Antithrombins Wibble and Wobble (T85M/K): archetypal conformational diseases with in vivo latent-transition, thrombosis, and heparin activation

The inherent variability of conformational diseases is demonstrated by two families with different mutations of the same conserved aminoacid in antithrombin. Threonine 85 underlies the opening of the main beta-sheet of the molecule and its replacement, by the polar lysine, in antithrombin Wobble, resulted in a plasma deficiency of antithrombin with an uncharacteristically severe onset of thrombosis at 10 years of age, whereas the replacement of the same residue by a nonpolar methionine, antithrombin Wibble, gave near-normal levels of plasma antithrombin and more typical adult thromboembolic disease. Isolated antithrombin Wibble had a decreased thermal stability (Tm 56.2, normal 57.6 degreesC) but was fully stabilized by the heparin pentasaccharide (Tm 71.8, normal 71.0 degreesC), indicating that the prime abnormality is a laxity in the transition of the main sheet of the molecule from the 5- to 6-stranded form, as was confirmed by the ready conversion of antithrombin Wibble to the 6-stranded latent form on incubation. That this transition can occur in vivo was shown by the finding of nearly 10% of the proband's plasma antithrombin in the latent form and also, surprisingly, of small but definitive amounts of latent antithrombin in normal plasma. The latent transition will be predictably accelerated not only by gross mutations, as with antithrombin Wobble, to give severe episodic thrombosis, but also by milder mutations, as with antithrombin Wibble, to trigger thrombosis in the presence of other predisposing factors, including the conformational stress imposed by the raised body temperatures of fevers. Both antithrombin variants had an exceptional (25-fold) increase in heparin affinity and this, together with an increased inhibitory activity against factor Xa, provides evidence of the direct linkage of A-sheet opening to the conformational basis of heparin binding and activation.     

IL-2 rescues antigen-specific T cells from radiation or dexamethasone-induced apoptosis. Correlation with induction of Bcl-2

Most studies of apoptosis on T lymphocytes have examined the effects of various stimuli on immature T cells from the thymus. Previous work has indicated that apoptosis of mature memory T cells may be an important pathophysiologic mechanism in diseases such as AIDS, cancer, and autoimmunity. The effect of IL-2 on apoptosis of T cells is not clear. Therefore, we studied the ability of IL-2 to rescue Ag-specific T cells from apoptosis. We found that IL-2, in a dose-dependent manner, prevented T cells from entering apoptosis induced by gamma-irradiation, mitomycin C, or dexamethasone. This effect was specific for IL-2; IL-1 beta, IL-6, or IFN-gamma could not reproduce it. In contrast to Ag-specific T cells, immature T cells and naive mature peripheral T cells could not be rescued by IL-2 from radiation-induced apoptosis. Apoptosis rescue by IL-2 was associated with the induction of bcl-2 mRNA and protein. This induction could not be attributed to the effects of IL-2 on the cell cycle, as T cells that were prevented from cell cycle progression by irradiation showed a similar induction of bcl-2. Rescued cells retained their Ag-specific proliferative capacity and in vivo functions. These findings demonstrate that the apoptotic death of Ag-specific T cell lines, cells which can be regarded as a model for memory T cells, can be prevented with IL-2. This effect may have important therapeutic implications for patients receiving chemotherapy or radiotherapy, and for patients with AIDS who develop immunodeficiency primarily as a result of loss of Ag-specific memory T cells.     

Transformation of hematopoietic cell lines to growth-factor independence and induction of a fatal myelo- and lymphoproliferative disease in mice by retrovirally transduced TEL/JAK2 fusion genes

Recent reports have demonstrated fusion of the TEL gene on 12p13 to the JAK2 gene on 9p24 in human leukemias. Three variants have been identified that fuse the TEL pointed (PNT) domain to (i) the JAK2 JH1-kinase domain, (ii) part of and (iii) all of the JH2 pseudokinase domain. We report that all of the human TEL/JAK2 variants, and a human/mouse chimeric hTEL/mJAK2(JH1) fusion gene, transform the interleukin-3 (IL-3)-dependent murine hematopoietic cell line Ba/F3 to IL-3-independent growth. Transformation requires both the TEL PNT domain and JAK2 kinase activity. Furthermore, all TEL/JAK2 variants strongly activated STAT 5 by phosphotyrosine Western blots and by electrophoretic mobility shift assays (EMSA). Mice (n = 40) transplanted with bone marrow infected with the MSCV retrovirus containing either the hTEL/mJAK2(JH1) fusion or its human counterpart developed a fatal mixed myeloproliferative and T-cell lymphoproliferative disorder with a latency of 2-10 weeks. In contrast, mice transplanted with a TEL/JAK2 mutant lacking the TEL PNT domain (n = 10) or a kinase-inactive TEL/JAK2(JH1) mutant (n = 10) did not develop the disease. We conclude that all human TEL/JAK2 fusion variants are oncoproteins in vitro that strongly activate STAT 5, and cause lethal myelo- and lymphoproliferative syndromes in murine bone marrow transplant models of leukemia.     

Modified radial head--capitellum projection in elbow trauma

A new technique is described for evaluating trauma to the elbow. The modified radial head--capitellum view is an alternative radiological projection to that described by Greenspan and Norman (the radial head--capitellum view). This new projection is useful in demonstrating minimally displaced or non-displaced fractures of the radial head, capitellum and coronoid process.     

Thyroid carcinoma after high-dose external radiotherapy for Hodgkin's disease: report of three cases

Three patients (two female and one male), who had received mantle irradiation for Hodgkin's disease eight, ten, and twelve years previously, developed papillary thyroid carcinoma. The radiation doses to the necks overlying the site of thyroid cancers were 3000, 4000, and 4100 rads, respectively. It has been stated that there is no risk of developing thyroid cancer with such high doses of external irradiation but apparently this complication will be encountered in a small number of patients.     

The flavin-containing monooxygenase 2 gene (FMO2) of humans, but not of other primates, encodes a truncated, nonfunctional protein

Flavin-containing monooxygenases (FMOs) are NADPH-dependent flavoenzymes that catalyze the oxidation of heteroatom centers in numerous drugs and xenobiotics. FMO2, or "pulmonary" FMO, one of five forms of the enzyme identified in mammals, is expressed predominantly in lung and differs from other FMOs in that it can catalyze the N-oxidation of certain primary alkylamines. We describe here the isolation and characterization of cDNAs for human FMO2. Analysis of the sequence of the cDNAs and of a section of the corresponding gene revealed that the major FMO2 allele of humans encodes a polypeptide that, compared with the orthologous protein of other mammals, lacks 64 amino acid residues from its C terminus. Heterologous expression of the cDNA revealed that the truncated polypeptide was catalytically inactive. The nonsense mutation that gave rise to the truncated polypeptide, a C --> T transition in codon 472, is not present in the FMO2 gene of closely related primates, including gorilla and chimpanzee, and must therefore have arisen in the human lineage after the divergence of the Homo and Pan clades. Possible mechanisms for the fixation of the mutation in the human population and the potential significance of the loss of functional FMO2 in humans are discussed.     

Experimental pyeloureterectomy and calyceal neck transection with autotransplantation and bladder advancement

OBJECTIVE: To determine whether Dexon mesh, closely applied to the kidney, provides purchase for sutures to permit bladder/parenchymal apposition on autotransplantation and that, if this line of apposition were some distance from but surrounding renal papillae, urothelium would proliferate to cover exposed parenchyma to form a widely patent lumen; this should facilitate removal of the whole of an upper tract collecting system, retaining renal parenchyma alone. MATERIALS AND METHODS: To test this possibility and explore the practicability of the concept, nine dogs underwent bilateral nephrectomy followed by unilateral autotransplantation: the other kidney was discarded. Because the canine renal pelvis is intrarenal, the ureter was stretched maximally before passing fine scissors into the renal hilum to transect the collecting system as close to the kidney as possible in six of the nine dogs. In the remaining three dogs, partial nephrectomy was performed with division of the calyceal necks under vision. Thinned bladder wall was sutured to Dexon mesh some distance from the collecting tubules; omentum was applied to the suture line. RESULTS: Three dogs were killed prematurely at < 2 weeks because of perioperative complications. Four were killed at 2, 4, 5 and 8 weeks and two at 12 months. Dexon mesh proved to be an effective anchoring fabric, providing close apposition of bladder wall and parenchyma. There was no adhesion of the kidney to peritoneal contents. Urothelial proliferation to cover exposed parenchyma occurred early and by 12 months, a thin stroma was interposed between parenchyma and epithelium. The kidney was preserved in all but one removed electively, this dog having both cystitis and pyelonephritis at 12 months. CONCLUSIONS: This study showed that autotransplantation of a kidney after removal of its collecting system and advancement of thinned bladder wall to renal parenchyma is practicable, with regenerated urothelium bridging the deficiency by covering exposed parenchyma, to create a widely patent lumen.