Ultrastructural localization of human platelet thrombospondin, fibrinogen, fibronectin, and von Willebrand factor in frozen thin section

We have investigated the localization of thrombospondin (TSP), fibrinogen, fibronectin, and von Willebrand factor in human platelets by transmission electron microscopy of antibody-stained ultrathin frozen sections. In negatively stained thin sections, alpha granules were identified on the basis of their smooth, roughly spherical shape, size, single limiting electron-lucent 100 A membrane, and frequent presence of electron-dense nucleoid. In contrast, mitochondria exhibited characteristic double membranes and cristae. Sections were separately stained with affinity-purified polyclonal antibodies to these proteins as well as with three monoclonal anti-TSP antibodies. Antibody specificity was documented in radioimmunoassays, by immunofluorescent cross-blocking, and by staining of bands of appropriate mobility in Western blots of whole platelets. Bound antibody was visualized using a 5-nm colloidal gold-avidin conjugate. In resting cells, staining of virtually all alpha granules was observed for all four proteins. In contrast, consistent staining was absent from other organelles, including plasma membranes, mitochondria, and vacuolar structures that may represent the open canalicular system.     

Expression of platelet-derived growth factor and its receptors by two pre-B acute lymphocytic leukemia cell lines

Platelet-derived growth factors (PDGF) are potent regulators of cell proliferation. The three isoforms of PDGF AA, AB, and BB are encoded by two genes: PDGF A and PDGF B. The v-sis oncogene is homologous to the PDGF-B gene. v-sis can transform cells that express the appropriate PDGF receptors. Two different types of receptors, PDGF-alpha and PDGF- beta, also encoded by two genes, have been identified. We show that two cell lines. SMS-SB and NALM-6, both derived from pre-B-cell acute lymphocytic leukemias, express the PDGF-A chain gene, and one of them, SMS-SB, releases PDGF-A chains into the media. The SMS-SB cells also express the PDGF-beta receptor, whereas NALM-6 cells express the PDGF- alpha receptor and bind PDGF. This extends the possible targets for PDGF to the B-cell lineage lymphocytes.     

Response to 2'-deoxycoformycin after failure of interferon-alpha in nonsplenectomized patients with hairy cell leukemia

Two patients with hairy cell leukemia with massive splenomegaly and severe pancytopenia were treated with recombinant alpha-A interferon (IFN-alpha-2a). There was no significant response to a trial of IFN- alpha-2a (11 and 20 weeks) with respect to blood counts or spleen size. Subsequent treatment with 2'-deoxycoformycin (dCF) for 8 consecutive weeks (4 mg/m2/wk) resulted in normalization of spleen size and a normalization of peripheral blood counts and bone marrow in one patient. The second patient demonstrated a reduction in spleen size and improved blood counts following 9 weeks of dCF therapy but eventually became refractory. This demonstrates that dCF is non-cross-resistant with interferon and confirms the efficacy of dCF in nonsplenectomized patients.     

The effects of dietary supplementation with n-3 polyunsaturated fatty acids in patients with rheumatoid arthritis: a randomized, double blind trial

STUDY OBJECTIVE: To determine the effect of dietary supplementation with n-3 polyunsaturated fatty acids (n-3 PUFA) on disease variables in patients with rheumatoid arthritis. DESIGN: Multicenter, randomized, placebo controlled, double blind. SETTING: Three Danish hospital Departments of Rheumatology. PATIENTS: Fifty-one patients with active rheumatoid arthritis. INTERVENTION: Random allocation to 12 weeks of treatment with either six n-3 PUFA capsules (3.6 g) or six capsules with fat composition as the average Danish diet. MAIN RESULTS: Significant improvement of morning stiffness and joint tenderness. No significant effect on the four other assessed clinical parameters. No serious side effects. CONCLUSIONS: Dietary supplementation with n-3 PUFA in patients with rheumatoid arthritis improved two out of six patient reported disease parameters. Further studies are needed to clarify the more precise role of n-3 PUFA in the treatment of rheumatoid arthritis.     

Cell-mediated immunity to chemically xenogenized tumors--IV. Production of lymphokine activity by, and in response to, highly immunogenic cells

To determine whether a novel pattern of lymphokine production might be involved in the superior immunogenicity of chemically xenogenized tumors over that of parental cells, we tested a panel of murine tumors xenogenized by DTIC for production of soluble factors with lymphokine-like activity and induction of lymphokine release from na?ve or specifically sensitized lymphocytes. In the L5178Y tumor system, a majority of xenogenized but not parental clones produced an IL-1-like factor, and this was associated, as a rule, with class II antigen expression and antigen-presenting ability. However, no such properties were exhibited by the xenogenized variants of P815 and L1210Ha cells, which nevertheless occasionally expressed other lymphokine (GM-CSF, IL-3) activities. On examining the ability of xenogenized and parental tumors to cause release of IL-1, IL-2, IL-3, IFN-gamma, TNF/LT and GM-CSF from T-cells, we found, as a rule, an increased lymphokine production when lymphocytes primed in vivo to a xenogenized tumor were restimulated in vitro with the same or parental cells.     

TREATMENT OF SUPERFICIAL MYCOSES IN THE TROPICS: WHITFIELD'S OINTMENT VERSUS CLOTRIMAZOLE

Background. In tropical primary health care, essential drugs should be safe, effective, and as inexpensive as possible. To treat the very common dermatophyte infections of the skin, one may use inexpensive Whitfield's preparations, more expensive topical imidazole derivatives, or extremely expensive oral antifungals. Because a cream base is felt to be more appropriate than an ointment in tropical conditions, we wanted to compare the effectiveness of Whitfield's cream and a topical imidazole derivative in field conditions in the tropics. Methods. A double-blind trial was performed involving 153 patients with a dermatophyte infection of the skin in Karonga District, Northern Malawi, including 25 patients who were Hiv-i-seropositive, comparing Whitfieid's cream with clotrimazole cream. Results. 75 patients were treated with Whitfield's cream and 78 with clotrimazole cream for a period of 6 weeks. Cure rates ranged from 80% to over 90% depending on the definition of cure. If positive cultures after treatment were used as criterion for treatment failure, six were found in each treatment group. One in each treatment failure group was an mv-i-seropositive patient. Conclusions. The great majority of patients in the tropics with a dermatophyte infection of the skin can be cured with a topical antimycotic preparation and do not need expensive oral therapy. This also proved to be valid for HIV-I-seropositive patients. Whitfield's cream and clotrimazole cream are both very effective. The lower cost makes Whitfield's cream the treatment of choice in dermatophyte infections of the skin in tropical primary health care.     

Functional cell surface expression by a recombinant single-chain class I major histocompatibility complex molecule with a cis-active β2-microglobulin domain

As a preliminary step towards the use of cell surface single-chain class I major histocompatibility complex (MHC) molecules as T cell immunogens, we have engineered a recombinant gene encoding a full-length cell surface single-chain version of the H-2D^d class I MHC molecule (SCβD^dm) which has β₂-microglobulin (β₂m) covalently linked to the amino terminus of a full-length H-2D^d heavy chain via a peptide spacer. The single-chain protein is correctly folded and stably expressed on the surface of transfected L cells. It can present an antigenic peptide to an H-2D^d-restricted antigen-specific T cell hybridoma. When expressed in peptide-transport-deficient cells, SCβD^dm can be stabilized and pulsed for antigen presentation by incubation with extracellular peptide at 27° or 37 °C, allowing the preparation of cells with single-chain molecules that are loaded with a single chosen antigenic peptide. SCβD^dm can be stably expressed in β₂m-negative cells, showing that the single-chain molecule uses its own β₂m domain to achieve correct folding and surface expression. Furthermore, the β₂m domain of SCβD^dm, unlike transfected free β₂m, does not rescue surface expression of endogenous class I MHC in the β₂m-negative cells. This strict cis activity of the β₂m domain of SCβD^dm makes possible the investigation of class I MHC function in cells, and potentially in animals, that express but a single type of class I MHC molecule.