The cytotoxic activity of hematoheme: evidence for two different mechanisms

Hematoheme displays a potent cytolytic activity toward erythrocytes either in the presence of hydrogen peroxide and a halide ion (system I) or in the presence of oxygen and a reducing agent (system II). In system I it resembles the cytotoxic activity of various peroxidases, whereas in system II it resembles the destructive activity of bleomycin and a variety of metal complexes. Both types of reactions presumably involve the generation of active oxygen species, which are responsible for the damaging effects. In a first attempt to compare the chemical mechanisms of the two types of reactions we used various traps and scavengers of active oxygen species. Tryptophan as well as tyrosine and uric acid were found to be potent inhibitors of the hematoheme-H2O2-halide reaction but do not significantly inhibit the hematoheme-O2-ascorbate reaction. Pyridine, on the other hand, inhibits the oxygen-mediated reaction, but does not affect the peroxide-halide-mediated activity. The cytolytic activity of photoactivated hematoporphyrin, which involves the generation of singlet oxygen, is activated by pyridine and is strongly inhibited by diphenylisobenzofuran. The latter compound is a weak activator of both hematoheme reactions. We conclude that the two hematoheme reactions proceed by two different mechanisms and probably generate different toxic intermediates. The results further suggest that the toxic intermediate generated by photoactivated hematoporphyrin (singlet oxygen) does not play a dominant role in either of the two hematoheme reactions.

The mechanism of peroxidase-mediated cytotoxicity. I. Comparison of horseradish peroxidase and lactoperoxidase

The kinetics of the cytolytic activity expressed by lactoperoxidase and horseradish peroxidase toward erythrocytes in the presence of H2O2 and iodide have been investigated at physiological pH. The action of both enzymes was found to be very similar with respect to their kinetic mechanisms. Both enzymes showed saturation kinetics at higher enzyme concentrations under conditions where substrate concentrations were not limiting. Optimal concentrations of H2O2 and iodide were found to be 40 and 25 microM, respectively, for both enzymes. Higher concentrations of H2O2 inhibited the cytolytic activity. The pH dependence of the cytolytic reaction is also very similar for both enzymes, showing maximal activity at about pH 6.3. Moreover, the cytolytic activities of both enzymes were inhibited by tyrosine, tryptophan, cysteine, and to a lesser extent by histidine. We conclude from these data that the mechanisms of horseradish peroxidase and lactoperoxidase in promoting the lysis of erythrocytes are closely related if not identical.

The cytotoxic activity of hematoporphyrin: studies on the possible role of transition metals

Hematoporphyrin acquires a potent cytolytic activity toward erythrocytes when activated by visible light. Considerable evidence has been obtained suggesting that this toxic activity is mediated by certain active oxygen species, including singlet oxygen and hydroxyl radicals. These active oxygen species have also been proposed as intermediates in the toxic activity of peroxidases, hemin, and a variety of metal complexes. Unlike hematoporphyrin, all these compounds contain a liganded Fe atom, which appears to play a central role in the activation of molecular oxygen. In order to ascertain whether the generation of active oxygen by hematoporphyrin may also involve the participation of a metal ion we have compared the cytolytic activity of hematoporphyrin with that of hematoheme. The participation of a metal ion in the light-activated hematoporphyrin reaction was ruled out on the basis of four criteria: no increase in cytolytic activity was observed upon the addition of Fe or Cu ions; no evidence could be obtained for the incorporation of a metal ion into hematoporphyrin during light activation; hematoporphyrin is a more potent cytolytic agent than hematoheme on an equimolar basis; and the activities of the two cytolytic agents are affected differently by various activators and inhibitors of the toxic reaction. Our results further indicate that the mechanism of the cytolytic activity promoted by light-activated hematoporphyrin is distinctly different from that promoted by hematoheme in the presence of ascorbate. We conclude that the two cytolytic reactions are most likely propagated by two different forms of active oxygen.

Infectious and non-infectious mutants of cauliflower mosaic virus DNA

Mutants of cauliflower mosaic virus (CaMV), generated in vitro by modification of recombinant DNA plasmids containing the viral genome, either retained the ability to induce disease symptoms on turnip plants, produced less severe symptoms or failed to induce symptoms. Wild-type symptoms were produced by a variant CaMV DNA of the Cabbage S isolate that had 4 bp in open reading frame (ORF) III replaced with a 16 bp sequence. Less severe symptoms, due to a delay in symptom appearance relative to inoculation with wild-type DNA, were induced by a mutant with a frameshift mutation in ORF II (pSA103). CaMV DNA, recovered from plants infected with pSA103, contained a second mutation which restored the original translation reading frame. Nucleic acid hybridization to 'squishes' of leaf tissue from plants that had been inoculated with mutant DNAs that included DNAs modified in each of the six major ORFs of CaMV DNA revealed that only those plants that appeared diseased had detectable CaMV nucleic acid in uninoculated leaves. Replicated CaMV DNA was also not detected in non-encapsidated and virion DNA fractions from inoculated leaves of non-diseased plants.

Comparison of several control standard endotoxins to the National Reference Standard Endotoxin--an HIMA collaborative study

A collaborative study, initiated under the auspices of the Health Industry Manufacturers Association (HIMA), was designed to establish the relationship of Escherichia coli O55:B5 endotoxin (the control standard endotoxin of HIMA and the Food and Drug Administration's Office of Medical Devices) to the U.S. National Reference Standard Endotoxin and to two internationally used control standard endotoxins. By using two Limulus amoebocyte lysate test systems, it was established that the E. coli O55:B5 endotoxin lot originally used by HIMA and the Office of Medical Devices to establish Limulus amoebocyte lysate release test criteria for pyrogen testing of medical devices contains approximately 4.5 endotoxin units (EU) per ng. Thus, the 1.0-ng/kg endotoxin dose limit currently established for medical devices is approximately the same as the 5.0-EU/kg endotoxin limit (on an activity basis) established by several other Food and Drug Administration agencies for human and animal parenteral drugs and biological products.

Treatment of resistant malignant lymphoma with cyclophosphamide, total body irradiation, and transplantation of cryopreserved autologous marrow

Twenty-seven patients with malignant lymphoma in whom primary chemotherapy had failed and the prognosis was poor were treated with cyclophosphamide, total body irradiation, and transplantation of cryopreserved autologous marrow. The median time to recovery of more than 500 neutrophils per microliter and more than 10,000 platelets per microliter was 18 and 24 days, respectively. Complete remission was achieved in 15 patients (56 per cent), five of whom were in continuous remission at this writing 19 to 71 months after transplantation without further therapy and one of whom was alive in a subsequent remission at 20 months. Fifteen patients died of lymphoma, three of interstitial pneumonitis, two of sepsis, and one of congestive heart failure. This experience shows that intensive therapy and autologous-marrow transplantation can produce prolonged remissions in patients with malignant lymphoma in whom conventional chemotherapy has failed.

In vitro effect of LH-releasing factor on the content of cyclic cytidine 3' 5' monophosphate (c-CMP) in the rat anterior pituitary

The effect of LH-RF on pituitary content of cyclic cytidine 3' 5' monophosphate (c-CMP), one of the newly detected cyclic nucleotides, was examined by the RIA procedure. In results showed that the pituitary content of c-CMP was lower than in various other organs of the rat. When incubated in vitro in the presence of 0.5 ng LH-RF/ml incubation medium, c-CMP content of the anterior pituitaries was reduced slightly, but the difference was not statistically significant when compared with the controls. No difference in c-CMP content was observed between the controls and the 5 ng LH-RF/ml group. C-CMP content in the rat anterior pituitary tissue did not change significantly during an in vitro time-course study (5, 15, and 30 min.) in the presence of 5 ng LH-RF/ml. In contrast, c-AMP content of the pituitary was significantly (P less than 0.05) elevated by the stimulation of 5 ng of LH-RF/ml at a 15 minutes of incubation. These data suggest that c-CMP content, unlike c-AMP, might not be changed significantly by hypothalamic gonadotropin releasing hormone.

The skeleton, an important site of lipogenesis in the chick

Studies in vitro and in vivo with chicks using 14C-1-acetate have shown that the bone could be an important site of lipogenesis. The in vitro relative activities of various bones in incorporating 14C into fatty acids varied from one tenth to one third of hepatic activity. The bone marrow activity attained about two thirds that of the liver. In vitro and in vivo activities of bones were highly correlated (r = 0.902). The activity of compact parietal bones was the lowest. Estimates of lipogenesis in vivo in various tissues (% of total incorporation) were as follows: liver, 45; skeleton, 23; skin and small intestine, 6. Incorporation by muscles, adipose tissue and kidneys were negligible.

[Study on anterior-pituitary function during pregnancy and puerperium by radioimmunoassay of human FSH-subunits (author's transl)]

In order to observe the anterior pituitary function of pregnant women in terms of FSH secretion, specific and sensitive radioimmunoassays for human FSH-alpha and -beta subunits were utilized for this study. Blood levels of hFSH-alpha during pregnancy increase acutely and the values of the subunits are as follows: 428.0 +/- 92.64 ng/ml (mean +/- SE., 5-10 weeks of gestation), 962.8 +/- 132.5 ng/ml (11-20 weeks), 1889.0 +/- 137.60 ng/ml (21-30 weeks), 2959 +/- 323.40 ng/ml (31-40 weeks). After child delivery, serum levels of hFSH-alpha decreased to 22.92 ng/ml. In contrast, blood levels of hFSH-beta were not altered significantly through gestation. hFSH-beta subunits: 1.97 +/- 0.74 ng/ml (5-10 weeks of gestation), 2.66 +/- 0.52 ng/ml (11-20 weeks), 2.27 +/- 0.52 ng/ml (21-30 weeks), 2.07 +/- 0.37 ng/ml (31-40 weeks), respectively.

Inhibitor of peritoneal mononuclear phagocyte colony forming cells

We investigated an inhibitory factor present in mouse L-cell conditioned medium. This soluble factor, colony inhibitory factor (CIF), selectively inhibits the clonal growth of mouse peritoneal exudate (PE) macrophages in vitro. CIF appears to be a non-dialyzable macromolecule which was eluted by Sephadex G200 gel filtration at post-albumin fractions. It can be fractionated by ammonium sulfate precipitation within the range of 60%--70% saturated solution at room temperature. CIF is moderately heat labile and is destroyed by incubation at high pH. CIF is more effective on PE cells from C57 mice than on those from C3H or DBA mice. It also inhibits the clonal growth of committed stem cells for both granulocytes and macrophages present in bone marrow but to a much lesser degree. CIF is not interferon since no antiviral activity is demonstrable in the CIF preparation.

8-Hydroxyanthracyclinones from epsilon-rhodomycinone

epsilon-Rhodomycinone was converted into 8,9-dehydro-zeta-rhodomycinone, which gave a cis diol with osmium tetroxide and a pair of epimeric epoxides with m-chloroperbenzoic acid. Acid-catalyzed opening of the epoxides gave the corresponding trans diols. In contrast, acid treatment of the trimethyl ethers of these epoxides gave predominantly a lactone and an eta-rhodomycinone derivative, with only small amounts of the diols. None of the new rhodomycinones were active against Bacillus subtilis, but 8,9-dehydro-zeta-rhodomycinone was active in the induction of lytic phage in Escherichia coli.

Influence of diet on in vitro and in vivo rates of fatty acid synthesis in coho salmon [Oncorhynchus kisutch (Walbaum)]

The site and the influence of diet on fatty acid synthesis in juvenile coho salmon were investigated. Tritiated water was used to obtain estimates of the rates of fatty acid synthesis. Liver slices and mesenteric glucose and tritiated water. The rate of fatty acid synthesis averaged 1172 +/- 126 and 40 +/- 8 nmoles tritium incorporated into fatty acids per 2 hours per 100 mg of liver and adipose tissue, respectively. The pattern of [1-14C]acetate incorporation into fatty acids in the liver slices indicated that de novo fatty acid synthesis, rather than chain elongation, was occurring. In vivo rates of fatty acid synthesis in liver were approximately linear for 30 minutes. In vivo rates of fatty acid synthesis averaged 244 +/- 14 and 44 +/- 11 dpm of tritium incorporated into fatty acids per 20 minutes per 100 mg of liver and adipose tissue, respectively. Consumption of a high-fat diet or fasting for 2 days decreased the in vitro and in vivo rates of fatty acid synthesis in fish liver. Refeeding fasted (48 hours) fish with a high-carbohydrate diet for 4 hours increased the rate of hepatic fatty acid synthesis. The major site of fatty acid synthesis in coho salmon appears to be the liver, and dietary alterations influence the rate of fatty acid synthesis in the liver.

Effects of fasting and feeding various diets on hepatic lipogenic enzyme activities in coho salmon (Oncorhynchus kisutch (Walbaum))

The influence of fasting and diet composition on the time sequence of changes in hepatic lipogenic enzyme activities in coho salmon was investigated. Young coho salmon fed a high-carbohydrate diet for 3 weeks were then fasted for 2, 6, or 23 days. Liver preparations were assayed for fatty acid synthetase, citrate cleavage enzyme, malic enzyme, glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase activities. Fasting the fish for 2 or 6 days did not influence the activities of these enzymes; however, by the end of the 23-day fast the activities of all these enzymes had decreased. Changing the diet of the fish from high-carbohydrate to high-fat had only a minimal influence on the activities of the hepatic lipogenic enzymes after 7 to 14 days. Longer-term studies demonstrated that high-fat diets did eventually depress lipogenic enzyme activities. The effect of fasting and feeding on the level of lipogenic enzyme activities was observed only after several weeks, in contrast to hours in the rat. This may reflect a difference between poikilothermous and homoiothermous animals.

Influence of dietary lipid on lipogenic enzyme activities in coho salmon, Oncorhynchus kisutch (Walbaum)

Coho salmon (Oncorhynchus kisutch), 8 to 18 months of age, were maintained in culture tanks and were fed three semipurified diets. The diets contained 40% of energy from protein and 11.5%, 23%, or 46% of energy from lipid. The body weight gain and food conversion factors were similar among groups of fish fed the diets in each of the three experiments. Wet weight of mesenteric adipose tissue increased with increased amount of lipid in the diet; however, epaxial muscle lipid content was not influenced by the lipid content of the diet. Several hepatic and adipose tissue lipogenic enzymes (fatty acid synthetase, citrate cleavage enzyme, malic enzyme, glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, and NADP-isocitrate dehydrogenase) were assayed. These lipogenic enzymes exhibited high activities in liver and relatively low concentration in adipose tissue of the fish. The activities of all the hepatic lipogenic enzymes assayed, except for NADP-isocitrate dehydrogenase, were depressed as the level of lipid in the diet was increased; however, the activities of these enzymes in mesenteric adipose tissue were not influenced by the diets fed. The results of this study indicate that dietary lipid depresses hepatic lipogenic enzyme activities and that the liver may be a more important site for fatty acid synthesis than is adipose tissue in coho salmon.

Colony formation in vitro by mouse blood monocytes

Mouse blood monocytes were induced to proliferate and form discrete colonies of mononuclear phagocytes in liquid culutre. The proliferation of these cells in vitro required a factor or factors present in medium conditioned by L cells. For this class of colony-forming cells, the value of Do to gamma irradiation in vitro was 195 rads.

Nuclear magnetic resonance studies of the interaction of general anesthetics with 1,2-dihexadecyl-sn-glycero-3-phosphorylcholine bilayer

Sonicated 1,2-dihexadecyl-sn-glycero-3-phosphorylcholine forms liposomes. Studies by Fourier transform proton magnetic resonance of the interaction of these bilayers with some general anesthetics, i.e., chloroform, halothane, methoxyflurane, and enflurane, show that the addition of a general anesthetic to the liposomes and raising the temperature have a similar effect in cuasing the fluidization of the bilayer. General anesthetics act on the hydrophilic site (choline group) in clinical concentrations and then diffuse into the hydrophobic region with the addition of larger amount of anesthetics. There is evidence that the lecithin choline groups are involved in the interaction with protein and that the general anesthetics change the conformation of some polypeptides and proteins. We conclude that the general anesthetics, by increasing the motion of positively charged choline groups and negatively charged groups in protein, weaken the Coulomb-type interaction and cause the liprotein conformational changes.

The accessory optic fiber system of the golden hamster with special reference to retinohypothalamic projection

The hamster accessory optic fiber system has been investigated with the use of de Olmos-Ingram and Fink-Heimer silver methods following the production of unilateral ocular enucleation. It was found that this fiber system consists of both crossed and uncrossed inferior and superior fasciculi. The fibers of the inferior fasciculus (anterior accessory optic tract) run along the medial edge of the cerebral peduncle and terminate within the medial terminal nucleus of the accessory optic system. The fibers of the superior fasciculus (posterior accessory optic tract) leave the main optic tract, pass superficially over the medial geniculate nucleus and the cerebral peduncle; they synapse within the dorsal, the lateral and the medial terminal accessory optic nuclei. The presence of a retinohypothalamic tract could not be confirmed.

Schedule-dependent effect of phase-specific cytotoxic agents on production of hemolytic plaque-forming cells

The proliferative phase of the primary response of mice to sheep red blood cells (SRBC) was used to study quantitatively the schedule-dependent effect of four phase-specific cytotoxic agents: 1-beta-D-arabinofuranosylcytosine (ARA-C), methotrexate (MTX), 5-fluorodeoxyuridine (5-FUDR), and 5-fluorouracil (5-FU). The multiple injections of ARA-C- GIVEN 24-60 HOURS AFTEr SRBC injection caused a 100-fold greater inhibition in the production of direct hemolytic plaque-forming cells (PFC) on day 4 than the maximum inhibition obtained by a single injection. A similar, but lesser, enhancing effect was observed with 5-FUDR. Although a single injection of either MTX or 5-FU given 24 or 48 hours after the immunization alone was effective in suppressing PFC production, multiple injections of MTX at 6-hour intervals could cause the same degree of inhibition with a smaller total dose. In contrast, there was no difference for 5-FU, whether given as a single injection or in a divided dose. When only two doses of cytotoxic agents were used, 8- and 14-hour intervals with ARA-C and MTX, respectively, gave the maximum degree of inhibition.

Concanavalin A (NSC-143504): its action on experimental tumor cells and possible use in cancer chemotherapy

Concanavalin A administered to mice kills KHT fibrosarcoma tumor cells and, less markedly, AKR lymphoma cells at doses where it has no effect on numbers of normal hematopoietic colony-forming cells. Concanavalin A in vitro agglutinates suspensions of cells prepared from murine and human tumors but does not agglutinate suspensions prepared from most normal mouse tissues. In spite of its selective action against tumor cells at the cellular level, the possibilities for using concanavalin A therapeutically are limited by its unusual toxicity, a generalized vasculitis that is seen in the mouse, monkey, and pig at approximately the same dose level.

On the methylated purine content of tRNA present in tumours

The methylated purine content of tRNA bulk extracted from human hepatomata has been compared with that in normal human liver. The analyses were carried out with the aid of ion-exchange chromatography. The molar proportions of 5 bases detected in acid hydrolysates of tumour tRNA (N(2)-methylguanine, 1-methylguanine, 7-methylguanine, N(2)-dimethylguanine and 1-methyladenine) were not abnormally elevated.