Biomedical subjects

Shuji Noda

Publications and source records attributed to Shuji Noda.

At least 19 recordsLinked to original sources

PubMed2006

A novel ruthenium sensitizer with a hydrophobic 2-thiophen-2-yl-vinyl-conjugated bipyridyl ligand for effective dye sensitized TiO2 solar cells.

A hydrophobic and 2-thiophen-2-yl-vinyl-conjugated ruthenium complex, cis-Ru(dhtbpy)(dcbpy)(NCS)2 [dhtbpy = 4,4'-di(hexylthienylvinyl)-2,2'-bipyridyl; dcbpy = 4,4'-dicarboxy-2,2'-bipyridyl], was newly designed, synthesized and applied successfully to sensitization of nanocrystalline TiO2-based solar cells, giving a conversion efficiency of 9.5% under irradiation with AM 1.5 solar light.

Journal Article↗

PubMed2005

Ability of the Hershberger assay protocol to detect thyroid function modulators.

In vivo screening methods for detection of thyroid function modulators are now under development in many research laboratories. We assessed the applicability of the Hershberger assay protocol to screen for thyroid function modulators. In experiment 1, castrated male BrlHan WIST@Jcl (GALAS) rats were administered a potent thyroid peroxidase inhibitor, 3-amino-1,2,4-triazole (AT), in doses of 0, 40, 200, and 1,000 mg/kg/day with gravimetric endpoint, and in experiment 2, castrated and intact male rats were administered in doses of 0, 40, and 200 mg/kg/day, with quantification of the extent of hypertrophy of the thyroid epithelium, to assess the effects of castration, by gavage to 8-week-old for 10 consecutive days. At necropsy of both experiments, the thyroid glands and hypophysis were collected and fixed with 10% neutral-buffered formalin. To avoid crushing during weighing because of their fragility, the thyroid glands and hypophysis were weighed approximately 24 h after fixation with 10% neutral-buffered formalin. All animals were sacrificed approximately 24 h after the final dose. In experiment 2, the thyroid glands of all animals were stained with hematoxylin and eosin for histological examination and morphometry of follicular epithelial height. In experiment 1, absolute and relative thyroid weights in all of the AT groups were statistically increased in a dose-dependent manner, regardless of the testosterone propionate (TP)-injection. In experiment 2, the results showed a significant increase in thyroid weight in the 200 mg/kg groups of both castrated and intact rats. Hypophyseal weight was unaltered by AT, but comparison of vehicle-treated groups showed that the hypophyseal weight of the castrated rats was greater than that of the intact rats. Enlarged thyroid glands were observed in the AT-treated rats at necropsy. Histological examination of the thyroid glands of all the AT-treated animals showed hypertrophy and hyperplasia of the follicular epithelial cells, and the height of follicular epithelium of the thyroid glands increased in a dose-dependent manner in both the castrated and intact rats. In experiment 1, assessment of the (anti-) androgenic action of AT in seminal vesicle weight revealed a significant increase in the 200 and 1,000 mg/kg + TP groups in a dose-dependent manner. These results suggest that the effect of AT can be detected by the Hershberger assay 10-day administration protocol and may be useful for screening for thyroid function modulators regardless of whether the animals have been castrated.

Amitrole↗

PubMed2005

Preliminary evaluation of an in utero-lactation assay using 6-n-propyl-2-thiouracil.

In this preliminary study, the potential of an in utero-lactation assay to detect thyroid effectors was evaluated by treating three dams/group with 6-n-propyl-2-thiouracil (PTU), a known thyroid antagonist, by oral gavage at doses of 0, 0.0032, 0.016, 0.08 and 0.4 mg/kg/day during fetal organogenesis and lactation. Hearing disturbances and an elevated relative thyroid weight were observed in offspring of both sexes in the 0.4 mg/kg/day group. The Biel-type water T-maze test showed an increase in the number of errors made by females in the 0.4 mg/kg/day group. Histopathologically, flattening of follicular epithelium, a decrease in resorptive colloid droplets, degeneration of follicular epithelium, and hyperplasia of follicular epithelium were observed in males belonging to the 0.4 mg/kg/day group. Histopathological abnormalities were also observed in some offspring belonging to the 0.08 mg/kg/day group. In the dams, hypertrophy of the follicular epithelium of the thyroid was observed in the 0.4 mg/kg/day group. Although we could not explain the mechanism for the difference in the effects seen in the offspring and the dams, the effect of PTU in utero through lactational exposure is apparently different from that resulting from exposure in homeostatically mature rats. Most reports studying PTU have involved administration in water or in food, and reports on the oral gavage of PTU during the fetal organogenesis and lactation period are very rare. This assumes that dosages >0.4 mg/kg/day would also produce clear anti-thyroid effects by oral gavage and, possibly, emphasizes that dosages <0.4 mg/kg/day did not have a noticeable effect. Based on the present results, a study to determine the reproducibility of the data in a much larger number of dams will be performed to confirm the findings in the present study, and to evaluate other endpoints, such as hormonal evaluation of dams and their offspring, sexual developmental landmarks, and fertility of the offspring.

Animals↗

PubMed2005

Effects of in utero and lactational exposure to flutamide in SD rats: comparison of the effects of administration periods.

Pregnant CD(SD) IGS rats were given flutamide (FLUT) orally at doses of 0.4, 2, or 10 mg/kg/day from gestational day 6 to postnatal day (PND) 20, and the effects of FLUT exposure on male offspring were examined 10 weeks after birth, and compared to the effects in offspring treated after weaning and in offspring untreated after weaning. Although the body weight of the dams treated with FLUT remained normal, two dams in the 10 mg/kg/day group were killed because of abnormal parturition periods and loss of all the pups. The number of stillborns and dead newborns at birth was significantly higher in the 10 mg/kg/day group than in the control groups. No abnormalities in the reproductive parameters of the other dams treated with FLUT were detected. The body weights of the male offspring in each group remained normal from birth until the end of the study. The ano-genital distance was significantly shortened in 2 and 10 mg/kg/day groups. Changes in the organ weights and gross findings were detected in the 2 and/or 10 mg/kg/day groups with or without the continuous administration of FLUT after weaning; these changes were more appreciable in groups treated with FLUT after weaning than in groups untreated after weaning. The prolongation of preputial separation was observed in the 0.4 and 2 mg/kg/day groups treated with FLUT after weaning, but this change was not detected in the same dose groups untreated after weaning. The testosterone levels were higher in the 10 mg/kg/day group treated with FLUT after weaning. The present data demonstrated that the endocrine-mediated effects on rats were more appreciable in offspring treated with FLUT after weaning than in offspring untreated after weaning.

Abnormalities, Drug-Induced↗

PubMed2005

Effects of in utero and lactational exposure to tamoxifen in SD rats.

Pregnant CD (SD) IGS rats were given tamoxifen (TMX) orally at doses of 0.12, 0.6, or 3 microg/kg/day from gestational day 6 to postnatal day 21, and the effects of TMX exposure on all offspring were examined 10 weeks after birth; the reproductive performance of the offspring was also evaluated. Although the body weights of the dams treated with TMX remained normal from gestational day 6 until the day of autopsy (postnatal day 21), three dams in the 3 microg/kg/day group died during the pregnancy or partum periods. These deaths were regarded as the toxicological effects of TMX. No changes were detected in the reproductive parameters of all the TMX groups except for a decrease in the number of newborns/live newborns in the 3 microg/kg/day group. No abnormal clinical signs, body weight change, ano-genital distance, vaginal opening, or organ weight changes were detected in any of TMX groups, but the day of preputial separation was prolonged in the male offspring of all TMX groups and cleft phallus was detected in the female offspring of the 0.6 and 3 microg/kg/day groups. No abnormalities were detected in the reproductive performance of the male and female offspring.

Administration, Oral↗

PubMed2004

Comparative study of the uterotrophic potency of 14 chemicals in a uterotrophic assay and their receptor-binding affinity.

We performed an immature rat uterotrophic assay of 14 chemicals having various receptor-binding affinities in order to assess the relationship between their uterotrophic potency and receptor-binding affinity. The chemicals tested were phthalic acid di-n-hexyl ester, phthalic acid di-n-amyl ester, phthalic acid di-n-propyl ester, 2-ethylhexyl-p-hydroxybenzoate, 4,4'-biphenol, 4,4'-sulfonyldiphenol, 4,4'-dihydroxydiphenylmethane, 2,4-dihydroxybenzophenone, 4,4'-cyclohexylidenebisphenol, 4-t-butylpyrocatechol, clomiphene citrate, 4,4'-(1,3-phenylenediisopropylidene)bisphenol, p-t-butylphenol, and diallylterephthlate. Two of the 14 chemicals, phthalic acid di-n-propyl ester and diallylterephthlate, exhibited no receptor-binding affinity, and the receptor-binding affinity of phthalic acid di-n-hexyl ester and phthalic acid di-n-amyl ester was lower than that of the other chemicals. Ten of the chemicals showed uterotrophic potency, the exceptions being phthalic acid di-n-propyl ester, diallylterephthlate, phthalic acid di-n-hexyl ester, and phthalic acid di-n-amyl ester. The results of the present study demonstrate that the affinity of the chemicals in the receptor-binding assay correlated well with their potency in the uterotrophic assay except for a few chemicals with very low receptor-binding affinity.

Animals↗

PubMed2004

Differences in responsiveness of mouse strain against p-benzoquinone as assessed by non-radioisotopic murine local lymph node assay.

The non-radioisotopic modification of murine local lymph node assay (LLNA) by using 5-bromo-2'-deoxyuridine (BrdU) was conducted to investigate the strain-related difference of the responsiveness of mice to p-benzoquinone (PBQ) with BALB/cAnN, CBA/JN and CD-1 mouse strains. Strain and dose related differences were analyzed by two-way analysis of variance (two-way ANOVA). CBA/JN was considered to be the highest responsive strain to PBQ, and interaction was detected between CD-1 and each of the other inbred strains. These results support the recommendation in the OECD test guideline 429 and the skin sensitization test guideline of US-EPA with regard to the selection of mouse strain for LLNA.

Analysis of Variance↗

PubMed2003

In utero through lactational exposure to ethinyl estradiol induces cleft phallus and delayed ovarian dysfunction in the offspring.

Most of the attention currently focused on endocrine-active chemicals is directed to their effects on the development of offspring exposed to them in utero or during the neonatal period. Pregnant Crj:CD(SD)IGS rats were given ethinyl estradiol (EE) orally in doses of 0.5-50 microg/kg/day from gestational day 7 to postnatal day 18, and their offspring were examined for its effects. Our previous study according to a similar protocol demonstrated the occurrence of cleft phallus in the female offspring exposed to 50 microg/kg of EE in utero and during the lactation period. The present study was designed to assess (1) the reproducibility of the induction of cleft phallus, (2) the fertility of female rats with cleft phallus, and (3) whether any delayed effects, possibly delayed anovulation, were induced. At 50 microg/kg cleft phallus was observed in almost all of the female offspring, and slight retardation of body weight gain was detected in both sexes. At 15-17 weeks of age the animals with cleft phallus could copulate and had fertility comparable to the control group. At 6 months of age, on the other hand, 6/8 of the female offspring at 50 microg/kg exhibited abnormal cyclicity, including persistent estrus, and histological examination revealed follicular cysts and absence of corpora lutea in the ovaries of the rats with persistent estrus. These findings are consistent with delayed anovulation syndrome. The results suggest that observation of cyclicity at 6 months old is able to detect possible delayed ovarian dysfunction induced by perinatal exposure to chemicals.

Abnormalities, Drug-Induced↗

PubMed2002

Immature uterotrophic assay of estrogenic compounds in rats given diets of different phytoestrogen content and the ovarian changes with ICI 182,780 or antide.

To investigate the influence of phyotestrogens in the diet, an immature uterotrophic assay of ethinylestradiol, bisphenol A, 4-nonylphenol or genistein was performed in rats given the formula MF diet, modified NIH-07 open formula diet, or modified NIH-07 phytoestrogen-lowered-diet (study 1). The chemicals were administered subcutaneously from 20 days of age for 3 days. Doses of ethinylestradiol, bisphenol A, 4-nonylphenol or genistein were 0.06-0.6 micro g/kg per day, 1-10 mg/kg per day, 10-100 mg/kg per day or 1-20 mg/kg per day, respectively. In another study, an immature uterotrophic assay of genistein and ethinylestradiol together with ICI 182,780 or antide was performed to compare the ovarian changes with these chemicals (study 2). Doses of genistein or ethinylestradiol were 30 mg/kg per day or 0.6 micro g/kg per day, respectively, and these chemicals were injected subcutaneously from 20 days of age for 3 days. In study 1, there were no essential differences in the uterus weights among the various phytoestrogen-content diets. In study 2, the ovary weights in rats given genistein were significantly higher than in the controls, whereas the ovary weights in rats given ethinylestradiol were lower than in the controls. The ovary weights in the ICI 182,780 plus genistein group were significantly higher than in the genistein group, but decrease of the ovary weights was detected in the antide plus genistein group. There was no significant difference in ovary weights between the ICI 182,780 plus ethinylestradiol group and the ethinylestradiol group, but decrease of ovary weights was detected in antide plus ethinylestradiol group. In a histological examination of the ovary, fluid-filled follicles in the genistein group were more numerous than in other groups and increase of granulosa cell fragmentation was seen in the ethinylestradiol and other groups with the exception of the genistein group. The present findings demonstrate that the sensitivity of the immature rat uterotrophic assay is not influenced by the relatively low level of phytoestrogen in diets and that the ovarian changes occurring with genistein and ethinylestradiol are different.

Animals↗

PubMed2002

Changes of serum alpha 2u-globulin in the subacute oral toxicity study of ethynyl estradiol and bisphenol A based on the draft protocol for the 'Enhanced OECD Test Guideline No. 407'.

To investigate the usefulness of serum alpha 2u-globulin changes as a new parameter for detecting endocrine-mediated effects, we performed a 28-day repeated-dose toxicity study using the administration of bisphenol A (BPA) or ethynyl estradiol (EE) in male rats, based on the draft protocol of the 'Enhanced OECD Test Guideline 407 (enhanced TG 407)'. BPA at doses of 0, 40, 200 and 1000 mg/kg per day or EE at doses of 0, 15, 75 and 375 microg/kg per day were orally administered to SD rats. The highest dose of BPA was reduced to 600 mg/kg per day from the second week of the study onwards because a male rat given 1000 mg/kg per day of BPA died within the first week, showing toxic clinical signs. In the assay using BPA, a reduction in the level of alpha 2u-globulin was detected in the group receiving a dose of 600 mg/kg per day. Reductions in the absolute and relative ventral prostate weights were only observed in the 600 mg/kg per day group. In the assay using EE, the alpha 2u-globulin level decreased significantly in the 375 microg/kg per day group. A reduction in the absolute and relative dorsolateral prostate weights was also observed in the 75 and 375 microg/kg per day groups, morphologically abnormal sperm were observed in the 375 microg/kg per day group. Furthermore, atrophic changes in the prostate and seminal vesicle and degenerative changes in the testis were observed in the 375 microg/kg per day group. Although the alpha 2u-globulin level was reduced in this assay using BPA and EE, further studies are necessary before this assay becomes a useful method for detecting endocrine-mediated effects.

Administration, Oral↗

PubMed2002

Comparison of toxicity studies based on the draft protocol for the 'Enhanced OECD Test Guideline no. 407' and the research protocol of 'Pubertal Development and Thyroid Function in Immature Male Rats' with 6-n-propyl-2-thiouracil.

Two repeated-dose studies of 6-n-propyl-2-thiouracil (PTU) in male rats based on the research protocol 'Pubertal Development and Thyroid Function in Immature Male Rats' (pubertal assay) proposed by the Endocrine Disrupter Screening and Testing Advisory Committee (EDSTAC) and the draft protocol of the 'Enhanced OECD Test Guideline 407' (enhanced TG 407) were performed to investigate the suitability of both assays as screening methods for the detection of endocrine-mediated effects and to compare their sensitivity for the endocrine-mediated effects. In the pubertal assay, PTU at doses of 0, 0.01, or 1 mg/kg per day was orally administered to male Sprague-Dawley rats for 30 days, starting at 23 days of age. In the enhanced TG 407 the same doses of PTU were orally administered to male Sprague-Dawley rats for 28 days, starting at 7 weeks of age. In the pubertal assay, decreased serum thyroxine (T4) and triiodothyronine (T3), increased thyroid and pituitary weights, hypertrophy of follicular epithelial cells in the thyroid, and increased basophilic cells in the pituitary were detected as endocrine-mediated effects of PTU in the 1 mg/kg group. In the enhanced TG 407, decreased T4 and T3 were detected in both the 0.01 and 1 mg/kg groups, together with increased thyroid-stimulating hormone in the 1 mg/kg group, increased thyroid and pituitary weights in the 1 mg/kg group, and hypertrophy of follicular epithelial cells in the thyroid and increased basophilic cells in the pituitary of the 1 mg/kg group. Thus, among the parameters tested, the thyroid hormone levels, organ weight changes, and the histopathological assessment allowed detection of the endocrine-related effects of PTU in both the pubertal assay and the enhanced TG 407, but the sensitivity of the hormone analysis was higher in the latter.

Animals↗

PubMed2002

Subacute oral toxicity study of ethynylestradiol and bisphenol A, based on the draft protocol for the "Enhanced OECD Test Guideline no. 407".

We performed a 28-day repeated-dose toxicity study of ethynylestradiol (EE) and bisphenol A (BPA) based on the draft protocol of the "Enhanced OECD Test Guideline no. 407", and assessed the sensitivity of a list of parameters for detecting endocrine-related effects of endocrine disruption. Doses of EE at 0, 10, 50 or 200 microg/kg per day, or BPA at 0, 40, 200 or 1000 mg/kg per day were orally administered to Sprague-Dawley rats. The highest dose of BPA was decreased to 600 mg/kg per day from the second week of administration because a male rat given 1000 mg/kg BPA had died within 1 week with toxic clinical signs. In the assay using EE, the decrease of prostate, seminal vesicle and pituitary weights, increase of the testis weight, atrophic changes of the prostate, seminal vesicle and mammary gland, and degenerative changes in the testes were detected in male rats in the 50 and/or 200 microg/kg groups. In females of the 200 microg/kg group, decrease of the ovary weight, increase of the uterine weight, atrophy of the ovary, hypertrophy or squamous metaplasia of the uterine epithelial cells and mucification in the vagina were observed. Furthermore, diestrous, estrous or the unknown stage was prolonged in the 50 and 200 microg/kg groups of rats. Endocrine-mediated effects of EE were not detected in general observations, hematology, serum biochemistry, or hormonal or spermatological examinations. In the assay using BPA, the diestrous stages were prolonged at the highest dose, but changes related to endocrine effects were not detected in other examinations. Thus, among the parameters tested, the weight of endocrine-linked organs and their histopathological assessment and estrous cycle stage allowed the detection of the endocrine-related effect of EE, whereas the estrous cycle stage was only a useful parameter to detect the effect of BPA.

Administration, Oral↗

PubMed2002

The efficacy of endocrine disruptor screening tests in detecting anti-estrogenic effects downstream of receptor-ligand interactions.

Several predictive test methods for endocrine disrupters have been evaluated by international organizations. In this study, we performed a series of predictive tests for endocrine disrupters, i.e. the receptor binding assay, reporter gene assay, and immature rat uterotrophic assay, on all-trans retinoic acid (tRA), which may cause antiestrogenic activity via their receptors, interfere with estrogenic action at estrogen responsive element level, and we examine the efficacy of endocrine disruptor screening tests in detecting anti-estrogenic effects downstream of receptor-ligand interactions. Despite showing complete lack of binding affinity to ER in the receptor binding assay, tRA exhibited clear antagonist activity without any agonist activity in the reporter gene assay. In the in vivo test, tRA was subcutaneously administered to immature Crj:CD (SD) IGS rats at doses of 5 and 25 mg/kg per day for 3 days, beginning at 20 days of age. Additional groups of rats given tRA at the above doses were also subcutaneously injected with ethinyl estradiol (EE) at a dose of 0.6 microg per rat per day. A vehicle control group given olive oil alone and a positive control group given EE alone were also established. Although no uterotrophic activity was detected in any of the rats given only tRA, co-treatment with 5 and 25 mg/kg tRA and EE reduced the EE-induced increases in uterine weight. We confirmed that the ER antagonist activity of tRA may be mediated by transcriptional interference after ER-ligand complex binding to an estrogen responsive element of the gene by the gel mobility shift analysis. These findings suggest the reporter gene assay and uterotrophic assay can detect anti-estrogenic effects downstream of receptor-ligand interactions, but the receptor binding assay can not detect this type of interference. In any case, a screening strategy for endocrine disrupters, especially the primary screening battery for prioritizing the chemicals to be tested in the higher screening stages, should be designed to detect various kinds of chemicals possessing endocrine modulating activity including a retinoid-like endocrine modulator. Accordingly, reporter gene assay or uterotrophic assay should be conducted in the early stage of screening process for endocrine disrupting chemicals, because they can detect antagonist activity caused by both inhibition of receptor-ligand interaction and transcriptional interference. Particularly, the reporter gene assay may be a promising prescreening procedure, because it can be adopted in the high throughput screening process for thousands of chemicals and it requires no use of experimental animals.

Animals↗

PubMed2002

Uterotrophic and Hershberger assays for n-butylbenzene in rats.

We performed the uterotrophic and Hershberger assays proposed by the OECD to investigate the estrogenic and androgenic effects of n-butylbenzene (nBB). For the uterotrophic assay, nBB was injected subcutaneously at doses of 0, 40, 200, 1000 and 2000 mg/kg to 19-day-old rats for 3 days. In some rats, ethynylestradiol (EE) was also injected subcutaneously at a dose of 0.6 microg/kg after the administration of nBB. There were essentially no differences in the uterine wet or blotted weights between the control and any of the nBB-treated groups, or between the control and any of the nBB plus EE-treated groups. For the Hershberger assay, nBB was administered orally at doses of 0, 200 and 600 mg/kg to 56-day-old castrated rats for 10 days. In some rats, 0.4 mg/kg testosterone propionate (TP) was also administered by subcutaneous injection after the administration of nBB. Doses of 0, 200 and 600 mg/kg nBB were also administered orally to non-castrated rats. The weights of the accessory sex organs of the castrated rats showed no significant differences between the control and any of the nBB-treated groups or between the control and the nBB plus TP-treated groups. No significant differences in the weights of the accessory sex organs of the non-castrated rats were observed between the control and the nBB-treated groups. These findings suggest that nBB does not have any endocrine-disrupting properties on in vivo screening tests.

Administration, Oral↗

PubMed2002

Age-related changes of genital systems in the female Crj:CD (SD) IGS rats during sexual maturation.

The age-related changes of vaginal opening, body weight, the weights of the uterus and ovary, together with histological examination, serum 17beta-estradiol (E2) and progesterone levels were examined in intact female Crj:CD (SD) IGS rats between 21 and 36 days of age to understand the basic biological profile of changes of the female genital system during sexual maturation in the rat for female pubertal assays. With the beginning of the elevation of serum E2 level from 28 days of age, all parameters except body weight started to show drastic change until 31 days of age. The highest incidence of vaginal opening was recorded at 34 days of age. On macroscopic examinations, a number of rats showed uterine imbibition but vaginal opening. Immediately after the confirmation of the vaginal opening, the genital systems of three rats were observed microscopically. Both ovaries already had multiple corpora lutea, and degeneration of endometrial epithelial cells was observed. In conclusion, we obtained essential data on genital tract development of female Crj:CD (SD) IGS rats for in vivo screening assays that will contribute to detect potential endocrine active chemicals. In addition, it is assumed that the first ovulation precedes or occurs simultaneously with vaginal opening.

Age Factors↗

PubMedDate not supplied

Advantage of using CBA/N strain mice in a non-radioisotopic modification of the local lymph node assay.

The murine local lymph node assay (LLNA) is currently recognized as a stand-alone test method for determining the skin sensitizing potential of chemicals. It has been incorporated into the official test guidelines published by some authorities, including the OECD. To avoid the use of radioisotopes, efforts have been made recently to develop non-radioisotopic modifications of the LLNA. A non-radioisotopic modification of the LLNA was developed previously using 5-bromo-2'-deoxyuridine (BrdU) incorporation (non-RI LLNA). However, the non-RI LLNA was found to be somewhat less sensitive than the standard assay. This study reports the advantage of using mice of the CBA/N strain in the non-RI LLNA to improve the sensitivity of this method. The non-RI LLNA was performed using CBA/JN and CBA/N mice exposed to one of four confirmed skin sensitizers, 2,4-dinitrochlorobenzene (DNCB), eugenol (EG), isoeugenol (IEG) or alpha-hexylcinnamic aldehyde (HCA), and to one non-sensitizer, propylene glycol (PG). The EC3 values for DNCB, IEG, EG, HCA and PG were calculated to be 0.1%, 9.6%, 40.6%, 45.5% and >50% in CBA/JN mice and 0.08%, 1.9%, 10.7%, 20.3% and >50% in CBA/N mice, respectively. The EC3 values for DNCB, IEG, EG, HCA and PG in the standard LLNA using CBA/Ca mice and radioisotopes were reported elsewhere as being 0.08%, 1.3%, 13.0%, 8.0% and >50%, respectively. The EC3 values derived from the CBA/N mice in the non-RI LLNA were nearly equivalent to the EC3 values obtained using the standard radioisotopic LLNA with CBA/Ca mice. These data suggest that the use of CBA/N mice may provide a realistic opportunity to develop a version of the LLNA that does not have a requirement for the use of radioisotopes, but which nevertheless has sensitivity approaching, or comparable to, the standard method.

Acrolein↗

PubMedDate not supplied

Assessment of the skin sensitization potency of eugenol and its dimers using a non-radioisotopic modification of the local lymph node assay.

Allergic contact dermatitis is a serious health problem. There is a need to identify and characterize skin sensitization hazards, particularly with respect to relative potency, so that accurate risk assessments can be developed. For these purposes the murine local lymph node assay (LLNA) was developed. Here, we have investigated further a modi fi cation of this assay, non-radioisotopic LLNA, which in place of tritiated thymidine to measure lymph node cell proliferation employs incorporation of 5-bromo-2'-deoxyuridine. Using this method we have examined the skin sensitizing activity of eugenol, a known human contact allergen, and its dimers 2,2'-dihydroxyl-3,3'-dimethoxy-5,5'-diallyl-biphenyl (DHEA) and 4,5'-diallyl-2'-hydroxy-2,3'-dimethoxy phenyl ether (DHEB). Activity in the guinea pig maximization test (GPMT) also measured. On the basis of GPMT assays, eugenol was classified as a mild skin sensitizer, DHEA as a weak skin sensitizer and DHEB as an extreme skin sensitizer. In the non-radioisotopic LLNA all chemicals were found to give positive responses insofar as each was able to provoke a stimulation index (SI) of >or=3 at one or more test concentrations. The relative skin sensitizing potency of these chemicals was evaluated in the non-radioisotopic LLNA by derivation of an ec(3) value (the concentration of chemical required to provoke an SI of 3). The ec(3) values calculated were 25.1% for eugenol, >30% for DHEA and 2.3% for DHEB. Collectively these data suggest that assessments of relative potency deriving from non-radioisotopic LLNA responses correlate well with evaluations based on GPMT results. These investigations provide support for the proposal that the non-radioisotopic LLNA may serve as an effective alternative to the GPMT where there is a need to avoid the use of radioisotopes.

Allergens↗

PubMedDate not supplied

Effect of gonadotropin-releasing hormone antagonist on ovarian and uterine weights in immature female rats.

The immature rat uterotrophic assay has been proposed as a screening test method for detecting estrogenic and antiestrogenic chemicals. Although the immature rat uterotrophic assay is advantageous because the test animals are not traumatized by the ovariectomizing process, the effect of endogenous estrogen on ovarian and uterine weight in the immature animals that are used in immature rat uterotrophic assay has not received much attention. In this study, 19-day-old rats were treated with antide, a gonadotropin-releasing hormone antagonist, antide, to block gonadal production of endogenous estrogen. Uterine and ovarian weights of the antide-treated animals were markedly lower than those of control animals. This finding suggests that endogenous gonadal estrogen may already be acting on the uterus and ovaries in immature rats. Blocking endogenous estrogen with a gonadotropin-releasing hormone antagonist may enhance the sensitivity of the immature rat uterotrophic assay; however, the possibility that this protocol may interfere with the ability of the immature rat uterotrophic assay to detect centrally-mediated effects can not be discounted.

Animals↗