Low-grade fibrosarcoma of the proximal humerus

We present the clinical, radiographical and pathological features of low-grade fibrosarcoma of the left proximal humerus in a 23-year-old man in whom it was necessary to distinguish the tumor from desmoplastic fibroma, malignant fibrous histiocytoma and intramedullary well-differentiated osteosarcoma. The patient presented with a 10-day history of pain in his left upper arm sustained when trying to break his fall with his left hand when slipping in the street. Plain radiography revealed an expanding multilobular osteolytic lesion from the proximal metaphysis to the diaphysis of his left humerus, accompanied by a pathological fracture at the distal portion of the lesion. Open biopsy of the lesion was performed twice; however, a conclusive diagnosis could not be obtained. The patient underwent wide excision and prosthetic replacement of the left proximal humerus. Histologically, the resected tumor was composed of both cellular areas and hypocellular areas. Cellular areas revealed a proliferation of bundles of uniform fibroblastic spindle-shaped cells with minimal cellular atypia, mixed with abundant intercellular collagenization. Mitotic figures were occasionally seen. Hypocellular areas showed myxoid features with loose bundles of collagen fibers. The patient demonstrates no evidence of disease 42 months after surgery. It is important to detect the scant atypical cells for the differential diagnosis of low-grade fibrosarcoma and desmoplastic fibroma of bone.     

Multilocular thymic cyst associated with follicular hyperplasia: clinicopathologic study of 4 resected cases

We report here 4 cases of multilocular thymic cysts (MTCs) with reactive lymphoid follicular hyperplasia. They were admitted to our hospital to examine anterior mediastinal masses demonstrated on chest computed tomographic scans. Three patients presented high-grade intermittent fever, and 2 patients were associated with Sjogren syndrome with elevated serum antinuclear antibody levels. All patients were subjected to extended thymectomy. Interestingly, their fever disappeared immediately after surgery. Histologically, the lesions were characterized by several cystic spaces separated by various thick walls with dense lymphoid tissue containing large reactive germinal centers. The inner cyst walls were lined by flattened cuboidal epithelia in some portions. Columnar epithelia with focal cilia were partially observed in 2 cases. These pathological findings led to a diagnosis of MTCs that were thought to result from cystic transformation of medullary duct derivatives by acquired inflammatory processes. The pathological findings, together with clinical courses of our cases, suggest that inflammation accompanied by autoimmune diseases may play, in part, an important role in the development of MTCs.     

Role of nectin in organization of tight junctions in epithelial cells

BACKGROUND: In polarized epithelial cells, cell-cell adhesion forms specialized membrane structures comprised of claudin-based tight junctions (TJs) and of E-cadherin-based adherens junctions (AJs). These structures are aligned from the apical to the basal side of the lateral membrane, but the mechanism of this organization remains unknown. Nectin is a Ca2+ independent immunoglobulin-like cell-cell adhesion molecule which localizes at AJs. Nectin is associated with E-cadherin through their respective cytoplasmic tail-binding proteins, afadin and catenins, and involved in the formation of AJs in cooperation with E-cadherin. We show here that nectin is also involved in the formation of TJs. RESULTS: During the formation of the junctional complex consisting of AJs and TJs in Madin-Darby canine kidney (MDCK) cells, claudin and occludin accumulated at the apical sites of the nectin-based cell-cell adhesion sites. This accumulation of claudin and occludin was inhibited by inhibitors acting on the trans interaction of nectin. The barrier function of TJs was also impaired by the nectin inhibitors. It has been shown that a phorbol ester promotes the formation of a TJ-like structure in an E-cadherin-independent manner. This phorbol ester-induced formation of the TJ-like structure was also inhibited by the nectin inhibitors. CONCLUSIONS: These results suggest a role of the nectin-afadin system in the organization of TJs as well as AJs in epithelial cells.     

Functional analysis of simian immunodeficiency virus SIVAGM long terminal repeat

We have previously shown that long terminal repeats (LTRs) derived from various isolates of SIV_AGM share a unique functional property. In the absence of viral Tat, all SIV_AGM LTRs act as much more efficient promoters than any of the other LTRs derived from representative primate immunodeficiency viruses. In the presence of Tat, however, SIV_AGM LTRs are activated relatively inefficiently. To map the elements that confer these features on the SIV_AGM LTR, a number of deletion mutants were constructed, and their promoter activities were determined using a bacterial CAT gene as a marker. The results obtained indicated that various elements located in the U3 region may contribute to the high basal promoter activity and that no negative elements are present in the region. The Tat-responsive sequence TAR was localized to the R region as observed for the other LTRs. A mutant carrying a single nucleotide deletion in this region completely lost responsiveness to Tat protein.     

A novel synthetic route to poly(β-ketone)s via poly(alkoxyethyne)s

Isopropoxyethyne (1a) and tert-butoxyethyne (1b) were polymerized using group 5 and 6 transition metal catalysts to give poly(isopropoxyethyne) (2a) and poly(tert-butoxyethyne) (2b) , respectively. The weight-average molecular weight (M?_w) of the resulting poly(alkoxyethyne)s was up to 1.0 × 10⁴. Among the transition metal catalysts, a tungsten alkoxide or a molybdenum alkoxide having low Lewis acidity were found to effectively promote the polymerization without causing side reactions. Poly(tert-butoxyethyne) was successfully converted to poly(β-ketone) 3 by acid hydrolysis of the tert-butyl vinyl moiety.     

Novel missense mutations in the human lysosomal sialidase gene in sialidosis patients and prediction of structural alterations of mutant enzymes

Three novel missense mutations in the human lysosomal sialidase gene causing amino acid substitutions (P80L, W240R, and P316S) in the coding region were identified in two Japanese sialidosis patients. One patient with a severe, congenital form of type 2 sialidosis was a compound heterozygote for 239C-to-T (P80L) and 718T-to-C (W240R). The other patient with a mild juvenile-onset phenotype (type 1) was a homozygote for the base substitution of 946C-to-T (P316S). None of these mutant cDNA products showed enzymatic activity toward an artificial substrate when coexpressed in galactosialidosis fibroblastic cells together with protective protein/cathepsin A (PPCA). All mutants showed a reticular immunofluorescence distribution when coexpressed with the PPCA gene in COS-1 cells, suggesting that the gene products were retained in the endoplasmic reticulum/Golgi area or rapidly degraded in the lysosomes. Homology modeling of the structural changes introduced by the mutations predicted that the P80L and P316S transversions cause large conformational changes including the active site residues responsible for binding the sialic acid carboxylate group. The W240R substitution was deduced to influence the molecular surface structure of a limited region of the constructed models, which was also influenced by previously identified V217M and G243R transversions. Received: Stptember 21, 2001 / Accepted: November 2, 2001     

The time course of leucocyte colony-formation in cultures of bone-marrow progenitor cells from rats and dogs

The colony-forming units granulocyte and macrophage (CFU-GM) assay, using either rat or dog haematopoietic progenitor cells, assesses the toxicity of new compounds. To identify the characteristics of colony formation in this system, a time-course study of CFU-GM assays using rat and dog bone marrow cells was tested. Neutrophil colonies, macrophage colonies and mixed colonies of neutrophils and macrophages were formed in soft agar medium. Neutrophil colonies reached their maximum number on days 3–4 and decreased markedly thereafter. Macrophage colonies reached their maximum number on days 7–8 and remained steady thereafter. Only a small number of mixed colonies of neutrophils and macrophages were formed beginning around day 4. There were no significant differences between rat and dog bone marrow cells in the occurrence of these maxima, or in any other growth phenomenon. This result suggests that to evaluate the influence of compounds on neutrophil colonies and macrophage colonies, observations should be made on days 4 and 8, respectively.     

A case of hyper-HDL-cholesterolemia presenting peculiar lipoprotein patterns in agarose gel electrophoresis

Lipoprotein metabolism was analyzed in a patient with marked hyper-HDL-cholesterolemia. A 50 year old male with no symptom of ischemic heart disease or xanthoma had a serum cholesterol level between 293 and 410 mg/dl, and a markedly elevated, HDL-cholesterol level (160-190 mg/dl). The cholesterol content of ultracentrifugally separated HDL2 was exclusively increased, while it was normal in the HDL3 fraction. Analytical ultracentrifugation and HPLC revealed that HDL particles became remarkably larger than the control and, on the contrary, LDL particles became smaller. LPL and LCAT activities were higher in this case, but H-TGL activity was normal. Agarose gel electrophoresis of lipoproteins showed an abnormal broad band which was located between alpha and pre beta band. Serum levels of apolipoprotein A-I, A-II, C-II, C-III and E were higher, while apolipoprotein B level was slightly lower than the control. Cholesteryl ester transfer protein (CETP) activity was demonstrated to be completely deficient in this case, as determined in 10 microliters serum using [3H] CE-labeled HDL3 as donor and VLDL + LDL fraction as acceptor. Since CETP was considered to catalyze the cholesteryl ester transport from HDL to VLDL and LDL, the deficiency of this activity might be the cause of the marked hyper-HDL-cholesterolemia in this patient.     

A Morphological and Immunohistochemical Study of Lymphoid Germinal Centers in Synovial and Lymph Node Tissues from Rheumatoid Arthritis Patients with Special Reference to Complement Components and Their Receptors

Rheumatoid arthritis (RA) is one of the immune complex (IC) diseases in which lymphoid germinal centers (GCs) are found in the synovial tissue. Simultaneously, patients with RA often show swelling of lymph nodes. The morphology and function of the lymph node GCs in patients with RA is not clear. The aim of this study was to evaluate the differences in morphology and immunoreactions to complement (C) components, their receptors, and lgM-rheumatoid factor (RF) between synovial GCs and lymph-node GCs in RA. Furthermore, the relationship between these immuno-reactive substances and follicular dendritic cells (FDCs) in GCs was investigated. The tissues examined were 41 RA synovial specimens, seven RA lymph nodes with massive lymphadenopathy, and 10 non-RA lymph nodes. The number of synovial GCs was relatively decreased in comparison with lymph-node GCs in RA, and the diameter of each synovial GC was smaller than that of each lymph-node GC. The synovial GCs were edematous and less cellular, and moreover, those from RF-seronegative cases were smaller than those from RF seropositive cases. On the other hand, the lymph-node GCs in RA were larger, more cellular and hyperplastic, but contained more tingible-body macro-phages (TBMs) and neutrophils. In the GCs of both synovial tissues and lymph nodes in RA, early C components (C1q, C4, C3c, C3d), IgM RF, and C3b receptor (C3bR) and C3d receptor (C3dR) were expressed as a lacy network by light microscopy, and were demonstrated on the surfaces of FDCs and lymphocytes, and in the intercellular spaces by electron microscopy. Furthermore, immuno-staining for dendritic reticulum cells (DRC, DAKO DRC1) was observed in a lacy pattern by light microscopy and on the cell surface of FDCs by electron microscopy. In the GCs of non-RA lymph nodes, early C components, C3bR, C3dR, and DRC showed a similar reaction pattern, but IgMRF did not. Consequently, no marked difference in immunoreactions in the GCs, except for the immunoreactions of late C components, was found between synovial tissues and lymph nodes in RA. On the basis of these findings, we discuss the possibility of the presence of a RF-IC.     

Quantitation of human chorionic gonadotrophin by the planimetry of latex agglutination-inhibition results on microtiter plates

A new type of heavy latex particle (LP) coated with the conjugates of human chorionic gonadotrophin (hCG) and bovine serum albumin (BSA) was used as indicator for the microtiter agglutination-inhibition assay of hCG using a monoclonal antibody (McAb) to hCG. The precipitation patterns of LP were measured by an automatic planimetry system. The detection limit of this method was 4 to 8 IU/l. Human luteinizing hormone (hLH) and follicle-stimulating hormone (FSH) caused hardly any cross-reaction in the presence of 3,350 IU/l and 1,500 IU/l, respectively. This planimetric immunoassay (PMIA) method provides a potentially useful method for hormone assay.