Tokutaro Makita

Bone disorders in spontaneously hypertensive rat

SummaryThe bones of adult (26 weeks old) spontaneously hypertensive rats (SHR) were examined chemically and histologically by comparing them with those of the corresponding normotensive Wistar-Kyoto (WKY) rats. The mean cortical thickness, the mean ash weight per unit bone volume, and the ash as percentage of dry weight of femur were significantly lower in SHR than in WKY. Besides, the percent cortical area measured on tibial cross-section was also reduced in SHR compared with WKY. These findings strongly suggest that the development of osteoporotic bone disorders exists in adult spontaneously hypertensive rats.

Immobilization osteoporosis and active vitamin D: effect of active vitamin D analogs on the development of immobilization osteoporosis in rats.

SummaryThe therapeutic effects of vitamin D analogs, 1,24(R)-dihydroxycholecalciferol [1,24(R)(OH)2D3], 1,24(S)-dihydroxycholecalciferol [1,24(S)(OH)2D3], and 1,25-dihydroxycholecalciferol [1,25(OH)2D3] on immobilization osteoporosis were studied in rats. The right hind limb was immobilized through application of a plaster cast following the section of the sciatic nerve. The left hind limb was intact. Vitamin D analogs were orally administered for 6 weeks at dose levels of 0.02 and 0.10µg/kg/day, respectively. The mean lengths of the immobilized femurs were not significantly different from those of the intact femurs in all the experimental groups. In the immobilized femur of animals treated with 1,24(R)(OH)2D3, 0.10µg/kg, dry and ash weights were heavier and calcium and phosphorus contents greater than those in the nontreated group. Furthermore, the amount of calcified bone mass and the cortical thickness of the femurs of the immobilized limb in 1,24(R)(OH)2D3-treated animals were greater than those in the nontreated animals. Treatment with 1,25(OH)2D3 at 0.10µg/kg caused an increase of the bone mass in both immobilized and intact femurs when compared with those of the control group.It was concluded that the administration of 1,24(R)(OH)2D3 diminished the effect of immobilization in the development of osteoporosis without any side effects.

Mechanism of induction of micronuclei and chromosome aberrations in mouse bone marrow by multiple treatments of methotrexate

Methotrexate (MTX), an inhibitor of dihydrofolate reductase (DHFR), slightly induced micronuclei and this induction of micronuclei was enhanced by multiple treatments with the drug (Yamamoto et al., 1981; Hayashi et al., 1984; CSGMT/JEM.MMS, 1990). More micronuclei and chromosomal aberrations in mouse bone marrow cells were induced by multiple than by single treatment. The MTX level in mouse plasma and bone marrow showed little (or no) differences between single and quadruple treatments several hours after the injection(s). On the other hand, the DHFR activity in bone marrow cells 3 h after one and four injections was decreased to approximately 38 and 0%, respectively, of that in non-treated mice. Furthermore, the intracellular MTX level in the bone marrow cells (but not in total bone marrow) after four injections was about 10-fold higher than that after one injection. The amount of MTX bound to protein 3 h after four injections, as assayed by gel filtration (Sephadex G-25), was approximately 8-fold greater than after one injection. Therefore, the multiple-dose effects of MTX on the induction of micronuclei and chromosomal aberrations may be explained by the intracellular accumulation of MTX resulting in an enhancement of enzyme inhibition.

Parathyroid Morphology in Rats After Administration of Active Vitamin D3

The morphology of the parathyroid gland was examined in rats treated for one month with an active vitamin D3, 1α‐hydroxyvitamin D3. On continuous adiministration of 12.5 μg/kg/day of 1α‐hydroxyvitamin D3, the first histological change of the parathyroid gland, seen on day 10, was atrophy of the chief cells with marked accumulation of prosecretory granules. Replacement of the parenchyma by small or large cysts was evident on days 20 and 30. The remaining portion of the parathyroid parenchyma showed various histological changes: widened intercellular spaces intermingled with many cytoplasmic processes, shrinkage of the cytoplasm of the chief cells, and the presence of a few ghost cells in cysts. The appearance of cysts may be caused by suppression of parathyroid hormone secretion and is a characteristic lesion in hypervitaminosis in rats induced by treatment with active vitamin D3.

The preclinical safety evaluation of human monoclonal antibody against cytomegalovirus

The human monoclonal antibody against cytomegalovirus (Mab C23) was examined pharmacokinetically and toxicologically as part of the preclinical studies prior to approval for human use. Rats given repeated intravenous administrations of Mab C23 produced no antibodies against Mab C23 and maintained a blood Mab C23 level in a dose-dependent manner. However, pregnant rabbits produced antibodies against Mab C23. The half-life of Mab C23 in plasma was 15.9 days in rats, which was similar to that of normal human serum gamma-globulin (NHSG). Neither behavioral effects nor circulatory disturbance was found in mice, rats, and dogs even after a single intravenous injection of 100 or 200 mg/kg, which corresponds to 50 or 100 times the intended clinical dosage. The repeated doses of 2, 10, or 20 mg/kg of Mab C23 on six occasions with 1- or 2-week intervals elicited a transient decrease in leukocyte counts in rats given 10 or 20 mg/kg, but no adverse effects in cynomolgus monkeys. Mab C23 did not cause any reproductive or developmental toxicity when administered to rats and rabbits at dose levels of 20 mg/kg or less. However, pregnant animals showed lower plasma levels of Mab C23 than non-pregnant animals. The chromosomal aberration test disclosed no clastogenicity in human lymphocytes. An immunostaining for Mab C23 revealed no localizations in several tissues of cynomolgus monkeys given intravenous doses of Mab C23.(ABSTRACT TRUNCATED AT 250 WORDS)

Teratogenesis study of tolnaftate, an antitrichophyton agent

Abstract Tolnaftate did not affect average litter size, fetal mortality, or sex ratio of mouse fetuses surviving to term. The mean body weight of live fetuses from mothers treated with 1000 mg/kg subcutaneously was slightly lower than that of the control. A few external malformations were observed in every group including the control. No significant difference in their incidence, however, was detcted between the control and treated groups. They may be considered as incidental, and not attributable to administration of the drug. Examination of rat fetuses at term in the treated groups revealed no differences in average litter size, fetal mortality, and sex ratio of survivors from the control. A slight decease in mean body weight was noted in the fetuses from mothers treated with 500 mg/kg of tolnaftate. External gross malformations were not observed in either the control or the treated groups. Investigation of cleared skeletons stained with Alizarin Red S showed no significant difference in incidence of malformations in the treated groups of either species as compared to their respective controls. Retardation of ossification, however, was noticed in some portions of the skeleton in the fetuses of treated rats, but not in other parts. Therefore, it cannot be determined whether tolnaftate had played a role in that finding. Postnatal development of the young of both species was quite satisfactory. It is concluded that tolnaftate did not exert a deleterious effect upon the fetal and postnatal development of mice and rats under the experimental conditions of the present studies.

Toxicologic studies of the hormonal form of vitamin D3: Acute and subacute toxicity of 1α-hydroxycholecalciferol

Abstract Toxicologic examination of 1α-hydroxycholecalciferol (1α-HCC) revealed its acute toxicity to be high, and the sex variation in sensitivity of the rat to be slightly different. In subacute toxicity studies in rats, body weight gain was extremely inhibited in the animals which received 12.5, 25 and 50 μg/kg. Urinalysis revealed higher calcium concentration in the urine of experimental groups while excretion of urinary phosphate was reduced in the rats receiving 12.5, 25 and 50 μg/kg. Proteinuria was seen in rats of 12.5 μg/kg and higher dose groups. Blood cell counts showed moderate leukocytosis in the higher dose groups than in the 12.5 μg/kg group. Laboratory tests in blood indicated that plasma calcium concentration, total protein, total cholesterol, and blood urea nitrogen in the 12.5-μg/kg and higher dose groups were elevated significantly. Though scattered histological changes were seen in the kidney, heart, aorta, testes, thymus, lung, liver, thyroid, and intestinal mucosa. The main action of 1α-HCC was recognized in the necrosis of the intima of the arteriole in the heart, in digestive tracts and in voluntary muscles, resulting from the degeneration and fibrosis of muscles. However, all those lesions which were caused by the administration of 1α-HCC were fully reversible after 50 days in the recovery group. In rats, oral administration of 2.5 μg/kg of 1α-HCC for 30 days was considered to be a nontoxic dose under the conditions of this experiment.

Toxicological aspects of feprazone, a new nonsteroidal anti-inflammatory drug

Abstract The subacute and chronic toxicities of oral feprazone were studied in rats and beagle dogs. Administration of more than 150 mg/kg/day of feprazone to rats for 1 month induced retardation of growth and liver enlargement. In addition, treatment with 600 mg/kg/day of feprazone caused death, gastrointestinal ulcers, decreased hemoglobin concentration, and leucocytosis. Treatment of rats with 540 mg/kg/day of feprazone for 6 months had similar effects to those described above except that it did not cause death or gastrointestinal ulcers. Toxic nephropathy, nontoxic goiter, hepatomegaly, and increase of ovarian weight were observed in rats given more than 60 or 180 mg/kg/day of feprazone for 6 months. Injection of 1080 mg/kg/day of feprazone into dogs, caused one of six animals to become moribund on Day 18 and one to die on Day 7. The dogs surviving after administration of 360 and 1080 mg/kg/day of feprazone for 1 month showed anemia, leucocytosis, and elevations of phenolsulfonphthalein retention and serum alkaline phosphatase (ALP) activity. Similar effects were observed in dogs surviving after treatment with 150 or 375 mg/kg/day of feprazone for 12 months; in addition, increased ALP activity was observed even at a dose of 60 mg/kg/day. Liver enlargement was observed in dogs treated with all doses of feprazone for 1 or 12 months, and cytoplasmic inclusion bodies were observed in liver cells of dogs given more than 120 mg/kg/day of feprazone for 1 month.

In‐vivo and in‐vitro hepatoprotective effect of 4‐thia‐prostaglandin E1 and 7‐fluoroprostacyclin in rats

Abstract— 4‐Thia‐prostaglandin E1 and to a lesser extent 7‐fluoroprostacyclin showed a potent protective effect against carbon tetrachloride‐induced liver injury in‐vivo and in‐vitro in rat.