Thyroid proliferative lesions induced by anti-thyroid drugs in rats are not always accompanied by sustained increases in serum TSH

To examine changes in serum TSH and determine whether the sustained excess is necessary for the development and/or progression of thyroid tumors, male F344 rats were administered drinking water containing thiourea (TU), at 0.1 or 0.05%, or sulfadimethoxine (SM), at 0.025 or 0.0125%, for one week in Experiment I. All of the treated animals showed decreased serum levels of T3 and T4 and an increased TSH. In Experiment II, male rats were given a s.c. injection of N-bis(2-hydroxypropyl) nitrosamine (DHPN:1500 mg/kg BW) and, starting one week later, received drinking water containing the same doses of TU or SM as in Experiment I for the following 20 weeks. Thyroid follicular proliferative lesions were induced in most rats treated with TU and SM. However, these treated animals did not demonstrate any consistent alterations in serum T3, T4 and TSH levels, except for the high dose TU group. The present studies thus suggest that thyroid tumors can grow even under conditions of fluctuating serum TSH levels during the progression phase, although TSH stimulation might be an absolute requirement in the early phase of tumor development.

Time course observation of thyroid proliferative lesions and serum TSH levels in rats treated with thiourea after DHPN initiation

Time course changes in serum TSH and quantitative data for thyroid proliferative lesions in male F344 rats administered N-bis(2-hydroxypropyl)nitrosamine (DHPN: 2000 mg/kg body weight, single s.c. injection) followed by 0.1% thiourea (TU), were assessed at weeks 1, 2, 4, 8, 12 and 16 of treatment. The serum T4 level in the TU group was markedly decreased at week 1 and remained significantly lowered throughout the experiment. Serum TSH levels, in contrast, were elevated up to a peak at around week 4 with a return to the normal range at week 12. Thyroid weights in the TU group were increased significantly in a treatment period-dependent manner. Histopathologically, marked hypertrophy of thyroid follicular cells occurred at the early stage of TU treatment. Proliferative lesions, such as hyperplasia and adenomas, occurred from weeks 2 and 4, respectively, and increased with the later treatment period. The cell proliferative activity of follicular cells, assessed by BrdU incorporation, was high until week 2, but then returned to normal. The initially appearing hyperplasias and adenomas were characterized by marked proliferation but this also greatly decreased at later stages when TSH was no longer elevated. The results of our study thus suggest that a high serum TSH level plays an important role in the early phase of thyroid tumorigenesis and 8 weeks treatment with test substances is sufficient for detection of thyroid tumor promoter potential in two-stage thyroid carcinogenesis models.

Synergistic effects of phenobarbital and thiourea on proliferative lesions in the rat liver

To evaluate the effects of phenobarbital (PB) and thiourea (TU), alone or in combination, on proliferative lesions of the liver, thyroid and lung, male F344 rats initiated with 2000 mg/kg body weight N-bis(2-hydroxypropyl) nitrosamine (DHPN) were given diet and/or drinking water containing 0% PB/TU (group 1), 1000 ppm PB (group 2), 0.1% TU (group 3) and 500 ppm PB and 0.05% TU (group 4), from weeks 2 to 20 for 19 weeks. Group 4 showed remarkable increases in the number of hepatocellular altered foci per animal, the values being superior to the averages of groups 2 and 3. The number of thyroid proliferative lesions per animal was highest in group 3 and lowest in group 2. Lung proliferative lesions were induced in all groups, but no modifying influence on their development was evident in the combined group. The present results indicate that combined administration of PB and TU exerts synergistic enhancing effects on hepatocarcinogenesis.

[Efficacy of individual smoking cessation instructions for general smokers among clients of a health center]

Smoking cessation instruction for individuals using a standardized smoking cessation manual and a handout developed by the authors was studied in a controlled trial among employees who visited a health center for Industrial Safety and Health Law mandated annual health examinations. Smokers in the study group were given 5-10 minutes smoking cessation instruction mainly by public health nurses and nutritionists following the above-mentioned manual and using the handouts. Subjects in both groups were interviewed by telephone to assess changes in smoking habits one month after the first contact. Smoking clients who came on Friday (132) and on Monday (93) were assigned to study and control groups, respectively. One hundred and nineteen members (90.2%) of the study group and 88 (94.6%) of the control group were successfully followed until one month after the initial contact. Seven subjects in the study group were not smoking one month after the instruction, while no one gave up smoking in the control group (p less than 0.05). It was confirmed by telephone survey that 6 of the 7 subjects who were not smoking at one month were still maintaining abstinence from smoking one year after the instruction. Smokers who did not stop smoking reported a reduction in their smoking dose in the study group. Lighter smokers reacted more readily to instruction than did heavier smokers and the knowledge level of subjects was positively associated with the success rate.

[Sequential changes of the activities of the dog tracheal secretory cells caused by intraduodenal application of brovanexine]

The effects of brovanexine (BvX) on secretory activities of tracheal secretory cells and on behavior of mucus glycoprotein in these cells were investigated histologically and histochemically using the biopsy technique. When BvX was given at 10 or 20 mg/kg intraduodenally to anesthetized dogs, the thickness of the acini of submucosal glands (SG) and the ratio of the acinar inner diameter to the tracheal wall thickness (A1WR) markedly increased dose-dependently after 2 to 6 hr. The numbers of goblet cells (GC) and glandular cells showing a stain index B&P with a combination of alcian blue (AB) at pH 2.5 or pH 1.0 and periodic acid-Schiff (PAS) were reduced dose-dependently after 1 to 6 hr, while the number of cells with a stain index R were increased. Both the BvX-induced histological changes in SG and histochemical changes in GC and SG reached a peak after 4 hr. These histological and histochemical changes were also found for the BR-227-, a metabolite of BvX, and bromhexine (BH)-treated groups. BR-227- or BH-induced histological changes were to the same degree as those induced by BvX, but BvX- or BR-227-induced histochemical changes were slighter than those induced by BH. The total number of GC stained positively with a combination of AB at pH 2.5 and PAS was unaffected by BvX or BH treatment, while BR-227 tended to decrease it. These findings suggest that BvX both has a secretagogic action selectively on SG and a mucolytic action toward acid glycoprotein in granules of secretory cells in vivo, and these actions are durable.

[Irritation test of dexamethasone valerate (DV-17) and other steroid ointments in rabbits. Skin and eye primary irritation tests, and skin cumulative irritation test]

The skin and eye primary irritation tests, and skin cumulative irritation test were performed on male rabbits, which were topically treated with a volume of 1 g/body of 0.06% and 0.12% dexamethasone valerate (DV-17) ointments as a test drug, and 0.1% hydrocortisone butyrate (HB) and 0.12% betamethasone valerate (BMV) ointments as an active control drug in order to evaluate the topical and systemic effects. No skin and eye primary irritations except minimal skin erythema and slight conjunctival redness were seen in above four corticosteroids. Judging from the results such as skin atrophy, inhibition of body weight gains, and decreases of thymus, spleen and adrenal weights, the potency of toxicities among the four corticosteroid ointments appeared to be as follows: 0.12% DV-17, 0.12% BMV greater than 0.1% HB greater than 0.06% DV-17.

[Comparative toxicity test of dexamethasone valerate (DV-17) and other steroid ointments in rats]

The comparative toxicity test was performed on male rats, which were topically treated with a volume of 0.25 g/kg of 0.12% dexamethasone valerate (DV-17) ointment as a test drug, and 0.1% dexamethasone (DEX), 0.05% fluocinonide (FAA), 0.025% beclomethasone dipropionate (BMD), 0.1% hydrocortisone butyrate (HB), 0.05% clobetasol propionate (CP) and 0.12% betamethasone valerate (BMV) ointments as an active control drug for 30 consecutive days to evaluate on the effects of following items: body weight changes, adrenal functions (organ weight, histological changes of the cortex and serum contents of corticosterone), pathological changes of hypophysis and lymphatic systems (thymus, mesenteric lymph nodes and spleen), and skin changes. Furthermore, the recovery test was also carried out. The severity of topical toxicities was in parallel with that of systemic toxicities. Judging from the results obtained in this study, the potency of toxicities among seven corticosteroid ointments appeared to be as follows: FAA greater than DEX much greater than CP greater than BMV, DV-17 greater than HB greater than BMD. The toxicities of DV-17 were comparable with that of BMV, and these side effects were found to be minimized on the recovery test.