Spermatocytic seminoma with neuroectodermal differentiation and sertoli cell tumor in a dog.

Two distinct nodules developed in a cryptorchid testis of an 8-year-old male West Highland White Terrier. One nodule was a Sertoli cell tumor. The other was a spermatocytic seminoma with focal primitive neuroectodermal differentiation: formation of Homer-Wright rosettes and perivascular pseudorosettes, with immunoreactivity for S-100 protein, neuron-specific enolase, synaptophysin, neurofilament-68 kDa, microtubule-associated protein 2, and vimentin. The dog was alive and healthy 2 years after castration.

Prostate cancer screening strategies with re-screening interval determined by individual baseline prostate-specific antigen values are cost-effective.

AIMS: To determine whether prostate cancer screening strategies with re-screening interval determined by individual baseline prostate-specific antigen values are cost-effective. METHODS: Based on the results of an actual contemporary screening program, we established Markov decision analytic models of prostate cancer screening with personalized re-screening interval strategies using cutoff baseline PSA levels for biennial screening as well as a model of uniformly annual or biennial screening. These strategies were compared in terms of cumulative incidence of early cancer and cost-effectiveness. RESULTS: Early cancer detection rates were similar among all strategies. Personalized strategies were more cost-effective compared to uniform screening strategies. If all participants with negative PSA results uniformly omit annual screening, it would be more costly but less effective (dominated). Contrary, annual screening for all participants would cost too much. These results were robust throughout sensitivity analysis incorporating every assumption in the models. CONCLUSIONS: This study adds important evidence that personalized rescreening strategies based on individual baseline PSA have advantages of cost-effectiveness against conventional uniform strategies.

Chronic toxicity and carcinogenicity of dietary administered ammonium sulfate in F344 rats.

Chronic toxicity and carcinogenicity studies of ammonium sulfate, used as a food additive in fermentation, were performed in male and female Fisher 344 rats at dietary concentrations of 0%, 0.1%, 0.6% and 3.0% in a 52-week toxicity study and 0%, 1.5% and 3.0% in a 104-week carcinogenicity study. Treatment with ammonium sulfate caused significant increase in kidney and/or liver weights in males and females of the 3.0% diet group, but no effects were found on survival rate, body weights, and hematological, serum biochemical or histopathological parameters at any dose levels in the chronic toxicity study. Regarding carcinogenicity, ammonium sulfate did not exert any significant influence on the incidences of tumors in any of the organs and tissues examined. It was concluded that the no observed adverse effect level of ammonium sulfate was the 0.6% diet, which is equivalent to 256 and 284 mg/kg b.w./day in males and females, respectively, and the compound is non-carcinogenic under the conditions of the study.

Detection of telomerase activity in exfoliated cells in urine from patients with bladder cancer.

BACKGROUND: Telomeres are specific structures located at the ends of chromosomes that help maintain chromosome stability. In most tissues, telomeres become shorter as cells divide, a phenomenon thought to be associated with limitations on normal cell proliferation. Almost all types of cancer cells, including bladder cancer cells, express the enzyme telomerase, which can maintain or extend telomere length. PURPOSE: We examined telomerase activity in tumor specimens from a cohort of patients with bladder cancer and determined whether telomerase could be detected in exfoliated cancer cells present in urine from these patients. METHODS: Spontaneously voided urine specimens and bladder-washing fluids (obtained by propelling normal saline into the bladder through a catheter and then withdrawing the liquid contents) were taken from 45 patients before they underwent surgery. Telomerase activity was examined by means of the TRAP (telomeric repeat amplification protocol) assay on extracts of tumor samples from 42 patients and extracts of exfoliated cells in urine and bladder-washing fluid from 42 and 43 patients, respectively. Standard cytologic examination (Pap staining) of urine specimens was also used to detect exfoliated cancer cells. RESULTS: Telomerase activity was found in 41 (98%; 95% confidence interval [CI] = 87%-100%) of the 42 tumor samples examined. In contrast, it was not detected in normal bladder tissue from two autopsied individuals who were free of bladder cancer and five of six individuals who had bladder cancer. Telomerase was detected in exfoliated cells in 23 (55%; 95% CI = 39%-70%) of the 42 spontaneously voided urine specimens and in 36 (84%; 95% CI = 69%-93%) of the 43 bladder-washing fluids examined. Considering voided urine specimens and bladder-washing fluids together, telomerase was detected in exfoliated cells from 40 (89%; 95% CI = 76%-96%) of the 45 patients. Telomerase activity was not detected in bladder-washing fluids from 12 cancer-free individuals. Cancer cells were detected by means of standard cytologic examination in the urine of 19 (42%; 95% CI = 28%-58%) of the 45 patients. Urine cytologic examination detected cancer cells in one (8%; 95% CI = 0%-38%) of 12 patients with grade 1 tumors and in 13 (46%; 95% CI = 28%-66%) of 28 patients with grade 2 tumors. In contrast, telomerase activity was detected in exfoliated cells (in voided urine or bladder-washing fluids) from nine (75%; 95% CI = 43%-95%) of 12 patients with grade 1 tumors and from 27 (96%; 95% CI = 82%-100%) of 28 patients with grade 2 tumors. CONCLUSION AND IMPLICATION: Telomerase activity can be detected in exfoliated cells in urine from patients with bladder cancer, and measurement of this activity appears to be more sensitive in detecting the presence of cancer than standard urine cytologic examination. These findings suggest that measuring telomerase activity in exfoliated cells would be useful in the diagnosis and follow-up of patients with bladder cancer, a possibility that warrants further study.

Clonal and chronological genetic analysis of multifocal cancers of the bladder and upper urinary tract.

Recent molecular genetic studies have suggested that multifocal urothelial cancers are derived from an identical progenitor cell. However, the clonal origin of multifocal urothelial cancers of a low-grade superficial type has not been fully defined. Using microsatellite markers, we examined genetic alterations at 20 loci on eight chromosomal arms (2q, 4p, 4q, 8p, 9p, 9q, 11p, and 17p) in 87 metachronous and/or synchronous multifocal urothelial cancers, which included 84 low-grade superficial papillary tumors from 29 patients. Judging from the patterns of loss of heterozygosity, microsatellite shifts, and the subchromosomal partial deletion, multifocal tumors in at least 20 (80%) of the 25 evaluable patients were considered to be derived from a single progenitor cell, although the possibility remained that multifocal tumors in a small subset of patients might develop from distinct progenitor cells due to field cancerization. In 13 of the 20 patients, a chronological genetic analysis was available: genetic heterogeneity was detected in 3 (23%) patients, and an apparent accumulated pattern of genetic alterations was detected in only 1 (8%) patient. In the 20 patients with multifocal tumors of an identical clonal origin, discordant microsatellite alterations were observed, with significantly lower frequencies on chromosome 9 compared to those on the other chromosomes tested. The results indicate that most multifocal low-grade superficial urothelial cancers are genetically stable despite their incidence of frequent recurrence, and genetic divergence occurs in a subset of patients. This heterotopic spread and genetic divergence may occur long before the clinical manifestation of multiplicity from a single transformed cell. These data support the previous view that heterotopic spread of transformed progenitor cells and genetic divergence occur after chromosome 9 alterations in most of low-grade superficial urothelial cancers.

A histological study of the cardiac conduction system in a heifer with complete atrioventricular block.

A case of complete atrioventricular (AV) block of congenital origin in a 16-month-old Holstein heifer was studied histologically with serial sectioning of the cardiac conduction system. The heart was enlarged and showed moderate dilatation of the left and right ventricles. Histologically, the abnormally placed and poorly formed AV bundle was observed in association with abnormality in the tricuspid extension of the central fibrous body, suggesting that the pathological state of the AV bundle had been responsible for the complete AV block. This type of anatomical fault in the AV bundle is considered to be part of an embryological, developmental malformation of the central fibrous body.

Long-term prognosis of medically treated patients with internal carotid or middle cerebral artery occlusion: can acetazolamide test predict it?

BACKGROUND AND PURPOSE: The importance of hemodynamic parameters for predicting outcome in patients with occlusive carotid disease remains controversial. The present study was aimed at testing the hypothesis that regional cerebrovascular reactivity (rCVR) to acetazolamide can be a reliable predictor of subsequent ischemic stroke in medically treated patients with internal carotid artery or middle cerebral artery occlusion. METHODS: Seventy-seven symptomatic patients were enrolled in this prospective, longitudinal cohort study. All patients met inclusion criteria of cerebral angiography, no or localized cerebral infarction on MRI or CT, and no or minimal neurological deficit. Regional cerebral blood flow (rCBF) and rCVR to acetazolamide were quantitatively determined by (133)Xe SEPCT. All patients were categorized into 4 types on the basis of SPECT studies. RESULTS: During an average follow-up period of 42.7 months, 16 total and 7 ipsilateral ischemic strokes occurred. The annual risks of total and ipsilateral stroke in patients with decreased rCBF and rCVR were 35.6% and 23.7%, respectively, risks that are higher than those in other types of patients. When strokes were categorized into patients with and without decreased rCBF and rCVR, Kaplan-Meier analysis revealed that the risks of total and ipsilateral stroke in patients with decreased rCBF and rCVR were significantly higher than in those without (P<0.0001 and P=0.0001, respectively, log-rank test). Relative risk conferred by decreased rCBF and rCVR was 8.0 (95% CI, 1.9 to 34.4) for ipsilateral stroke and 3.6 (95% CI, 1.4 to 9.3) for total stroke. CONCLUSIONS: Decreased rCBF and rCVR to acetazolamide may identify a subgroup of patients who have a higher risk of subsequent ischemic stroke when treated medically.

Carcinogenicity of methylmercury chloride in ICR mice: preliminary note on renal carcinogenesis.

ICR mice (60/group) were fed diets containing methylmercury chloride (MMC) in 0, 15 or 30 ppm for 78 weeks. The majority of mice in the 30-ppm group died due to the neurotoxicity by week 26. The first renal mass was grossly seen in a male of the 15-ppm group at week 58. Histopathology on kidney tissue from all animals surviving after 53 weeks revealed renal tumors in 13 of 16 males of the 15-ppm group in contrast with 1 of 37 males of the control. No renal tumors were seen in the female treated groups and/or control groups.

Carcinogenicity of N-nitroso-ethylenethiourea in female mice.

The nitrosation product of ethylenethiourea (ETU), N-nitroso-ETU, was tested for tumorigenicity in female ICR mice. Ten weekly oral administrations of this compound (0.66-2.64 mg/dose) caused apparently dose-dependent increases in the number of mice with pulmonary and lymphocytic neoplasms.

Promoting effects of 6-mercaptopurine on carcinogenesis in various organs of F344 rats.

Possible promoting effects of 6-mercaptopurine (6-MP) on carcinogenesis in various organs, including the hematopoietic system, were investigated in female F344 rats, using a 2-stage carcinogenesis model. 6-MP was given as a dietary supplement (50 ppm) for 35 weeks subsequent to wide-spectrum initiation with N-ethyl-N-nitrosourea (ENU). Various tumors were observed in the carcinogen-initiated groups. No significant influence of 6-MP on their development, including the occurrence of leukemia, was apparent. However, the incidences of some proliferative lesions in the lung, intestine and kidney were slightly higher in the ENU/6-MP group than the ENU group. Further studies may be needed on promoting effects of 6-MP, based on dose-effect relation using several 6-MP doses and/or other initiators.

Effect of thyroid stimulating hormone on the development and progression of rat thyroid follicular cell tumors.

Time course changes in cell proliferative activity of thyroid focal hyperplastic and tumorous lesions as well as blood thyroid-related hormones in male F344 rats initiated with N-bis(2-hydroxypropyl)nitrosamine (DHPN: 2800 mg/kg body weight, single s.c. injection) were examined following chronic administration of 0.1% sulfadimethoxine (SM) in the drinking water for 1, 4, 8, 12 and 16 weeks and at the end of a subsequent 4-week recovery period. Serum thyroid stimulating hormone (TSH) levels increased rapidly from week 1 of SM treatment, reaching a peak at week 8, and then decreased gradually with prolongation of treatment period, although remaining significantly elevated as compared with the corresponding controls at all time points up to week 16. Follicular cell hyperplasias and adenomas of the thyroid occurred from week 4 and carcinomas from week 8. All of these lesions showed high cell proliferative activities corresponding to high serum TSH levels during the early stage, but the levels in hyperplasias and adenomas decreased rapidly with prolongation of SM treatment. After the recovery period, serum TSH levels had returned to below the normal range and cell proliferation in follicular hyperplasias and adenomas had stopped or was very low. Some carcinomas demonstrating invasive growth also showed remarkable decreases in the cell proliferative activity. The results of our study strongly suggest that a high serum TSH level plays an important role in the early stage of thyroid tumorigenesis and that some tumors exhibiting invasive growth are still dependent on TSH stimulation.

Effect of rat thyroid proliferative lesion development by intermittent treatment with sulfadimethoxine.

To determine whether production of thyroid proliferative lesions would be enhanced by intermittent rather than continuous treatment with a goitrogen, male F344 rats initiated with N-bis(2-hydroxypropyl)nitrosamine (DHPN, 2800 mg/kg body weight, single s.c. injection) were given water containing 0.1% sulfadimethoxine (SM) for 20 weeks (group 1) or 0.1% SM for the first 8 weeks followed by 2 cycles consisting of 2 weeks withdrawal and 4 weeks retreatment with 0.1% SM (group 2). Control rats (group 3) were untreated for 20 weeks after the DHPN initiation. Serum T3 and T4 levels were significantly decreased in groups 1 and 2 compared to group 3. Serum thyroid stimulating hormone level was significantly increased in all treated groups compared to group 3. The numbers of follicular cell hyperplasias were significantly increased in group 2 compared to group 1. BrdU labeling indices for follicular cells and hyperplasias were also significantly elevated in group 2 compared to group 1. Electron microscopic examination of thyrotrophs in the anterior pituitary in groups 1 and 2 revealed dilated rough ER cisternae with intracisternal dense granules. The number of intracytoplasmic secretory granules in group 2 was moderately decreased compared to group 1. Therefore, the results of the present study suggest that it may be possible to enhance production of thyroid neoplastic lesions by intermittent treatment.

Pulmonary fibrosis caused by N-methyl-N-nitrosourethane inhibits lung tumorigenesis by urethane in transgenic mice carrying the human prototype c-Ha-ras gene.

Male and female transgenic mice carrying the human prototype c-Ha-ras gene (rasH2 mice) and their wild littermates (non-Tg mice) received three subcutaneous injections of 0.3 mg N-methyl-N-nitrosourethane (MNUR) once every 2 weeks for the first 4 weeks followed by a single intraperitoneal injection of 1000 or 0 mg/kg urethane (UR) 2 weeks later. They were then maintained without any other treatment for a further 13 weeks and sacrificed for assessment of pulmonary pathology. Inflammatory lesions, such as macrophage infiltration, alveolar bronchiolization and/or fibrosis, were induced in both rasH2 and non-Tg mice treated with MNUR or MNUR + UR. Lung proliferative lesions were induced in 100% of the UR-treated rasH2 mice but to a significantly lesser extent in the MNUR + UR case. The incidences of lung tumors in non-Tg mice treated with UR or MNUR + UR were relatively low. Point mutations of the transgene were detected in approximately 80% of lung tumors in rasH2 mice treated with UR and MNUR + UR, but murine Ki-ras mutations were rare. No marked difference in the mutation pattern was found between the UR-treated and the MNUR + UR-treated rasH2 mice. In non-Tg mice treated with UR or MNUR + UR, point mutations of the murine c-Ki-ras gene were observed in about 50% of the lung tumors examined. The present study confirmed that rasH2 mice are very sensitive to lung tumor induction by UR and suggested that alveolar epithelial cells in the reparative stage during pulmonary fibrosis are resistant to DNA damage by this carcinogen.

Lack of susceptibility of transgenic mice carrying the human c-Ha-ras proto-oncogene (rasH2 mice) to phenolphthalein in a 6-month carcinogenicity study.

Phenolphthalein has carcinogenic activity, causing malignant lymphomas in B6C3F1 mice at a dietary dose of 3000 ppm in a 2-year carcinogenicity study and in heterozygous p53-deficient female mice at the same dose in a 6-month study. To examine whether phenolphthalein carcinogenic potential can be detected in male and female transgenic (Tg) mice carrying the human c-Ha-ras gene (rasH2 mice) and their wild-type littermates (non-Tg mice), a diet containing 3000, 6000 or 12000 ppm was given for 6 months. Unequivocal induction of neoplastic lesions was not apparent, suggesting that rasH2 mice are resistant to the induction of malignant lymphomas by the treatment of phenolphthalein.

Carcinogen dose-dependent variation in the transgene mutation spectrum in urethane-induced lung tumors in transgenic mice carrying the human prototype c-Ha-ras gene.

Urethane-induced lung tumors and their genetic changes were investigated in transgenic (Tg) mice carrying a human prototype c-Ha-ras gene (rasH2 mice). Male and female rasH2 mice and non-transgenic (non-Tg) littermates were injected intraperitoneally with 1000 mg/kg of urethane once or three times at 2-day intervals. Hyperplasias and adenomas of the lung were observed in all animals of each group from week 10, and carcinomas were observed in male and female rasH2 mice of the triple injection group from week 10 and female non-Tg mice of the single injection group at 15/20 weeks. The multiplicities of lung proliferative lesions including hyperplasias, adenomas and carcinomas, in treated rasH2 mice were significantly higher than those in treated non-Tg mice. CAG to CTG transversions were observed in the c-Ha-ras gene in these lung proliferative lesions of rasH2 mice of the single injection group at high incidence (male: 58.3%, female: 62.5%), but no mutations of the mouse c-Ki-ras gene were evident in either rasH2 or non-Tg mice. In the triple injection group, transgene mutations were detected at a relatively low incidence, and mouse c-Ki-ras gene mutations(CAA to CGA) were observed in both rasH2 and non-Tg mice. These results suggest that the variation of the lesions induced by different doses of urethane was not the cause of the variation of the mutation spectrum and mutations of both transgene and mouse c-K-ras gene are not principal genetic events in urethane-induced lung proliferative lesions in rasH2 mice.

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.

Analysis of proliferative activity in renal lesions induced by N-nitrosobis(2-oxopropyl)amine (BOP) in male Syrian golden hamsters.

Binding of a specific antibody to proliferating cell nuclear antigen (PCNA) and staining of argyrophilic proteins associated with nucleolar organizer regions (AgNORs) were investigated in proliferative lesions induced by N-nitrosobis(2-oxopropyl)amine (BOP) in the hamster kidney. Thirty male Syrian golden hamsters were given three weekly s.c. injections of BOP (10 mg/kg body wt.) and sacrificed for characterization of proliferative changes 30 weeks after the first BOP treatment. Morphologically, lesions of the tubular epithelia were classified either as tubular adenoma or dysplasia, the latter being further classified into small cluster, acidophilic cell, clear cell and cystic types. Immunohistochemistry for PCNA revealed significant increases of cell proliferation activity in adenomas and acidophilic cell types of dysplasia, along with significantly elevated mean numbers of AgNORs per nucleus. The results thus indicate that the acidophilic cell type of dysplasia may be of prime significance as the preneoplastic renal lesion induced by BOP.

Promoting effect of large amounts of vitamin A on cell proliferation of thyroid proliferative lesions induced by simultaneous treatment with thiourea.

In order to examine modifying effects of simultaneous treatment with large amounts of vitamin A (VA) and thiourea (TU) on the thyroid tumorigenesis in rats, male F344 rats were initiated with N-bis(2-hydroxypropyl)nitrosamine (2800 mg/kg body weight, single s.c. injection), and starting 1 week later received diet containing 0.1% VA (VA group), drinking water containing 0.2% TU (TU group), 0.2% TU + 0.1% VA (TU + VA group) or tap water/basal diet (control group) for 19 weeks. Serum T3 and T4 in the TU and TU + VA groups were significantly decreased as compared to the control group, while serum TSH levels were remarkably increased. The ratios of T3 and T4 decrease and TSH increase in the TU + VA group were remarkably more pronounced than in the TU group. Thyroid neoplastic lesions were only induced in the TU and TU + VA groups. The multiplicity of intracapsular follicular cell proliferative foci in the TU + VA group was significantly increased as compared to the TU group value. Cell proliferation of hypertrophic and subcapsular follicular cells, as well as in hyperplasias, and neoplasias with adenomatous growth pattern was significantly higher in the combined treatment case than after TU alone. In the liver, centrilobular hypertrophy of hepatocytes was seen in the TU and TU + VA groups, this being especially marked in the latter group. In the combined group case the affected cells were strongly positive for GST-P antibody binding. The results of the present study suggest that cell proliferation of thyroid follicular cell proliferative lesions in rats is enhanced by strong TSH stimulation with simultaneous treatment of TU and large amounts of VA.

Tumor-promoting activity of 2,6-dimethylaniline in a two-stage nasal carcinogenesis model in N-bis(2-hydroxypropyl)nitrosamine-treated rats.

The potential promotion activity on nasal carcinogenesis of 2,6-dimethylaniline (DMA), an alpha2-adrenergic agonist metabolite of xylazine which is used for food-producing animals as a sedative agent, was examined. Male F344 rats received diet containing 0 or 3000 ppm DMA for 52 weeks after initiation with N-bis(2-hydroxypropyl)nitrosamine (DHPN). Histopathological assessment showed the incidence of carcinomas in the DHPN+DMA group (33%) to be significantly elevated as compared with that for the DHPN-alone group (5%). Incidences and/or multiplicity of epithelial hyperplasias and dysplastic foci were also increased in the DHPN+DMA group. These lesions were exclusively observed in the olfactory mucosa. The lowest plasma levels of DMA in tumor- and dysplastic foci-bearing rats were 0.05 and 0.20 microg/ml, respectively. These results indicate that DHPN acts as an appropriate initiator for nasal carcinogenesis and that DMA exerts a tumor-promoting effect on the olfactory mucosa in the rat nasal cavity.