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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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The Korean Society of Toxicology
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Volume 8, Issue 2 - Dec 1992
Volume 8, Issue 1 - Jun 1992
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Effects of 8-Fluorociprofloxacin And Ciprofloxacin on the Central Nervous System
Kim, Young-Hoon ; Kim, Dal-Hyun ; Choi, Kyung-Eob ;
Toxicological Research, volume 8, issue 2, 1992, Pages 161~170
The objectives of this sutdy were to investigate the effects of 8-fluorociprofloxacin(8-FCP) on the central nervous system (CNS) and to compare with those of ciprofloxacin(CP). The
values of intravenous 8-FCP were similar or slightly lower in rat (M;203.6mg/kg, F;186.1mg/kg)and markedly lower in mice (M;126.5mg/kg, F;163.1mg/kg), as compared to those of CP. However, no recognizable differences in the clinical signs and recovery were found between 8-FCP and CP in both species. In combination with fenbufen, the convulsive liability of 8-FCP was higher than that of CP. At an intravenous dose of 10mg/kg, 8-FCP provoked convulsive signs and subsequent death in mice, whereas CP produced convulsion at a dose of 40mg/kg. The hexobabital -induced sleeping time was markedly lengthened by the oral administration of 8-FCP, but slightly increased by CP. In addition, the two quinolone derivatives had analgesic effects. The analgesic activity of 8-FCP was approximately two times higher than that at CP. However, both 8-FCP and CP had little effects of pentylenetetrazole-or strychnine-induced convulsion and muscle relaxation. Our finding that 8-FCP had more remarkable CNS effects than CP strongly suggests that there should be differences in the pharmacokinetic characteristics and/or in the binding affinity for specific biologic targets, or receptors, in the CNS.
A Short Term Screening Method for Carcinogenic Quinone Compounds
Cho, Dae-Hyun ; Hong, Jin-Tae ; Park, Jeong-Sik ; Hong, Youn-Tack ; Chin, Kang ; Jung, Myung-Hee ; Lee, Byung-Mu ;
Toxicological Research, volume 8, issue 2, 1992, Pages 171~177
To investigate a short term screening method for carcinogenic quinone compounds, 8-hydroxydeoxyguanosine (8-OHdG), an oxidative DNA damage, was determined in the kidney and liver DNA isolated from Sprague-Dawley rats after i.p.injection of 7 mg/kg adriamycin (AM), 7mg/kg tetrahydropyranyladriamycin (THP), and 10mg/kg daunomycin (DM) by HPLC-electrochemical detector system. 8-OHdG was also determined from rat hepatocvtes and calf thymus DNA exposed to AM, DM and THP. When rats were treated with DM and THP, 8-OHdG was significantly increased in the kidney compared to control group, and remained at high level (7.9~9.0, 8-OHdG/dG
)at the end of experiments (48hr after treatment). 8-OHdG level in cultured hepatocyte exposed to AM, DM and THP was 1.5~2 fold higher than control at all time points. (1,2,3,4hr after treatment). From calf thymus DNA exposed to AM, DM and THP, 8-OHdG was 2.5 fold higher than of control. These results suggest that quantitation of 8-OHdG may provide a useful marker for identifying target organ in oxidative chemical carcinogenesis and for short term screening of free radical generating carcinogens.
Immunopathology of Spleen following 7,12-Dimethylbenz[a]anthracene Treatment in BALB/C Mice
Lee, Duck-Yoon ; Han, Sang-Seop ; Lee, Sang-Mog ;
Toxicological Research, volume 8, issue 2, 1992, Pages 179~189
This study was carried out to investigate the immunopathological effects of 7,12-Dimethylbenz[a]anthracene(DMBA) on spleen in mice. DMBA was administered subcutaneously to BALB/C mice by interscapular single injection of 50 or 100
of body weight. Each DMBA treatment group and additional corn oil control group of mice were studied on day 1,3,7,14 and 21 following the injection of DMBA. DMBA treatment resulted in marked decrease in weights and cellularity of spleen. Spleen weights showed the greatest decrease at 14days after 50
DMBA treatment, and at 21days after 100
DMBA treatment. Spleen cellularity was similarly deceased in comparison with spleen weights. Spleen showed morphologically no typical changes throughout the experiment after 50
DMBA treatment. Following the treatment of 100
DMBA the spleen showed severe fibrosis, hemosiderin precipitation, and megakaryocytes decrease in red pulp at 14 days, while hemopoietic function was partly restored in addition to the appearance of a few megakaryocytes at 21 days. In spleen sections treated with antibodies to IgM or Thy1.2, lymphocytes strongly stained with IgM antibody were infiltrated around the central artery within the white pulp, and T-lymphocytes of periarterial lymphatic sheath (PALS) were diminished and destructed in sections treated with Thy1.2 antibody, at 14 days after the treatment of 100
DMBA. By the electron microscopy phagocytic epithelial cells or macrophages were remarkably increased in spleen at 14and 21days following the treatment of 100
Immunosuppressive Effects of Safrole in BALB/c Mice
Kim, Byung-Sam ; Jeong, Tae-Cheon ; Choe, Suck-Young ; Yang, Kyu-Hwan ;
Toxicological Research, volume 8, issue 2, 1992, Pages 191~203
The immunosuppressive effects of safrole were studied in female BALB/c mouse. Mice were given 100,200and 400mg safrole/kg daily for 14days and evaluated on day 15. The day 4 immunogloblin-M antibody response to T-dependent antigen, sheep red blood cells (SRBC) was inhibited dose-dependently in all doses studied. In vitro antibody response to polyclonal antigen, lipopolysaccharide (LPS) by spleen cell suspensions from safrole-treated mice were also significantly inhibited. When safrole was treated for 14days to mice, and mitogen-induced proliferation of splenocytes were assayed on day 15, there were significant suppression of responses to B-cell mitogen, LPS and T-cell mitogen concanavalin A(Con A) at a dose of 400mg safrole/kg. Direct addition of safrole on the splenocyte culture also produced a dose dependent suppression on in vitro antibody response to LPS, and mitogen-induced lymphoproliferatin at doses of 100,200,400 and 800
safrole. The role of metabolic activation in safrole-induced suppression of in vitro antibody response was studied using splenocyte-hepatocyte coculture system. The suppression of in vitro antibody respose to LPS by safrole was not altered when safrole were incubated in the splenocyte-hepatocyte system for 4hr as compared with direct addition of safrole in splenocytes culture. Neither the addition of salicylamide, sulfotransferase inhibitor, nor the addation of inorganic sulfate, sulfation cofactor to the splenocyte-hepatocyte coculture, altered the suppression of antibody response by safrole. These results suggest that the immunosuppression by safrole may not by produced by the reactive metabolites which are mediated in carcinogenesis of safrole.
Acute toxicity of cis-Malonato[(4R,5R)-4,5-bis(aminomethyl)-2-isopropyl-1,3-dioxolane]platinum(II)(SKI 2053R) in rats and Mice
Kang, Kyung-Sun ; Shin, Dong-Jin ; Cho, Jae-Jin ; Kim, Hyoung-Ook ; Kim, Bae-Hwan ; Lee, Yong-Soon ;
Toxicological Research, volume 8, issue 2, 1992, Pages 205~216
cis-Malonato[(4R,5R)-4,5-bis(aminomethyl)-2-isopropyl-1,3-dioxolane]platinum(II)(SKI 2053R), an antitumor platinum complex, was selected for clinical evaluation on the basis of its experimental antitumor and toxicologic profiles in preclinical studies. These studies were performed to obtain information on its toxic signs, orgnas which are mainly affected, and to estimate its lethality in mice and rats given SKI 2053R through two routes of administration. In male and female rats given a single intragastrical dose of SKI 2053R, we estimated that
values were over 3.00g/kg, respectively. In male and female mice given a signle intragastrical dose of SKI 2053R, we estimated that
values were 2.44g/kg and 1.59g/kg, respectively, In a single intraperitoneal dose of SKI 2053R, we determined that
values of male and female rats were 227mg/kg and 182mg/kg, and those of male and female mice were 198mg/kg and 207mg/kg, respectively. In gross and histopathological examinations on dead animals, we found that kidney and liver were mainly affected.
Subacute Toxicity of cis-Malonato[(4R,5R)-4,5-bis(aminomethyl)-2-isopropyl-1,3-dioxolane]platinum(II)(SKI 2053R) in rats
Kim, Hyoung-Ook ; Kang, Kyung-Sun ; Shin, Dong-Jin ; Cho, Jae-Jin ; Kim, Bae-Hwan ; Seo, Kwang-Won ; Nam, Ki-Hoan ; Lee, Yong-Soon ;
Toxicological Research, volume 8, issue 2, 1992, Pages 217~233
This study was performed to determine the toxic effects of graded dose levels of SKI 2053R after repeated administration. Three groups of Sprague-Dawley rats(10M and 10F per group) were given a total of 25 i.v. injections of SKI 2053R (1.50,3.75,9.38mg/kg/day). In order to compare the toxic effects of SKI 2053R with those of cisplatin, one group of Sprague-Dawley rats (10M and 10F per group) were given a total of 25 i.v.injections of cisplatin (1.70mg/kg/day). The dosing schedule was divided into five courses of 5 consecutive days with 16-day dose-free intervals between each course. No drug-related toxicity occurred in low dose level group (1.50mg/kg/day) of SKI2053R. From the results of hematological examination, peripheral WBC counts, RBC counts and hemoglobin of high dose level group(9.38mg/kg/day)of SKI 2053R were significantly lower than those of no-treated group. Other toxicities including reduced final body weight, proteinuria and hematuria were observed in high dose level group of SKI 2053R. But, no change was detected in serum biochemical values of SKI 2053R treated groups. All of the rats in cisplatin treated group were died between 3 and 13 weeks, while rats treated with SKI2053R survived to the end except one rat of middle dose level group(3.75mg/kg/day). In histopathological examinations, rats that received cisplatin manifested severe tubular damage in kidney and hemosiderosis in spleen, but no critical pathological lesion was observed in rats of other groups. Considering the results of this study, it was concluded that non-toxic dose of SKI 2053R in this treatment schedule was estimated to be 3.75 mg/kg/day and the maximum tolerated dose was to be higher than 9.38mg/kg/day. The toxic profiles fo SKI 2053R were different from those of cisplatin, and its toxicity was considerably lower than that of cisplatin.
Subacute toxicity of cis-Malonato[(4R,5R)-4,5-bis(aminomethyl)-2-isopropyl-1,3-dioxolane]platinum(II)(SKI 2053R) in Beagle Dogs
Lee, Yong-Soon ; Kang, Kyung-Sun ; Shin, Dong-Jin ; Cho, Jae-Jin ; Kim, Hyoung-Ook ; Kim, Bae-Hwan ; Lim, Yoon-Kyu ;
Toxicological Research, volume 8, issue 2, 1992, Pages 235~253
A subacute toxicity study of cis-Malonato[(4R,5R)-4,5-bis(aminomethyl)-2-isopropyl-1,3-dioxolane]platinum(II)(SKI 2053R) was carried out to obtain information on its toxicological profiles, and to determine the maximum tolerated dose in beagle dogs. Four groups of beagle dogs (2M and 2F per group, 0,0.5,1.0,2.0mg/kg/day)were given 15 i.v. injections of SKI 2053R. In order to compare the toxic effects of SKI 2053R with those of cisplatin, one group was treated with cisplatin(0.7mg/kg/day)according to the same treatment schedule. The dosing schedule was divided into 3 courses of 5 consecutive days with 23-day dose-free intervals between each course. After completion of the treatments, remaining dogs were necropsied under established guidelines. Three of four dogs in the high dose group and one of four dogs in the middle dose group treated with SKI 2053R died of hypovolemic shock secondary to hemorrhagic and ulcerative enterocolitis. No toxicity-related mortality occurred in the low dose group of SKI 2053R. No survivor was observed in the group of cisplatin. Clinical signs including vomiting, diarrhea, anorexia and loss body weight were apparent in dogs given either cisplatin or high and middle doses of SKI 2053R. Severe thrombocytopenia and leukocytopenia were observed in the high dose group of SKI 2053R and cisplatin-treatment group, while toxicities as bone marrow suppression were reversible. The significant elevation of serum ALP values in group of SKI 2053R(2.0 mg/kg/day and 1.0mg/kg/day) and cisplatin(0.7mg/kg/day)was observed. Slight proteinuria waa observed in high and middle dose level groups of SKI 2053R. In histopathological examinations, pathological alterations of liver, kidney and spleen were noted dose-dependantly in dogs treated with SKI 2053R, and there was no overt sign of toxicity in low dose group of SKI 2053R. Compared to SKI 2053R, more severe durg-related toxicities occurred in dogs treated with cisplatin. It waw estimated that maximum tolerated dose of SKI 2053R in this treatment schedule was 0.5~0.7mg/kg/day. In conclusion, overall toxic potential of SKI 2053R was approximately 3 times lower than that of cisplatin with respect of lethality.
Antigenicity test of cis-Malonato[(4R,5R)-4,5-bis(aminomethyl)-2-isopropyl-1,3-dioxolane]platinum(II)(SKI 2053R) in Guinea Pigs and Mice
Lee, Yong-Soon ; Kang, Kyung-Sun ; Shin, Dong-Jin ; Kim, Hyoung-Ook ; Cho, Jae-Jin ; Kim, Bae-Hwan ; Nam, Ki-Hoan ; Seo, Kwang-Won ;
Toxicological Research, volume 8, issue 2, 1992, Pages 255~263
SKI 2053R and SKI 2053R-human serum albumin(HSA) mixture were examined for their antigenicity in Hartley guinea pigs as well as C57BL/6 mice in comparison with distilled water (DW), HSA and DW-HSA conjugate. Several antigenicity tests, including acitive systemic anaphylaxis(ASA), passive systemic anaphylaxis (PSA), passive cutaneous anaphylaxis (PCA) and indirect hamagglutination test (IHA), were performed according to the Established Regulations of National Institute of Safety Research. The results were as follows: 1. When guinea pigs were sensitized with SKI2053R or SKI2053R-HSA emulsified with complete Freund's adjuvant(CFA), these animals showed negative reactions in ASA and PSA. 2.No blue spot was observed on the back skin of guinea pigs in the PCA test. 3. Sera from guinea pigs revealed a negative reaction in IHA. 4.Guinea pigs were sensitized by HSA emulsified with CFA as a positive control, and these animals showed positive reactions in ASA, PSA, PCA, and IHA. As shown above, SKI2053R was considered to possess neither antigenic, nor haptenic properties, and confirmed not to have the haemagglutinating activity.
Potentiation of Carbon Tetrachloride Hepatotoxicity induced by Repeated Physical Exercise in adult Female rats
Kim, Su-Nyeon ; Kim, Young-Chul ;
Toxicological Research, volume 8, issue 2, 1992, Pages 265~272
Effects of repeated physical exercise on the carbon tetrachloride (
) hepatotoxicity were examined in adult female rats. Rats were introduced into a cylindrical rotating cage and forced to exercise for 1 hr each day, 6days/week, for 5 consecutive weeks at a speed starting from 10m/min, increased by 1m/min per day until the speed reached 27m/min. Significantly less body weight gain was observed in the exercise group suggesting that physical fitness had been induced in these animals. Eighteen hours following termination of the last exercise bout rats were treated with
(2 mmol/kg.ip). The
-induced heptotoxicity was significantly potentiated in the repeated exercise group compared to the resting sedentary animals as determined by changes in serum sorbitol dehydrogenase (SDH), glutamic oxaloacetic transaminase(GOT), glutamic pyruvic transaminase (GPT), and glucose-6-phosphatase(G-6-Pase) activities when measured 24hrs following the
treatment. Hepatic drug metabolizing activity was determined in order to elucidate the underlying mechanism of potentiating action of the
hepatotoxicity induced by repeated physical exercise. Repeated exercise increased the hepatic microsomal cytochrome P-450 contents and aminopyrine N-demethylase activity. The results suggest that the potentiation of
hepatotoxicity by repeated exercise is associated with induction of the mixed function oxidase (MFO) enzyme system mediating the metabolism of
to its active metabolite(s).
Inhibitory Effect of Dimethyl Sulforxide on Phenytoin-induced Fetal Cleft Palate and Maternal Corticosterone Level
Lee, Jae-Kwon ; Lee, Chang-Eop ; Lee, Mun-Han ; Ryu, Pan-Dong ; Lee, Young-Jae ; Sung, Ha-Jung ;
Toxicological Research, volume 8, issue 2, 1992, Pages 273~284
It is well known that phenytoin (PHT), a commonly prescribed anticonvulsant, has teratogenicity in experimental animals and human. The major malformation induced by PHT in mouse is cleft palate. The mechanisms of the embryotoxic effects of PHT are unknown. However, PHT and synthetic glucocorticoids share several features with respect to their teratogenicity, and it was known that PHT increased maternal corticosterone level. Therefore PHT-induced cleft palate may be mediated indirectly by elevated maternal corticosterone. Recently it was reported that secalonic acid Dinduced cleft palate and elevated endogenous corticosterone level, and that such effects were antagonized by DMSO. The purpose of this work was to investigate whether the elevated maternal corticosterone is associated with the teratogenicity of PHT in the ICR mouse fetuses by treatment with PHT or PHT plus DMSO. PHT (74mg/kg, BW) was daily administered intraperitoneally on day 10~12 of gestation with and without DMSO(2ml/kg, BW), and the fetal malformation was observed on day 18. Maternal serum corticosterone and fetal PHT levels were determined by HPLC. The results are summarized as follows. 1)The percentage of cleft palate incidense in fetuses following treatment with PHT on day 10~12 of gestation was 51.7%. 2)There was a significant decrement in the cleft palate incidence in fetuses to 30.8% in the group treated with PHT plus DMSO compared with 51.7% in that with PHT alone. 3) Maternal serum corticosterone levels following treatment with PHT on day 10~12 of gestation increased by 116~343% compared with that of vehicle control. Such effect was antagonized by DMSO. 4)PHT concentration in the fetuses was not affected by DMSO. These results suggest that PHT-induced cleft-palate in fetuses seems to be closely associated with the elevation of maternal corticosterone level.
Primary Culture of Human Hepatocytes from Small Size Sample
Oh, Goo-Taeg ; Ahn, Chang-Joon ; Ahn, Byung-Min ; Hyun, Byung-Hwa ; Choi, Jae-Yoon ; Kim, Hwan-Mook ;
Toxicological Research, volume 8, issue 2, 1992, Pages 285~302
Human and rat hepatocytes were isolated by nonperfusion method and cultured for longer than 5 days. Human liver biopsy sample and rat liver were used as hepatocyte source. Several physical and chemical factors which were influencing on hepatocyte isolation procedure were examined and a batch isolation procedure was established for small size sample of rat liver. Isolated hepatocytes showed normal morphlologica characteristics in microscopy and electron microscopical examinations and a morphologica response to phalloidin. Isolated cells were cultured as a monolayer and proven to have intact morphological characteristics for longer than 15 days. Because human liver sample is harder and tighter compared with rat liver, a standard procedure for rat hepatocytes was slightly modified to reduce mechanical damage. Similarly with rat hepatocytes, isolated human hepatocytes showed a normal morphological characteristics and could be cultured for longer than 15days. Human and rat hepatocytes were examined on their functional integrities including cytochrome-P450 related enzyme activity and it's inducibility, hormonal inducibility of AIB uptake and TAT activity, albumin synthesis, DNA synthesis, cellular protein maintenance. In all parameters used in the present study, human and rat hepatocytes showed normal functional characteristics.
An Essential Radiotracer Technique Radioluminography for Pharmacokinetics and Metabolic Studies in the safety Evaluation of new Drugs in Animals
Shigematsu, Akiyo ;
Toxicological Research, volume 8, issue 2, 1992, Pages 303~316
Methodology of Human Cancer Risk Assessment for Chemical Carcinogens
Lee, Byung-Mu ;
Toxicological Research, volume 8, issue 2, 1992, Pages 317~329
Fifty chemicals are currently classified as human carcinogens based on epidemiologic and animal data. Humans are daily exposed to them from various sources of exposure via inhalation, dermal contact and oral ingestion. To reduce cancer risk to man, these human carcinogens should be appropriately regulated and monitored environmentally or biologically for routine human cancer risk assessment. A number of mathematical risk assessment models have been introduced, but any realistic and relevant model system is not available for humans. A mechanistic process for human cancer risk assessment was comprehensively reviewed and problems were also discussed. Here, a new conceptual approach using epidemiology and biological human monitoring was suggested for the most relevant method to study human cancer risk assessment.
Molecular Cloning of Chicken Major Histocompatibility Complex Class II Molecules
Sung, Aree-Moon ;
Toxicological Research, volume 8, issue 2, 1992, Pages 331~342
The chicken major histocompatibility complex (MHC), the B complex, is beginning to be analyzed at the DNA level. Inbred lines of chickens have been reported to possess 3~5 MHC class II genes. To further analyzed the molecular structure of the chicken MHC class II genes, cDNA clones coding for chicken MHC class II (B-L)
chain molecules were isolated from chicken spleen and liver. Tissue-specific transcription of B-L
genes was studied by Northern blot analysis. A high level of expression was detected for spleen poly(A)
RNA whereas a faint signal was detected for liver poly(A)
RNA. Twenty-nine cDNA clones were isolated from the spleen and eight cDNA clones were isolated from the liver. Based on restriction maps, most clones could be clustered into one family of genes. Four cDNA clones were sequenced (S7, S10 and S19 from the spleen and L1, which was identical to S19, from the liver). Complete amino acid sequences of B-L
chain molecules were predicated from the nucleotide sequences of the cDNA clones. Although both the nature and the location of the conserved residues were similar in chicken and mammalian sequences, some species-specific differences were found, suggesting that the structures of the B-L molecules are similar, but not identical to their mammalian counterparts.
Regulation of Tumor Neceosis Factor-
Receptors and Signal Transduction Pathways
Han, Hyung-Mee ;
Toxicological Research, volume 8, issue 2, 1992, Pages 343~357
Tumor necrosis factor-
(TNF), a polypeptide hormone secreted primarily by activated macrophages, was originally identified on the basis of its ability to cause hemorrhagic necrosis and tumor regression in vivo. Subsequently, TNF has been shown to be an important component of the host responses to infection and cancer and may mediate the wasting syndrome known as cachexia. These systemic actions of TNF are reflected in its diverse effects on target cells in vitro. TNF initiates its diverse cellular actions by binding to specific cell surface receptors. Although TNF receptors have been identified on most of animal cells, regulation of these receptors and the mechanisms which transduce TNF receptor binding into cellular responses are not well understood. Therefore, in the present study, the mechanisms how TNF receptors are being regulated and how TNF receptor binding is being transduced into cellular responses were investigated in rat liver plasma membranes (PM) and ME-180 human cervical carcinoma cell lines.
-TNF bound to high (
)affinity receptors in rat liver PM. Solubilization of PM with 1% Triton X-100 increased both high affinity (from
pmoles/mg protein) and low affinity (from
pmoles/mg protein) TNF binding without affecting the affinities for TNF, suggesting the presence of a large latent pool of TNF receptors. Affinity labeling of receptors whether from PM or solubilized PM resulted in cross-linking of
130 kDa, 90 kDa and 66kDa complexes. Thus, the properties of the latent TNF receptors were similar to those initially accessible to TNF. To determine if exposure of latent receptors is regulated by TNF,
-TNF binding to control and TNF-pretreated membranes were assayed. Specific binding was increased by pretreatment with TNF (P<0.05), demonstrating that hepatic PM contains latent TNF receptors whose exposure is promoted by TNF. Homologous up-regulation of TNF receptors may, in part, be responsible for sustained hepatic responsiveness during chronic exposure to TNF. As a next step, the post-receptor events induced by TNF were examined. Although the signal transduction pathways for TNF have not been delineated clearly, the actions of many other hormones are mediated by the reversible phosphorylation of specific enzymes or target proteins. The present study demonstrated that TNF induces phosphorylation of 28 kDa protein (p28). Two dimensional soidum dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE) resolved the 28kDa phosphoprotein into two isoforms having pIs of 6.2 and 6.1. The pIs and relative molecular weight of p28 were consistent with those of a previously characterized mRNA cap binding protein. mRNA cap binding proteins are a class of translation initiation factors that recognize the 7-methylguanosine cap structure found on the 5' end of eukaryotic mRNAs. In vitro, these proteins are defined by their specific elution from affinity columns composed of 7-methylguanosine 5'-triphosphate(
GTP)-Sepharose. Affinity purification of mRNA cap binding proteins from control and TNF treated ME-180 cells proved that TNF rapidly stimulates phosphorylation of an mRNA cap binding protein. Phosphorylation occurred in several cell types that are important in vitro models of TNF action. The mRNA cap binding protein phosphorylated in response to TNF treatment was purifice, sequenced, and identified as the proto-oncogene product eukaryotic initiation factor-4E(eIF-4E). These data show that phosphorylation of a key component of the cellular translational machinery is a common early event in the diverse cellular actions of TNF.