The mutagenicity of bovine lactoferrin, which is an iron-binding glycoprotein in milk, was evaluated by the Ames mutagenicity test. A total of 5 test strains including 3 base-pair substitution-type strains, Salmonella typhimurium TA100, TA1535 and Escherichia coli WP2uvrA, and 2 frameshift-type strains, TA98 and TA1537, were used in the test. The test was performed by both the direct method and the metabolic activation method with preincubation applied in each instance. The concentration range of the test solution was 0.16 to 5.00 mg / 100μl (plate). Results of the test revealed that the number of revertant colonies at each concentration of the test solutions was less than 1.4 times that of the control group. In the test system used, bovine lactoferrin did not exhibit mutagenicity.

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In our previous investigation, which focused on two-stage carcinogenicity in the thyroid, rats were administered N-bis(2-hydroxypropy1)nitrosamine(DHPN), followed by thiourea(TU)over an experimental period of 19 weeks. Simultaneous treatment with a high level of vitamin A(VA)enhanced the induction of proliferative lesions that originated from the thyroidal follicular epithelium. To examine whether hormone synthesis in the thyroid could be inhibited by simultaneous treatment with a large amount of VA and TU, all of the rats were initially given a single subcutaneous injection of 2, 800 mg DHPN / kg followed by a supply of 0% TU+0% VA(DHPN only, control group), 0.2% TU in their drinking water(DHPN / TU group), 0.1% VA in their diet(DHPN / VA group), or 0.2% TU+0.1% VA(DHPN / TU+VA group)during an experimental period of 4 weeks. Results obtained indicate that the iodine uptake and organification, namely iodination of tyrosine residue in thyroglobulin, of the thyroid, were significantly decreased in the DHPN / TU group compared to the DHPN control group. The variation in these values was attributable to the inhibitory effect of TU upon thyroid hormone synthesis. Results obtained from the DHPN / TU+VA and DHPN / TU groups were comparable. Therefore, the possibility that modification of hormone synthesis contributes to the enhancing effect of simultaneous treatment with a large amount of VA on thyroidal tumor induction by TU is considered to be very minimal.

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The comedogenicity of squalene peroxides was examined on the rabbit ear skin after topical application of squalene-monohydroperoxide (Sq-OOH), the initial product when squalene was irradiated with UV-A. Since comedogenic products from UV-irradiated squalene were extracted with methanol solution, we isolated Sq-OOH by reverse-phased HPLC with a methanol mobile phase solvent. The degree of comedogehnic reaction induced by Sq-OOH was higher than that of well-known comedogenic cosmetic ingredients. Unlike two other mono-peroxides, tert-butyl hydroperoxide and cumene-mono-hydroperoxide, Sq-OOH induced comedo-formation in the rabbit ear skin. However, the comedogenicity of reduced SqOOH, squalene-hydroxide (Sq-OH) and squalene itself was lower than that of Sq-OOH. These results indicate that Sq-OOH is a potent comedogenic mono-hydroperoxide chemical to rabbit skin.

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Crj:CD(SD)IGS rats were orally administered valproic acid at doses of 250, 500 or 1000 mg / kg / day for 4, 7 or 10 weeks. At each dose, one group of male rats was euthanized after 4-week dosage (4-week dose group) and the other two were mated with untreated females after 4 (7-week dose group) or 7 (10-week dose group) weeks of treatment with valproic acid and their fertility was evaluated. Females were euthanized on day 14-l7 of gestation, and numbers of corpora lutea, implantations and live and dead fetuses were recorded. After 4, 7 or 10 weeks of treatment, males were euthanized, genital organs were weighed, the number of sperm in the cauda epididymis was counted, sperm motion analyzed, and histopathological examination of testes performed. The male rats of the 1000 mg / kg dose group died or were moribund 3 or 4 days after the start of treatment. No effects on fertility of male rats were observed up to the 500 mg / kg 10-week dose group. Treatment for 4 weeks at 500 mg / kg / day decreased epididymis weight. After 7 weeks at 500 mg / kg / day, the weights of epididymis, seminal vesicles and prostate were decreased, and the number of sperm heads per cauda epididymis and percentage of motile sperm were reduced. In the 500 mg / kg 10-week dose group, the weight of testis was decreased. On histopathological examination of the testis, degeneration of seminiferous tubules and loss or exfoliation of spermatids were observed, and the ratio of retention of step 19 spermatids in stage IX-XI was increased in the 500 mg / kg 4-, 7- and 10-week dose groups. These results suggest that analysis of sperm motion and histopathological evaluation of testes are sensitive methods for assessing toxicity of valproic acid on male reproductive organs.

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Peripheral neuropathy, which accompanies aging, occurs during the long-term rearing of laboratory animas. The present study set out to delineate the clinical and functional features of this neuropathy. A total of 2000 B6C3F1 female mice, in groups of 5 to 20 mice, were sacrificed and autopsied each week beginning at 5 weeks and continuing to 130 weeks of age. Examination for histopathologic changes was conducted on the dorsal nerve roots, sciatic nerves, peroneal nerves, tibial nerves, plantar nerves and brachial nerve plexuses. At 90 weeks of age or later, peripheral neuropathy, characterized by axonal degeneration and Schwann cell proliferation, were observed mainly in the sciatic nerves, brachial nerve plexus and peroneal nerves. These spontaneous age-related nerve lesions appeared in all animals by 100 weeks of age in all nerves, and increased with increasing age. The nerve lesions were most prominent in the distal sciatic nerve. The rectal and hind-limb surface temperatures, motor nerve conduction velocity, blood glucose and HbA_1c decreased with increasing age. Elevation of sorbitol contents in sciatic nerves and reduction of myo-inositol levels were also detected in 120-week-old mice. However, except for blood glycemic parameters, no correlation with peripheral nerve lesions could be demonstrated. Spontaneous hypoglycemia(<40 mg / dL)persisted throughout the day in a small percentage(<5%)of animals aged 80 weeks or more; these animals had extensive lesions in the peripheral nerves and showed decreased plasma levels of HbA_1c and frucutosamines and increased plasma levels of ketones. These results suggest that spontaneous peripheral nerve disorders which accompany aging might worsen if spontaneous age-related hypoglycemia is also present. Such age-related changes must be taken into consideration in experimental studies performed on mice of this age.

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To cast light on whether the carcinogenic risk of 2, 6-dimethylaniline (DMA), a metabolite of xylazine, may increase by ingestion of edible tissues from domestic animals treated with xylazine, the following studies of xylazine and DMA were performed. In Experiment I, male F344 rats received a single oral administration of 150 mg / kg of xylazine hydrochloride. Rats showed symptoms suggesting loss of sensation and pain immediately after the treatment. These signs had disappeared after 3 hr, but the animals died of hydrothorax and pulmonary edema by 9 hr. The plasma concentration of xylazine was 2.88±0.95μg / ml at 15 min, and then decreased to 0.10±0.01μg / ml at 6 hr. The plasma level of DMA remained at 0.03 to 0.04μg / ml during the measurement period. In Experiment II, male F344 rats were fed a diet containing 1000 ppm of xylazine hydrochloride, regarded as the maximum tolerated dose, for 4 weeks. No clear clinical signs were evident and the plasma levels of xylazine and DMA were at the detection limit(0.02μg / ml)or less, although follicular cell hypertrophy of the thyroid was observed in all the treated animals. In Experiment III, male F344 rats were fed a diet containing 3000 ppm or 300 ppm of DMA for 4 weeks. Histological changes, such as atrophy of Bowman's gland and irregular arrangement of olfactory epithelial cells, were only observed in the olfactory epithelium of the 3000 ppm group. The plasma levels of DMA were 0.20 to 0.36μg / ml in the 3000 ppm group, but under the detection limit in the 300 ppm group. These results suggest that the probability of nasal carcinogenic effects of DMA on consumers via ingestion of edible tissues from food-producing animals treated with xylazine is extremely low, since DMA levels in the blood of rats subjected to continuous administration of high doses of xylazine remained under the detection limit.

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In this study, 72 newborn infants who were followed with the diagnosis of poisoning in Erciyes University Faculty of Medicine, Department of Pediatrics, Division of Neonatology, between 1975 and 1997 were evaluated retrospectively. Our purpose was to emphasize the importance of newborn poisoning among general poisoning in childhood. The age of infants ranged from 10 min to 25 days(0.82±2.81days). Forty-seven(65.2%)infants were poisoned before or during delivery. Of the 47 infants' mothers, 46 had preeclampsia or eclampsia, and 27 received only magnesium sulfate ; nine magnesium sulfate+diazepam ; four magnesium sulfate+nifedipine ; and the others received various drug combinations. Aside from these, one mother had Addison's disease and she used long-term dexamethasone during her pregnancy. In the newborn period, five(6.9%)infants inhaled organophosphate insecticides ; eight(11.1%)ingested corrosive agents(four benzalkonium chloride ; three chlorhexidine gluconate+cetrimide and an infant ammonium) ; four(5.5%)were poisoned by overdose of digoxin ; three(4.1%)ingested overdose of phenobarbital ; and two(2.7%)received acepromazine maleate. In addition, each infant ingested diphenoxilate HCL+atropine sulfate, pipenzolate bromid and tizanidine HCL. Follow-up period of the infants ranged from 24 hr to 26 days(0.82±2.81 days). The mortality rate was 17%(12 / 72). Death was not noted in the infants who were followed with poisoning after delivery. The causes of death were as follows : sepsis in four infants, meningitis, respiratory distress syndrome and necrotizing enterocolitis in two infants each, and the effects of overdose of magnesium sulfate and diazepam in two infants, respectively. In conclusion, we would like to stress that newborn infants whose mothers received magnesium sulfate or another drug during pregnancy or delivery should be closely monitored, and calculation of drug doses should be carefully taught to hospital nurses. When baby-rooms are disinfected with organophosphate insecticides in a hospital or house, infants should be removed from the room for at least 24 hr, and use of drugs should be explained in detail to the mothers.

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We studied the effects of semotiadil fumarate(SF), a new calcium antagonist with a unique benzothiazine structure, on the thyroid gland and liver in rats and compared them with those of another calcium antagonist, nicardipine(NCD), a well-known thyroidal hypertrophic agent and microsomal enzyme inducer, phenobarbital(PB), and goitrogen propylthiouracil(PTU). In oral 2-week treatment, SF caused increases in hepatic microsomal protein levels, uridine diphosphate glucuronosyltransferase(UDPGT)activity and an increase in serum thyroid stimulating hormone(TSH)level together with decreases in serum thyroid hormone levels. These results suggest that SF accelerates peripheral disposition of thyroid hormones and subsequently stimulates secretion of TSH from the pituitary gland as a compensatory response. PB and NCD had similar effects on the thyroid gland and the liver. PTU showed obvious thyroid hyperplasia and an increase in relative liver weight. Drastic increase in TSH level was observed in the PTU-treated group together with significant decreases in serum thyroid hormone levels and an increase in hepatic UDPGT activity. Histopathologically, PTU depleted the colloids in follicles, suggesting the inhibition of thyroid hormone synthesis. SF, PB and NCD showed thyroidal hyperplasia, but the extent of the change was far more moderate than that induced by PTU. These results indicate that the effect of SF is similar to those of PB and thyroid hypertrophy seen in the oral 2-week treatment with SF, and may be caused by indirectly elevated TSH levels which resulted from the induction of hepatic UDPGT activity.

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The mouse popliteal lymph node assay(PLNA)has been proposed as an immunotoxicological test to predict allergenic chemicals. However, PLN response is also observed in association with non-specific activation induced by some irritants. We, therefore, examined the kinetics of the PLN cellularity indices of primary and secondary responses. Flow cytometric analysis was used to measure the proportions of T and B cells in PLN. Male ICR mice were subcutaneously injected with TNBS(an allergenic compound)or SDS(an irritant compound)in the left hind footpad, and with vehicle in the right one. On day 28 after first injection, mice were injected with 1 / 10 or 1 / 100 dose of the initial injection. On day 7 after first injection of TNBS, primary response reached maximal PLN cellularity index(16.5). On day 2 after second injection, secondary response reached maximal PLN cellularity index(13.1).A marked increase in proportion of B cells was observed in the PLN. On the other hand, after first injection of SDS, primary response reached maximal PLN cellularity index(2.8)on day 10, but neither secondary response nor increase in the B cell proportion were observed. These results suggest that the detection of secondary response and the flow cytometric analysis are useful in differentiating responses to allergenic and irritant compounds in the PLNA.

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The effect of insulin-induced hypoglycemia on spontaneous peripheral neuropathy in aged mice was examined. Ninety-five-week-old female B6C3F1 mice were infused subcutaneously for 2 weeks with 40 or 80 IU / kg / day of insulin with a micro osmotic pump. Blood glucose level was decreased during the infusion(4.3-6.8 mmol / L in mice receiving 40 IU / kg / day of insulin or 2.4-5.4 mmol / L in mice receiving 80 IU / kg / day of insulin versus 6.5-7.6 mmol / L in control mice). In histopathological examination, axonal degeneration and / or remyelination were observed in a small number of nerve fibers of control mice. Similar nerve fiber lesions were observed in mice receiving 40 IU / kg / day of insulin, whereas severer lesions with an increase in segmental axonal degeneration of nerve fibers were observed in 4 / 7 mice receiving 80 IU / kg / day of insulin. These findings suggest that spontaneous peripheral neuropathy in aged mice is exacerbated by sustained hypoglycemia induced by insulin treatment.

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[in Japanese]

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[in Japanese]

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