Structure-activity relationships for unsaturated dialdehydes 7. The membrane toxicity of 15 sesquiterpenoids measured as the induction of ATP leakage in ELD cells. The correlation of the activity with structural descriptors by the multivariate PLS method.

The ability of 15 sesquiterpenoids containing an unsaturated dialdehyde functionality to damage cellular membranes, measured as the induction of ATP leakage in ELD cells, has been investigated. In spite of the structural similarities of this class of compounds, large differences in potency were noted. The results from the ATP leakage assay were correlated (by the multivariate PLS method) with a number of structural descriptors, such as intra-atomic distances and angles, atomic charges, and lipophilicity, to obtain quantitative structure-activity relationships. A component consisting of the distance and the dihedral angle between the two aldehyde groups, the dipole moment, the lipophilicity, and the chemical stability, was found to be correlated with the activity in the ATP leakage assay. This indicates that the activity of the unsaturated dialdehydes depends on their accumulation in lipophilic parts of a cell (e.g. the membranes), the way they orient themselves in a membrane, and their chemical reactivity towards proteins associated with a membrane.

Structure-activity relationships for unsaturated dialdehydes. 6. The mutagenic activity of 11 compounds in the V79/HGPRT assay.

The mutagenic activity of 11 sesquiterpenoid unsaturated dialdehydes in the V79/HGPRT assay has been determined, and is compared with previously published data on the mutagenicity of the same compounds towards Ames Salmonella strains. One compound, isovelleral, is a potent mutagen in both assays, while six compounds, which are positive in the Ames Salmonella/microsome assay, show no significant activity in this study. One compound, acetylmerulidial, is negative in the Ames Salmonella/microsome assay but significantly although weakly mutagenic in the V79/HGPRT assay. The remaining three compounds are inactive in both assays. The study is part of a general investigation of quantitative structure-activity relationships for unsaturated dialdehydes, a class of natural occurring compounds known for their potent and numerous biological activities.

The cytotoxicity of 22 sesquiterpenoid unsaturated dialdehydes, as determined by the neutral red absorption assay and by protein determination.

The neutral red absorption assay, complemented by protein determination, was used to measure the cytotoxic activity of 22 sesquiterpenoid unsaturated dialdehydes towards hamster fibroblasts in monolayer culture (cell line V79). No significant differences between the activities determined by the two assays were found for the compounds assayed, indicating that their inhibitory effects on cell growth are related to general cytotoxicity. In spite of the apparent similarity between the chemical structures of the assayed compounds, the most active was approximately 200 times more cytotoxic than the least active. Isovelleral and its derivatives are the most cytotoxic substances, but the ranking in order of general cytotoxicity within this subgroup differed from that found in a previous study of mutagenic activity. Marasmic acid and its derivatives are also potent cytotoxic agents, but two of the most cytotoxic compounds in this group have been reported to be the least mutagenic. Such differences between cytotoxic and mutagenic activities indicate that the molecular targets for these two activities differ. The cytotoxicity of polygodial found in this study is lower than that previously reported from other cytotoxicity assays, which suggests that different tests of general cytotoxicity may have different molecular targets. Because of the diverse cytotoxic activities of the unsaturated dialdehydes, it should be possible to study them in a quantitative structure-activity relationship (QSAR) multivariate analysis.

Intracellular compartmentation of diadenosine tetraphosphate (Ap4A) and dTTP in rat liver.

1. The intracellular compartmentation of diadenosine tetraphosphate (Ap4A) and of dTTP was studied in rat liver cells using non-aqueous glycerol for the isolation of cell nuclei. 2. This method allows a stepwise removal of cytoplasm from the nuclei. 3. The decrease in Ap4A or dTTP during the process was compared to the simultaneous decrease in RNA, which was taken to represent the cytoplasm. 4. In regenerating liver excised 24 hr after partial hepatectomy, Ap4A was almost equally distributed between the nucleus and cytoplasm. 5. In livers from unoperated control rats, the nuclear concentration of Ap4A was slightly elevated compared to that of whole cells. dTTP was only investigated in regenerating liver. 6. Significantly higher concentrations were found in the nuclear fractions. 7. The purest nuclei contained about 26% of whole cell levels of dTTP, while their RNA values had decreased to 7% of the whole cell RNA. 8. Considering that the liver cell nucleus comprises about 7% of the entire cell mass, a nuclear dTTP concentration of 26% indicates significantly higher dTTP levels in the nuclear compartment than in the cytoplasm of regenerating rat liver cells.

Early increase in diadenosine tetraphosphate in regenerating rat liver.

Diadenosine tetraphosphate (Ap4A), a candidate for a signal molecule in the induction of DNA synthesis, was measured in regenerating livers of young adult rats at 12 and 24 h and of older rats at 24 h after partial hepatectomy. dATP and dTTP levels, which indicate the degree of proliferation in the livers, were determined by high-performance liquid chromatography and an enzymatic method, respectively. The Ap4A levels were increased in the beginning of DNA synthesis. In young rats the levels were about 140% of those of unoperated rats and in older rats about 300%. This increase was considerably smaller than that found in another study comprising two regenerating rat livers excised 20 h after partial hepatectomy, but still supports the hypothesis that Ap4A might take part in the onset of proliferation. The greater Ap4A increase in older rats may suggest a possible need for a stronger triggering mechanism to start proliferation in aged tissue. However, the experiments do not prove a function for Ap4A in the induction of DNA synthesis and it cannot be excluded that Ap4A is a product of an independent reaction.

Effects of pH on the stability of the indium-113m blood protein complex and the selective binding of indium-113m to transferrin.

Indium-113m (t1/2 = 100 min; gamma-emission of 393 keV) in trace amounts was injected i.v. in rats. Blood was collected by heart puncture 15 min after the injection, and blood plasma was separated by centrifugation. Gel filtration of plasma on Sephadex G-25M equilibrated with glycine/HCl (pH 2.2-3.6), NaHCO3/CO2 (pH 4.0-11.0) glycine/NaOH (pH 8.6-10.6) or sodium acetate/acetic acid (pH 3.0-5.0) was used to separate free indium from indium bound to macromolecular proteins. Determination of radioactivity in eluted fractions showed that more than 85% of the plasma indium was bound to macromolecules at pH values between 5.0 and pH 10.6. However, dissociation of the indium plasma protein complexes occurred at pH values below 5.5, and more than 90% of the indium radioactivity was found in the low molecular weight fraction at pH 2.2. Affinity chromatography using immobilized antibodies to rat transferrin was used to isolate transferrin at pH 7.4 and 5.5. Immunodiffusion and electrophoresis were used to identify the proteins in fractions obtained by affinity chromatography. It was found that the indium-113m activity was correlated with the content of transferrin and that 80%-90% of this activity was found in fractions that had affinity to antitransferrin. These fractions contained transferrin exclusively at pH 7.4, but additional protein fractions of albumin and alpha1-globulin mobility at pH 5.5. At pH 7.4 and 5.5, 10%-20% of the indium activity was detected in molecular fractions that had no affinity to antitransferrin. Immunologic analyses showed that these fractions contained transferrin.(ABSTRACT TRUNCATED AT 250 WORDS)

Hepatic artery administration of degradable starch microspheres: II. Effects on incorporation of uridine and uracil into RNA of an adenocarcinoma transplanted to rat liver.

Effects of degradable starch microspheres administered via the hepatic artery were examined in rats in which an adenocarcinoma was transplanted into the liver. 3H-uridine or 3H-uracil with cold uridine and uracil, respectively, in amounts corresponding to therapeutic doses of these two pyrimidines as fluoro compounds, were administered with or without microspheres. Labeling of the acid-soluble fraction and RNA of tumor, liver, small intestine, spleen, kidney, and bone marrow was examined after 3 and 60 min after injection. When microspheres were added, the specific radioactivity of tumor RNA was significantly higher at both 3 min (P less than 0.05) and 60 min (P less than 0.01) in the rats given uridine, and in rats given uracil it was higher at 60 min after injection (P less than 0.05). There were no such differences in the labeling of the normal tissues. The results indicate that arterial administration of cytostatic drugs, such as 5-fluoropyrimidines, together with degradable starch microspheres might increase the cytotoxic effect on tumors nourished by the artery.

Isotachophoretic and HPLC determination of nucleotides in rat liver cell nuclei isolated by non-aqueous technique.

Rat liver whole cells and cell nuclei were prepared by a non-aqueous technique (glycerol). The nuclear preparations were of different purity as determined by RNA/DNA ratios (0.17-1.60) and accordingly were divided into 3 subgroups (mean values 0.29, 1.04 and 1.48). RNA nucleotides were separated by isotachophoresis and HPLC and calculated per mg DNA. Two of the nuclear subgroups (RNA/DNA = 1.04 and 1.48) had significantly elevated nucleotide values in relation to RNA/DNA. UDP-N-acetylhexosamine/DNA, on the contrary, was reduced in conformity with RNA in the preparations. Our findings may indicate different nucleotide concentrations in different parts of the cell.

Variation of incorporation of [3H]orotic acid into the nucleotide and RNA fractions of different parts of the same liver lobe in the rat.

1. Anaesthetized rats were given [3H]orotic acid either intraperitoneally or via a catheter into the hepatic artery with or without degradable starch microspheres. 2. The radioactivity in the acid soluble and RNA fractions of five pieces of the left lateral liver lobes was determined. 3. A variation of the distribution of the precursor into the different parts of the same liver lobe was shown. 4. This variation was most pronounced (3000-17,000 cpm/micrograms in the acid soluble fraction) when the precursor was administered via the artery and without microspheres. 5. The correlation between the radioactivity in the acid soluble and RNA fractions within each liver piece was 0.85, 0.90 and 0.75 in the three groups respectively. 6. It is suggested that the variation of the distribution depends on circulatory differences within the liver.

Some applications of the indium-113m-transferrin technique for gamma-radiation detection of microvascular effects of serotonin and ischemia.

The distribution of systematically injected In-113m (t1/2 = 100 min) in organs of the rat was analyzed, and the use of the isotope for in vivo and in vitro gamma-radiation detection studies of blood plasma protein extravasation was demonstrated in skin, muscle, and tumor. In-113m was slowly excreted from rats. One to 6 h after injection the blood held 3% and 2%, respectively, of injected radioactivity/g tissue wet weight; skin and muscle held 0.1%-0.2%/g; liver, colon, and spleen held approximately 1%/g; lungs 1.5%-1.3%/g and kidneys 2.8%-3.3%/g. Scintillation camera technique revealed 40%-80% extraaccumulation of In-113m in a control extremity upon local administration of serotonin and 20%-40% in an extremity with a transplanted tumor, thus indicating a lower effect of serotonin in tumor microvascular circulation than in muscle and skin. In vitro detection of In-113m radiation by a well-counter in dissected tissues showed no effects of serotonin in the tumor and a four- to five-fold increase of radioactivity in muscle and skin, thus confirming blood protein extravasation upon serotonin treatment in these tissues. External analyses of In-113m in the vascular system using one miniaturized probe directed toward an area of interest showed that the method was too sensitive to movements of the animal, and second probe directed toward a control area is needed.

Hepatic artery administration of degradable starch microspheres. I. Effect on energy charge and incorporation of precursors into rat liver nucleic acids.

The effects of hepatic artery administration of degradable starch microspheres on liver energy charge and nucleic acid anabolism were studied in rats. Liver energy charge was evaluated 20 and 60 min after the injection of degradable starch microspheres. As compared to controls the microspheres had no effect on liver energy charge. The incorporation of orotic acid, uracil, and thymidine into liver RNA or DNA was studied 1 h after hepatic artery injection of precursor alone or together with degradable starch microspheres. Orotic acid and uracil incorporation into RNA was studied in normal rats and the DNA incorporation of thymidine in animals with regenerating livers. Orotic acid and thymidine were given in trace amounts. Uracil was given in amounts corresponding to a therapeutic dose of 5-fluorouracil. The addition of microspheres had no effects on the incorporation of the nucleic acid precursors into RNA or DNA. Thus, in the normal liver degradable starch microspheres administered by the hepatic artery had no influence on liver energy charge or RNA anabolism in the liver. Also the microspheres had no negative effects on the DNA anabolism in proliferating liver cells.

The endoplasmic reticulum in regenerating liver cells.

Light-microscopic analysis of mouse liver homogenates six days after partial hepatectomy, showed a higher percentage of nuclei with adherent cytoplasm than homogenates from normal liver. This observation was true for animals with either a slow or rapid recovery of body weight after the operation. The phenomenon was not a function of the changes in the proportions of parenchymal and non-parenchymal tissue in the regenerating liver. Electron-microscopic analysis of random samples from normal and regenerating livers indicated an increase in the perinuclear rough endoplasmic reticulum, and a displacement of the glycogen depots within the regenerating cells six days after partial hepatectomy. The marked resistance towards homogenization, shown by the cytoplasm of the regenerating cells, may have been due to the observed increase of perinuclear membranes. However, qualitative changes of the cell membranes and a general decrease of proteolytic activity connected with liver regeneration may also have contributed.

Utilization of labelled uridine, cytidine and orotic acid for determination of ribonucleic acid synthesis in mouse liver.

[3H]uridine and [3H]orotic acid were equally utilized for labelling of RNA in mouse liver. Incorporation of [3H]cytidine was 2-3 times as high as that of [3H]-labelled uridine or orotic acid. These results differ from findings in rat liver, where both cytidine and orotic acid are better utilized for RNA labelling than is uridine. The ratio between liver RNA [3H]-activity and volatile [3H]-activity was 2, 3 and 13, respectively, at 300 min after injection of labelled uridine, orotic acid and cytidine, indicating an efficient chanelling of cytidine into liver anabolic pathways.

RNA synthesis in regenerating mouse liver evaluated by incorporation of [methyl-14C]methionine and by determination of RNA polymerase activity.

The synthesis of RNA during mouse liver regeneration was studied by two different methods at 24 and 48 h after partial hepatectomy. Total chromatin-bound RNA polymerase activity showed an increase of 32% at 24 h after partial hepatectomy. At 48 h a slight increase in total activity was also observed in regenerating liver, but the difference was not significant. The increase in total RNA polymerase activity was due to a rise in RNA polymerase I plus III activity. This enzyme activity was increased at both 24 and 48 h. The increase was 57% at 24 h and 51% at 48 h. When [methyl-14C]methionine was used for labelling of methyl groups in rRNA, there was an increased specific radioactivity of this class of RNA at both 24 h and 48 h. The increases were 263 and 103% at 24 and 48 h respectively. Thus both methods revealed an increased synthesis of rRNA during mouse liver regeneration. The results are discussed in relation to previous results from this laboratory [Yngner, Carlberg, Lewan & Engelbrecht (1979) Hoppe-Seyler's Z. Physiol. Chem. 360, 1069-1074; Yngner, Engelbrecht, Lewan & Annerfeldt (1979) Biochem. J. 178, 1-8; Yngner, Bengtsson, Carlberg, Engelbrecht & Wieslander (1980) Exp. Cell. Biol. 48, 393-403], which have shown that the incorporation of orotic acid or uridine into RNA is not increased in mouse liver regenerating after partial hepatectomy.

Modulation of 5-fluorouracil metabolism by thymidine. In vivo and in vitro studies on RNA-directed effects in rat liver and hepatoma.

The effects of thymidine (TdR) co-administration on the cytotoxicity and incorporation of 5-fluorouracil (5-FU) into RNA of various tissues was studied in rats bearing an ascites hepatoma (AH 130). The role of pyrimidine degradation in determining the modulating effects of TdR on the formation of FU-RNA was studied in hepatocytes and AH 130 cells in vitro. TdR (500 mg/kg) potentiated the antitumour effect of 5-FU (150 mg/kg) and also increased host toxicity as judged by changes in body weight. TdR given alone did not significantly affect tumour growth and body weight gain. Examination of the effect of TdR on the incorporation of 5-FU into RNA revealed a differential modulation of RNA-directed toxicity in different tissues. Incorporation of 5-FU into RNA in tumour and bone marrow was increased 2- and 4-fold, respectively. In spleen and kidney the incorporation increased by approximately 50%, but the values did not reach statistical significance. In contrast, the incorporation into RNA of liver and intestinal mucosa was decreased to ca 35% of the control. TdR at concentrations of 40 microM-40 mM progressively inhibited the degradation of 5-FU and decreased the incorporation of 5-FU into RNA of hepatocytes in vitro. In AH 130 cells in vitro TdR did not significantly influence the metabolism of 5-FU and the incorporation into RNA. These results demonstrate that the enhanced incorporation of 5-FU into tumour RNA in vivo after pretreatment with TdR is related not to local effects on the tumour cells but rather to an increased bioavailability of the drug. Although co-administration of TdR did not selectively enhance the antitumour effect of 5-FU, a differential toxicity in host tissues was indicated by the modulated incorporation of 5-FU into RNA.

Intraarterial and intraportal in vivo catheterization of the regenerating rat liver. Effects upon body and liver weights and DNA synthesis.

A method for concomitant partial hepatectomy and catheterization of the arterial and portal systems of the liver in the rat is described. Catheters were inserted into the gastroduodenal artery and the ileocolic vein. Continuous saline perfusion was performed during 36 hours. In catheterized rats recovery of liver and body weight lagged behind that of non-catheterized rats. The more extensive surgery and the presence of catheters also caused decreased incorporation of 3H-thymidine into liver DNA 24 hours postoperatively. The variation in thymidine incorporation between animals was large. It was shown that by pre-labelling liver DNA with 14C-thymidine the rats can serve as their own controls during acute experiments involving 3H-thymidine, thus reducing the inconsistency of individual variation.

Irradiation effects upon ischemic regenerating rat liver cells.

Starch particles injected into the arterial and portal systems of the liver of the rat caused a temporary blockage of the liver circulation and consequent hypoxia in the liver cells. In the regenerating liver this resulted in a 30-40% decrease of thymidine incorporation into DNA, when analysed 1.5 hours after injection. Irradiation-induced cell damage, evaluated by thymidine incorporation 1.5 hours after irradiation with a single dose of X-rays, was not ameliorated by the ischemic condition. It is suggested that this depends on an inhibited nucleotide metabolism and DNA synthesis leading to an additive metabolic hypoxic effect of the starch particles on radiation damage. An equal level of thymidine incorporation, however, was found in an ischemic and a non-ischemic group of animals 16 hours after irradiation. In this case the liver cells in the ischemic group had overcome the additional inhibition of DNA synthesis caused by temporary hypoxia.

Interrelations between uptake of [14C]orotic acid and labeling of UTP and RNA in rat and mouse liver after partial hepatectomy.

The uptake and utilization of [6-14C]orotic acid for UTP and RNA synthesis were studied in rat and mouse liver at 24 h after partial hepatectomy. Rat liver concentrated radioactivity relative to blood several-fold better than did mouse liver after both sham-operation and partial hepatectomy. The results showed that in mouse liver, contrary to rat liver, the orotic acid uptake was not increased after the partial hepatectomy. In rat liver, the precursor uptake and the labeling of UTP increased by about 75% whereas the specific radioactivity of RNA increased 2 to 3-fold after the operation, thus indicating an increased RNA synthesis. Mouse liver showed no increased [14C]orotic acid uptake or labeling of UTP or RNA at 24 h after partial hepatectomy.