[An autopsy case of Smith-Lemli-Opitz syndrome]

A 17 month-old girl was found dead in her bed. The findings of a juditial autopsy revealed that she had a cleft palate, low-set and accessory ears, and syndactyly of right and left second and third toes and right third and fourth toes. Her birth size was small and subsequently she failed to thrive. Organ anomaly, such as atriaol septal defect, accessory spleens, and uterus bicornis bicollis were found. From these findings, this case was diagnosed as a Smith-Lemli-Opitz syndrome.

Dietary carcinogens and mammary carcinogenesis. Induction of rat mammary carcinomas by administration of heterocyclic amines in cooked foods

Grilled or fried meat and fish contain various mutagenic heterocyclic amines, and structures of at least 19 compounds have already been determined. Among these, 10 have been examined for long term carcinogenicity, all proving to be positive. 2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), for example, preferentially induced mammary adenocarcinomas in 47% of Fischer 344 female rats when supplemented into the diet at a concentration of 400 parts per million (ppm) for 52 weeks. Moreover, 100 ppm of PhIP for 104 weeks yielded the same incidence. PhIP in the diet for 48 weeks also induced mammary cancer in Sprague-Dawley female rats with incidences of 72 and 25% at 200 ppm and 100 ppm. 2-Amino-3,4-dimethylimidazo[4,5-f]quinoline in the diet at 300 ppm also induced a 25% incidence of mammary adenocarcinomas within 40 weeks. Analysis of PhIP-induced rat mammary carcinomas for ras mutations by polymerase chain reaction-single-strand conformation polymorphism and direct sequencing revealed Ha-ras activation in 3 of 17 carcinomas; all were G-->A transitions at the second letter of codon 12 replacing glycine by glutamic acid. A p53 gene mutation was also found in 1 of 10 carcinomas examined; a G-->T transversion was detected at the third letter of codon 130, with a substitution of asparagine for lysine. PhIP is the most abundant mutagenic and carcinogenic heterocyclic amine in grilled meat, and, therefore, a role for this compound in human carcinogenesis is strongly implied.

A novel site of erythropoietin production. Oxygen-dependent production in cultured rat astrocytes

It has been shown that neurons express erythropoietin (Epo) receptor, but the production of Epo protein in neural tissues has not been demonstrated. Cerebral cells of rat fetuses were cultured, and Epo in the spent medium was measured with an enzyme-linked immunoassay. Production of the immunoreactive Epo was dependent on O2 tension for cell culture; hypoxia enhanced the production. The immunoreactive Epo purified from the spent medium stimulated the growth of Epo-dependent myeloid cells and formation of fetal liver erythroid colonies. These biological activities were completely inhibited by the anti-Epo antiserum and the extracellular domain of the Epo receptor capable of binding with Epo. When brain Epo was compared with serum Epo, brain Epo was smaller in size and more active in vitro at low ligand concentrations. These differences appear to be caused by the different extent of sialylation. Analyses with the reverse transcription-polymerase chain reaction method indicated that the regulation of Epo production by oxygen operates at the level of its mRNA. Immunochemical staining of the immortalized clonal cells revealed that astrocytes produced brain Epo. These results provide a novel site of Epo production and suggest that Epo acts on neurons in a paracrine fashion.

The creep behavior of denture-supporting tissues and soft lining materials

This study examined the desirable properties of a soft denture liner. The physical behavior of palatal mucosa of young adults was quantified by analyzing creep behavior using Voigt's four-element model. Instantaneous elastic recovery was significantly smaller than instantaneous elastic displacement, and delayed elastic recovery was significantly larger than delayed elastic displacement (P < .05). Viscous recovery was small but detectable. To ascertain whether the characteristics of the mucosa can be replaced with a soft material, a new soft lining material was developed and both behaviors, especially after load release, were compared with each other. It was indicated that by properly controlling the amounts of the crosslinking agent and inorganic filler of the soft material, its properties may be made to approximate those of the mucosa.

A mutant of protein phosphatase-1 that exhibits altered toxin sensitivity

A chimeric mutant was constructed in which a 4-amino acid region (GEFD, residues 274-277) of rabbit muscle protein phosphatase-1 was replaced with the sequence YRCG corresponding to residues 267-270 of rabbit protein phosphatase-2A. This was based on the findings of a gene mutation in okadaic acid-resistant cells which results in a Cys-->Gly conversion in protein phosphatase-2A. The YRCG mutant of protein phosphatase-1 was expressed and purified. The properties of the mutant enzyme were investigated in terms of its sensitivity toward several toxin inhibitors (okadaic acid, microcystin, nodularin, calyculin A, and cantharidic acid), as well as inhibitor-2. The mutant enzyme exhibited a gain of function in the form of a 10-fold increased sensitivity toward okadaic acid that suggests this region is involved in toxin binding. Significant changes in sensitivity to inhibitor-2 and several of the other toxins were also observed, indicating that these may have a common binding region.

Identification and dynamics of paraquat in the bone marrow, thymus and spleen in rats using immunohistochemical techniques

We reported the immunohistochemical identification of paraquat in the immune and hematopoietic systems such as bone marrow, spleen and thymus. Twelve paraquat-poisoned rats were sacrificed in 3 h, 12 h, 3 days, 7 days and 10 days after intravenous administration of paraquat. In the bone marrow, paraquat was localized in several types of blood cells (granulocyte, erythrocyte and megakaryocyte) and their precursors between 24 h and 7 days after the injection. In the thymus, paraquat was mainly localized in the medulla between 12 h and 7 days after the injection, whereas in the spleen, it was mainly localized in the red pulp between 12 h and 10 days after administration of paraquat.

Identification of N-(deoxyguanosin-8-yl)-2-amino-3,4-dimethylimidazo[4,5-f]quinoline (dG-C8-MeIQ) as a major adduct formed by MeIQ with nucleotides in vitro with DNA in vivo

The N-hydroxylamine of a carcinogenic heterocyclic amine, 2-amino-3,4-dimethylimidazo[4,5-f]quinoline (MeIQ), was reacted with four 2'-deoxynucleoside 3'-monophosphates after O-acetylation. 32P-Postlabeling analysis demonstrated that the adduct was formed with only the guanine nucleotide, and the structure of the compound in the obtained adduct spot was determined to be N-(deoxyguanosin-8-yl)-MeIQ 3',5'-diphosphate (3',5'-pdGp-C8-MeIQ). DNA samples from livers of mice fed MeIQ were also 32P labeled under standard conditions and additionally treated with nuclease P1 and phosphodiesterase I. A single adduct spot was obtained and the structure of the adduct was identified as 5'-pdG-C8-MeIQ. Thus, MeIQ binds at the C-8 position of guanine in vitro and in vivo, like other heterocyclic amines.

Intercellular localization of leukotoxin (9:10-epoxy-12-octadecenoic acid) in lungs in rats by an immunoelectron microscopy

In this paper intercellular localization of leukotoxin (9:10-epoxy-12-octadecenoic acid, LTx) in neutrophils and alveolar macrophages of rats exposed to the 100% oxygen was demonstrated by a pre-embedding method of an immunoelectron microscopy. The Sprague-Dawley rats were treated with the 100% oxygen for 72 hrs, and the lungs were stained with anti-LTx IgG (Fab) by an immunocytochemical method and examined by a transmission electron microscope. The positive reactions with anti-LTx IgG (Fab) was shown strongly in the rough-surfaced endoplasmic reticulum (rER) and cell membranes of the neutrophils and alveolar macrophages. This result indicates that LTx is produced in biomembrane-rich organelle of alveolar macrophages as well as neutrophils dependently on the treatment period under hyperoxia conditions, suggesting that LTx is closely related to biological reactions and is an important chemical mediator on pulmonary diseases.

Presence of p53 mutations in 3Y1-B clone 1-6: a rat cell line widely used as a normal immortalized fibroblast

The 3Y1 cell line, established from a rat whole embryo, is widely used as a normal immortalized fibroblast. We analyzed p53 mutations in four clonal lines derived from the 3Y1 cell line; 3Y1-B clone 1-6, 3Y1-C and two clonal lines (3Y1 cl-3 and 3Y1 cl-6) which had been transformed by the human papilloma virus E6 gene. Polymerase chain reaction (PCR)-single strand conformation polymorphism (SSCP) analysis and DNA sequencing showed that three clonal lines had a double mutation at codons 130 and 136 on the same allele and that the other clonal line, 3Y1 cl-3, had no mutations. 3Y1-B clone 1-6, which has been registered as the standard clonal line at the Japanese Cancer Research Resources Bank, demonstrated weak bands of the wild type allele, suggesting the existence of heterogeneous cell types in this "clonal" line. PCR-SSCP analysis of 25 subclones obtained by limiting dilution of 3Y1-B clone 1-6 cells revealed a mixture of two types of cells; 12 subclones showed only the bands of mutated allele, and 13 subclones showed both bands of the wild and mutated p53 alleles. These findings should be taken into consideration when using this cell line as a normal immortalized cell line.

Abnormal glycosylation of motor neurons with N-acetyl-D-galactosamine in a case of subacute motor neuronopathy associated with lymphoma

Lectins, glycine max (SBA) and Vicia villosa (VVA), which identify terminal N-acetyl-D-galactosamine (GalNAc), stained the motor neurons of a patient with subacute motor neuronopathy associated with neoplastic angioendotheliosis. In normal controls and in patients with other neurological disorders including amyotrophic lateral sclerosis, neither lectin stained motor neurons. Abnormal glycosylation of motor neurons with terminal galNAc may be associated with the pathogenesis of subacute motor neuronopathy in this patient.

Synergistic enhancement of hepatic foci development by combined treatment of rats with 10 heterocyclic amines at low doses

Potential synergism between 10 carcinogenic heterocyclic amines [3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1), 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2), 2-amino-6 methyldipyrido[1,2-a:3',2'-d]imidazole (Glu-P-1), 2-amino-dipyrido[1,2-a:3',2'-d]imidazole (Glu-P-2), 2-amino-3-methylimidazo[4,5-f]quinoline (IQ), 2-amino-3,4-dimethyl-imidazo[4,5-f]quinoline (MeIQ), 2-amino-3,8-dimethyl-imidazo[4,5-f]quinoxaline (MeIQx), 2-amino-3-methyl-9H-pyrido[2,3-b]indole (MeA alpha C), 2-amino-9H-pyrido[2,3-b]indole (A alpha C) and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP)] in rat liver carcinogenesis was examined. Male F344 rats were initially given diethylnitrosamine (200 mg/kg, i.p.) and beginning 2 weeks later received heterocyclic amines individually at doses 1/10 of that proven to be carcinogenic or in combination at 1/10 or 1/100 doses for 6 weeks. All animals were subjected to partial hepatectomy at week 3 and killed at week 8. The induction of immunohistochemically demonstrable placental glutathione S-transferase positive foci was significantly increased in rats given all 10 chemicals in combination at the 1/10 dose level while values were almost the same as in controls with the 1/100 dose mixture and the individual chemicals, except for Glu-P-1 which significantly increased foci development and Glu-P-2 and A alpha c which significantly decreased levels of foci at the 1/10 dose level. Thus apparent synergism was observed with the 1/10 dose level combination. When the data are considered together with our previous results obtained with five heterocyclic amines using 1/1, 1/5 and 1/25 dose levels, combined effects were found to be related to the number of chemicals included and the dose levels of each, with a possible isoadditive influence being common. The findings are of particular significance since heterocyclic amines and other carcinogenic agents might be simultaneously generated during cooking.

p53 gene mutation in hepatocellular carcinoma induced by 2-amino-3-methylimidazo[4,5-f]quinoline in nonhuman primates

2-Amino-3-methylimidazo[4,5-f]quinoline (IQ) is one of several heterocyclic amines formed during the cooking of proteinaceous foods. IQ is a potent carcinogen in rodent bioassays and causes a high incidence of hepatocellular carcinomas in nonhuman primates. We examined 20 hepatocellular carcinomas (HCCs) from nonhuman primates for mutations of the p53 gene using polymerase chain reaction-single strand conformational polymorphism analysis. Mutations in the p53 gene were detected in 4 of 20 HCCs (20%) with 3 showing G-to-T transversions and one a G-to-A transition. Three of these mutations were observed in codons 175 and 248 that are known mutational hot spots in human cancers. These data indicate that part of the IQ-induced HCCs in nonhuman primates may involve inactivation of the p53 gene and suggest that IQ and possibly other heterocyclic amines may participate in human carcinogenesis by a similar mechanism.

Expression of endothelial leukocyte adhesion molecule-1 (ELAM-1) in chronic inflammatory demyelinating polyneuropathy

We used immunocytochemical methods to identify activated endothelial cells and the ligands of infiltrating cells in sural nerve biopsies from 30 patients with peripheral neuropathy. In chronic inflammatory demyelinating polyneuropathy (CIDP), the endothelial leukocyte adhesion molecule (ELAM-1; E-selectin) was detected in the epineurial vessels of five of the 10 patients. CD68-positive monocytes were usually at ELAM-1-positive endothelial sites and in perivascular tissues, while sialyl-Lewis x-positive cells were detected mostly in the lumina adherent to ELAM-1-positive endothelial cells. The location of activated T cells was not correlated with activated endothelial cells, and endoneurial vessels were not immunostained for ELAM-1. In view of the transient expression of ELAM-1 in response to cytokine stimulation, these findings suggest that endothelial cells play a role in the extravasation of infiltrating cells in CIDP.

Absence of p53 mutations in rat colon tumors induced by 2-amino-6-methyldipyrido[1,2-a:3',2'-d]imidazole, 2-amino-3-methylimidazo[4,5-f]quinoline, or 2-amino-1-methyl-6-phenylimidazo]4,5-b]pyridine

Colon tumors were induced in F344 rats by three heterocyclic amines (HCAs), 2-amino-6-methyl-dipyrido[1,2-a:3',2'-d]imidazole (Glu-P-1), 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) or 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), and examined for p53 mutations. Seven carcinomas induced by Glu-P-1, and nine carcinomas and two adenomas induced by IQ were examined by cDNA-polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) analysis from codon 103 to 391 of p53, which encompasses the conserved regions II to IV. Nine carcinomas induced by PhIP were examined by genomic PCR-SSCP analysis of exons 5 to 7 (from codon 124 to 304), which encompasses the 3' half of the conserved region II and all the conserved regions III-V. No band shifts were found in any of these tumors under at least two conditions of SSCP analysis. Our previous study had shown a Ki-ras mutation in only one Glu-P-1-induced adenocarcinoma among the same 27 colon tumors, and no other mutation of ras family genes had been found. HCA-induced rat colon tumors appear to represent a group of human colon tumors in which neither Ki-ras nor p53 is involved.

Infrequent mutation of Ha-ras and p53 in rat mammary carcinomas induced by 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine

2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) is the most abundant of the heterocyclic amines, a group of potent carcinogens contained in cooked meat and fish. Female F344 rats fed a diet containing 100 or 400 ppm PhIP developed mammary carcinomas within 104 or 52 wk, respectively, at the rate of 47% for each group; these carcinomas were examined for mutations in three members of the ras gene family and in the p53 gene. Single-strand conformation polymorphism (SSCP) analysis and direct sequencing demonstrated a G-->A transition at the second position of Ha-ras codon 12, with the resultant substitution of glutamic acid for glycine, in two of 10 carcinomas induced by 100 ppm PhIP and in one of seven induced by the 400 ppm dose. No mutations in Ki-ras or N-ras were detected. cDNA polymerase chain reaction-SSCP analysis and direct sequencing demonstrated a G-->T transversion at the third position of p53 codon 130, with the resultant substitution of asparagine for lysine, in one of the 10 carcinomas induced by 100 ppm of PhIP for which freshly frozen samples were available. PhIP-induced rat mammary carcinogenesis can be regarded as a unique system in that rat mammary carcinomas are negative for ras and p53 mutations.

A regulatory subunit of smooth muscle myosin bound phosphatase

The relationship between two putative myosin-binding subunits of smooth muscle myosin phosphatase was investigated. A monoclonal antibody (MoAb) to the 58 kD component of smooth muscle myosin-bound phosphatase (MBP) cross-reacted with a 130 kD protein in extracts of fresh chicken gizzards. The MoAb in combination with protein A immunoprecipitated from gizzard extracts a complex of the 130 kD protein plus the 38 kD catalytic subunit of the type 1 delta protein phosphatase. It is proposed that the 130 kD component is a native subunit of MBP and that the 58 kD protein is its proteolytic degradation product. The distribution of the 130 kD component in chicken tissues was screened using the MoAb. An immunoreactive band of appropriate mass was detected in all tissues except liver and skeletal muscle. Higher concentrations of the 130 kD component were evident in the smooth muscle samples.

PP1 gamma 2, a testis-specific protein-serine/threonine-phosphatase type 1 catalytic subunit, is associated with a protein having high sequence homology with the 78-kDa glucose-regulated protein, a member of the 70-kDa heat shock protein family

Protein phosphatase 1 gamma 2 (PP1 gamma 2) is a testis-specific isotype of the protein-serine/threonine-phosphatase type 1 catalytic subunit. Three native forms of PP1 gamma 2 were detected in a crude fraction of rat testis by electrophoresis in a nondenaturing polyacrylamide gel. We purified a major native form of PP1 gamma 2 to homogeneity by successive column chromatography on Mono Q-Sepharose, EAH-agarose, protamine-agarose, and G3000SW and by electrophoresis in a nondenaturing polyacrylamide gel. The G3000SW-purified PP1 gamma 2 native form had an apparent molecular mass of 170 kDa. The purified holoenzyme from nondenaturing polyacrylamide gel was composed of the catalytic subunit and two noncatalytic subunits, of 78 kDa and 55 kDa. Partial amino acid sequence analysis of the 78-kDa protein suggested that it is the 78-kDa glucose-regulated protein, a member of the 70-kDa heat shock protein family. The 78-kDa protein may possibly function as a chaperone or by confining substrate specificity of PP1 gamma 2.

Personal identification from human remains using morphological characteristics and DNA analysis

This report describes personal identification of four parts of a dismembered human body on the basis of physical characteristics and DNA analysis. A 69-year-old woman suffering from depression went missing from her home in May 1992. Five days after her disappearance, a female torso was found in a river. In a two-week period thereafter, a left forearm, a female head and neck and a right forearm were found consecutively in the same river. Although the end of the cervical vertebra was anatomically identical to that of the torso, the two forearms did not match. However, DNA analyses with a single-locus DNA probe pYNH24, DO alpha typing and a multi-locus DNA probe "Myo", indicated that these four parts came from the same person. The missing woman had undergone lobectomy of the right pulmonary upper lobe, and had suffered from slight scoliosis of the thoracic vertebrae and a second lumbar vertebral compression fracture. These characteristics were also observed in the torso. In order to obtain more conclusive evidence, DNA fingerprinting using DNA extracted from the torso, the missing woman's brother and her daughter was performed using the DNA probes described above. The data obtained indicated that the remains were those of the missing woman.

Role of fat and calcium in cancer causation by food mutagens, heterocyclic amines

We investigated the modulation by dietary corn oil and calcium levels of carcinogenesis by heterocyclic amines (HCA), a new class of important carcinogens in the human nutritional environment, since they are formed during cooking. Two approaches involved (i) a chronic bioassay in male and female F344 rats, and (ii) an abbreviated test, the induction of foci of aberrant crypts in the colon in male F344 rats. One typical HCA, 2-amino-3-methylimidazo [4,5-f]quinoline (IQ) was fed at 75 ppm for 12 months to male and female rats that were held three and six months longer, respectively, on control diets. Neoplasms were induced in the Zymbal gland, skin (predominantly in male rats), liver, mammary and preputial glands, colon, and lung. Diets with 23.5% corn oil increased carcinomas in the liver in males, and in the mammary gland in females, compared with a 5% corn oil diet. Males on the low-fat diet had more cancers in the lip, and females had more ear duct cancers, than did rats on the high-fat diet. Another HCA, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), fed at 400 ppm for nine weeks induced foci of aberrant crypts in the lower intestinal tract of male F344 rats. There were significantly more aberrant crypts on the high-fat than on the low-fat diet. On the low-fat diet, there were fewer aberrant crypts on the higher calcium level. Thus, dietary fat modulates the carcinogenic action of HCA food carcinogens in specific organs of male and female F344 rats. Also, both fat and calcium affected the induction of aberrant crypts in the distal intestinal tract of male F344 rats.

Cloning and activation of the Syrian hamster neu proto-oncogene

Point mutations of the Syrian hamster neu proto-oncogene have been observed in the transmembrane domain of N-nitroso-N-ethylurea (ENU)-induced neurofibromas. Genomic DNA derived from tumor tissue showed transforming activity in an NIH 3T3 assay and a cDNA clone of the hamster neu gene, containing the entire protein-coding region, was isolated from a transformant cDNA library. The encoded product is 92 and 88% homologous to the rat neu and the human c-erbB-2, respectively. The product of the mutated hamster neu gene showed increased autophosphorylation of Tyr residues.

Expression of the ret proto-oncogene product in human normal and neoplastic tissues of neural crest origin

The histological localization of the ret proto-oncogene (proto-ret) product was examined in neural crest-derived and neuronal tissues together with their neoplastic counterparts by immunohistochemistry using a polyclonal antibody. Schwann cells, neurons, sympathetic ganglia, and cells of the adrenal medulla were positive for the proto-ret product, whereas melanocytes were negative. Positive results were obtained from neural crest-derived tumours such as schwannoma (69 per cent, 11/16), neurofibroma (59 per cent, 13/22), neuroblastoma (80 per cent, 4/5), phaeochromocytoma (100 per cent, 3/3) and medullary thyroid carcinoma (100 per cent, 3/3). The antibody reacted with all of the 22 astrocytomas examined. With negative proto-ret expression in melanocytic tumours, proto-ret expression was considered to correlate with the differentiation of some lineages of neural crest-derived cells.

Localization of mRNA for protein phosphatase 2A in the brain of adult rats

The gene expression for alpha and beta isoforms of type 2A protein phosphatase (PP2A-alpha and -beta) in the adult rat brain was examined by in situ hybridization analysis. No marked difference in the gene expression was discerned between the two isoforms in large portions of brain, except for the thalami in which the expression level for the alpha isoform was similar to that in the cerebral neocortex whereas that for the beta was lower than that in the neocortex. The gene expression was observed intensely in the piriform cortex, the cerebellar Purkinje and granule cell layers, and the hippocampal pyramidal and dentate granule cell layers, and the locus ceruleus, whereas the moderate levels of its expression were observed in the olfactory mitral cells and the pontine nuclei. The cerebral neocortex expressed the mRNA moderately to weakly without any laminar patterns, whereas the expression level in the caudate-putamen was very low. This expression pattern is basically similar to that of PP2C reported previously, except for the plexus choroideus and ependyma having no significant expression for PP2A.

Microtubules stability in human peripheral nerves

We examined the cold stability of microtubules (MT) in biopsied sural nerves. In control nerves, cold treatment reduced the density of MT in unmyelinated axons. The proportion of cold-insoluble MT was approximately 30% by morphological study. By contrast, the extraction study using essentially the same nerves showed that the ratio of cold-insoluble tubulin was 60-75%. These findings suggest the existence of a subpopulation of cold-stable tubulin which may not make up MT. However, in 2 patients with acute dysautonomia the proportion of cold-stable MT or tubulin was decreased compared to that in controls in both the morphological and extraction study. This suggests the altered local process involving MT in primary axonal degeneration.

neu proto-oncogene mutation is specific for the neurofibromas in a N-nitroso-N-ethylurea-induced hamster neurofibromatosis model but not for hamster melanomas and human Schwann cell tumors

Point mutations of the transmembrane domain coding region of the neu proto-oncogene in N-nitroso-N-ethylurea-induced hamster neurofibromas were found at high frequency (93%; 14 of 15). They involved codons 659 as well as 658, the latter not having been reported previously in rat tumors. The mutational change was seen even in the early stage neurofibroma. On the other hand, no mutations were detected in melanomas or Wilms' tumors induced in the same N-nitroso-N-ethylurea-treated animals, even when the melanomas demonstrated extensive schwannian differentiation. Moreover, any human Schwann cell tumors including neurofibroma, schwannoma, and malignant schwannoma did not show the mutation of c-erbB-2 gene (0 of 34), which is homologous to the hamster neu. Since high expression of neu mRNA is evident in the hamster Schwann cell at the late gestational and neonatal stages, transplacental administration of N-nitroso-N-ethylurea is considered to interact directly to carcinogenesis of the hamster Schwann cell through neu gene mutation.