David L. Smalley

Direct binding to and tyrosine phosphorylation of the alpha subunit of the type I interferon receptor by p135tyk2 tyrosine kinase.

Binding of type I interferons (IFNs) to their receptors induces rapid tyrosine phosphorylation of multiple proteins, including the alpha and beta subunits of the receptor, the polypeptides that form the transcriptional activator ISGF3 alpha (Stat113, Stat84, and Stat91), and the p135tyk2 and Jak-1 tyrosine kinases. In this report, we demonstrate that the alpha subunit of the type I IFN receptor (IFN-R) corresponds to the product of a previously cloned receptor subunit cDNA and, further, that the p135tyk2 tyrosine kinase directly binds and tyrosine phosphorylates this receptor subunit. Glutathione S-transferase (GST) fusion proteins encoding the different regions of the cytoplasmic domain of the alpha subunit can bind the p135tyk2 contained in human cell lysates. The association between the alpha subunit and Tyk2 was demonstrated by immunoblotting with anti-Tyk2 and antiphosphotyrosine antibodies and by using an in vitro kinase assay. Analogous experiments were then performed with recombinant baculoviruses encoding constitutively active Jak family tyrosine kinases. In this case, p135tyk2, but not Jak-1 or Jak-2 protein, binds to the GST-IFN-R proteins, suggesting that the interaction between these two proteins is both direct and specific. We also demonstrate that Tyk2, from extracts of either IFN alpha-treated human cells or insect cells infected with the recombinant baculoviruses, can catalyze in vitro phosphorylation of GST-IFN-R protein in a specific manner. Deletion mutants of the GST-IFN-R protein were used to localize both the binding and tyrosine phosphorylation site(s) to a 46-amino-acid juxtamembrane region of the alpha subunit, which shows sequence homology to functionally similar regions of other cytokine receptor proteins. These data support the hypothesis that the Tyk2 protein functions as part of a receptor complex to initiate intracellular signaling in response to type I IFNs.

The immunopathology of siliconosis. History, clinical presentation, and relation to silicosis and the chemistry of silicon and silicone.

Recent evidence confirms the fundamental involvement of the human immune system in the reaction to implantation of siliconebased medical devices. An as yet-to-be particularized epitope of many complex substances sharing siloxane structures is presented through the MHC-II apparatus with development and retention of T cell memory. This memory can be tested for in practical terms using one or more forms of silica, which links the immunohistopathology and autoimmune attributes of “silicosis” with those of “siliconosis.” The lesions of siliconosis are typical of those for persistent antigens and delayed, cell mediated hypersensitivity. The basic descriptive pathology of the reaction to silicone has been known since soon after introduction of silicones in medical procedures, with the exception of some details related to the more recent discoveries on the role of cytokines in the immunopathic process. The clinical consequences of siliconosis are common and can be severe in some individuals implanted with silicone devices.

Comparison of microbiologic characteristics of pathogenic and saprophytic coagulase-negative staphylococci from patients on continuous ambulatory peritoneal dialysis

Twenty-one microbiologically documented episodes of coagulase-negative staphylococcal peritonitis occurred in 21 continuous ambulatory peritoneal dialysis patients. All strains involved in these infections were tested for antimicrobial susceptibility and in vitro adherence assays. Twenty of the strains were species identified using two commercially available systems. For comparison, 20 saprophytic strains of coagulase-negative staphylococci obtained from the nares and axillae of 10 uninfected, peritoneal dialysis patients were included for in vitro characterization. Staphylococcus epidermidis was the species most often identified for both clinical and saprophytic strains. Eighteen of the 21 (86%) clinical strains were resistant to penicillin G. Methicillin resistance, which was present in five clinical strains, was not found in saprophytic strains. Adherence assay determinations showed marked differences between clinical versus colonization strains, with the clinical isolates significantly more adherent (p less than 0.025) than colonization strains. Electron microscopic examination of silastic catheter segments incubated with a strain of S. epidermidis in used and unused dialysis fluids demonstrated marked differences in attachment of bacteria to catheter material.

Electrophysiologic, morphologic, and serologic features of chronic unexplained nausea and vomiting: Lessons learned from 121 consecutive patients

BACKGROUND Despite substantive morbidity, unexplained nausea and vomiting has not been evaluated in a systematic manner via surgically obtained biopsies and direct electrophysiology of the gut, and this information has not been correlated with serologic information. We investigated consecutive patients with unexplained and refractory chronic nausea and vomiting to define the presence of morphologic, physiologic, and/or serologic abnormalities. METHODS In all, 101 of 121 consecutive patients who experienced chronic nausea and vomiting of unknown etiology evaluated in 1 tertiary referral center over a 10-year period were profiled qualitatively by full-thickness small bowel biopsies with hematoxylin and eosin (H&E) and Smiths Silver stains, quantitatively by intraoperative gastric electrophysiology, and semiquantitatively, when it became available, by serum autoimmune Western blot analysis. RESULTS Overall, 79 of 101 patients had abnormal full-thickness biopsy (70 neuropathies and 9 myopathies) and frequent serum autoimmune abnormalities (mean score = 13.2, normal < 3.0). In addition, 96 of 101 patients had abnormal frequency and/or uncoupling on gastric electrophysiology. Patients with small-intestinal myopathy showed a diversity of diagnoses; some patients with neuropathy had abdominal pain that correlated with autoimmune scores on Western blot. CONCLUSION Patients with refractory and unexplained nausea and vomiting have a high incidence of both small bowel morphologic abnormalities (primarily neuropathies) and gastric electrophysiologic abnormalities, which are associated commonly with serologic autoimmune activation. Similar histomorphologic, physiologic, and serologic measures should be considered in the diagnostic evaluation of any patient with refractory or unexplained nausea and vomiting.

Monocyte-Dependent Stimulation of Human T Cells by Silicon Dioxide

Mononuclear cells were isolated by Ficoll-Hypaque density gradient centrifugation from randomly selected silicone breast implant recipients for testing. Restricted antibody to HLA-DR (28–33 kD) depleted the concanavalin A mitogenic response which was expected but failed to inhibit the proliferative response to silicon dioxide. Further testing with monoclonal antibodies to HLA-DP, -DQ, and a second -DR with specificity for the NS1 region of the MHC class II genome, all markedly inhibited proliferation of T cells despite otherwise adequate stimulation by concanavalin A or silicon dioxide. Monoclonal antibodies directed against B7-1 also inhibited proliferation of T cells following stimulation with concanavalin A or silicon dioxide. These results confirm the T-cell response to silicon dioxide is monocyte-dependent and not a superantigen as has been speculated.

Hepatitis E virus infection in an immigrant to the United States.

A patient who had recently traveled from India to Tennessee was found to have acute hepatitis E. Improved recognition and serologic testing have increased the diagnosis of hepatitis E in the United States. For those at risk, hepatitis E should be considered in the differential diagnosis of acute hepatitis.

LYMPHOCYTE RESPONSE TO SILICA AMONG OFFSPRING OF SILICONE BREAST IMPLANT RECIPIENTS

The current study evaluated immune response to silicon dioxide in children born to women with silicone breast implants. In part one of the study, the T lymphocytes of 21 of 24 such children were significantly stimulated by silicon dioxide (silica). Part two consisted of eleven children, four born preimplantation and seven born postimplantation. None of the preimplant offspring showed T cell responses to silica; five of the seven postimplant children were positive for T cell memory for silica. Part three was a blinded study based on statistically significant differences in T cell stimulation with silicon dioxide between postimplant children and controls. These findings indicate a common immune reaction, that of T cell memory, occurs in mothers and their children born after exposure to silicone mammary implants placed prior to pregnancy. Since not all such children were breast fed the result favors transplacental passage of immunogens such as silicone oligomers or through maternofetal cellular traffic.

Memory problems in an older person

A 73 year old woman is brought by her daughter with a one year history of worsening forgetfulness. She lives on her own and has been knocking on neighbours’ doors in the middle of the night saying she needs to go shopping. History —Gather as much detail about the forgetfulness as possible from the patient and her daughter. When did it begin? How was it noticed? What does she forget? Is it getting worse? Does she have insight? Does she misidentify people? Does she have difficulty in looking after herself? Is she incontinent? Does she remember to take her medications? Is she anxious or depressed? Is she eating and drinking enough? Is she paying her bills? Does she have any major medical problems such as stroke, transient ischaemic attack, diabetes mellitus, Parkinson’s disease? Does she have any risk factors for cerebrovascular disease? Does she smoke or drink alcohol excessively? What medication is she taking? A more detailed assessment may be carried out at a later …

T Lymphocyte Memory in Non-mammary Silicone Encounters

Purpose: To study the effect of injected or implanted silicones other than mammary devices on siloxane T H cell immune memory by lymphoblast transformation. Design: Study of 43 individuals with silicone implants compared with controls. Materials and Methods: Twenty-two men and 21 women, injected or implanted with silicones other than mammary devices, were tested for siloxane T H cell immune memory by lymphoblast transformation. They received an arm muscle implant, block silicone as bone grafts, penile and testicular devices, silicone-containing temporomandibular joint prostheses, silicone-sheathed cardiac pacemaker wires, chin implants, toe replacements, tissue injections, or heavy industrial exposure. The control subjects were drawn from the medical center staff. Concanavalin A (Con A) was the mitogenic control. Results: The mean stimulation indexes for the Con A control were 269.78 - 30.24 (subjects) and 284.17 - 39.18 (controls), p = 0.3857, not significant. The mean stimulation index for siloxan...

High incidence of protein S abnormalities in patients with catheter-related thrombosis

Background: Patients with gastroparesis requiring IV access are at risk for catheter-related thrombosis (CRT). In this group of patients at risk for thrombosis, the incidence of Protein S deficiency and the occurrence of subsequent CRT is not known. Methods: We aimed to evaluate the occurrence of a baseline hematologic or autoimmune abnormalities in patients (pts) with Upper GI motor disorders (UGIMD) needing IV access who were followed for subsequent catheter-related thrombosis (CRT). We studied 53 pts (6 m, 47 f, mean age 39 ) with gastroparesis (6 with diabetes mellitus and 47 with idiopathic disease) who underwent evaluation for hypercoagulable states and/or auto antibodies by Western blot (GE 108(4): A734, 1995). After IVA placement, pts were classified into 2 groups: those with clinical thrombosis (CLOT) vs. those without (NO CLOT). Results were analyzed by T-tests and reported as mean ± SE. Results: 53 pts with baseline hematologic and autoimmune evaluations are summarized below. CRT was noted in 14 out of 53 pts (26%) See Tables Conclusions: A high frequency of protein S deficiency was noted in this group of pts with GI motor disorders and catheter related thrombosis. Protein S deficiency as seen in these pts, might result from underlying inflammation and acute phase protein release. Further prospective studies are indicated to explore possible underlying mechanisms of this observed increase of thrombosis in pts with gastrointestinal motor disorders.