Tsutomu Shimizu

Neonatal exposure to zearalenone causes persistent anovulatory estrus in the rat

The effect of neonatal administration of zearalenone on the female reproductive system was studied in the rat. A single subcutaneous injection of 1.0 mg zearalenone to 3- or 5-day-old rats caused persistent vaginal estrus in adulthood. Ovaries in these animals contained many large follicles but no newly formed corpora lutea. The same effects were observed in rats which had received 100 μg estradiol-17β in the neonatal period. Most rats which had received 100 μg zearalenone or 10 μg estradiol-17β showed regular 4-day estrous cycles and had newly formed corpora lutea in their ovaries. These results demonstrate that neonatal exposure to zearalenone produces persistent anovulatory estrus in the rat, the potency being about one tenth that of estradiol-17β.

Effects of fusarenon-X and T-2 toxin on intestinal absorption of monosaccharide in rats.

In order to delineate the effects of Fusarenon-X (FX) and T-2 toxin (T-2) on intestinal absorption of monosaccharide, jejunal absorption in vivo and uptake in vitro of 3-0-methyl glucose (m-glucose) and l-glucose were studied in rats. Jejunal absorption in vivo was assessed by determining the rate of appearance of the sugars in plasma of the mesenteric vein draining the jejunal segment, which was perfused with the medium containing radiolabelled m-glucose or l-glucose. Jejunal uptake in vitro was assessed by determining the m-glucose or l-glucose uptake by the everted jejunum taken from toxin-treated rats, m-Glucose absorption was reduced 1 or 3 h after either toxin was injected into the jejunal lumen. A reduction of m-glucose absorption was also noted after intravenous injection of the toxins, although the timing and magnitude of the reduction were slightly different from those seen after the luminal injection. These results suggest that both toxins impair the jejunal function relating to monosaccharide absorption in the early stages of intoxication. The reduction in m-glucose absorption was associated with a reduction in l-glucose absorption and unchanged or increased uptake of l-glucose. The active transport component, which was indicated by the difference between absorption or uptake of the two sugars, was also reduced in association with the reduction of m-glucose absorption. These results suggest that the toxins cause specific damage in the active transport system for monosaccharides on the one hand, and impairment of their diffusional movement from the epithelial layer to the mesenteric vein on the other.

Teratogenicity of Aino virus in the chick embryo

Aino virus (JaNAr 28 strain), a possible agent of a congenital anomaly of calves, was inoculated into the yolk sac of chick embryos at a dose of 10(2), 10(3), 10(4) or 10(5) TCID50 0.2 ml-1 at four, six or eight days of incubation. At 21 days of incubation all the unhatched embryos or hatched chickens in the experimental and control groups were sacrificed for pathological examination. The incidence of hydranencephaly, cerebellar hypoplasia or agenesis and arthrogryposis or scoliosis was highest (85 per cent in the chicks inoculated with 10(3) TCID50 0.2 ml-1 at eight days of incubation. The lesions were very similar to those found in congenital abnormalities in calves suspected of a natural infection with Aino virus.

Proliferation and Teratogenicity of Aino Virus in Chick Embryos

Aino virus (AIV; JaNAr 28 strain) 103 TCID50/0.2 ml was inoculated in the yolk sac of 8‐day‐old chick embryos. Recovery and titration of the virus from various organs including the central nervous system (CNS) and skeletal muscle were performed at 2, 4, 7, 10 and 13 days after inoculation (PI). AIV was systemically disseminated and proliferated even 2 days PI. The titers of the recovered virus from the CNS and from skeletal muscle was the highest at 4 days PI and declined with time, whereas hydranencephaly, arthrogryposis and cerebellar hypoplasia developed at 7 days PI and gradually progressed until 13 days PI.

Effect of local hyperthermia and chemotherapy on MC29 virus-induced liver tumor transplanted into subcutis of chickens

1. A transplantable liver tumor induced by MC29 virus, whose specific utilization of glutamine in growth of the tumor had been well-demonstrated, was implanted in the subcutis of day-old chickens, and after 7-8 days, when the tumor had reached a soybean size, local hyperthermia with microwave and/or chemotherapy with 6-diazo-5-oxo-1-norleucine (DON), an inhibitor of glutamine metabolism, were given once a day for 7 days successively. 2. At the 7th day of experiment, the tumor growth ratio, expressed by mean +/- standard deviation was, in the tumor control group, 14.3 +/- 1.81; in DON group, 6.93 +/- 0.95; in local hyperthermia group, 3.24 +/- 2.25, and in DON+hyperthermia group, 0.61 +/- 0.57. 3. The body weight-gain ratio in the local hyperthermia group was evidently higher than that in the tumor control group. DON suppressed body weight gain most remarkably. 4. In the present transplantable tumor system, microwave local hyperthermia was more effective in tumor suppression and less hazardous to the host than our former whole-body hyperthermia.