immunoprecipitation of snRNP antigen prepared in this manner revealed clearly distinct patterns of Sm and RNP immunorecognition . While Sm sera precipitated all eight labeled snRNP proteins, RNP antibodies precipitated only two of the eight. However, a brief pulse followed by periods of cold chase demonstrated that RNP sera can eventually coprecipitate all components of the complete particle. In addition to antibodies to the other six snRNP peptides, all Sm sera tested have been found to contain the RNP-like reactivity with snRNP proteins A and C. RNP reactivity with these two components is of particular interest because these proteins are unique in the metabolism of snRNPs. Defining and distinguishing the precise peptides recognized by Sm and RNP antibodies has helped to clarify the biochemical basis of the standard laboratory tests for these antigen reactivities.     

High-dose etoposide and cyclophosphamide without bone marrow transplantation for resistant hematologic malignancy

Seventy-five patients with resistant acute leukemia or lymphoma received high-dose cyclophosphamide and etoposide to explore the activity of this combination in resistant hematologic malignancies, and to determine the maximum doses of these drugs that can be combined without bone marrow transplantation. Etoposide was administered over 29 to 69 hours by continuous infusion corresponding to total doses of 1.8 g/m2 to 4.8 g/m2. Cyclophosphamide, 50 mg/kg/d, was administered on 3 or 4 consecutive days total 150 to 200 mg/kg ideal body weight). At all dose levels myelosuppression was severe but reversible. Mucosal toxicity was dose-limiting with the maximum tolerated dose level combining etoposide 4.2 g/m2 with cyclophosphamide 200 mg/kg. Continuous etoposide infusion produced stable plasma levels that were lower than would be achieved after administration by short intravenous infusion, and this could explain our ability to escalate etoposide above the previously reported maximum tolerated dose. There were 28 complete (35%) and 12 partial (16%) responses. Median duration of complete response (CR) was 3.5 months (range 1.1 to 20+). Seventeen of 40 patients (42%) with acute myelogenous leukemia (AML) achieved CR, including 6 of 20 (30%) with high-dose cytosine arabinoside resistance. We conclude that bone marrow transplantation is not required after maximum tolerated doses of etoposide and cyclophosphamide. This regimen is active in resistant hematologic neoplasms, and the occurrence of CR in patients with high-dose cytosine arabinoside-resistant AML indicates a lack of complete cross-resistance between these regimens.     

A survey of different high resolution visualization modes of a volumetric object with applications

Summary In view of the variety of 3D representation techniques, a clinical study was carried out in order to evaluate their respective usefulness. It appears that a single technique cannot be claimed to be valid for all clinical situations and that a combination of representations brings more relevant information. Among the different techniques a clear delineation must be established between those which allow the accurate definition of landmarks (multiplanar reformation, surface representation), and those which do not (integral shading, reconstructed radiology). The main point is the possibility to recognize anatomical landmarks on these latter modes and to choose oblique cut planes in relation to them. Visualization quality is strongly dependent upon the acquisition protocol which must provide a spatial resolution as isotropic as possible.

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Une revue de différents modes de visualisation en haute résolution d'un objet volumique avec des applications

Résumé Face à la variété des techniques de représentation 3D une étude clinique a été conduite pour évaluer leurs utilités respectives. Il apparait qu'une technique unique ne peut pas convenir à toutes les situations cliniques et qu'une combinaison de différents modes de présentation apporte une information plus pertinente. Parmi les différentes techniques une distinction claire doit être établie entre celles qui autorisent la prise de repères précis (reformatage multiplanaire, représentation de surface), et celles qui ne le permettent pas (ombrage intégral, radiologie reconstruite). Le point principal est la possibilité de reconnaître des repères anatomiques sur ces derniers modes et de choisir des plans de coupe en relation avec eux. La qualité de la visualisation dépend étroitement du protocole d'acquisition qui doit fournir une résolution aussi isotrope que possible.

     

Fixator-assisted nailing of tibial fractures: New surgical technique and presentation of first 30 cases

Background

Intramedullary nailing is considered a “gold standard” for treatment of tibial shaft fractures. However, some types of fractures are typically considered as “difficult for nailing”. This group includes the periarticular fractures, fractures of both bones at the same level, comminuted and segmental fractures of the tibia. Fixator-assisted nailing (FAN) is an effective method treatment of these types of fractures. The main requirements for the ideal reduction device are an ease of its installation and an ability of multiplanar fracture reduction. Fixator-assisted nailing (FAN) with the use of two perpendicular to each other monolateral tubular frames perfectly meets these requirements. In this study we present this new surgical technique and the analysis of first 30 cases.

Bile reflux in benign and malignant barrett’s esophagus: Effect of medical acid suppression and nissen fundoplication

Bile reflux has been implicated in the pathogenesis and malignant degeneration of Barrett’s esophagus, but clinical studies in patients with adenocareinoma arising in Barrett’s esophagus are lacking. Ambulatory esophageal measurement of acid and bile reflux was performed with the previously validated fiberoptic bilirubin monitoring system (Bilitec) combined with a pH probe in 20 asymptomatie volunteers, 19 patients with gastroesophageal reflux disease (GERD) but no mucosal injury, 45 patients with GERD and erosive esophagitis, 33 patients with GERD and Barrett’s esophagus, and 14 patients with early adenocarcinoma arising in Barrett’s esophagus. Repeat studies were done in 15 patients under medical acid suppression and 16 patients after laparoscopie Nissen fundoplication. The mean esophageal bile exposure time showed an exponential increase from GERD patients without esophagitis to those with erosive esophagitis and benign Barrett’s esophagus and was highest in patients with early carcinoma in Barrett’s esophagus (P <0.01). Pathologic esophageal bile exposure was documented in 18 (54.5%) of 33 patients with benign Barrett’s esophagus and 11 (78.6%) of 14 patients with early adenoearcinoma in Barrett’s esophagus. Nissen fundoplieation but not medical acid suppression resulted in complete suppression of bile reflux. Bile reflux into the esophagus is particularly prevalent in patients with Barrett’s esophagus and early cancer. Bile reflux into the esophagus can be completely suppressed by Nissen fundoplication but not medical acid suppression alone. (J GASTROINTEST SURG 1998;2:333-341.) Presented at the Thirty-Eighth Annual Meeting of The Society for Surgery of the Alimentary Tract, Washington, D.C., May 11–14, 1997     

Differentiating Suicide Attempters from Suicide Ideators: The Role of Capability for Suicide

This study examined whether different components of capability for suicide (i.e., fearlessness about death, pain tolerance, pain insensitivity, preparation for suicide, suicide plan, and courage), as well as painful and provocative events, nonsuicidal self-injury, depressive symptoms, and hopelessness, could distinguish between suicide attempters, suicide ideators, and non-suicidal controls. A total of 930 Chinese adolescents completed questionnaires, and a multinomial logistic regression was conducted to identify factors that could distinguish among the 3 groups. We found that higher levels of pain tolerance, more detailed suicide plans, more positive attitudes towards suicide, as well as more painful and provocative experiences and more severe depressive symptoms were positively associated with increased likelihood of the engagement in both suicide ideation and suicide attempts. Only nonsuicidal self-injury increased the likelihood of falling in the suicide attempt group as compared to the suicide ideation group. Findings of this study emphasize the role of nonsuicidal self-injury in intervening suicidality.     

Expression and purification of functional recombinant epitopes for the platelet antigens, PlA1 and PlA2

The platelet antigens, PlA1 and PlA2, are responsible for most cases of posttransfusion purpura (PTP) and neonatal alloimmune thrombocytopenia (NAIT) in the caucasian population and are determined by two allelic forms of the platelet glycoprotein GPIIIa gene. To study the interaction between these antigens and their respective antibodies, we inserted the sequence that encodes the signal peptide and the N- terminal 66 amino acids of the PlA1 form of GPIIIa into the expression vector pGEX1. To express the PlA2 antigen, nucleotide 196 of the PlA1 coding sequence was mutated to the PlA2 allelic form. When transformed and induced in Escherichia coli, the two constructs produce glutathione S-transferase (GST)/N-terminal GPIIIa fusion proteins, one containing leucine at position 33 (PlA1), the other proline (PlA2). These proteins are easily purified in milligram quantities using glutathione-Sepharose and react specifically with their respective antibodies by immunoblot and enzyme-linked immunosorbent assay. Antigenicity of the PlA1 fusion protein in reduced glutathione increases with time; moreover, the addition of oxidized glutathione accelerates this process, presumably because of formation of the native disulfide bonds. Neutralization assays indicate that the PlA1 fusion protein competes for all of the anti-PlA1 antibody in the serum of patients with PTP and NAIT that is capable of interacting with the surface of intact platelets. This study shows that the GST/N-terminal GPIIIa fusion proteins contain conformational epitopes that mimic those involved in alloimmunization, and that regions other than the amino terminal 66 amino acids of GPIIIa are not likely to contain or be required for the development of functional PlA1 epitopes. Furthermore, these recombinant proteins can be used for the affinity-purification of clinical anti-PlA1 antibodies and specific antibody identification by western blotting, making them useful in the diagnosis of patients alloimmunized to PlA1 alloantigens.