Early occurrence of spontaneous tumors in CD-1 mice and Sprague-Dawley rats

It is sometimes difficult to assess the relevance of tumors that occur in treated animals in short-term studies. This report is intended to establish a general profile of tumor occurrence in young control CD-1 mice and Sprague-Dawley rats. Data from 20 rat and 20 mouse carcinogenicity studies conducted between 1990 and 2002 at Huntingdon Life Sciences, UK. were collected and evaluated. The route of administration was either dietary oral gavage, and the analysis was confined to sporadic deaths (decedents) in control groups occurring during the first 50 weeks of study. In addition, tumor occurrence between 50-80 weeks were compared. In mice, the most common tumor was lymphoma, followed by bronchiolo-alveolar adenoma. In rats, the most common tumor was adenoma of the pituitary gland, followed by mammary fibroadenoma, and adenocarcinoma. When studies of up to 50 weeks, between 50 and 80 weeks, and at 2-year termination were compared, there was no great difference in tumor occurrence except in male rats, in which the most common tumor up to 50 weeks on study was lymphoma, whereas the most common tumor between 50-80 weeks and at 2 years was pituitary adenoma.     

Mortality, major cause of moribundity, and spontaneous tumors in CD-1 mice

Mortality, major causes of moribundity, and spontaneous tumors in CD-1 mice were studied in 891 males and 890 females, which were used as controls in 11 different 2-year chronic and oncogenicity studies during the past 5 years. Average mortality of males and females at 83 weeks of age was 32.6% and 28.6%, respectively, and at 109 weeks of age was 66.4% and 63.3%, respectively. Mortality was significantly lowered in males and females born after 1980 in accordance with an abruptly decreased occurrence of systemic amyloidosis in these animals. The major cause of death or moribundity included systemic arteritis, systemic amyloidosis, auricular thrombosis, glomerulosclerosis, lymphoma, and pulmonary adenocarcinoma in both sexes. Dysuria and hepatocellular carcinoma in males and mammary adenocarcinoma in females were also critical lesions. The major tumors occurring at more than 3% incidence were systemic lymphoma, adenoma/adenocarcinoma of the lung, adenoma/carcinoma of the liver and adenoma/adenocarcinoma of the Harderian gland for males, and systemic lymphoma, adenoma/adenocarcinoma of the lung, adenoma/carcinoma of the liver, leiomyoma/leiomyosarcoma of the uterus, adenoma/adenocarcinoma of the pituitary (anterior), adenoma/adenocarcinoma of the mammary gland and adenoma/adenocarcinoma of the Harderian gland for females. Intralaboratory heterogeneities in the incidence were recorded as follows: systemic lymphoma in 1 of 11 control groups (1/11) and adenoma/adenocarcinoma in 1/11 for males, and systemic lymphoma in 3/11, adenoma/adenocarcinoma of the lung in 2/11, adenoma/adenocarcinoma of the liver in 1/11, and adenoma/adenocarcinoma in 1/11 for females.     

Association of renal tubular hyaline droplets with lymphoma in CD-1 mice

In mice, hyaline droplets in renal proximal tubules have been associated with histiocytic sarcoma but have not been reported with lymphoma. Tissues from CD-1 mice in a 2-year carcinogenicity bioassay were examined microscopically. Twenty-five mice with hyaline droplets in renal tubules were identified. Immunohistochemistry to detect IgA, IgG, IgM, lysozyme, albumin, CD3, and CD79a was performed on kidneys of 21 affected mice. Hyaline droplets were present in the kidneys of 11 mice with lymphoma (1 male, 10 female), of which 1 female also had histiocytic sarcoma. Hyaline droplets were also present in 7 other mice with histiocytic sarcoma, 2 with chronic progressive nephropathy, 3 with renal cortical tubular necrosis, and 2 with granulocytic leukemia. Five of the 11 lymphomas were CD3+, indicating a T lymphocyte origin. Hyaline droplets in mice with lymphoma did not stain for IgA, IgG, or IgM, except in one questionable case. Results of other immunohistochemical stains were inconclusive. Although the droplet composition could not be determined immunohistochemically, the study findings indicate that renal tubular hyaline droplets may be associated with lymphoma in mice.     

52例胃神经内分泌肿瘤临床病理分析

目的 对胃内分泌肿瘤进行分型,并探讨其临床病理意义。方法 收集５２例胃神经内分泌肿瘤,应用组织学及免疫组织化学学ＡＢＣ法及透射电镜技术对肿瘤及其瘤旁粘膜进行观察。参照Ｂｏｒｄｉ和Ｒｉｎｄｉ分类将肿瘤分成Ⅰ、Ⅱ、Ⅲ型,并设有阳性、阴性和替代对照组。结果 胃神经内分泌肿瘤可分为３个临床病理类型,其病理学特点、生物学行为及治疗方案均有不同。Ⅰ型伴有萎缩性胃炎型类癌（２６例）：分为单发及多发两型。单发型多     

Gastric goblet cell carcinoma concurrent with a neuroendocrine tumor

Goblet cell carcinoma, a tumor that is assumed to originate from crypt base stem cells, is a distinct type of tumor, that occurs typically in the appendix, however, extra-appendiceal locations were also described in few cases. We herein present a unique case of a 48-year-old male with a diagnosis of primary gastric Goblet cell carcinoma that was initially discovered at the time of an endoscopy performed to evaluate an unremitting abdominal pain that was accompanied by remarkable weight loss; four polypoid fragments of the gastric mucosa were sent for histopathologic examination which showed a moderately differentiated goblet cell carcinoma in addition to classical neuroendocrine tumor. Later, laparoscopic D2 total gastrectomy with appendectomy were performed and confirmed the previously mentioned findings along with a normal histopathology of the appendix.     

Adrenocortical tumors with neuroendocrine differentiation

18 adrenocortical tumours and 5 pheochromocytomas were studied immunohistochemically. Expression of synaptophysin and chromogranin A was found in cells of cortical adenomas, "frontier" neoplasms and in 20-75% of carcinoma cells, this ultramicroscopically was confirmed by observation of typical neuroendocrine granules. Some groups of cells of cortico-medullary tumours also expressed proteins of neural differentiation (protein S-100).     

Twenty-one-month evaluation of misoprostol for carcinogenicity in CD-1 mice

Misoprostol, a synthetic prostaglandin E1 methyl ester analogue with anti-ulcer potential, was evaluated for its carcinogenic potential in CD-1 strain mice. The compound was given daily by gavage at 160, 1,600, and 16,000 micrograms/kg for 21 months. Necropsies were done on all animals and the incidences of non-neoplastic and neoplastic changes analyzed for significance by life table methods. The only statistically significant non-neoplastic compound-related findings were epithelial hyperplasia and hyperkeratosis of the gastric mucosa and hyperostosis of bone in the marrow cavity of sternebrae and femurs. The changes in the gastric epithelium are characteristic of some prostaglandins and were expected. The bone hyperostosis was associated with misoprostol in high dosages, and was considered unique to the mouse. Other non-neoplastic findings were typical of known spontaneous conditions in mice. The most frequent neoplasm was the hepatocellular adenoma followed by lymphosarcoma, lung alveolar carcinoma, and Harderian gland adenoma. Several proliferative lesions of the duodenum were considered to be spontaneous. These were focal avillous hyperplasia, focal atypical hyperplasia, and junctional polyp. There was no evidence that misoprostol is carcinogenic for CD-1 mice.     

肾脏原发性神经内分泌肿瘤4例临床病理学观察

目的探讨肾脏原发性神经内分泌肿瘤(primary renal neuroendocrine tumors,PRNET)的临床病理学特征。方法对4例PRNET切除标本行HE染色、免疫组化染色,电镜下观察其形态结构、免疫表型及超微结构特点,并复习相关文献。结果4例PRNET中3例男性,1例女性;年龄39~73岁,平均50岁。2例PRNET因腰背部疼痛就诊,2例PRNET患者体检发现入院。4例PRNET镜下结构相似,肿瘤细胞呈管状、条带状紧密排列生长,部分呈巢、团状;肿瘤细胞规则一致,核深染,染色质细腻,核仁不易见,核分裂象均﹤3个/10 HPF。免疫表型:4例Syn均呈强阳性,2例Cg A呈阳性,2例CKpan呈局灶阳性,1例P504S呈阳性;CD10、CD117、PAX2、PAX8、PLAP、Ksp-cadherin均阴性;Ki-67增殖指数1%~5%。1例PRNET于电镜下见胞质内有大量神经内分泌颗粒,细胞间有桥粒连接。结论 PRNET是一种罕见的肾脏肿瘤,可发生于肾脏任何部位,无明显性别差异。诊断多依靠病理学检查,并结合免疫表型,必要时辅助电镜技术以明确诊断。     

Olfactory discrimination ability of CD-1 mice for a large array of enantiomers

With use of a conditioning paradigm, the ability of eight CD-1 mice to distinguish between 15 enantiomeric odor pairs was investigated. The results demonstrate a) that CD-1 mice are capable of discriminating between all odor pairs tested, b) that the enantiomeric odor pairs clearly differed in their degree of discriminability and thus in their perceptual similarity, and c) that pre-training with the rewarded stimuli led to improved initial but not terminal or overall performance. A comparison between the proportion of discriminated enantiomeric odor pairs of the CD-1 mice and those of other species tested in earlier studies on the same discrimination tasks (or on subsets thereof) shows a significant positive correlation between discrimination performance and the number of functional olfactory receptor genes. These findings provide the first evidence of a highly developed ability of CD-1 mice to discriminate between an array of non-pheromonal chiral odorants. Further, they suggest that a species' olfactory discrimination capabilities for these odorants may be correlated with its number of functional olfactory receptor genes. The data presented here may provide useful information for the interpretation of findings from electrophysiological or imaging studies in the mouse and the elucidation of odor structure-activity relationships.     

Differentiation of lesions caused by mycotoxin T-2 from autolytic morphologic change in CD-1 mice

Experiments with topically applied T-2 trichothecene mycotoxin were undertaken to determine whether lesions caused by this toxin could be differentiated from autolysis. Two pathologists, who had previously seen lesions caused by T-2 toxin, graded lesions without knowledge of treatment group and stated whether the animal had received the toxin or not. Both pathologists differentiated T-2 toxin-treated mice up to 6 h post-mortem. Failure to distinguish between treated and control mice resulted in false-negative diagnoses only. It was concluded that the diagnosis of trichothecene mycotoxicosis would probably be missed more than 6 h post-mortem.     

Electron-microscopic study of neuroendocrine tumors of the lung

An electron-microscopic study was made of carcinoids, malignant carcinoids and small-cell lung cancer. These neoplasms are shown to represent one histogenetic group--neuroendocrine tumours (apudomas) of the lung. One can distinguish 3 main structural forms among them, i.e. epithelioid, sarcoma-like and symplastic. According to the ultrastructural criteria the neoplasms mentioned can be classified by their differentiation degree, as well, intermediately and poorly differentiated variants. This classification correlates well enough with the catamnesis of patients and may serve for prognosis of the disease.     

Pulmonary neuroendocrine tumors with nuclear inclusion

Nuclear inclusion or pseudoinclusion is a peculiar cytological feature, and its recognition in appropriate clinicopathological settings can aid in the diagnosis of several disease entities. To the best of our knowledge, only 1 case of pulmonary neuroendocrine tumor (NET) with nuclear pseudoinclusion has been reported. A review of 227 patients who had undergone surgical resection for pulmonary NETs revealed 2 tumors with different mechanisms of nuclear inclusion. To explore the cause of nuclear inclusion, NET with nuclear inclusion was characterized immunohistochemically and ultrastructurally. Nuclear inclusions were observed in 2 of the 227 (0.9%) patients with pulmonary NETs. The first patient was a 46-year-old woman with small cell carcinoma. Tumor cells with nuclear inclusions were distributed focally. Ultrastructural analysis showed that these inclusions were pseudoinclusions. The second patient was a 62-year-old man with large-cell neuroendocrine carcinoma. Nuclear inclusions were observed in the focal area of the tumor. Immunohistochemical analysis revealed that the intra-nuclear materials consisted of biotin and aberrant cytoplasmic and nuclear accumulation of β-catenin. Mutational analysis revealed a CTNNB1 gene mutation. Although very rare, diagnostic errors may be observed in cases of pulmonary NETs with nuclear inclusions. The mechanisms of nuclear inclusion differed, with one due to herniation of the cytoplasm into the nucleus (pseudoinclusion) and the other due to accumulation of biotin resulting from a CTNNB1 gene mutation.     

hASH1基因与肺神经内分泌肿瘤的关系

肺神经内分泌肿瘤(neuroendocrine tumor，NET)是由具有多向分化潜能的肿瘤细胞组成，这些肿瘤细胞具有分泌多种活性激素的功能。肺NET的发生、发展与hASH1(human achaete-scute homologue 1), MEN1(multiple endocrine neoplasia type 1), pRB和E2F1等基因相关，其中hASH1基因成为近年来研究的热点，该基因能促进肺NET的内分泌分化，降低肿瘤的分化程度，并且有临床资料显示hASH1基因的表达还与小细胞肺癌的低生存率有关，可以作为临床预后的一个标准。     

LKB1 protein expression in neuroendocrine tumors of the lung

During a recent investigation of LKB1 gene abnormality in lung lesions, strong expression of LKB1 protein in normal neuroendocrine (NE) cells of the bronchial epithelium was found. Because LKB1 functions as a tumor suppressor gene, the question of whether alteration of LKB1 expression is related to the development of pulmonary NE tumors of various grades was investigated. LKB1 immunohistochemistry was examined in a total of 68 primary pulmonary NE tumors consisting of 30 specimens of small cell lung carcinoma (SCLC), 23 large cell neuroendocrine carcinomas (LCNEC), two atypical carcinoids, and 13 typical carcinoids. Loss or low expression (<20% immunoreactive cells) of LKB1 protein expression was more frequently observed in high-grade NE tumors (SCLC and LCNEC; 45/53, 84.9%) than in typical and atypical carcinoids (3/15; 20%). The difference in LKB1 immunoreactivity between the high-grade NE tumors and the carcinoid group was statistically significant ( P  < 0.0001). In conclusion, marked reduction of LKB1 expression in high-grade NE tumors of the lung suggests a possible role of LKB1 inactivation in its tumorigenesis. Although a few previous studies indicated rare genetic alterations of LKB1 in SCLC, further studies including analysis of other NE tumors and focusing on epigenetic abnormalities of LKB1 gene are warranted.     

Attenuation of maternal behavior in virgin CD-1 mice by methylphenidate hydrochloride

The administration of methylphenidate hydrochloride (MPH) to girls and women has increased in the last decade and the potential for mothers to receive this medication has also increased. Because substances that alter the dopaminergic systems can also disrupt maternal behavior, and MPH acts on dopaminergic neurons, we evaluated the influence of MPH on maternal behavior. The maternal induction paradigm allowed us to assess changes in spontaneous maternal behavior as a result of repeated exposure to MPH without exposing pups to the drug. Virgin female CD-1 mice received MPH (5 mg/kg) or saline daily, starting 3 days before pup exposure, and for the duration of the 10-day test period. Naïve groups of three pups were placed with the female each day and maternal behavior was assessed during 10-minute observation periods 1 h post-injection. MPH-treated females showed significantly less maternal behavior, including reduced pup licking and crouching over pups, compared to saline treated females. MPH-treated females also exhibited higher activity levels than saline treated females. Given the disruption in spontaneous maternal behavior of MPH-treated mice, further research examining the relationship between maternal behavior and MPH exposure is warranted.     

Malignant spinal meningioma in a CD-1 mouse

Spontaneous meningiomas are extremely rare tumors in small laboratory animals, except in some strains of rats and in the B6C3F1 mouse. We report the case of a male CD-1 mouse in poor health condition, with severe apathy and partial paresis of hindlegs. No macroscopic lesion was noticed at necropsy. Microscopic examination revealed the presence of a malignant meningioma (approximately 3mm in diameter) at the distal lumbar level of the spinal cord, invading the vertebral canal, and bilaterally the ventral and dorsal nerve roots and the dorsal root ganglia. The tumor displayed highly cellular sheets of polygonal cells with a well-delineated, abundant, eosinophilic cytoplasm and scarce fibrovascular stroma; epithelioid and sarcomatous areas were also present. The mitotic activity was moderate. Tumor cells expressed vimentin immunoreactivity and were negative for periodic acid-Schiff (PAS), silver impregnation for reticulin, chromogranin A, glial fibrillary acidic protein (GFAP), cytokeratin (CK) and S-100 protein. The diagnosis of malignant spinal meningioma was based on the morphologic features of the neoplasm, the evidence of local invasion and the immunohistochemical results.     

SATB2 is a sensitive marker for lower gastrointestinal well-differentiated neuroendocrine tumors

Special AT-rich sequence binding protein-2 (SATB2) is selectively expressed in the lower gastrointestinal tract mucosa and has been identified as a sensitive marker for colorectal adenocarcinomas. The goal of this study was to investigate the expression of SATB2 in well-differentiated neuroendocrine tumors to explore its potential as a diagnostic marker for hindgut well-differentiated neuroendocrine tumors. Immunohistochemical staining with a monoclonal antibody to SATB2 was performed on full tissue blocks in 167 well-differentiated neuroendocrine tumors of various origins. The staining was semi-quantitatively scored as 0 (no tumor cell staining), 1+ (1-25%), 2+ (26-50%), 3+ (51-75%) and 4+ (76-100%). Positive SATB2 staining was seen in 17% foregut (14/84, 12/66 primary and 2/18 metastatic), 12% midgut (3/22, 3/18 primary and 0/7 metastatic), and 90% hindgut (52/58, 44/49 primary and 8/9 metastatic) well differentiated neuroendocrine tumors. Most hindgut well-differentiated neuroendocrine tumors (41/58) showed 4+ staining. The specificity of SATB2 for foregut, midgut and hindgut well-differentiated neuroendocrine tumors was 34%, 54% and 84%, respectively. Our results indicate that SATB2 is a sensitive marker for hindgut well-differentiated neuroendocrine tumors though it is not entirely specific. SATB2 should be included in the immunohistochemical panel in working out metastatic well-differentiated neuroendocrine tumor of an unknown origin.     

Frequency and time trends of spontaneous tumors found in B6C3F1 mice oncogenicity studies over 10 years

Historical data from 2883 B6C3F1 mice used as controls in 29 two-year oncogenicity studies terminated between 1988 and 1998 were analyzed for possible time trends in mortality, terminal body weight and tumor incidences. There was no time trend in terminal body weights. Concerning mortality data a slight decreasing trend (p > 0.05) was evident in males, whereas in females mortality rates increased significantly (p = 0.0009). The overall tumor spectrum of the collectives used was roughly in line with the tumor profile known for B6C3F1 mice. Most tumor types occurred in the hematopoietic tissue, liver, lungs, Harderian glands, vascular system, endocrinium (pituitary, adrenals and thyroids) or female reproductive organs. In comparison to literature data mice used in our lab exhibited less hepatocellular tumors and lung adenomas. Hepatocellular adenomas (females only) and carcinomas (both sexes) as well as adenomas in the Harderian glands decreased significantly over the time examined. For ovarian cystadenomas as well as uterine polyps and uterine stromal sarcomas significantly positive time trends were calculated. A positive time trend was also found for adrenal adenomas in males (p < 0.05) and histiocytic sarcomas in females (p > 0.05). Lymphomas occurred with increasing incidences over time in males (p < 0.05) and females (p < 0.05). Other factors such as genetic drifts might be responsible for these trends rather than changes in the body weights, which remained stable over 10 years.