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At least 271 records · Page 15Linked to original sources
PubMed1984

Chemotactic behaviour of peripheral and synovial neutrophils during rifamycin SV therapy in rheumatoid arthritis.

The effect exerted by rifamycin SV, used intra-articularly in the treatment of rheumatoid arthritis, on polymorph function was studied. Random and directional locomotion of synovial fluid neutrophils was compared with that of peripheral blood cells in 10 patients followed up during 5 drug applications. PMNs from the two sources were characterized by different responsiveness to this pharmacological agent: blood cells activated chemotaxis in a dose-response way during rifamycin therapy, whereas synovial polymorphs did not modify their locomotor behaviour. It is proposed that the presence of immune complexes and/or factors produced by cell-cell interactions in the articular space may change the synovial neutrophil response to stimuli.

Adolescent↗
PubMed1983

Correlation of structure and activity in ansamycins. Molecular structure of sodium rifamycin SV.

The crystal and molecular structure of the sodium salt of rifamycin SV (clinically known as rifacin) as the monohydrate ethanol solvate has been determined to study the conformation of the ansa chain in unsubstituted rifamycins and also to clarify the metal complexation with rifamycins. The crystals belong to the space group P2(1)2(1)2(1) with cell dimensions (estimated standard deviations in parentheses) of a = 12.061 (2), b = 13.936 (2), and c = 24.731 (4) A. The structure was solved by direct methods and refined to an R factor of 0.069. The conformation of the ansa chain differs from that of other active rifamycins, e.g., rifampcin and rifamycin B at the joining point of the ansa chain to the naphthohydroquinone chromophore. The conformation of the middle part of the ansa chain, which is essential for activity against DNA-dependent RNA polymerase, remains the same. The sodium ion is penta-coordinated and has a trigonal bipyramidal geometry. The intermolecular hydrogen bonding involves O(9), O(10), O(5), and O(6) through water and ethanol molecules. A two-step mode of action of rifamycins has been postulated, and the conformations of antibiotics suitable for penetration of the membrane barrier and that for antibiotic-enzyme complex formation have been suggested.

Anti-Bacterial Agents↗
PubMedDate not supplied

[Agranulocytosis induced by rifamycin SV in a patient with Hodgkin's disease. Immunologic considerations and pathogenetic interpretations].

Alter a comprehensive introduction, intended to vocalize the pharmacologically-induced leukopenia problem, it is herein described an agranulocytosis case, Rifamicin SV-induced, in an abdominal Hodgkin subject. In the process determinism, much probably immunological, we deem two factors, at least, having acted in convergence: the Rifamicin haptenic activity and the immunosuppressive action of the same. We also believe that, in the pathogenesis of the hematological situation observed, a fundamental role must be ascribed to the immuno-deficient conditions peculiar to patients affected by Hodgkin's disease.

Agranulocytosis↗
PubMed1981

[Effect of rifamycin SV on neutrophil functions in patients with rheumatoid arthritis].

The antibiotic rifamycin SV (RSV) has been successfully used by others on the local treatment of rheumatoid arthritis (R.A.). Since polymorphonuclear leukocytes (PMNL) are involved in the synovial inflammatory process we tested the 'in vitro' effect of RSV on PMNL functions, such as locomotion and phagocytosis. PMNL locomotion was evaluated by using modified Boyden Chamber and phagocytosis was tested by the number of yeast particles ingested and by NBT reduction. The, the functions of PMNL derived from 7 R.A. patients in therapy only with non steroidal anti-inflammatory drugs were compared with those of PMNL from 14 patients with non inflammatory disease (osteoporosis and osteoarthrosis) in the same therapy and with neutrophils from healthy subjects. It was demonstrated that PMNL derived from patients with both R.A. and non inflammatory disease activated their directional locomotion towards RSV, on the contrary, cells from healthy subjects were unresponsive. Moreover, only patients with R.A. showed a defective phagocytic capacity and a depression in NBT reducing activity, when PMNL were treated with RSV. This phenomenon might be correlated with beneficial effect observed after local treatment of R.A. with RSV.

Arthritis, Rheumatoid↗
PubMed1976

Surface activity of drugs: oximes of 3-formylrifamycin SV.

The surface activity of a series of oximes of 3-formylrifamycin SV, carrying an n-alkyl chain from C1 to C12 has been investigated. The oximes can be classified into two main groups, depending on the length of the chain and having different CMC, ageing effect and area/molecule values. Two different orientations of the rifamycin molecule at the surface are proposed for the two groups: the first one occurring in the oximes with ALKYL SUBstituents C1 to C3 and induced by the hydrophobic region located in the ansa of the base molecule, the second one occurring in the oximes with alkyl substitutents C1 to C12 and induced by the hydrophobic substituent itself. The oxime with the C8 chain is the most efficent surfactant of the series. Some biological implications are discussed for the inhibition of bacterial strains resistant to rifampicin and of viral RNA dependent DNA polymerases.

Oximes↗
PubMed2003

Induction of globin mRNA expression by interleukin-3 in a stem cell factor-dependent SV-40 T-antigen-immortalized multipotent hematopoietic cell line.

Erythropoiesis requires the stepwise action on immature progenitors of several growth factors, including stem cell factor (SCF), interleukin 3 (IL-3), and erythropoietin (Epo). Epo is required to sustain proliferation and survival of committed progenitors and might further modulate the level of expression of several erythroid genes, including globin genes. Here we report a new SCF-dependent immortalized mouse progenitor cell line (GATA-1 ts SCF) that can also grow in either Epo or IL-3 as the sole growth factor. When grown in SCF, these cells show an "open" chromatin structure of the beta-globin LCR, but do not significantly express globin. However, Epo or IL-3 induce globin expression and are required for its maintainance. This effect of IL-3 is unexpected as IL-3 was previously reported either to be unable to induce hemoglobinization, or even to antagonize it. This suggests that GATA-1 ts SCF cells may have progressed to a stage in which globin genes are already poised for expression and only require signal(s) that can be elicited by either Epo or IL-3. Through the use of inhibitors, we suggest that p38 may be one of the molecules modulating induction and maintenance of globin expression.

Animals↗
PubMed1978

2-amino-isobutyric acid and 3-O-methyl-D-glucose transport in 3T3, SV 40-transformed 3T3 and revertant cell lines.

In order to further investigate the connection between transport and growth control, 3T3 cells, SV40 transformed 3T3 cells (SV101), and three revertant cell lines derived from SV101 which have regained certain manifestations of growth control were used. Transport rates of 2-amino-isobutyric acid and 3-O-methyl-D-glucose were measured in sparse, confluent, serum-starved, and serum-stimulated cultures. As shown before, cessation of 3T3 cell growth in G0 under conditions of confluence or serum deprivation was associated with reduced rates of transport for both compounds, whereas the density and serum dependence of growth and transport was largely eliminated in SV101. The density revertant F1SV101, which has regained density regulation of growth similar to 3T3 cells, has also regained density regulation of transport. Neither growth nor transport were serum dependent. The serum revertants AgammaSV7 and LsSV6 have regained both density and serum regulation of growth, but not according to the original mechanism of 3T3 cells of entry into a Go state. Transport was high under conditions of confluence or serum deprivation. Thus for these cells rates of transport were not reduced simply as a consequences of slower cell growth nor were low transport rates responsible for growth arrest. The data are consistent with the possibility that growth arrest specifically in the G0 state could shut off a number of cellular activities, including transport.

Aminoisobutyric Acids↗
PubMed2001

SV-40 large T antigen reversibly inhibits expression of tyrosinase, TRP-1, TRP-2 and Mitf, but not Pax-3, in conditionally immortalized mouse melanocytes.

Transformation of mouse melanocytes with a variety of exogenous oncogenes or chemical carcinogens frequently results in irreversible loss of pigmentation. We have infected mouse melanocytes with a temperature-sensitive mutant of the simian virus 40 (SV40) large tumour antigen to study the molecular mechanisms underlying depigmentation during melanocyte transformation. The results show that, out of six cell lines analyzed at the permissive temperature of the oncoprotein, three epidermal and two dermal melanocyte clones remained pigmented and retained the ability to synthesize melanin and to express the melanocyte-specific genes, including tyrosinase, tyrosinase related protein-1, tyrosinase related protein-2 and Mitf. In contrast, one dermal melanocyte clone (DMEL-3) gradually depigmented. This depigmentation was characterized by enhanced growth and down-regulation of melanocyte-specific gene expression. When the oncogene was inactivated by culture at the non-permissive temperature, the pigmented phenotype in DMEL-3 cells could be rescued, and there was a corresponding time-dependent increase in melanocyte-specific gene expression. After extended passage, this rescue could not be achieved. Our results provide direct evidence for the role of the SV40 large T antigen in melanocyte de-differentiation. Expression of Pax-3, a transcription factor implicated in melanocyte differentiation, was unaltered during the SV40-initiated de-differentiation, and de-differentiated melanocytes expressed normal levels of Pax-3 message. We speculate on the mechanism by which the oncoprotein might be regulating Mitf gene expression and of the role of Pax-3 in this process.

3T3 Cells↗