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F Podo

Publications and source records attributed to F Podo.

At least 55 records · Page 3Linked to original sources
PubMed1989

Interleukin-1 beta induces tumor necrosis and early morphologic and metabolic changes in transplantable mouse tumors. Similarities with the anti-tumor effects of tumor necrosis factor alpha or beta.

Peri-tumoral injection of recombinant human interleukin-1 beta in mice transplanted s.c. with Friend erythroleukemia cells (FLC) resulted in marked inhibition of tumor growth and increased survival. However, in vitro treatment of FLC (745 or 3Cl-8) with IL-1 beta barely inhibited cell multiplication. IL-1 beta, injected into established solid tumors, induced marked morphologic changes. Vascular congestion and focal extravasation of erythrocytes were observed as early as 6 hr after injection with IL-1 beta of FLC and L1210 tumors and HeJ16 fibrosarcomas. Focal areas of disaggregation of tumor cells and tumor necrosis were observed 6 and 24 hr after IL-1 injection. These morphologic changes were similar to those observed in FLC tumors or HeJ16 fibrosarcomas treated with TNF-alpha or beta. These cytokines determined morphological changes in tumor blood vessels of FLC tumors within 1 hr of injection. Freshly dissected FLC tumors and their tissue extracts were studied by Nuclear Magnetic Resonance (NMR) spectroscopy, shortly after peri-tumoral injection of IL-1 beta or TNF-beta. After 6 hr, both cytokines induced a 3-fold reduction in the levels of two catabolites, glycerophosphorylcholine and glycerophosphorylethanolamine, an accumulation of sn-glycerol 3-phosphate and a more than 10-fold increase in the choline/phosphorylcholine ratio. These results are similar to those reported for TNF-alpha, and can be interpreted on the basis of an activation of glycerophosphorylcholine phosphodiesterase (EC 3.1.4.2) and partial inhibition of choline kinase (EC 2.7.1.32). IL-1 beta and TNF-beta (like TNF-alpha) also induced alkaline shifts (0.10-0.25 units) in the average intratumoral pH value. We suggest that alterations of tumor blood vessels may be the primary events in solid tumors treated with IL-1 beta or TNF. Such alterations lead to early changes in tumor metabolism and subsequent tumor cell degeneration.

Animals↗
PubMed1989

[Nuclear magnetic resonance and positron emission tomography: diagnostic potential in tissue characterization].

Nuclear magnetic resonance (NMR) and positron emission tomography (PET) are among the most advanced methodologies providing, with different physical approaches, diagnostic images of the body. In this framework, NMR and PET are particularly well known, not only for the high quality of their present results, but also for the expectations of further developments at clinical and diagnostic level. Common feature of NMR and PET is the capability of associating the anatomical image with information on the physico-chemical and/or biochemical properties of tissues. NMR imaging (MRI) is in fact based upon the acquisition of signals, whose intensities indirectly but closely depend upon particular physico-chemical and biophysical properties of biological tissues. NMR spectroscopy (MRS) and PET allow, on the other hand, quantitative studies on metabolic reactions, as they occur in intact tissues, in vivo and in situ. This review is aimed at summarizing the basic principles of tissue characterization by NMR and PET and discussing their perspectives of clinical application. Emphasis will be given to the special requirements of tissue characterization by these methodologies, referring to the need of improving accuracy and precision of measurements, as well as at evaluating, on a quantitative basis, the performance of the equipment.

Chemical Phenomena↗
PubMed1988

Tumor necrosis factor alpha induces early morphologic and metabolic alterations in Friend leukemia cell tumors and fibrosarcomas in mice.

Morphologic and metabolic studies have been carried out on Friend leukemia cell (FLC) tumors (grown in DBA/2 mice) or fibrosarcomas (grown in C3H/HeN or C3H/HeJ mice) shortly after peritumoral injection of recombinant mouse tumor necrosis factor (TNF) alpha. Marked vascular congestion and focal extravasation of erythrocytes were observed as soon as 1 hr after injection of either FLC tumors or fibrosarcomas with TNF. Focal areas of disaggregation of tumor cells were observed 1 hr after injection of TNF. Intraluminal thrombi (composed of degranulated platelets and fibrin) were detected 3 and 6 hr after TNF treatment, and were associated with areas of depletion of endothelial cell cytoplasm. To correlate these morphologic changes in the tumor with alterations in tumor metabolism, NMR spectroscopy and biochemical studies were undertaken on freshly dissected FLC tumors and fibrosarcomas shortly after injection of TNF. The earliest metabolic alterations observed after 1 hr in TNF-treated FLC tumors of fibrosarcomas were: (i) increase in the average intratumoral pH; (ii) decrease in the levels of ATP. These phenomena were not associated with a reduced glycolytic capacity of TNF-treated tumors as, at these early times after injection, the levels of lactic acid were virtually the same for TNF-treated or control treated tumors. Alterations in the levels of some products of phospholipid degradation (GroPCho, GroPEtn, GroP and Cho) also occurred in these tumors as early as 3 hr after TNF treatment. These metabolic changes were not observed in ascitic FLC tumors after TNF treatment. We suggest that TNF induces alterations in tumor blood vessels which subsequently lead to changes in tumor metabolism and tumor degeneration.

Adenosine Triphosphate↗
PubMed1987

Nuclear magnetic resonance analysis of tumor necrosis factor-induced alterations of phospholipid metabolites and pH in Friend leukemia cell tumors and fibrosarcomas in mice.

The alterations induced on the pool sizes of five phospholipid metabolites, glycerol 3-phosphorycholine, glycerol 3-phosphorylethanolamine, phosphorylcholine, sn-glycerol 3-phosphate, and choline were studied by nuclear magnetic resonance (NMR) spectroscopy in murine tumors injected with recombinant murine tumor necrosis factor (TNF). Solid tumors were obtained by s.c. injection of either Friend leukemia cells (clones 3C1-8 and 745) in DBA/2 mice or murine fibrosarcoma cells (HeN4) in C3H/HeN mice. After tumor nodules had developed, TNF or bovine serum albumin was injected intratumorally. Treatment of both tumors with TNF resulted in a marked inhibition of tumor growth. 31P-NMR analyses of Friend leukemia cell tumors (and tissue extracts), 6 h after injection of TNF, showed: (a) a 1.5- to 3.5-fold decrease in the pool sizes of glycerol 3-phosphorylcholine and glycerol 3-phosphorylethanolamine; (b) a 7- to 8-fold increase of sn-glycerol 3-phosphate; (c) a 2- to 3.5-fold decrease of phosphorylcholine; (d) an alkaline shift (0.2 units) in intratumoral pH. Similar metabolic alterations occurred in TNF-treated HeN4 fibrosarcoma. 1H-NMR analyses of Friend leukemia cell tumor extracts also indicated, 6 h after tumor injection with TNF: (a) elevated choline levels (9X); (b) a 19-fold increase in the ratio [choline]/[phosporylcholine]; (c) elevated (1.4X) levels of lactic acid; and (d) a 1.6-fold decrease in the [taurine]/[glycine] ratio. The results are interpreted in the light of possible alterations in the activity of enzymes controlling the de novo biosynthesis and catabolism of phospholipids. We concluded that NMR spectroscopy can be a useful means to monitor the level of some phospholipid precursors and/or derivatives as early markers of therapeutic efficacy in intact neoplastic tissues.

Animals↗
PubMed1986

Anti-tumor effects of interferon in mice injected with interferon-sensitive and interferon-resistant Friend leukemia cells. V. Comparisons with the action of tumor necrosis factor.

A number of similarities and dissimilarities in the anti-tumor effects of TNF and interferon alpha/beta have been observed in DBA/2 mice injected with Friend erythroleukemia cells (FLC). Mouse TNF exerted marked anti-tumor effects in mice injected either s.c. or i.p. with FLC lines 3C18 or 3 gamma R8 resistant in vitro to the cytotoxic effects of TNF. Likewise, mouse interferon alpha/beta had anti-tumor activity in mice injected with these FLC, resistant to the action of interferon alpha/beta or gamma in vitro. The results of histopathologic examination and 31P nuclear magnetic resonance analyses of 3C18 FLC s.c. tumors injected with TNF resembled the results previously obtained for 3C18 FLC tumors injected with interferon alpha/beta, although the effects of TNF occurred more rapidly. Injection of mice with antibody to mouse interferon alpha/beta or gamma did not abrogate the anti-tumor effects of TNF in mice injected i.p. with FLC. Our results suggest that in this experimental system the anti-tumor effects of TNF, like interferon alpha/beta, do not result from a direct effect on the tumor cells themselves but are host-mediated.

Animals↗
PubMed1986

A 19F nuclear magnetic resonance study of uptake and metabolism of 5-fluorocytosine in susceptible and resistant strains of Candida albicans.

The metabolism of the antifungal drug 5-fluorocytosine (5-FC) was studied in intact viable cells of Candida albicans by 19F nuclear magnetic resonance (NMR). The uptake of the drug and its conversion to the deaminated product 5-fluorouracil (5-FU) were easily observed by NMR analysis of both the cells and the supernatants of the incubation mixture. In the 5-FC-resistant mutant D14 of C. albicans, which lacked cytosine deaminase activity, the resonance peak of 5-FU was not observed. In intact cells of all 5-FC-susceptible strains the metabolism of 5-FU progressed to the formation of other fluorinated derivatives which were visualized as a single, broad resonance band at a lower field with respect to 5-FC and 5-FU. This band was resolved into three distinct peaks in the acid extract of treated cells, one of these peaks being attributable to 5-fluoro-dUMP (5-FdUMP). In strain 72R of C. albicans, which is 5-FC resistant because of a low level of UMP-pyrophosphorylase activity, the broad, low-field resonance band was detected later and with much less intensity than in the 5-FC-sensitive strains. This suggests that, besides 5-FdUMP, this band is also contributed to by 5-FUMP and possibly other phosphorylated derivatives. 19F NMR analysis also revealed that a significant amount of 5-FU is secreted into the external medium, the rate of secretion being higher in 5-FC-resistant strain 72R than in 5-FC-sensitive strain 72S. Although not all resonances were definitely identified, this study shows that 19F NMR spectroscopy may be an important tool for noninvasive analysis of the metabolism of fluorinated drugs in yeasts.

Candida albicans↗
PubMed1986

31P-nuclear magnetic resonance analysis of interferon-induced alterations of phospholipid metabolites in interferon-sensitive and interferon-resistant Friend leukemia cell tumors in mice.

Adult DBA/2 mice were given injections s.c. with either interferon-sensitive (745) or -resistant (3Cl-8) Friend erythroleukemia cells (FLC). After tumor nodules had developed, mouse interferon-alpha/beta was injected daily into the tumor. 31P-Nuclear magnetic resonance (NMR) spectroscopy examinations were undertaken on freshly dissected tumors at different days of treatment with either interferon or control preparations. Analysis of 745 FLC tumors in untreated mice at different days of tumor growth (day 8 to 13 after tumor implantation) showed marked increases in the levels of phosphorylcholine (PCho), glycerophosphorylethanolamine (GroPEtn) and glycerophosphorylcholine (GroPCho). In contrast high levels of PCho, GroPEtn and GroPCho were already detectable in the 3Cl-8 FLC tumors on day 8, and no significant changes were observed during subsequent tumor growth. The intracellular pH value remained practically constant in both FLC tumors. Daily intratumoral administration of either partially purified (10(7) IU/mg of protein) or highly purified (10(9) IU/mg of protein) mouse interferon-alpha/beta to both cell tumors resulted in decreases in the levels of PCho, GroPEtn and GroPCho and in increases in the intracellular pH with respect to tumors treated with control preparations or left untreated. Two days of daily treatment of mice with interferon sufficed to induce these metabolic changes which preceded the appearance of necrosis in the tumors. Treatment of FLC tumors with X-rays on day 12 of tumor growth did not result in any comparable metabolic changes 2 days after irradiation. Changes in the levels of phospholipid metabolites were not observed when 745 or 3Cl-8 cells were cultivated in the presence of interferon. As interferon induced these changes in both interferon-sensitive and -resistant tumors we conclude that interferon treatment results in host-mediated effects on the biosynthesis and/or catabolism of tumor cell phospholipids.

Animals↗
PubMed1984

Modulations of glycerophosphorylcholine and phosphorylcholine in Friend erythroleukemia cells upon in vitro-induced erythroid differentiation: a 31P NMR study.

A 31P NMR study has been carried out on Friend erythroleukemia cells (FLC) induced to undergo erythroid differentiation in vitro. Significant levels of glycerophosphorylcholine (GroPCho) and phosphorylcholine (P-Cho) were identified both in the untreated cells and in their PCA extracts. In FLC treated 4 days in vitro with either dimethylsulfoxide (DMSO) or hexamethylenebisacetamide (HMBA), the intracellular concentration of P-Cho was markedly increased, whereas that of GroPCho appeared to be significantly reduced. HMBA was more effective than DMSO in producing this effect. The concomitant modulations of GroPCho and P-Cho in differentiated FLC suggest the hypothesis that erythroid differentiation involves modifications of the regulatory mechanisms controlling biosynthesis and catabolism of phospholipids.

Acetamides↗
PubMed1984

A 31P NMR study on uptake and metabolism of hexose monophosphates in rat diaphragm muscle.

Phosphorus nuclear magnetic resonance spectroscopy was used to study uptake and metabolic conversion of glycolytic intermediates in rat diaphragm muscles. The resonances of several phosphorus-containing metabolites were identified in the intact tissues and in their ethanolic extracts. Experiments on muscles preincubated with glucose 6-phosphate or glucose 1-phosphate indicated that: 1) both substrates penetrate into the tissue and actively participate in glycolytic reactions; 2) glucose 1-phosphate is completely converted into other metabolites, including glucose 6-phosphate and its products; 3) preincubation with either hexose monophosphate in the presence or in the absence of insulin produced the same set of phosphorylated metabolites. Addition of insulin to preincubation media induced a conspicuous spread of chemical shifts in the band arising from phosphorylated sugars in tissues incubated with glucose 1-phosphate but not in those treated with glucose 6-phosphate. The different responses to insulin exhibited by the 31P n.m.r. spectral profiles of tissues incubated with the two substrates substantiate the hypothesis that glucose 6-phosphate and its products may undergo their metabolic conversions in the tissue along distinct intracellular enzymatic pathways, on which insulin would exert different regulatory effects. This study indicates that 31P n.m.r. may provide a useful approach to the elucidation of metabolic processes involving sugar phosphates in intact tissues.

Adenosine Diphosphate↗
PubMed1983

31P nuclear magnetic resonance study of growth and dimorphic transition in Candida albicans.

A 31P NMR study of the fungal pathogen Candida albicans was carried out. Yeast-form cells at different phases of growth, as well as germ tubes and hyphae were examined. In all cases, the NMR spectra showed well separated resonance peaks arising from phosphorus-containing metabolites, the most prominent being attributable to inorganic phosphate (Pi) polyphosphates, sugar phosphates and mononucleotides, NAD, ADP and ATP. Relevant signals were also detected in the phosphodiester region. The intensity of most signals, as measured relative to that of Pi, was clearly modulated both at the different phases of growth and during yeast-to-mycelium conversion, suggesting significant changes in the intracellular concentration of the corresponding metabolites. In particular, the intensity of the polyphosphate signal was high in exponentially growing, yeast-form cells, then progressively declined in the stationary phase, was very low in germ tubes and, finally, undetectable in hyphae. NMR spectral analysis of the Pi region showed that from early-stationary phase, Pi was present in two different cellular compartments, probably corresponding to the cytoplasm and the vacuole. From the chemical shift of Pi, the pH values of these two compartments could be evaluated. The cytoplasmic pH was generally slightly lower than neutrality (6.7-6.8), whereas the vacuolar pH was always markedly more acidic.

Candida albicans↗
PubMed1982

Dependence of melittin structure on its interaction with multivalent anions and with model membrane systems.

The conformation and the aggregation state of melittin were investigated in aqueous solutions having different pH values and ionic composition as well as upon interaction with phospholipids. While circular dichroism could only show the existence, in aqueous solution, of either a random-coil or of a right-handed helical conformation, high resolution 1H and 13C n.m.r. spectra, together with the results of photon correlation spectroscopy, produced evidence in favour of a number of different well-defined structural states, depending on anion concentration and charge and on pH. In pure water at neutral pH melittin appeared to exist as a flexible random-cell monomer; in dilute NaCl a monomeric form was found which was still essentially unordered, but presented a pronounced rigidity of structure, and could be approximated to a prolate ellipsoid. When divalent anions were present (or when high ionic strengths were reached even with monovalent anions) melittin molecules associated into a compact disc-like tetramer; by 31P n.m.r., correlations could be established between the binding of phosphate ions and the variations in the structure or in the aggregation state of the polypeptide chains. As alkaline pH a helical tetramer was also found, different, however, from that formed on the presence of divalent anions at neutral pH. Upon binding to phospholipids, melittin molecules can be visualized, similarly to what happens in aqueous phosphate solutions, as consisting essentially of a bent right-handed helix, with a grouping of polar residues along one face of the molecule. The glutamine and lysine residues were strongly immobilized, while there was no n.m.r. evidence for any self-aggregation of the peptide; the ability of melittin to induce dichromate efflux from phospholipid vesicles was in fact higher when the peptide was in the monomeric state than in the tetrameric one.

Anions↗
PubMed1979

PMR studies of phosphatidylcholine-cholesterol vesicles interacting with lucensomycin.

Spin-lattice relaxation times (T1) were measured above the phase transition temperature on sonicated vesicles of egg- or dipalmitoyl-phosphatidylcholine containing cholesterol and/or the polyenic antibiotic, lucensomycin. T1 values of only the terminal methyl groups of the fatty acyl chains were significantly reduced by cholesterol. Lucensomycin caused, more markedly in cholesterol-containing vesicles, a selective reduction of the T1 values of the N-methyl groups. An even more conspicuous decrease, occurring only in cholesterol-containing vesicles, was observed for the transverse relaxation times (T2) of the N-methyl signals upon addition of lucensomycin. The polyene failed to remove the well-known broadening effect of cholesterol on phosphatidylcholine methylene signals. These results indicate that as lucensomycin binds to cholesterol-containing membranes, there is a detectable perturbation of the dynamic structure of the N-methyl groups with an increase in the degree of motional anisotropy. But the non-polar region of the bilayer seems not significantly perturbed by the polyene.

Antifungal Agents↗
PubMed1979

Temperature dependence of 31P-NMR spectra of chicken erythrocyte nucleosomes.

The shape of the 31P-NMR signal of DNA in nucleosomes isolated from chicken erythrocytes has been examined in the temperature range of 15--80 degrees C at 40.48 MHz. This resonance is composed of at least two partially overlapping peaks with different line-widths and chemical shifts. The relative intensities of the peaks were found to vary with temperature. Although a quantitative analysis of the components is difficult at this frequency, the presence of various peaks under the resonance signal is further confirmed by inspection of the partially relaxed spectra at 15 degrees C. A comparison of the thermal behavior of protein-free DNA isolated from nucleosomes with that of DNA bound to histones indicates that DNA segments in nucleosomes take on several conformational states.

Animals↗