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At least 163 records · Page 9Linked to original sources
PubMed1977

3-N-Substituted aminomethyl derivatives of rifamycin SV. A convenient method of synthesis, cyclization of certain derivatives, and anticellular and antiviral activities of several derivatives.

A new synthesis of Mannich bases of rifamycin SV using the Borch2 procedure with rifaldehyde is described. This new synthesis offers two advantages over the previously published method. It provides a route to monoalkyl-aminomethylrifamycins (le-h) and to unsubstituted aminomethylrifamycins that were not accessible by the old procedure. The new method also offers a preparative route to Mannich bases 1a and 1b were needed in multigram quantities for biological testing. In addition, the cyclization of certain of the monoalkylaminomethylrifamycins to the novel N,15-didehydro-15-epi[methano(alkylimino)]rifamycin SV derivatives (2) is described. The anticellular and antiviral effects of representatives of both series of compounds against cultured mouse cells and murine oncornavirus are are discussed.

Animals↗
PubMed1988

Studies of non-metabolizable polyamines that support growth of SV-3T3 cells depleted of natural polyamines by exposure to alpha-difluoromethylornithine.

A number of synthetic polyamine derivatives that included five achiral gem-dimethylspermidines and two analogous tetramethylated spermines were tested for their abilities to serve as substrates for enzymes metabolizing polyamines and for their capacities to substitute for the natural polyamines in cell growth. It was found that none of the compounds were effective substrates for spermine synthase, and only one, namely 8,8-dimethylspermidine, was a substrate for spermidine/spermine N1-acetyltransferase. However, all of the spermidine derivatives and 1,1,12,12-tetramethylspermine were able to support the growth of SV-3T3 cells in which endogenous polyamine synthesis was prevented by the addition of alpha-difluoromethylornithine. These results suggest that either spermidine or spermine can support cell growth without the need for metabolic interconversion. In contrast with the result with 1,1,12,12-tetramethylspermine, 3,3,10,10-tetramethylspermine did not restore growth of polyamine-depleted SV-3T3 cells. Comparison of the properties of these derivatives may prove valuable in understanding the physiological role of polyamines.

Acetyltransferases↗
PubMed1991

p34cdc2-mediated phosphorylation at T124 inhibits nuclear import of SV-40 T antigen proteins.

The nuclear import of transcription regulatory proteins appears to be used by the cell to trigger transitions in cell cycle, morphogenesis, and transformation. We have previously observed that the rate at which SV-40 T antigen fusion proteins containing a functional nuclear localization sequence (NLS; residues 126-132) are imported into the nucleus is enhanced in the presence of the casein kinase II (CK-II) site S111/112. In this study purified p34cdc2 kinase was used to phosphorylate T antigen proteins specifically at T124 and kinetic measurements at the single-cell level performed to assess its effect on nuclear protein import. T124 phosphorylation, which could be functionally simulated by a T-to-D124 substitution, was found to reduce the maximal extent of nuclear accumulation whilst negligibly affecting the import rate. The inhibition of nuclear import depended on the stoichiometry of phosphorylation. T124 and S111/112 could be phosphorylated independently of one another. Two alternative mechanisms were considered to explain the inhibition of nuclear import by T124 phosphorylation: inactivation of the NLS and cytoplasmic retention, respectively. Furthermore, we speculate that in vivo T124 phosphorylation may regulate the small but functionally significant amount of cytoplasmic SV-40 T antigen. A sequence comparison showed that many transcription regulatory proteins contain domains comprising potential CK-II-sites, cdc2-sites, and NLS. This raises the possibility that the three elements represent a functional unit regulating nuclear protein import.

Amino Acid Sequence↗
PubMed1998

Effect of norepinephrine on proliferation, migration, and adhesion of SV-40 transformed human corneal epithelial cells.

PURPOSE: To determine the ability of norepinephrine to modulate proliferation, adhesion, and migration of SV-40 transformed human corneal epithelial cells. METHODS: Assays were performed using SV-40 transformed human corneal epithelial cells. For proliferation assays, cells were plated in 96-well plates coated with fibronectin and collagen (FNC). A dose-response curve was generated for norepinephrine in concentrations of 100 nM-100 microM. The cell number in each well was evaluated using the fluorochrome Calcein AM (an intracellular esterase cleavage substrate), and fluorescence was determined using an automated fluorescent plate reader. For cell adhesion, 25 x 10(-3) cells were plated onto FNC-coated 96-well plates, incubated in 10 nM-100 microM norepinephrine for 90 min, gently irrigated, and the remaining adherent cells quantitated. Cell migration was measured using blind-well migration chambers with a 10-microm pore size and FNC-coated filters. Cells (250 x 10(3)) were added to the upper chamber, incubated for 18 h in the presence of factors, after which time the cells that had migrated through the filter were quantitated. The toxicity of norepinephrine was evaluated using a standard Live/Dead assay employing the combined fluorochromes of ethidium homodimer (to indicate dead cells) and Calcein AM (to indicate viable cells). Varying concentrations of norepinephrine were added, and the cells incubated for 3 h and the fluorometric assay performed. RESULTS: Norepinephrine stimulated corneal epithelial cell proliferation and migration over a wide range of concentrations. It did not modulate cell adhesion and demonstrated cell toxicity only at the highest (supraphysiologic) concentration tested. CONCLUSIONS: Norepinephrine is normally found in the cornea and may be important in the maintenance of normal corneal homeostasis and in wound-healing processes.

Antigens, Polyomavirus Transforming↗
PubMed1982

SV-40 virus-induced neoplastic transformation of hamster brain cells in vitro. Studies with scanning and transmission electron microscopy.

Neoplastic transformation of one-day-old hamster brain cells was produced by infection with SV-40 virus and verified by phase contrast microscopy, growth in semisolid media, and intracranial tumor production after inoculation of the cells into other one-day-old hamsters. Transformed cells were studied by transmission and scanning electron microscopy. The numerous alterations in cell surface structure and in nuclear and cytoplasmic organization suggest a marked increase in cell metabolism and in the rate of mitosis and cell division. Cilia with a nine-to-zero pattern of microtubule doublets were present in cells with intermediate size filaments which stained for glial fibrillary acidic protein. The findings indicate that infection of one-day-old hamster brain cells in culture by SV-40 virus results in their transformation to a neoplastic state and the transformed cells are differentiating neoplastic astrocytes.

Animals↗
PubMed1990

Transfection and stable transformation of adult mouse Schwann cells with SV-40 large T antigen gene.

Cultured Schwann cells derived from adult mouse dorsal root ganglia and peripheral nerves were transfected with a plasmid containing SV-40 large T antigen gene, and 25 colonies of stable transformants were obtained, one of which was expanded and recloned. This transfected cell line, designated MS1, expressed SV-40 large T antigen and showed continuous cell growth with a doubling time of 27 hours. The MS1 cells had distinct Schwann cell phenotypes such as S-100 protein, laminin, 2',3'-cyclic nucleotide 3'-phosphodiesterase and P0 protein, as shown by immunofluorescence microscopy. When MS1 cells were exposed to dibutyryl cyclic adenosine-3',5'-monophosphate (dbc AMP), they extended long bipolar processes two- to ten-fold longer than those of untreated MS1 cells and frequently formed whorl-like alignments similar to palisade formations or organoid patterns observed in human Schwannomas and neurofibromas. These results suggest that transformed Schwann cells can be a useful model for analyzing regulatory mechanisms of Schwann cells, neuron-Schwann cell interactions and experimental Schwann cell neoplasms in vitro.

Animals↗
PubMed1979

Estimation of tubule or cylinder LV, SV and VV on thick sections.

The estimators of tubule or cylinder LV = 2NA, SV = 2IL, and VV = PP are considered in terms of bias due to section thickness, diameter, overlap, and grazing or fuzzy profiles. The superiority in a number of cases of the indirect estimation of SV and VV as functions of LV and profile diameter is discussed. Statistical aspects are dealt with in a practical example.

Animals↗
PubMed1975

The modification of DNA-dependent RNA polymerase from Escherichia coli by an alkylating derivative of rifamycin SV.

3-(2-Bromo[1-14C]acetamidoethyl)-thio-rifamycin SV, abbreviated BrAcNEtS-Rif, and alkylating derivative of rifamycin SV was synthesized. A four-fold excess of BrAcNEtS-Rif inhibited the enzymic activity of RNA polymerase from Escherichia coli to 97%. Incubation of RNA polymerase with Br[14C]AcNEtS-Rif led to covalent substitution. The reaction of Br[14C]AcNEtS-Rif with enzyme at a ratio of 1.4:1 and a concentration of 63 nM was found to proceed with a half life of 1 h at 37 degrees C. The enzyme could be protected from reaction with BrAcNEtS-Rif by either rifampicin or the hybrid [poly(dT)]-[r(Ap)5a]. The modification of holoenzyme by Br[14C]AcNEtS-Rif in the presence of p-hydroxymercuribenzene sulfonic acid (pOH-HgBzSO3H) or 4 M LiCl occurred with faster kinetics and led to a higher degree of substitution. Reaction of Br[14C]AcNEtS-Rif with RNA polymerase core enzyme caused predominant substitution of subunit beta. In the case of RNA polymerase holenzyme the radioactive substituents were evenly distributed between subunits beta and sigma. Apparently the topology of the rifamycin binding site of holoenzyme, similarly to core enzyme, precludes attacks of nucleophilic functions from beta' and alpha, but it allows nucleophilic functions from subunits beta and sigma to react with equal probability on BrAcNEtS-Rif. In the presence of a 20-fold excess of pOH-HgBzSO3H, the modification of holoenzyme was drastically altered. Virtually all substitution took place on subunit beta', very little on beta and none on subunits sigma and alpha.

Alkylating Agents↗
PubMed1982

Rheumatoid knee synovitis successfully treated with intra-articular rifamycin SV.

Thirty rheumatoid patients with persistent knee effusion were treated intra-articularly with rifamycin SV, 500 mg weekly, or with saline solution, 10 ml, in a double-blind study. A complete disappearance of effusion and an impressive clinical improvement was observed in the patients on rifamycin. The synovial fluid and membrane underwent some changes. In 2 patients the rifamycin caused a painful local reaction. After a follow-up of 5 years only one patient has experienced effusion relapse, 5 months after the termination of rifamycin SV treatment. The patients on saline showed no significant change. On the basis of the results obtained from the monoarthritis experimental model and from clinical trials it is tempting to consider that rifamycin has an antimitotic effect, impeding the synthesis of RNA and DNA polymerases in immunocompetent cells.

Arthritis, Rheumatoid↗
PubMed2002

Structural and biological characterization of highly purified hepta-acyl lipid A present in the lipopolysaccharide of the Salmonella enterica sv. Minnesota Re deep rough mutant strain R595.

One major component of the Salmonella enterica sv. Minnesota Re deep rough mutant (strain R595) lipopolysaccharide is hepta-acyl lipid A (LA(hepta)). In a recent publication [Tanamoto K-I, Azumi S. Salmonella-type heptaacylated lipid A is inactive and acts as an antagonist of lipopolysaccharide action on human line cells. J Immunol 2000; 164: 3149-3156] the corresponding synthetic hepta-acyl lipid A (compound 516) was reported to be agonistically inactive but to rather suppress pro-inflammatory activation by the endotoxic hexa-acyl lipid A (LA(hexa), compound 506) and S-form LPS from Escherichia coli in the human macrophage-like cell lines THP-1 and U937. These results, however, were in contrast to previous findings with human mononuclear cells (hMNC) isolated from peripheral blood, in which compound 516 was found to be an agonist, expressing low, but significant, cytokine-inducing activity as compared to LA(hexa). We have investigated the structure of natural LA(hepta) from the S. enterica sv. Minnesota Re deep rough mutant strain (R595) by TLC immunoblot, MALDI-TOF mass spectrometry and NMR spectroscopy. Using these techniques, the structural identity between LA(hepta) and the synthetic compound 516 was confirmed. In corroboration of previous findings with studies employing compound 516, purified LA(hepta) was found to induce the production of TNF-alpha, IL-1beta and IL-6 in hMNC, thus displaying moderate agonistic activity. Furthermore, we showed that LA(hepta) agonistically activated nuclear translocation of NF-kappaB in THP-1 cells, thus clearly ruling out the possibility that LA(hepta) is an antagonist and that its biological activity is influenced by the type of human myeloid cells used for testing endotoxicity (hMNC versus THP-1 cells).

Cell Line↗
PubMed2002

Dissociation of DNA damage and mitochondrial injury caused by hydrogen peroxide in SV-40 transformed lung epithelial cells.

BACKGROUND: Since lung epithelial cells are constantly being exposed to reactive oxygen intermediates (ROIs), the alveolar surface is a major site of oxidative stress, and each cell type may respond differently to oxidative stress. We compared the extent of oxidative DNA damage with that of mitochondrial injury in lung epithelial cells at the single cell level. RESULT: DNA damage and mitochondrial injury were measured after oxidative stress in the SV-40 transformed lung epithelial cell line challenged with hydrogen peroxide (H2O2). Single cell analysis of DNA damage was determined by assessing the number of 8-oxo-2-deoxyguanosine (8-oxo-dG) positive cells, a marker of DNA modification, and the length of a comet tail. Mitochondrial membrane potential, DeltaPsim, was determined using JC-1. A 1 h pulse of H2O2 induced small amounts of apoptosis (3%). 8-oxo-dG-positive cells and the length of the comet tail increased within 1 h of exposure to H2O2. The number of cells with reduced DeltaPsim increased after the addition of H2O2 in a concentration-dependent manner. In spite of a continual loss of DeltaPsim, DNA fragmentation was reduced 2 h after exposure to H2O2. CONCLUSION: The data suggest that SV-40 transformed lung epithelial cells are resistant to oxidative stress, showing that DNA damage can be dissociated from mitochondrial injury.

Journal Article↗
PubMed1989

Rat calvarial cell lines immortalized with SV-40 large T antigen: constitutive and retinoic acid-inducible expression of osteoblastic features.

Two new bone cell lines were established by immortalizing cells derived from embryonic rat calvariae with a recombinant retrovirus containing the cDNA for SV-40 large T antigen and the neomycin resistance gene. One cell line, RCT-1, isolated from early digest cells, a population which typically does not express osteoblastic features, displayed osteoblastic characteristics only after 3 days of treatment with 1 microM retinoic acid: alkaline phosphatase activity increased from 0.003 to 0.25 mumol/min.mg protein, the steady state level of type I procollagen mRNA increased 4-fold, and the cells acquired a PTH-stimulatable adenylate cyclase (EC50, 10 nM). mRNA for osteopontin, an abundant bone matrix protein, was induced in RCT-1 cells by 1,25-dihydroxyvitamin D3 (10 nM). The second cell line, RCT-3, isolated from late digest cells, a population previously shown to be enriched with differentiated osteoblasts, expressed constitutively the properties described above. In addition, RCT-3 cells responded to interleukin-1 by increased prostaglandin production (EC50, 20 pM) and to prostaglandin E2 by enhanced cAMP accumulation, features exhibited by calvarial cells in organ culture. Thus, the SV-40 immortalized cell lines we describe retained many of the characteristics of osteoblasts in primary culture, including hormonal regulation of phenotype-related genes. In RCT-1 cells the coordinate induction of several properties by retinoic acid offers a new model for the study of differentiation-related gene expression in bone cells.

1-Methyl-3-isobutylxanthine↗
PubMed1999

Molecular analysis and heterologous expression of the gene encoding methylmalonyl-coenzyme A mutase from rifamycin SV-producing strain Amycolatopsis mediterranei U32.

The conversion of succinyl-coenzyme A (CoA) into methylmalonyl-CoA, catalyzed by adenosylcobalamin-dependent methylmalonyl-CoA mutase (MCM), represents an important source of building blocks for rifamycin SV biosynthesis. The structural gene for MCM from rifamycin SV-producing strain Amycolatopsis mediterranei U32 was isolated by using a heterologous gene probe encoding the MCM of Streptomyces cinnamonesis. A 7.8-kbp fragment was sequenced and four complete open reading frames (ORFs) and two incomplete ORFs were found. Two central ORFs, ORF3 and ORF4, overlap by four nucleotides and were found to encode MCM small (602 residues) and large (721 residues) subunits, respectively. Comparison showed that the MCM gene of A. mediterranei U32 was quite similar to those from other sources. The functionally unknown ORF5, immediately downstream of the mutAB gene, was quite similar to the ORFs downstream of mutAB from S. cinnamonensis and Mycobacterium tuberculosis. Such a striking cross-species conservation of gene order suggested that ORF5 could also be involved in the metabolism of methylmalonyl-CoA. MCM gene was overexpressed in Escherichia coli under T7 promoter, and MCM activity could be detected in the recombinant E. coli clone harboring MCM gene after the addition of coenzyme B12. A purification procedure based on the B12 affinity column was established to purify the MCM from E. coli. The molecular weight of purified MCM from E. coli was determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis, which corresponds to that calculated from the MCM protein sequence and is also the same size as that of the enzyme purified directly from A. mediterranei U32. MCM gene was overexpressed in polyketide monensin producing S. cinnamonensis, and the total monensin production was increased by 32%.

Actinomycetales↗
PubMed2005

Forskolin and dexamethasone synergistically induce aromatase (CYP19) expression in the human osteoblastic cell line SV-HFO.

OBJECTIVE: Recent progress supports the importance of local estrogen secretion in human bone tissues to increase and maintain bone mineral density. In a previous study, we reported that the expression of aromatase (CYP19) is dexamethasone (Dex)-dependent and oncostatin M (OSM) increases the expression synergistically with Dex. In the present study, we examined the effects of forskolin (FSK) as another potential synergistic factor. RESULTS: Co-administration of 100 nM Dex and 10 microM FSK increased aromatase activity 4-fold compared with Dex alone. The results of reverse transcriptase (RT)-PCR suggest that the amount of CYP19 gene transcript was also up-regulated by FSK synergistically with Dex, and that promoter I.4, which is not activated by FSK alone, is activated by FSK synergistically with Dex. The results of RT-PCR also suggest that promoter II, which responds to FSK, was not activated even in the presence of FSK in SV-HFO. The promoter I.4 sequence that was transfected into SV-HFO was activated by FSK synergistically with Dex. CONCLUSIONS: Synergistic up-regulation of aromatase activity, CYP19 gene transcript, and promoter I.4 activity were Dex-dependent and not up-regulated by FSK alone. The results of this work may form the basis of bone-specific estrogen-replacement therapy that increases the estrogen concentration in bone tissue only.

Aromatase↗
PubMed1992

Induction of stress proteins in SV-40 transformed human RPE-derived cells by organic oxidants.

The expression and induction of heat shock proteins (HSPs) were examined in cultured SV-40-transformed human retinal pigment epithelial (RPE)-derived cells following exposure to chemical oxidants. Concentrations of hydrogen peroxide and the organic oxidants tert-butyl hydroperoxide, cumene hydroperoxide and linoleic acid hydroperoxide were used under conditions where cell viability was between 75% and 90% as determined by the trypan blue exclusion tests. The types of HSPs that are either induced and/or elevated from constitutive levels in cultured transformed cells were separated both by SDS-PAGE and by two-dimensional gel electrophoresis. Subsequent immunoblotting was performed with both a monoclonal antibody (MAb C92) specific for only the stress-inducible form of HSP 70, namely HSP 72, and with a monoclonal antibody (MAb N27) specific for both the stress-inducible HSP 72 and its constitutive form, HSP 73. As positive controls for comparison, other types of stressing agents were used that included heat shock at 41 degrees C for various times and exposure to the proline analogue, azetidine-2-carboxylic acid (AzC). Protein immunoblotting analysis demonstrate that: (a) Stress-inducible HSP 72 is present at low levels in non-stressed cultured transformed RPE-derived cells and in fresh bovine retina and RPE, but is not detectable in non-stressed cultured lung fibroblasts until induction with heat shock; and (b) Stress-inducible HSP 72 is elevated from constitutive levels in RPE-derived cultured cells after exposure to various oxidants. After cellular exposure to both organic oxidants and to AzC in the presence of L-[35-S]-methionine, two-dimensional gel electrophoresis confirmed the elevation of newly synthesized HSP 72. Thus, these results indicate that cultured human SV-40-transformed RPE-derived cells are capable of elevated HSP 72 biosynthesis under conditions of oxidative stress produced by organic oxidants.

Azetidinecarboxylic Acid↗
PubMed1993

Inactivated products of rifampicin by pathogenic Nocardia spp.: structures of glycosylated and phosphorylated metabolites of rifampicin and 3-formylrifamycin SV.

Rifampicin (1) was converted into four inactivated products by pathogenic Nocardia, RIP-1 and RIP-2 by N. brasiliensis and RIP-3 and RIP-4 by N. otitidiscaviarum. MS and NMR analysis showed the compounds to be 3-formyl-23-[O-(beta-D-glucopyranosyl)]rifamycin SV (2), 23-[O-(beta-D-glucopyranosyl)]rifampicin (3), 21-(O-phosphoryl)rifampicin (4) and 3-formyl-21-(O-phosphoryl)-rifamycin SV (5), respectively.

Drug Resistance↗
PubMed1976

The effect of rifamycin SV on the wound-healing process.

The influence of rifamycin SV on the healing process of a wound was studied in animal experiments. Measurement of the degree of cicatrization, determination of the free hydroxyproline in serum, and histological findings helped to demonstrate that local application of rifamycin SV leads to an increased fibrinous conglutination of the lips of the wound at an early phase of the healing process and the subsequent formation of fibres in the regenerative tissue is not impaired.

Animals↗
PubMed2001

Six-month results of small vessel stenting (2.0-2.8 mm) with the Biodivysio SV stent.

We report the 6-month follow-up results of our initial retrospective experience with the Biodivysio small vessel (SV) stent (Biocompatibles, Galway, United Kingdom) designed for 2.0-2.8 mm vessel diameters. This stent is manufactured with a smaller stainless-steel tube (1.0 mm) and is coated with phosphorylcholine. Procedural success was 95.7% and the major adverse cardiac events at 6 months were 20%. We conclude that the Biodivysio SV stent is a safe device that does not induce excessive acute thrombosis or early restenosis.

Aged↗