Mechanism of specific nuclear transport of adriamycin: the mode of nuclear translocation of adriamycin-proteasome complex

Adriamycin (ADM), an anthracycline anticancer agent, is selectively stored in the nuclei of a variety of proliferating cells, but the precise mechanism of specific nuclear transport of ADM is not well known. Recently, we demonstrated that ADM shows high binding affinity to the cytoplasmic proteasomes of L1210 mouse leukemia cells and that taken up ADM by the cells selectively binds to proteasomes. Nuclear targeting of proteasome in proliferating cells may be mediated by the nuclear localization signals that are found in several of the alpha-type subunits of the 20S proteasome. To confirm nuclear transport of the ADM-proteasome complex, we synthesized a photoactive ADM analogue, N-(p-azidohenzoyl)-ADM, and generated a photoaffinity-labeled proteasome complex. The 26S proteasome purified from the cytosol of L1210 cells had a high affinity to N-(p-azidobenzoyl)-ADM. SDS-PAGE analysis of the photoaffinity-labeled proteasome showed that low molecular weight bands (approximately 21-31 kDa) of 20S proteasome had the highest photoaffinity. The photoaffinity-labeled proteasome was distributed in the cytoplasm and nuclei of digitonin-permeabilized L1210 and B-16 mouse melanoma cells in the presence of the cytosolic fraction and ATP. The rate of nuclear translocation of the proteasome was low in the absence of ATP. These results suggest that the proteasome is a specific translocator of ADM from the cytoplasm to the nucleus and that 20S proteasome components are the dominant ADM-binding sites. The nuclear transport of ADM-proteasome complex is regulated by an ATP-dependent nuclear pore-mediated mechanism.

Differences in intracellular sites of action of Adriamycin in neoplastic and normal differentiated cells

PURPOSE

This study was performed to clarify the intracellular specificity of the differential cytotoxic effects of Adriamycin (ADM) on neoplastic and normal cells.

METHODS

The mouse lymphocytic leukemia cell line L1210 and pig kidney proximal tubular epithelial cell line LLC-PK1 were used as neoplastic and normal cells, respectively. These cells were treated with various concentrations of ADM for 24 h and toxicological parameters were determined.

RESULTS

ADM (0.1-10 microM) significantly down-regulated cell growth rate and [3H]thymidine incorporation into DNA in the log phase, and at concentrations of more than 1 microM reduced the viability of both cell lines. Lipid peroxidation was increased at 1 microM ADM in L1210 cells and at 10 microM ADM in LLC-PK1 cells. The microsomal and nuclear fractions of both cell lines showed approximately the same level of ADM-induced superoxide anion (O2-) production, while the mitochondrial fraction of differentiated LLC-PK1 cells produced the highest levels of O2-. Differentiated LLC-PK1 cells showed the highest mitochondrial NADH-cytochrome c reductase activity. L1210 cells showed lower mitochondrial activities of enzymes involved in scavenging of reactive oxygen species, such as superoxide dismutase, glutathione peroxidase and catalase, than the other cells.

CONCLUSIONS

These results suggest that ADM exerts cytostatic effects on neoplastic and normal undifferentiated cells through the inhibition of DNA synthesis by DNA intercalation, and cytotoxic effects on neoplastic cells through the accumulation of reactive oxygen species resulting from low scavenger enzyme activities. The cytotoxic effects on normal differentiated cells may be related to the high levels of production of reactive oxygen species due to high mitochondrial NADH-cytochrome c reductase activity.

Roles of oxygen radical production and lipid peroxidation in the cytotoxicity of cephaloridine on cultured renal epithelial cells (LLC-PK1)

To clarify the mechanism of cephalosporin nephrotoxicity, the cytotoxic effects of cephaloridine (CER), a nephrotoxic cephalosporin antibiotic, on the pig kidney proximal tubular epithelial cell line (LLC-PK1) were studied in culture. CER increased the content of hydrogen peroxide and decreased the activity of catalase in the treated cells, followed by an increase in the content of lipid peroxide and decreases in both glutathione peroxidase activity and in the non-protein sulfhydryl content. The levels of NADPH-dependent hydrogen peroxide and superoxide anion production by microsomes prepared from LLC-PK1 cells, and by NADPH-cytochrome P-450 reductase purified from the rat renal cortex were significantly increased by paraquat. The production of these molecules was antagonized by p-chloromer-curibenzoate, an inhibitor of NADPH-cytochrome P-450 reductase. On the other hand, CER did not significantly affect the production of hydrogen peroxide or superoxide anions. These results suggested that the cytotoxic effect of CER on cultured LLC-PK1 cells was due to the increases in hydrogen peroxide and lipid peroxide levels and not microsomal oxygen radical production, and that the mechanism of this cytotoxicity is very different from that of paraquat which induces microsomal oxygen radical production.

Cephaloridine-induced inhibition of cytochrome c oxidase activity in the mitochondria of cultured renal epithelial cells (LLC-PK(1)) as a possible mechanism of its nephrotoxicity

To clarify the mechanism of cephalosporin nephrotoxicity, the effects of cephaloridine (CLD), a nephrotoxic cephalosporin antibiotic, on the mitochondria of the pig kidney proximal tubular epithelial cell line LLC-PK(1) were studied in culture. The activity of cytochrome c oxidase in the mitochondria of LLC-PK(1) cells was significantly decreased from 9 h after addition of 1.0 mM CLD to the cultured cells. These effects were dose-dependent and accompanied with a significant decrease in the ATP content in the cells, followed by marked morphological changes in the mitochondria. These alterations were observed in the treated cells before the increase in lipid peroxidation. The activities of NADH-cytochrome c reductase and succinate dehydrogenase in the mitochondria and NADPH-cytochrome P450 reductase, NADH-cytochrome b(5) reductase, and 7-ethoxycoumarin O-deethylase in the microsomes of the treated cells were not affected. Superoxide anion production by the mitochondria prepared from LLC-PK(1) cells or NADH-cytochrome c reductase was not affected by addition of CLD (1-10 mM), but adriamycin (0.1 mM) or paraquat (0.1 mM) significantly increased the superoxide anion production. These results suggested that the primary action of CLD is inhibition of cytochrome c oxidase activity in the mitochondrial electron transport chain, which decreases intracellular ATP content in renal tubular epithelial cells and that these effects of CLD are followed by increased lipid peroxidation and cellular injury.

Differential toxic effects of gentamicin on cultured renal epithelial cells (LLC-PK1) on application to the brush border membrane or the basolateral membrane

Aminoglycoside antibiotics are generally accepted to accumulate in renal proximal tubule cells from the luminal surface and show toxic effects on the cells. The binding affinity and membrane permeability of aminoglycoside antibiotics are different at the brush border membrane (BBM) and the basolateral membrane (BLM) of proximal tubule cells. This study was performed, therefore, to investigate the differential effects of the aminoglycoside antibiotic gentamicin (GM) on cultured LLC-PK1 cells, a pig kidney proximal epithelial cell line, after addition to the BBM or the BLM side. LLC-PK1 cells were cultured on microporous membranes until forming confluent monolayers, and then GM was added to either the BBM or the BLM side. GM caused release of enzymes from the organelles, with a higher level of release observed following addition to the BBM side than that to the BLM side. Patterns of [3H]GM uptake by the cells differed in a manner dependent on whether it was added to the BBM or the BLM side. That is, the cellular uptake from the BBM side increased with incubation time, while that from the BLM side showed rapid saturation. These results suggested that aminoglycoside antibiotics show differential effects on cultured proximal epithelial cells and have differential patterns of cellular uptake when added to the BBM or the BLM side.

In situ photoaffinity labeling of proteasome with photoactive adriamycin analogue

An intracellular adriamycin (ADM)-binding protein purified from the cytosol of L1210 mouse lymphocytic leukemia cells had a molecular weight of 700-1500 kDa and hydrolyzed Suc-LLVY-MCA. When L1210 cells were incubated with a photoactive ADM analogue, N-(p-azidobenzoyl)-adriamycin (NAB-ADM), most of the NAB-ADM was found to localize in the nuclei. In situ photoaffinity labeling of L1210 cells with NAB-ADM resulted in low protease activity in the cytosol and nuclear extracts and the cells showed selective photoincorporation of NAB-ADM into the proteasome. These results suggest that the proteasome is a translocator of ADM from the cytoplasm to the nucleus and might therefore become a new candidate for cancer chemotherapy.

Fluoride-induced ultrastructural changes in exocrine pancreas cells of rats: fluoride disrupts the export of zymogens from the rough endoplasmic reticulum (rER)

Influence of fluoride on exocrine pancreas cells was examined morphologically with traditional and prolonged osmium fixation techniques for electron microscopy in the enamel fluorosis model rats injected subcutaneously twice a day with 20 mg/kg body weight of sodium fluoride. Although the rough endoplasmic reticulum (rER) of exocrine pancreas cells in control rats was laminated and oriented parallel to the circumference of the nucleus, the rER of the cells in NaF-treated rats was dilated, disrupted the laminated arrangement, and changed to the globular-shape rER. Many intracisternal granules were formed in these globular-shape rER of the cells exposed to fluoride. Lots of autophagosomes were also seen in the exocrine cells with NaF treatment. The autophagosomes were limited with a double or multiple membranes, and contained cytoplasmic organelles and/or the intracisternal granules. The outer and inner leaflets of double membranes of the autophagosomes were usually separated by a distinct electron-lucent area. In prolonged osmium fixation, the area between the double membranes of the autophagosome was filled with osmiun reaction deposits. Many autophagosomes were encircled with the single or multiple osmiophilic layers. In some cases, the osmium positive saccules also surrounded the free surface of the globular-shape rER containing intracisternal granules. These findings indicate that fluoride disrupts the export of zymogens from the rER, resulting in formation of intracisternal granules and autophagosomes, and that the osmiophilic saccules participate in sequestration of cytoplasmic organelles in forming autophagosomes.

Proprioceptive afferents survive in the masseter muscle of trkC knockout mice

Peripheral innervation patterns of proprioceptive afferents from dorsal root ganglia and the mesencephalic trigeminal nucleus were assessed in trkC-deficient mice using immunohistochemistry for protein gene product 9.5 and parvalbumin. In trkC knockout mice, spinal proprioceptive afferents were completely absent in the limb skeletal muscles, M. biceps femoris and M. gastrocnemius, as previously reported. In these same animals, however, proprioceptive afferents from mesencephalic trigeminal nucleus innervated masseter muscles and formed primary endings of muscle spindles. Three wild-type mice averaged 35.7 spindle profiles (range: 31-41), six heterozygotes averaged 32.3 spindles (range: 27-41), and four homozygotes averaged 32.8 spindles (range: 26-42). Parvalbumin and Nissl staining of the brain stem showed approximately 50% surviving mesencephalic trigeminal sensory neurons in trkC-deficient mice. TrkC-/- mice (n = 5) had 309.4 +/- 15.9 mesencephalic trigeminal sensory cells versus 616.5 +/- 26.3 the sensory cells in trkC+/+ mice (n = 4). These data indicate that while mesencephalic trigeminal sensory neurons are significantly reduced in number by trkC deletion, they are not completely absent. Furthermore, unlike their spinal counterparts, trigeminal proprioceptive afferents survive and give rise to stretch receptor complexes in masseter muscles of trkC knockout mice. This indicates that spinal and mesencephalic trigeminal proprioceptive afferents have different neurotrophin-supporting system during survival and differentiation. It is likely that one or more other neurotrophin receptors expressed in mesencephalic trigeminal proprioceptive neurons of trkC knockout mice compensate for the lack of normal neurotrophin-3 signaling through trkC.

Implanted tumor growth is suppressed and survival is prolonged in sixty percent of food-restricted mice

To examine the effect of food restriction on immune functions in the tumor-bearing state, mice were divided into a control group (fed 5.0 g diet/d; 71 kJ/d) and a 60% food-restricted group (fed 3.0 g diet/d; 43 kJ/d) at 8-wk of age, and 4 wk later, L1210 tumor cells were inoculated intradermally. In the food-restricted mice, tumor growth was significantly suppressed, and mean survival time after the tumor inoculation was prolonged (P < 0.05). The plasma concentrations of two antitumor cytokines, interferon-gamma (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha), were greater in the food-restricted group before tumor inoculation (P < 0. 05). Furthermore, the food-restricted mice had significantly higher plasma levels of IFN-gamma and TNF-alpha after tumor inoculation, although the treatment significantly increased these cytokine levels in both groups. Splenic natural killer cell cytotoxicity was also higher in the tumor-bearing food-restricted mice than in controls (P < 0.05). Food-restricted mice have strong antitumor immunity, and as a result, tumor growth is suppressed and survival time is prolonged in these mice.

Mechanism of toxic action of fluoride in dental fluorosis: whether trimeric G proteins participate in the disturbance of intracellular transport of secretory ameloblast exposed to fluoride

In enamel fluorosis model rats treated with sodium fluoride, secretory ameloblasts of incisor tooth germs exhibited disruption of intracellular trafficking. We examined whether heterotrimeric G proteins participated in the disruption of vesicular trafficking of the secretory ameloblast exposed to fluoride, using immunoblotting and pertussis toxin (IAP)-induced adenosyl diphosphate (ADP)-ribosylation for membrane fractions of the cell. Immunoblotting of crude membranes, post supernatants of the ameloblast, with anti-G(alpha i3/alpha o) and anti-G(alpha s) antibodies showed that Gi3 or Go proteins existed in the secretory ameloblast, but Gs protein did not. Immunoblotting of the subcellular membrane fractions indicated that the Gi3 or Go proteins were located in the Golgi membrane, but were not in the rough endoplasmic reticulum (rER) membrane. Autoradiograph of IAP-induced ADP-ribosylation, however, showed the existence of IAP-sensitive G proteins both in rER and Golgi membranes. Fluoride treatment decreased the G proteins bound to both membranes. These findings indicate that different G proteins, both of which are IAP-sensitive, are present in the rER and Golgi apparatus, and suggest that these G proteins participate in the disturbance of intracellular transport of the secretory ameloblast exposed to fluoride.

Proteasome is a carrier to translocate doxorubicin from cytoplasm into nucleus

When an effective concentration of doxorubicin (DXR) was added into L1210 of a mouse leukemia cell line, DXR was rapidly distributed much more in the nuclei than in the other organelle within a few minutes. A [14C]DXR-binding fraction was obtained from the cytosol prepared from L1210 cells. The fraction was adsorbed to hydroxylapatite matrix and eluted from the matrix by 50-150 mM potassium phosphate buffer. The fraction showed high DXR-binding and Suc-Leu-Leu-Val-Tyr-MCA-degrading activity. The binding of [14C]DXR was inhibited by unlabeled DXR. Gel chromatography of the fraction with Sephacryl S-300 separated two fractions of high molecular weight (Peak I, approx. 750 kDa) and low molecular weight (Peak II). Peak I showed proteolytic activity. [14C]DXR-binding Peak I had much higher affinity to DNA-cellulose than [14C]DXR-binding Peak II. [14C]DXR-Peak I complex also was retained into the nuclei isolated from L1210 cells, temperature-dependently. These results suggest that a specific carrier to translocate DXR from cytoplasm into nucleus exists in L1210 cell and the carrier is proteasome.

Influence of fluoride on secretory pathway of the secretory ameloblast in rat incisor tooth germs exposed to sodium fluoride

Fluoride, which is an environmental toxicant, is a potent inducer of mottled enamel in humans and rats. To define the influence of fluoride on the secretory pathway in enamel fluorosis, mottled enamel was induced in the incisor tooth germs of rats by subcutaneous injections of sodium fluoride for 4 days, and then morphological and cytochemical changes of the secretory ameloblast were examined in the tooth germs with HRP-labeled lectin (Con A, GS-I, SBA and PNA) and En3 antibody labeling amelogenins. The accumulation of small vesicles on the route of the secretory pathway between the rER and the Golgi apparatus, disorder of Golgi stacks, and formation of abnormal large granules in distal cytoplasm were seen in the secretory ameloblast. Lectin staining patterns of the secretory ameloblast indicated the disturbance of the vesicular transport between the rER and the Golgi apparatus, and disorganization of the Golgi stack. Immunolabeling of the cell showed disruption of the sorting and fusion process on the secretory pathway. These results suggest that the fluoride disturbs the intracellular transport in the synthesis-secretory pathway of the ameloblast, and that this effect of fluoride on the synthesis-secretory pathway participates in the formation of enamel fluorosis.

Effect of repeated administrations of neomycin on the neuromuscular functions and the enhancement of d-tubocurarine action in mice

Effects of repeated s.c. treatments with 50 mumol (approx. 31 mg)/kg/day of neomycin for 10 or 15 days were examined in mice. There were no significant differences between saline and neomycin treatment groups in the motor coordination assessed by rota-rod test and traction test. On tension recordings, an in vitro addition of d-tubocurarine inhibited the twitch tensions evoked by the nerve stimulations in both cases of saline or neomycin treatment. Neomycin treatments shifted the concentration-response curve between twitch tension and d-tubocurarine to the left, dependently on its injection days. These results suggest that repeated treatments with neomycin enhance the inhibitory effect of d-tubocurarine on the neuromuscular transmission in mice without eliciting motor incoordination and muscle relaxation.

Relation between the trans-Golgi network and the Golgi stack on development of the Golgi apparatus of the ameloblast in developing rat molar tooth germs

BACKGROUND

The problem of how the functional compartments of the Golgi apparatus organizes during cell differentiation to become a well-formed Golgi apparatus is as yet an unresolved issue. This study was designed to define the involvement of the trans-Golgi network (TGN) and the Golgi stack in organizing the Golgi apparatus.

METHODS

The distribution of the TGN marker enzyme was examined in the ameloblast of developing rat molar tooth germs using cytochemistry with Co-enzyme A phosphatase (CoA Pase) and cytidine monophosphatase (CMPase).

RESULTS

Typically formed Golgi apparatus was observed in the secretory ameloblast but not in the presecretory ameloblast. Organization of the Golgi apparatus through the presecretory ameloblast was noted. In the presecretory ameloblast, Golgi stacks of different sizes and clusters of small vesicles were located in the cytoplasm lateral to the nucleus. The saccules with enzymes marked for TGN were also observed in the cytoplasm lateral to the nucleus. These saccules were adjacent to the cluster of small vesicles and/or the Golgi stack. Upon cell differentiation, Golgi stacks were seen in line along the long axis of the cell, and the file of the stacks in the cytoplasm lateral to the nucleus was formed. The positive saccule was seen in a parallel line equal to the length of the Golgi stacks.

CONCLUSIONS

In organizing the Golgi apparatus, the development process of the TGN and the Golgi stack appear to be different, and new Golgi stacks seem to be formed through the accumulation of small vesicles near the pre-existing TGN.

Changes of lectin staining pattern of the Golgi stack during differentiation of the ameloblast in developing rat molar tooth germs

Changes of lectin staining patterns in the Golgi stack during cell differentiation were examined in the ameloblasts of developing rat molar tooth germs, using HRP-labeled lectins: Canavalia ensiformis (Con A), Griffonia simplicifolia I (GS-I), Glycine max (SBA), Ulex europeus I (UEA-I), Triticum vulgaris (WGA), and Arachis hypogaea (PNA). The Golgi stacks of the inner enamel epithelial cells and the presecretory ameloblasts were stained with the lectins, although the staining strength and pattern varied among the stacks with each lectin. In some cases, the reaction products for the lectins were observed in most or all saccules of the Golgi stack. In the secretory ameloblasts, however, discrete staining patterns of the Golgi stack were found for each lectin. The reaction products deposited in definite saccules of the Golgi stack of the secretory ameloblast, especially for UEA-I and PNA which stained only the trans Golgi saccules of the stack. The reaction-positive saccules distributed more extensively in the Golgi stack of the inner enamel epithelial cell and the presecretory ameloblast than in the secretory ameloblast. These findings suggest that the Golgi stack is not fully compartmentalized in the inner enamel epithelial cell and the presecretory ameloblast. It is proposed that, in the differentiating ameloblast, various glycosyltransferases may coexist in most saccules of the Golgi stack.

[Cardiotoxicity study of ME2303 with the interval intravenous injections to rats]

Cardiotoxic effects of ME2303 were studied upon interval intravenous administrations to rats in comparison with those of doxorubicin (ADR). ME2303 at two dose levels of 3 and 9 mg/kg/day or ADR at a dose levels of 3 mg/kg/day was injected once a week for 3 weeks to female Sprague-Dawley rats (SPF) of 5-weeks of age. ADR depressed body weight gain, decreased food intake and increased water intake. Microscopic observation on the myocardial tissues revealed that ADR caused necrosis and cell infiltration, edema and disarrangement of myofibrils in some of ADR-treated rats. On the other hand, ME2303 showed no significant effects except that some decrease of food intake was observed at a dose level 9 mg/kg/day. No changes in left ventricular functions were observed in perfused hearts isolated from ADR- or ME2303-treated rats. However, about 133 ng/g of ADR remained in the hearts even at 1 week after the final administration whereas ME2303 or its metabolites were not detected, suggesting that ADR may cause disturbance of ventricular function and more cardiomyopathy after a longer term than 1 week following the final administration. These results suggest that the cardiotoxicity of ME2303 is weaker than that of ADR in rats.

Micronucleus test with potassium chromate(VI) administered intraperitoneally and orally to mice

The effect of route of administration, intraperitoneal (i.p.) or oral gavage (p.o.), in the mouse micronucleus test was studied with K2CrO4 in 2 mouse strains (MS/Ae and CD-1). A simplified acute toxicity test to estimate the toxic dose levels of K2CrO4 showed that the LD50S were 50 mg/kg i.p. and 300 mg/kg p.o. for MS/Ae and 32 mg/kg i.p. and 180 mg/kg p.o. for CD-1. Based on results of a pilot micronucleus test to determine appropriate dose levels and the optimal sampling time, it was decided to sample bone marrow cells of both strains of mice 24 h after i.p. doses of 10-80 mg/kg and p.o. doses ranging from 20 to 320 mg/kg. K2CrO4 administered i.p. induced micronucleated polychromatic erythrocytes (MNPCEs) dose-dependently in both strains. In contrast, when administered p.o. the chemical failed to induce MNPCEs. These results suggest that this difference between i.p. and p.o. routes is related to a difference of absorption or metabolic fate of chromate in vivo.

Antibacterial activity and ototoxicity in guinea pigs, and nephrotoxicity in rats of arbekacin

Arbekacin (HBK), 1-N[(S)-4-amino-2-hydroxybutyl]-3',4'-dideoxykanamycin B, showed broad antibacterial spectra against gram-positive and gram-negative bacteria including Pseudomonas aeruginosa. It was also effective against gentamycin- or tobramycin-resistant bacteria. HBK was resistant to various aminoglycoside-inactivating enzymes except for AAC (2') and AAC (6')-IV, both of which slowly inactivated it. Even at higher dosages (150 mg/kg i.m. or greater, which resulted in some deaths), HBK never decreased the pinna reflex in guinea pigs, while 150 mg/kg or more of dibekacin (DKB) or amikacin (AMK) caused loss of this reflex. HBK has less ototoxicity than do DKB and AMK. This was confirmed by histopathological examination of the inner ear. The degree of nephrotoxicity of HBK was suggested to be similar to that of DKB as judged from serum biochemical tests, urinalysis, and histopathological findings.

[A study on the effect of (2"R)-4'-O-tetrahydropyranyladriamycin, a new antitumor antibiotic, on reproduction. III. Its effects on perinatal and postnatal rats]

This paper describes effects of (2"R)-4'-O-tetrahydropyranyladriamycin hydrochloride (THP) on perinatal and postnatal rats. The drug was administered intravenously to female rats at 0.01, 0.03 or 0.1 mg/kg daily from day 17 of pregnancy to 21 days after delivery. Results were described below. At any dose levels tested, THP did not affect the body weight gain, food and water consumption by pregnant rats, and length of gestation period or delivery rate. However, at the highest dose level, THP decreased spleen weight. THP, at any dose levels, did not have toxic effect on development, physiological functions, behavior, mating, fertility or pregnancy of the first generation offspring (F1). At the highest dose of 0.1 mg/kg, however, THP produced delayed ossification of sacrococcygeal vertebra in the second generation fetuses (F2). The results suggest that the maximum "no effect" dose of THP to pregnant rats and offsprings is 0.03 mg/kg/day intravenously.

[A study of the effect of (2"R)-4'-O-tetrahydropyranyladriamycin, a new antitumor antibiotic, on reproduction. II. Its teratogenicity in rats and rabbits]

This paper describes the embryotoxicity and teratogenic effects of (2"R)-4'-O-Tetrahydropyranyladriamycin (THP). The drug was administered intravenously to female rats at 0.01, 0.03, 0.1 or 0.3 mg/kg daily from day 7 to day 17 of pregnancy and to female rabbits at 0.01, 0.05 or 0.1 mg/kg daily from day 6 to day 18 of pregnancy. Results were summarized as follows. Rats THP, at the highest dose of 0.3 mg/kg, decreased body weight gains of pregnant females. This dose caused a decrease in body weights of fetuses, tendencies to increase the rate of death of fetuses or of resorption, an increase in the number of lumbar vertebrae and a delayed ossification of forelimbs of fetuses. Other parameters were not affected by THP at any dose levels. At any dose levels, THP did not produce external, visceral or skeletal malformations in the offspring (F1), nor did it affect the development, physiological functions, behavior, mating, fertility or pregnancy of the offspring. However, at the highest dose level, THP decreased the weight of testes of the offspring. The results suggest that the maximum "no effect" dose level of THP to pregnant females and offspring is 0.1 mg/kg/day intravenously. Rabbits The highest dose of THP, 0.1 mg/kg, decreased the consumption of food and water by pregnant females, but at any dose levels, it did not affect their body weight gain. THP did not cause teratological effects such as external malformation or visceral and skeletal anomalies in the fetuses at any dose levels tested. The results suggest that the maximum "no effect" dose of THP is 0.05 mg/kg/day intravenously to pregnant females and above 0.1 mg/kg/day intravenously to fetuses.

[A study on the effect of (2"R)-4'-O-tetrahydropyranyladriamycin, a new antitumor antibiotic, on reproduction. I. Its effect on the fertility of rats]

The effect of a new antitumor antibiotic on the fertility was studied using SD rats. (2"R)-4'-O-Tetrahydropyranyladriamycin (THP) was administered to each rat at 0.01, 0.03 or 0.1 mg/kg daily. Males were given the drug intravenously for 63 days prior to mating and during the mating period; females were given the drug intravenously from 14 days prior to mating until day 7 of pregnancy. All the pregnant rats were sacrificed on day 20 of pregnancy, followed by external, visceral and skeletal observations of their fetuses. Results were summarized as follows. THP, at 0.1 mg/kg, suppressed body weight gain in females during the late period of pregnancy but did not affect body weight gain in males. THP, at 0.1 mg/kg, increased the numbers of dead fetuses and of resorptions. It caused no external, visceral or skeletal anomalies at any dose levels. The results suggest that, in rats, the maximum "no effect" dose of THP is 0.03 mg/kg/day intravenously regarding fertility and fetal development.

[Toxicological studies on (2''R)-4'-O-tetrahydropyranyladriamycin, a new antitumor antibiotic. Its acute toxicity in rats]

(2''R)-4'-O-Tetrahydropyranyladriamycin (THP), a new antitumor antibiotic of anthracycline derivative, was given to Jcl-SD strain rats through intravenous (i.v.), intraperitoneal (i.p.), subcutaneous (s.c.) or oral (p.o.) administration routes and the animals were observed in respect of mortality, clinical signs and body weight for 21 days. Autopsy was done and histopathology on the tissues showing macroscopic abnormality was performed. The results were summarized as follows. Values of LD50 were 18.09 mg/kg i.v., 22.58 mg/kg i.p., 25.39 mg/kg s.c. and above 1,013 mg/kg p.o. for males and 18.07 mg/kg i.v., 20.30 mg/kg i.p., 21.76 mg/kg s.c. and above 1,013 mg/kg p.o. for females. No significant difference was found in LD50 values of different sexes. When higher than lethal dose levels of THP was given to animals, their clinical signs grew worse and weight loss occurred in about 5 days after the administration of the drug. Thereafter, deaths were observed. Macroscopic and microscopic observations on dead and survived rats revealed atrophy of spleen and thymus, whity clouding of spleen capsule, hemorrhage in mucosa of glandular stomach and congestion and hemorrhage in testes. These results suggest that THP shows weaker acute toxicity to rats than doxorubicin does, but the toxic effect of THP is approximately the same as that of other anthracycline derivatives.

[Toxicological studies on (2''R)-4'-O-tetrahydropyranyladriamycin, a new antitumor antibiotic. Its acute toxicity in beagle dogs]

(2"R)-4'-O-Tetrahydropyranyladriamycin (THP), a new antitumor antibiotic of anthracycline derivative, was given intravenously to male and female Beagle dogs, followed by observations for 2 weeks. The doses were 0.125, 0.25, 0.5 and 1.0 mg/kg. Observations were performed on mortality, clinical signs, body weight and temperature, food and water consumption, ECG, ophthalmoscopy, testicular measurement, hematology, serum biochemistry, urinalysis, autopsy, histopathology and electron microscopy. The results were as follows. All animals of 1 mg/kg-treated group died but there were no deaths in other groups. All the levels of doses caused vomiting and diarrhea. Furthermore, the highest dose caused bloody diarrhea and decreases in food consumption, motility and body weight, followed by death. These effects may be related to histopathological changes in mucosa of digestive tract. Some changes in water consumption, urine volume and renal histopathology were sporadically observed after treatment, but they were not treatment-related. These results suggest that a treatment with THP does not significantly cause renal disturbance. There were no treatment-related changes in body temperature, ophthalmoscopical observation and testicular measurement. THP produced flattening of T wave and prolongation of QRS interval only at high doses of more than 0.5 mg/kg for males and of 1 mg/kg for females but did not cause any histopathological or electron microscopical changes in hearts. It seems that the abnormalities caused by THP in ECG traces are due to the deterioration of general conditions rather than the direct effect on heart. High doses produce the significant changes in platelet, WBC, Hb, Neutro. (Seg.), Mono., Hb, RBC and Lymph. and further regressive changes in thymus, spleen and bone marrow. These results suggest that THP causes some effects on hemopoietic tissues. The sporadic changes in serum biochemistry and urinalysis were neither related to the treatment nor to the changes in organ weight, autopsy, histopathology and electron microscopy. Therefore, it is likely that THP does not cause toxicological effect on the other tissues and organs except hemopoietic tissues.

[Effect of fosfomycin on auditory organs and its transfer to cochlear lymph following application of its solution into a middle ear cavity]

Male guinea pigs were given 0.1 ml of 2, 3 or 5% fosfomycin (FOM) ototopical solution once a day for 5 days into a middle ear cavity through artificially perforated ear drum. Kanamycin A (KM) was used at 2% ototopical solution as control drug. Four animals of each group were sacrificed under pentobarbital anesthesia to isolate the cochlea 10 days after the final application. The cochlea was washed with 0.1 M phosphate buffer (pH 7.0), followed by fixing with 2.5% glutaraldehyde and 1% osmic acid. Cochlear specimens were prepared by standard method for scanning electron microscopic observation. The scanning electron microscopic observations revealed some damages in outer and inner hair cells, such as partial deformation or loss of auditory hair in hair cells, but these damages were not correlated to drug treatments. In order to determine the transfer of FOM and KM from middle ear cavity to cochlear lymph in male guinea pigs, the cochlear lymph was collected 0.5, 1, 2 and 4 hours after an application of 0.1 ml of 3 or 5% FOM and 2% KM ototopical solution into a middle ear cavity, followed by estimating content of these antibiotics in the lymph. The results showed the peak concentration in lymph at 1 to 2 hours after an application of 3% FOM was lower than that after 2% KM, but the AUC of 3% FOM was higher than that of 2% KM. The AUC value of FOM was dependent on the applied concentration of FOM. The value of half-life time was about 4.8 hours at FOM and about 2.3 hours at KM.(ABSTRACT TRUNCATED AT 250 WORDS)

[Preventive effect of fosfomycin on the renal toxicity of cisplatin]

Cisplatin caused toxic effects in adult male rats, such as renal disturbance, decrease of platelet and WBC, increase of RBC, elevation of GPT and GOT activity, decrease of plasma protein and albumin, loss of body weight gain and lethal effect when treated intravenously with 1 mg/kg/day of cisplatin for 12 days. Fosfomycin (FOM) exerted preventive effects on the renal disturbance, the changes in blood cells and plasma protein and the lethal effect induced by cisplatin when treated with a combination of FOM and cisplatin. However, FOM did not prevent the cisplatin-induced effects on GPT and GOT activity and body weight gain. These results suggest that FOM prevents the cisplatin-induced disturbance of renal and hematopoietic function but does not the cisplatin-induced hepatic disturbance.

[Toxicological studies on a new cephamycin, MT-141. XI. Immunological properties]

Immunogenicity, eliciting antigenicity of MT-141 and its cross-reactivity with other beta-lactam antibiotics were studied in mice, guinea pigs and rabbits. The results were as follows. Injections of MT-141 failed to produce IgE-type antibody in mice but injections of the MT-141 conjugated to rabbit serum albumin produced a trace of IgE-type antibody. No antibody was produced in the guinea pigs immunized with the MT-141 conjugated to rabbit serum albumin in alum or Freund's complete adjuvant. The conjugated MT-141 also failed to elicit anaphylactic shock in the immunized guinea pigs. The subcutaneous treatments with MT-141 in Freund's complete adjuvant produced an amount of hemagglutination antibody in rabbits. The intravenous treatments with MT-141 produced no antibody in rabbits. When rabbits were subcutaneously immunized with the MT-141 conjugated to rabbit serum albumin in Freund's complete adjuvant, production of specific antibody in the rabbits was demonstrated by observations of passive cutaneous anaphylaxis and hemagglutination. The results of hapten-induced inhibition of passive hemagglutination, passive cutaneous anaphylaxis, anaphylactic shock and hemagglutination by using conjugates of antibiotics and rabbit serum albumin as immunogens and conjugates of antibiotics and bovine gamma-globulin as eliciting antigen showed that MT-141 did not cross-react with other antibiotics. MT-141 did not cause the in vitro direct Coombs' reaction in the human blood even at a high concentration of 160 mg/ml. It is concluded from these results that immunological activity of MT-141 preparation is weak.

[Pharmacological studies on new cephamycin, MT-141. (1) Its effect on central nervous system, respiration and cardiovascular system]

The results on pharmacological effects of MT-141 were as follows. MT-141 did not exert effect on central nervous system in mice and rabbits but potentiated the anesthetic effect of thiopental at doses above 800 mg/kg i.v. MT-141 slightly raised a level of blood pressure in dogs and also caused a slight increase in the blood flow and heart rate when intravenously given more than 400 mg/kg. This compound did not affect the spontaneous contraction of isolated guinea pig atria and the blood vessels in perfused rabbit ears. MT-141 did not significantly affect the spontaneous contraction and coronary flow in isolated hearts of guinea pig. The body temperature was raised slightly by an injection of more than 400 mg/kg of MT-141. These results suggest that MT-141 does not possess specific effect on central nervous system but at a high dose slightly affects the autonomic nervous system such as blood pressure, body temperature, heart rate and blood flow in experimental animals.

[Toxicological studies on a new cephamycin, MT-141. V. Its subacute toxicity in beagle dogs]

The 30-day subacute toxicity of MT-141 was studied in adult Beagle dogs with intravenous (i.v.) administrations of 100 to 1,200 mg/kg/day. The obtained results were as follows. MT-141 at the doses lower than 800 mg/kg/day i.v. had no toxicity in male and female Beagle dogs. An increase in water intake was closely related to that in urine excretion after i.v. treatments with 1,200 mg/kg/day of MT-141 in the males and females. MT-141 at the doses higher than 1,000 mg/kg/day i.v. of MT-141 caused slight local irritation at the site of injection in the males and females. In the females, the dose-dependent changes induced by treatments with the doses above 1,000 mg/kg/day i.v. of MT-141 were a significant decrease in the level of serum K and a significant increase in the activity of serum LAP. In the males, this compound produced significant dose-dependent changes in toxicological parameters such as a decrease in the activity of GOT at the doses higher than 1,000 mg/kg/day i.v., a descent in the levels of U-K, U-Cl and OP at the dose of 1,200 mg/kg/day i.v., an elevation in the level of serum alpha 1- and alpha 2-G, and an increase in the volume of excreted urine at the dose of 1,200 mg/kg/day i.v. It is concluded from the above-mentioned results that the maximal "no effective" dose of MT-141 is 800 mg/kg/day i.v. and the toxic dose of MT-141 is above 1,000 mg/kg/day i.v. in male and female Beagle dogs.

[Toxicological studies on a new cephamycin, MT-141, IV. Its acute toxicity in beagle dogs]

The acute toxicity of MT-141 was studied in adult Beagle dogs with intravenous (i.v.) or intramuscular (i.m.) administration to obtain following results. MT-141 at the doses ranging from 2,500 to 7,500 mg/kg i.v. caused no effect on life, bodyweight, food intake, eyeground and ECG in male and female Beagle dogs. MT-141 produced an increase in water intake, urine volume, WBC and LAP and a decrease in Lymph., U-Na, U-K and OP, but any histopathological change was not caused in the organs and tissues. It is suggested that these changes in blood, serum and urine are due to mechanical and transient effects induced by infusing a large volume of hypertonic solution of MT-141 into cephalic vein. When 1,000 or 2,000 mg/kg of MT-141 was injected into the muscles of hind legs, the hind legs had difficulty in walking. It is very probable that this change was due to mechanical effects induced by injecting a hypertonic solution of MT-141 at a rate of 70--130 ml/dog. An injection of 1,000 or 2,000 mg/kg i.m. of MT-141 changed activity of GPT, GOT and CPK in the serum within the limit of physiological variations but did not caused any effect on the other toxicological parameters such as bodyweight, food intake, water intake, urine volume, eyeground examination, ECG and histopathological examination. It is concluded from the above-mentioned results that MT-141 at the dose of 2,500--7,500 mg/kg i.v. or 1,000--2,000 mg/kg i.m. has no significant toxicity in Beagle dogs.

[Toxicological studies on a new cephamycin, MT-141. VI. Its chronic toxicity in beagle dogs]

MT-141 was dosed to male and female Beagle dogs through intravenous (i.v.) route at 100, 200, 400 and 800 mg/kg/day for 182 days. The toxic effects of MT-141 were as follows. The male and female Beagle dogs exhibited no particular behavior and symptom except vomiting and soft stool after treatments with 800 mg/kg/day i.v. of MT-141. MT-141 even at the high doses of 400 to 800 mg/kg/day i.v. did not significantly change toxicological parameters such as consumption of food and water, volume of excreted urine, electrocardiogram, eyeground and analysis of blood, serum and urine. Only one of 4 male Beagle dogs died of severe intestinal invagination, which is not related to the drug effect, at 120th day after the start of treatments with the highest dose of 800 mg/kg/day i.v. of MT-141. The fatality of Beagle dogs for 800 mg/kg/day of MT-141 was 25% (1/4) in males and 0% (0/4) in females. MT-141 caused the hemorrhage accompanied with fibrosis and round cells at the site of injections but the change induced by MT-141 was not so much different from that by saline. MT-141 at the highest dose induced histopathological changes in only 2 females, such as atrophy and degeneration of cardiac muscle, necrosis and fibrosis of hepatic cells and hyperplasia of spleen and bone marrow cells. Electron-microscopic examinations revealed no ultrastructural change related to the toxicity of MT-141 in the livers and kidneys. It is considered from the above-mentioned results that the maximal "no effective" dose is 400 mg/kg/day i.v. in male and female Beagle dogs.

[Toxicological studies on a new cephamycin, MT-141. VII. Its locally-irritating activity in rabbits]

The local irritation of MT-141 was compared with that of cefmetazole (CMZ) in rabbits to obtain following results. Microscopic observations revealed that the irritative activity of 10% solution of MT-141 in blood vessels was not so much different from that of saline and 10% solution of CMZ when they were injected twice a day into vein retroauricularis of rabbits for 7 days. The histopathological changes induced by 10% solution of MT-141 were similar to those by 10% solution of CMZ but somewhat different from those by saline, because both compounds caused slight necrosis in the tissue around vessels. Histopathological observations suggested that the occurrence of necrosis was due to the leakage of them during injections. The local irritation of MT-141 by an injection of 1 ml of its solution into muscle vastus lateralis was compared with that of CMZ in rabbits. The potencies of irritative activity of the test solutions were summarized in the following order; saline less than 5% MT-141 less than 10% MT-141 not equal to 10% CMZ much less than 0.75% acetic acid less than 6.0% acetic acid. The above-mentioned results suggest that MT-141 has low irritating activity when injected through intravenous or intramuscular route for clinical practice as 5% or 10% solution.

[Toxicological studies on a new cephamycin, MT-141. X. Its perinatal and postnatal test in rats]

A perinatal and postnatal study of MT-141 was performed in SD rats. The dams were administered intramuscularly (i.m.) with MT-141 at the dose levels of 400, 800 and 1,600 mg/kg/day from the day 17 of gestation until the day 21 post delivery. The results are summarized as follows. No significant adverse effects of MT-141 were observed on the body weight gain, food consumption and water intake in dams of all groups treated with the drug during the perinatal and postnatal period. MT-141 did not change parameters of reproductive study in birth, development, physiological function and behavior of F1 rat. This compound had no effect on the fertility in F1 rats and also did not caused significant defects in the external appearance, viscera and skeleton of fetuses from dams (F1). It is concluded from these results that the maximal "no effective" dose of MT-141 is above 1,600 mg/kg/day i.m. for dams and the offsprings.

[Toxicological studies on a new cephamycin, MT-141. VIII. Its fertility test in rats]

A fertility study of MT-141 was performed in SD rats with the intramuscular (i.m.) injections at the dose levels of 400, 800 and 1,600 mg/kg/day. The male rats were injected with MT-141 for 63 days before mating and during the mating period, while the female rats were injected with MT-141 from the 14th day before mating up to the day 7 of gestation. All pregnant rats were sacrificed on day 20 of gestation followed by external, visceral and skeletal observations of their fetuses. The results are summarized as follows. The suppression of body weight gain was observed in males given above 800 mg/kg/day i.m. and in females of all treated groups during early period of gestation. However, no significant differences were found between treated groups and the control with regard to copulation rate and conception rate. Though no defects were observed for visceral and skeletal specimens in the fetuses of treated groups, MT-141 produced a delayed ossification of forelimbs in the fetuses at the doses above 800 mg/kg/day and of sternebrae at the dose of 1,600 mg/kg/day. It is concluded from the above-mentioned results that the maximal "no 'effective" dose of MT-141 on the fertility is above 1,600 mg/kg/day i.m. in parental rats and less than 800 mg/kg/day i.m. for the fetuses.

[Toxicological studies on a new cephamycin, MT-141 IX. Its teratogenicity test in rats and rabbits]

A teratogenicity study of MT-141 was performed in SD rats and Japanese white rabbits. The pregnant rats were administered intramuscularly (i.m.) with MT-141 at the dose levels of 200, 400, 800 and 1,600 mg/kg/day from the day 7 up to the day 17 of gestation. The pregnant rabbits were administered intravenously (i.v.) with the drug at the dose levels of 10, 20 and 40 mg/kg/day from the day 6 up to the day 18 of gestation. The results are summarized as follows. Rats: Though the administrations with MT-141 at all dose levels did not change body weight gain and water intake of treated dams, a slight suppression in the food consumption was produced by MT-141 at the dose of 1,600 mg/kg/day. The examinations on cesarean section revealed no effect of MT-141 on teratological parameters such as external malformation and frequency of visceral and skeletal anomalies in the fetuses. MT-141 at all dose levels exerted no toxic effect on developmental, functional and behavioral parameters in F1 rats and on mating, fertility and pregnancy of F1 rats. Furthermore, there was no effect of MT-141 on the findings in cesarean section of F1 rats. The fetuses from F1 rats had no malformation of external appearance, viscera and skeleton. Rabbits: MT-141 had no significant effect on body weight gain and food consumption of dams at the all dose levels, but caused a slight suppression in the water intake at the doses more than 20 mg/kg/day. One rabbit aborted in each group given 20 or 40 mg/kg/day. One rabbit died in the group given 20 mg/kg/day. Examinations on cesarean section showed that MT-141 at the dose of 40 mg/kg/day produced a decrease in body weights of females and an increase in dead or resorbed fetuses followed by a decrease in live fetuses. MT-141 is no effect malformation of external appearance, viscera and skeleton in the fetuses of all treated groups. The above-mentioned results suggest that MT-141 has no teratogenic effect on pregnant rats and rabbits. It is concluded from these results that the maximal "no effective" dose of MT-141 on fetal toxicity is above 1,600 mg/kg/day i.m. for pregnant rats and 10 mg/kg/day i.v. for pregnant rabbits.

[Toxicological studies of a new cephamycin, MT-141. II. Its subacute toxicity in rats]

In this subacute study, male and female rats were administered with 100, 200, 400, 800 and 1,600 mg/kg/day of MT-141 through an intramuscular (i.m.) route or with 50, 100, 200, 400 and 800 mg/kg/day through an intravenous (i.v.) route for 30 days. MT-141 did not cause lethal effect on male and female rats even at the high dosage of 1,600 mg/kg/day i.m. (approx. one-6th of LD50) and 800 mg/kg/day i.v. (approx. one-8th of LD50). Histopathological findings revealed that MT-141 induced slight local irritation at the sites of i.m. and i.v. injection. Only at a high dose of 1,600 mg/kg/day i.m., MT-141 reduced significantly the gain of body weight in male rats, which was closely related to the decrease of food intake. A slight decrease in serum Cr. and Glc. was observed in male rats at the doses more than 200 mg/kg/day i.m. and a slight decrease of liver weight at the doses more than 800 mg/kg/day i.m., while a slight increase of serum CPK, GOT, A1-P and LDH was perceived at the doses more than 800 mg/kg/day i.m. The distention of cecum was induced by the doses more than 400 mg/kg/day i.m. but histopathological findings revealed no abnormality in the cecum. These results suggest that MT-141 at the dosage level of 1,600 mg/kg/day i.m. causes nonspecific slight toxicity based on the disturbance of nourishment in male rats. In female rats given 100 to 1,600 mg/kg/day i.m., MT-141 at the high doses induced a slight increase of serum GOT, LDH and CPK and distention of the cecum. It is assumed from these results that MT-141 at the dosage level of 1,600 mg/kg/day causes nonspecific slight toxicity in female rats. In male rats given 50 to 800 mg/kg/day through an i.v. route, the level of serum Glc. and Cr. and the liver weight slightly decreased at the doses more than 200 mg/kg/day i.v. The cecum distended at the doses more than 100 mg/kg/day i.v. The dose of 800 mg/kg/day i.v. increased the activity of LDH and CPK in the serum. In female rats, MT-141 raised slightly the level of serum GOT, A1-P, LDH and CPK even at the doses more than 400 mg/kg/day i.v., reduced the liver weight at the dose of 800 mg/kg/day i.v. and distended the cecum at the all doses. These results suggest that MT-141 at the dosage level of 800 mg/kg/day i.v. induces nonspecific slight toxicity in male and female rats.(ABSTRACT TRUNCATED AT 400 WORDS)

[Toxicological studies of a new cephamycin, MT-141. III. Its chronic toxicity in rats]

The chronic toxicity of MT-141 was studied in male and female Wistar rats with 182-time intramuscular injections of 50, 100, 200, 400, 800 and 1,600 mg/kg/day and the following results were obtained. MT-141 at all dosage levels caused no lethal effect on rats. However, it induced local inflammatory changes at the site of injection, such as hemorrhage, infiltration of round cells and fibrosis particularly at high doses. MT-141 at a high dose of 1,600 mg/kg/day decreased the gain of body weights in male rats but not in female rats. MT-141 increased the water intake in male and female rats from 8th day till last day after treatments with the doses more than 800 mg/kg/day. This compound also softened the feces and distended the cecum. MT-141 at the highest dosage level of 1,600 mg/kg/day increased the weight of kidney in male and female rats. Electron-microscopic findings revealed dissociation of basal infolding and dilatation of endoplasmic reticulum in renal epithelial cells of rats treated with the doses more than 800 mg/kg/day. These results suggest that MT-141 may induce renal toxicity in rats at these doses. The administration of MT-141 changed some toxicological parameters in gross and histopathological examinations and analyses of blood, serum and urine. However, the changes were accidental, independent on the dose and within physiological variations. It is concluded from above-mentioned results that the maximal "no effective" dose of MT-141 is 400 mg/kg/day in male and female rats.

[Toxicological studies on a new cephamycin, MT-141. I. Its acute toxicities in mice and rats]

Acute toxicities of MT-141 were studied in mice and rats to obtain the following results. LD50 value of MT-141 by i.v. administration was 6,100 mg/kg for male mice and 5,200 mg/kg for female mice. The LD50 value by i.m. administration was 8,200 mg/kg for the males and 8,600 mg/kg for the females, respectively. The mice administered with a lethal dose of MT-141 showed abnormal syndromes such as decreased spontaneous movement, decreased rate of respiration, ataxic gait, sedative state and loss of righting reflex, followed by a decrease of body weight. Gross inspection revealed no remarkable change in the organs and tissues of mice after a treatment with a lethal dose of MT-141. LD50 value of this compound was 6,600 mg/kg for male rats and 5,700 mg/kg for female rats by i.v. administration, 8,600 mg/kg for the males and 8,550 mg/kg for the females by i.p. administration, 9,600 mg/kg for the males and 9,700 mg/kg for the females by i.m. administration and more than 15,000 mg/kg for both sexes by s.c. or p.o. administration, respectively. The rats given a lethal dose of MT-141 showed abnormal syndromes such as stepping gait, face-down position, decreased rate of respiration, ataxic gait, decreased spontaneous movement and loss of righting reflex, followed by a decrease of body weight. The rats exhibited stretching behavior when given MT-141 through i.p. route and manifested vocalization when given it through s.c. and i.m. routes. The results of gross inspection and histopathological observation suggested that high doses of MT-141 induced slight renal toxicity in rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Prevention by estradiol of aflatoxin-induced cytotoxicity in cultured chick embryo liver cells

Aflatoxin B1 at a final concentration of 10(-5) M depressed the sytheses of DNA, RNA and protein in cultured chick embryo liver cells. The same dose produced ultrastructural changes in the nucleus, such as nucleolar compactness or segregation of fibrillar and granular components and in the cytoplasmic area, such as vesiculation, dilatation or degranulation of endoplasmic meticulum. These acute toxic effects of aflatoxin B1 were partially decreased by an addition of 4 X 10(-5) M estradiol-17 beta. Namely estradiol-17 beta significantly reduced the nucleolar compactness and segregation of fibrillo-granular components but did not improve the vesiculation, dilatation and degranulation of endoplasmic reticulum. Estradiol-17 beta also protected the liver cells from the aflatoxin B1-induced inhibition of nucleic acid and protein synthesis. These results suggest that the protective effect of estradiol-17 beta against the acute hepatotoxicity of aflatoxin B1 is mainly due to an antagonistic interaction of both compounds on the synthesis of nucleic acid in nucleolus.

Effect of aminoguanidine on chick embryonic liver during organ culture

The addition of 10(-3) M aminoguanidine to culture medium caused no significant effect on the ultrastructure of cytoplasmic organellae in chick embryonic liver cells during organ culture but produced unique alterations in the nucleolar ultrastructure, such as increased density of protein matrix, increase of granular components, and fragmentation of nucleolar constituents. A high dose of aminoguanidine led the cultured liver cells to necrosis. Aminoguanidine also inhibited RNA synthesis rather than DNA synthesis in the cells. These results suggest that this agent may induce primary inhibition of RNA synthesis accompanied with significant changes of nucleolar structure in chick embryonic liver cells.

Effect of aflatoxin B1 on the ultrastructural and biochemical development of chick embryo liver during organ culture

When liver fragments from eleven-day chick embryos were maintained on Eagle's minimal essential medium by the established method of organ culture, they developed ultrastructural features similar to liver cells in vivo, except that they had small amounts of smooth endoplasmic reticulum and little glycogen. The cultured liver cells synthesized DNA, RNA and protein. The addition of aflatoxin B1 to the medium inhibited the synthesis of nucleic acid. Aflatoxin B1 also produced the segregation of granular and fibrillar components in nucleoli and the disarrangement of ribosomes attached to endoplasmic reticulum. Since these results were consistent with the known effects of the toxin in animals, we concluded that organ culture of chick embryo liver could be a useful technique for other studies.